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388 Cards in this Set
- Front
- Back
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Paroxysmal cough is characteristic of which microbe?
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Bordetella
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Paroxysmal cough for _ days (CDC) and _ days (WHO) are used for making the dx of pertussis
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14 and 21
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small, nonmotile, aerobic gram negative rod, nutritionally fastidious
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Bordetella pertussis
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Who or what is an important reservoir for Bordetella pertussis?
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Adults and Adolescents
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Transmission of Bordetella is by?
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respiratory route
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How does pertussis toxin(s) act?
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1.)Irreversibly inactivates Gi-protein via ADP ribosylation, resulting in prolonged stimulation of adenyl cyclase and a rise in cAMP which increases protein kinase activity.
2) tracheal cytotoxin kills ciliated cells 3)hemolysin kills mucosal epithelial cells |
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Pertussis causes what type of exudate?
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mucopurulosanguineous (yellow-greenish, pussy, with RBCs)
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Pertussis vaccine:
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is in combination with diptheria and tatanus toxoids (DTap) and shoul dbe given to all ages 6 weeks to 6 years.
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Are blood cultures positive or negative in acute exacerbation of chronic bronchitis?
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negative usually
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Haemophilus influenzae clinical features:
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otitis media, sinusitis, epiglottitis (eliminated since vaccine), meningitis, bacteremia (endotoxic shock), pneumonia, cellulitis
*normally occurs in children <2 years who are not vaccinated |
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Haemophilus is characterized by:
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gram negative coccobacillary rods
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species of Hi vary by requirements for X and V which are?
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heme and NAD respectively
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Species designated para-
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require factor V
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H. influenzae specifically requires:
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both X and V
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2 different groups of H. influenzae determined by the presence or absence of
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polysaccharide capsule
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group 1 subtype Hi
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capsulated, 6 subtypes (a-f)
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group 2 subtype Hi
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unencapsulated, called NTHi (nontypable Hi.)
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previously was major invasive pathogen of H. influenzae
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Hib
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NTHi are nontypable because:
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they cannot be serotyped with antisera to the capsule
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Are Haemophilus part of the normal flora?
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yes, in the upper respiratory tract
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group 2 causes disease in _ while group 1 causes disease in _
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adults and children
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transmission of Hi
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respiratory droplets from a carrier
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Who is at greatest risk of AECB?
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ppl with COPD and heavy smokers
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What 3 bacterial species are found in pts with COPD
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S. pneumoniae, H. influenzae (NTHi) and Moraxella catarrhalis
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IgA protease is associated with what bacteria?
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NTHi
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Tx of Hib or NTHi:
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macrolides (clarithromycin and azithromycin) and cephalosporins. If due to Hib- parenteral admin of 3-generation cephalosporin (cefotaxime and ceftriaxone)
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Is there a vacine for NTHi?
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No
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K. pneumoniae is seen in?
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Alcoholics
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What is a likely pathogen for postinfluenza?
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S. aureus
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gram positive, lancet shaped diplococci
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S. pneumoniae (aka pneumococcal pneumonia)
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catalase negative and Optochin sensitive
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S. pneumonia alpha-hemolytic colonies
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Does S. pneumoniae have a capsule?
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Yes
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S. pneumonia is transmitted via
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respiratory
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mulitfactorial pathogenesis:
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1) upper airway colonization
2) aspiration 3) failure of normal host defenses 4) bacterial proliferation 5) inflammatory response |
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What does bacterial generated IgA protease do?
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degrades IgA antibody produced by the host and favors mucosal adherence and colonization
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What do pneumococcal adhesins bind to?
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GlcNac B1,3-Gal disaccharide groups on epithelial cell glycoproteins and platelet activating factor receptors on epithelial cells
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Important for opsonization and phagocytosis of bacteria
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IgG and C3 (complement)
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pneumolysin
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is released during bacterial lysis; forms pores and is cytotoxic to every cell in the lung.
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1st stage of lobar pneumonia:
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Congestion: serous exudation, vascular engorgement, bacterial proliferation
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2nd stage of lobar pneumonia
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Red Hepatization: reflects liver-like appearance of the lung, PMNs, vascular congestion, extravasation of RBCs causes reddish color
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3rd stage of pneumonia
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Grey Hepatization: accumulation of fibrin, WBCs and RBCs, inflammatory exudates
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4th stage of pneumonia
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Resolution: resorption of exudate
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Tx for S. pneumoniae
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penicillin! if resistant: 3rd generation cephalosporin (ceftriaxone or cefotaxime) plus a macrolide or floroquinolone (levoflaxacin). If highly resistant - vancomycin.
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empyema
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bacteria spreading to pleural space, resulting in an abscess which is detected by the presence of pleural effusion on CXR
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cavity lesions imply:
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polymicrobial abscess or TB
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bacteria of cause in the homeless population
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K. pneumoniae
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what should rule out TB?
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homelessness
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k. pneumoniae properties
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short, plump gram negative, urease-positive, lactose-fermenting (anaerobic), nonmotile, No H antigens but has a polysaccharide capsule ("K" antigen; there are 77 "K" antigens) which is antiphagocytic, LPS with lipid A portion being endotoxic and "O" antigen (10 "O's")
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lives in water, soil, and occasionally food.. sometimes found in intestinal flora of humans
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K. pneumoniae
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who is at risk of getting K. pneumoniae?
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alcoholics, people with increased risk of seizures, and those who are hospitalized (since it is a nosocomial pathogen)
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adhesive properties are found on what in K. pneumoniae
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fimbriae (nonflagellar, filamentous projections)
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How does the capsular polysaccharide of Kp inhibit the activation of complement?
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It causes antigenic mimicry by selective deposition of C3b onto LPS, which results in inhibition of the formation of the membrane attack complex (C5B-C9)
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What usually follow Kp infection?
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bronchopneumonia
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How is Kp becoming more resistant to antibiotics?
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acquisition of transferable plasmids possessing the genes for B-lactamases
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Are vaccines available for Kp?
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No
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Bacteremia, hypotension due to LPS (endotoxin-mediated sepsis), DIC, UTIs, hospital-acquired wound infections and intra-abdominal infections are clinical features of?
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Klebsiella pneumoniae
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a CXR of what is consistent with atypical pneumonia?
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patchy infiltrates
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Which bacteria have no pulmonary clinical findings?
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Mycoplasma
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Causes GI symptoms and headache?
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Legionella
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What bacteria has a hx of exposure to birds, domestic animals or environment?
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Coxiella, Legionella, and C. psittaci
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known as "walking pneumonia"
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Mycoplasma pnuemonia
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isolation of Mycoplasma can take up to:
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6 weeks
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smallest, free-living, self-replicating organism?
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mycoplasma
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has no cell wall (and therefore does not gram stain)
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mycoplasma
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4 most important characteristics of atypical pneumonia?
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nonproductive cough, variable CXR (patchy infiltrates), no bacteria on smear, no response to B-lactam antibiotics
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Are gram stains and cultures useful for dx of Mycoplasma or any other atypical pathogen?
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No
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Is Mp seasonal?
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No, can get it throughout the year
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How do you transmit Mp?
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person-to-person; respiratory
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General risk age group for Mp?
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5-20 years (school age to young adults)
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Especially common in crowded military and institutional settings
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Mp
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Bacterial adherence leads to inhibition of ciliary movement (ciliostasis)- and prolonged cough
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Mycoplasma
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what is responsible for hemolytic anemia with mycoplasma?
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production of H2O2 which destroys erythrocytes (its cytotoxic)
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Mycoplasma stimulates what host immune responses?
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T and B lymphocytes, inducing the formation of IgM antibodies
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Drug of choice for mycoplasma?
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erythromycin or doxycycline
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Is there a vaccine for mycoplasma?
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No
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In untx pts with Mp, what are some clinical findings?
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tracheobronchitis, pericardtis, myocarditis, and Steven-Johnson syndrome (young males develop rash involving the mucus membranes)
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motile, flagellated, gram negative but stain faintly, aerobic, pleomorphic rods
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Legionellae
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definitive method for dx of Legionellae
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culture of BAL (bronchoalveolar lavage) with special medium
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Are Legionellae nutritionally fastidious
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Yes, grows slowly in 3-7 days on buffered charcoal yeast extract
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How many legionellae species?
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20 - based on fermentative rxns
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Most pathogenic Legionellae to humans?
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L. pneumophila, followed by L. micdadei
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Which serotype of L. pneumophila has been most common in causes legionellosis?
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LPS serogroup 1
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Legionelliosis occurs most often during what season?
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summer
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Where does the organism that causes Legionellosis survive?
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tap water and cooling towers in association with slimy growth of ameba and other protozoans.
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3 primary sources of infection for legionellosis
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1. environment (showers, humidifiers, whirlpools)
2. aerosolizing equipment (nebulizers) 3. aspiration (from contaminated water) |
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Legionellosis is transmitted person-to person... true or false
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false
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Risk factors for Legionellosis
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COPD, age, smoker, alcoholic, immunosuppressed, taking corticosteroids, malignancy
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strictly intracellular - by binding to C3 and favoring opsonization
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legionella
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Are legionella flagellated?
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Yes
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What gene allows legionella to survive in the phagosome?
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dot - delayed organelle trafficking, which prevents phagosome-lysosome fusion
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Primary host defense against legionella
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Cell-mediated immunity - activation of macrophages which produce cytokines
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What is responsible for lung tissue damage from legionella?
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cytokines and other reactive mediators of PMN's and T-cells -
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What would you see on CXR with legionella?
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patchy,diffuse infiltrates
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What meds do you tx legionella with? What med is NOT effective?
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a macrolide, quinolone, or doxycycline. B-lactams are not effective bc they cannot penetrate host cells
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Legionnaire's Disease
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the more severe form of legionellosis, presents with severe fibrinopurulet pneumonia with alveolitis and bronchiolitis
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Pontiac Fever
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acute onset, flu-like, non-pneumonic illness occuring after infection with L. pnrumophila, BUT NO SIGN OF PULMONARY INFILTRATES ON CXR
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ss-RNA genome with 8-segmented pieces that code for 10 proteins
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Influenza
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Is RNA positive or negative in Influenza?
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Negative
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helical or icosahedral capsid?
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helical
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enveloped or nonenveloped?
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enveloped with hemagglutin (attachment protein) and neuraminidase (severs virus as it buds from host)
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Current Human types of A type influenza?
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H1N1 and H3N2
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Occurs due to a genetic reassortment that results in a complete change in configuration of an epitope
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antigenic shift
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occurs when a point mutation results in a change in the configuration of a specific epitope
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antigenic drift
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leads to generation of new strains
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antigenic shift
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causes epidemic disease
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A and B
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causes sporadic disease
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C
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How does influenza spread?
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Person-to-person via coughing and sneezing
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incubation period of influenza?
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28-72 hours, avg is 48
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Active immunization of influenza produces which host immune response?
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humoral
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How many H spikes of influenza bind to sialic acid receptors in the host?
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500
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What degrades mucus?
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neuraminidase
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What initiates infection?
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fusion of the viral envelope to the cell's plasma membrane
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Is viremia common with influenza?
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No
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Where does influenza replicate?
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in mucus secreting ciliated cells
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What causes the symptoms of influenza?
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Cytokines
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Tx of influenza
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rimantidine or amantadine (if given within 48 hours) and given for 3-5 days
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Influenza predisposes the host to
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secondary bacterial infection
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neuraminidase inhibiting drugs (zanamivir or oseltamivir) are useful for which Type of influenza?
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B
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Reye syndrome is a rare, often fata childhood hepatoencephalopathy associated with analgesic use and is associated with
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influenza B
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Common in children less than 6 months old during certain times of the year
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RSV
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enveloped or nonenveloped RSV?
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enveloped
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negative or positive sense RNA?
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negative ss-RNA (nonsegmented)
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helical or ocosahedral capsid?
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helical
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Does RSV have hemeagluttin protein?
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No
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Why is RSV named so?
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bc its replication in vitro leads to fusion of neighboring cells and a characteristic alarge mutlinucleated syncytium
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How many antigenic types of RSV?
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2: A and B
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Is RSV stable in the environment?
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No and is easily killed with soap and water
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What months of the year is RSV most likely to occur?
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November through April w/ peak activity in January/February
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most frequently affected age group?
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2-6 months
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Transmission?
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through infectious material contact of eyes, nose or mouth
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This disease may involve an immunopathogenic mechanism with IgE and histamine
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RSV
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Integral to immune response in RSV
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F (fusion) protein and G (decond glycoprotein)
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bronchiolitis
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inflammation of the terminale bronchioles, necrosis, and sloughing of the epithelial lining of the bronchioles. commonly seen in RSV
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Tx of RSV
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only symptoms with acetaminophen
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Is vaccine available for RSV?
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on experimental basis
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Required for prevention of RSV
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Contact isolation and hand washing
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Any pt with exposure hx (emigration from an endemic country) with apical infiltrates and who does not respond to antibacterial agents should have studies done to rule out
|
TB
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Fever, cough, night sweats and blood in sputum should suggest
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TB
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Pulmonary infiltrates are commonly found in the __lobes of TB
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upper
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Aspiration pneumonia is usually seen in pts with
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poor dentition and altered mental status, i.e. dementia or alcholism
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PPD skin test results show with in
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48 hours
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Positive TB test shows
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thickening of skin and redness at the injection site
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Mycobacterium is what kind of bacteria? (Gram +/_/acid-fast)
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acid fast
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the cell wall of mycobacteria contain
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mycolic acid
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Mycobacteria grows on
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Lowenstein-Jensen agar
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What is the characteristic pattern of virulent mycobacteria growth?
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in parallel and serpentine patterns due to presence of cord factor
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What is cord factor
|
a virulence factor; 6,6' trehalose-dimycolate
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surface macromolecules of TB
|
PPD (purified protein derivative); a glycolipid - is antigenic!!!
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What contribute to enhanced virulence?
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LAM (lipoarabinomannan)
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Mycobacteria are resistant to dehydration, but not heat....True or False?
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True
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Transmission of TB
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Respiratory
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Mycobacteria are: facultative anaerobes, obligate anaerobes, or obligate aerobes?
|
obligate aerobes!
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LAM is recognized by
|
macrophage mannose receptor
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What triggers phagocytosis in Mycobacteria?
|
they express cell-wall C3 convertase activity, forming C3b on its surface which is recognized by the macrophage complement receptor CR4
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How does Mycobacteria evade phagocytotic killing?
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Inhibits fusion of the phagosome and lysosome.- mediates by a tryptophan-aspartate coat protein
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Hallmark of TB
|
granulomas
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what stimulates formation of granulomas?
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Cord factor - causes irreversible structural and functional damage to mitochondria
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What releases IFNy and what does it do?
|
CD4+ T cells release it, IFNy stimulates macrophage activation
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What are granulomas?
|
collections of macrophages that have taken on properties of epithelial cells (and are called epithelioid cells)
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What coalesces with in the granuloma to cause a multinucleated giant cell?
|
epitheloioid cells
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A fully developed granuloma encapsulated with fibrin; consists of a central area of large multinucleated giant cells containing tubercle bacilli, a midzone of epithelial cells, and a peripheral zone of fibroblasts, lymphocytes, and monocytes.
|
a tubercle
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Ghon focus or perihilar lymph node involvement reflects
|
primary infection
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cytokines for controlling TB
|
IFNy, IL-12 and TNF
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key molecule needed to kill TB
|
nitric oxide (released by macrophages)
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>5 mm skin rxn from PPD proves positive
|
FALSE, only in HIV or immunocompromised pts. >15mm is key
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Majority of TB infections are latent or lytic?
|
latent
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When do granulomas become caseous?
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during reactivation of infection
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Causes TB in cows and humans (rarely)
|
M. bovis
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causes pulmonary TB-like disease
|
M. kansasii
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found in water
|
M. marinum
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causes cervical lymphadenitis in children
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M. scrofulaceum
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found in hot water tanks
|
M. xenopi
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Causes cervical lymphdenitis in children, DIC in AIDS pts, and pulomary disease in elderly
|
MAC (mycobacterium avium-intracellulare)
|
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causes skin ulcers
|
M. ulcerans
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rapid growers
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M. fortuitum- chelonae
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uncultivable mycobacteria, armadillos are reservoirs in Lo and Tx, causes tuberculoid and lepromateous leprosy
|
Leprosy (M. leprae)
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Tx of TB
|
4 drug regiment: isonaizid, rifampin, pyrazinamind, and ethambutol
|
|
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Multidrug resistant TB is resistant to
|
INH and RIF (required 5 drugs instead)
|
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Who is at greatest risk of hepatic toxicity and in response to what drug?
|
>50 years, INH (isonaizid)
|
|
|
Characteristic of miliary TB
|
PPD +; CXR has appearance of millet seeds scattered in all lung fields
|
|
|
Pott Disease
|
untx infection disseminates to vertebral bodies, causing osteomyelitis.
|
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Cultures for TB show up in
|
3 weeks
|
|
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Vaccine for TB? in US?
|
Yes, BCG but not readily available in US
|
|
|
leukopenia and thrombocytopenia characteristic of
|
fungi
|
|
|
halo sign on CT characteristic of
|
Aspergillus fumigtus
|
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cytology staining for fungal elements
|
KOH/calcofluor, Giemsa, and silver stain
|
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Nocardia should always be considered in what pts?
|
immunocompromised
|
|
|
Most common mold that causes human infection
|
Aspergillus species
|
|
|
Characteristics of Aspergillus
|
thin hyphae that branch a V-shape (45 degree) angle
|
|
|
Aspergillus dimorphic?
|
Nope
|
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|
Most common Aspergillus species
|
A. fumigatus
|
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|
Aspergillus epidemiology
|
found in nature and associated with decaying vegetation
|
|
|
major mode of transmission
|
inhalation of spores (conidia)- NOT TRANSMITTED FROM PERSON TO PERSON
|
|
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What drugs increase susceptibility to this fungus?
|
cytotoic drugs that cause neutropenia (radiation, chemotherapy)
|
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involved in phagocytosis of Af
|
neutrophils and macrophages
|
|
|
Af also is characterized by this symptom found in TB
|
granulomas
|
|
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Cause of hemoptysis in Af
|
fungal hydrolases (serine protease of phospholipase) and toxic molecules (hemolysin) cause endothelial damage
|
|
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Tx of Af
|
Amphotericin B - but if invasive pulmonary aspergillosus=voriconazole
|
|
|
Second line agent for invasive pulmonary Af
|
caspofungin
|
|
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Vaccine for Aspergillus?
|
Nope
|
|
|
Recovery from Af requires
|
TX OF NEUTROPENIA- by reducing levels of cytotoxic chemotherapy and admin of GCSF (to improve neutrophil counts)
|
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enlarged hilar and mediastinal nodes with hilar infiltrates suggests
|
fungal infection
|
|
|
associated with pigeon droppings
|
Histoplasmosis
|
|
|
Histoplasma capsulatum properties
|
dimorphic fungus, grows as a mold in the environment but converts to yeast in the human
|
|
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Where is H. capsulatum found in the environment?
|
Soil; around ohio regions
|
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Giemsa or Wright stains are taken from what tissues?
|
bone marrow, sputum, blood or lung biopsy
|
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Growth of mold take up to
|
4 weeks
|
|
|
thick walled, finger-like projections that grow from the fungus
|
macroconidia (aerial mycelial growth)
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Mold produces what 2 glycoproteins?
|
H and M
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Where is Hc endemic?
|
in Central Eastern US, around Ohio and Mississippi river valleys.
|
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Hc grows in...
|
soil contaminated with bat or bird droppings
|
|
|
Is Hc transmitted via respiratory?
|
It is NOT person-to-person, BUT conidia can become airborne and infection results form inhalation from the source
|
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When do microconidia transform to budding yeast?
|
When they reach the alvelo and bind to CD2/CD18 family of integrins and are engulfed by both macrophages and neutrophils
|
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What is the most critical determinant of establishing infection in Hc?
|
transformation of mold-->yeast
|
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The yeasts grow intracellulary within the macrophages
|
True story
|
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What finding occurs with Hc that also occurs with TB?
|
granuloma formation which produces fibrinous calcified granulomas with areas of caseous necrosis in the lungs
|
|
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Ctyokine response to Hc produce what symtoms?
|
fatigue and weight loss
|
|
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How does Hc travel to distant sites such as reticuloendothelial system (liver, spleen, and bone marrow)?
|
by lymph via lymph nodes
|
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Tx of Hc?
|
most are self-limited and resolve on own. Oral itraconazole in immunocompromised pts
|
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In pts with unresolving infecting due to lung disease, their disease may resemble...
|
TB
|
|
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For severe disseminated Histoplasmosis, tx with
|
amphotericin B IV
|
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Vaccine for Hc?
|
No
|
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How do you reduce risk?
|
Use protective gear
|
|
|
Verrucous lesion that is tender and erythematous is characteristic of:
|
Blastomyces dermatitidis
|
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What would you see on CXR with Blastomyces dermatitidis?
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multiple nodular lesions, some which cavitate in the upper lobe
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Endemic mycoses (3)
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histoplasmosis, blastomycosis, and coccidioidomycosis
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All endemic mycoses may cause a pulmonary infection that is indistinguishable from... based on clinical presentation
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TB
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Upper-lobe disease is characteristic of
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TB
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What should you consider if culture for a fungus is negative?
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Sarcoidosis or malignancy
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What temperature must the yeast grow at on culture? hence, why they can only grow in humans...
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37 degrees Celsius
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B. dermatitidis is what kind of fungus?
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dimorphic
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Bd on culture is characteristic of:
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white fluffy mold that grows slowly at room temp (25C) on Sabouraud agar
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How many microcinidium are formed on culture?
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a single terminal microconidium which is round or oval
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If grown on blood agar at 37C, the fungus grows as
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brown, wrinkled colonies
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On biopsy with Bd
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large yeast forms with borad-bases budding
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Bd is endemic where?
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southeastern US (east of mississippi)
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Bd is also known as
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North American Blastomycosis
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South American blastomycosis is caused by which agent?
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Paracoccidioides braziliensis
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What kind of environment is Bd found?
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Wooded areas along waterways of decaying vegetation in warm, moist soil
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Infection of Bd results from
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inhalation of microconidia
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Shift from infection mold form to pathogenic yeast form occurs at what temp?
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37C
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Incubation time for Bd
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4-6 weeks
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Tissue response to Bd
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suppurative and granulomatous inflammation in lung parenchyma
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Spread to other organs by Bd occurs
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lymphohematogenously
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Skin involvement shows:
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pseudoepitheliomatous hyperplasia with focal micro-abscesses in papillary dermis. has pustular features
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Tx bd with
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Itraconazole for 6 months!! (Amphotericin B in really ill pts)
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Is Bd transmissible from person to person?
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Nope, and no vaccine either
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Erythema nodosum lesions are characteristic of
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Coccidioides immitis (coccidioidomycosis)
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CXR of Ci is characteristic of
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infiltrates in both lung fields with large cavities in upper lobes
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C. immitis is a
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dimorphic fungus that grows in soil as a mold with branching septate hyphae
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When the soil is disturbed with Ci fungus, what forms?
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arthroconidia (fragmented hyphae) that become airborne
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when arthroconidia reach alveoli they transform to
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thick-walled, nonbudding spherules (pathogenic form) which form septa and produce many uninucleate endospores
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Culture os Ci requires how long for incubation?
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very long, which is why it is usually not done when suspected bc it can be a danger to the lab... otherwise, looks like a fluffy white mold
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Test of choice if coccidioidomycosis is suspected?
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serology
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Ci is endemic:
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In southerwestern us, CALIFORNIA "valley fever" and western half of texas; maybe Mexico
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Reservoir for Ci
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soil in and around rodent burrows
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infection from Ci results from
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inhalation of athroconidia
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Where does the athroconidia settle in the lungs?
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terminole bronchiole b/c of its small size
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Recovery from Ci involves:
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Cell-mediated immunity
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Ci has a characteristic simular to TB which is:
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chronic granulomatous inflammation - caseation without calcification
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What is really cool about Ci?
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you have lifelong immunity after infection
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Tx of Ci
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fluconazole or itraconazole for 3-6 months (again, ampotericin B is really sick)
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Who is at higher risk of dissemination to the skin?
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anyone that is immunocompromised: pregnany women, HIV pts, caner pts, those receiving corticosteroids or undergoing organ transplants
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Sites of disemination:
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skin, meninges, bones, joints
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Which med is preferred for tx of fungus b/c it can enter CSF for meningitis?
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fluconazole- must tx is for life to prevent reactivation!
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CXR of Nocardia asteroides (nocariosis) shows
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extensive nodular infiltrates in R. middle and upper lobes and cavitary disease
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Chronic symptoms are associated with
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fungus and nocardia
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mycoplasma does or does not show up as a unilateral disease on CXR
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Does NOT!! usually B/L
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What is gram + and partially acid-fast positive?
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Nocardia
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Characteristics of Nocardia
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filamentous (beaded) bacteria, aerobic
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Most medically important Nocardia
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N. asteroides and N. brasiliensis
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Culture of nocardia takes:
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up to 4 weeks (grow slowly!)
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Mode of acquisition?
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inhalation of contaminated dust from soil environment
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Who is especially at high risk for disease by Nocardia?
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immunocompromised pts taking cytotoxic or immunosuppresive drugs as well as HIV pts
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Nocardiosis occurs as a skin lesion in tropical countries called
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Madura foot
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Nocardia on gram stain looks similar to
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fungi: have long branching filaments that resemble hyphae
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Are nocardia intracellular bacteria?
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Yes- facultative intracellular, they remain inside inactivated macrophages by preventing phagosome-lysosome fusion
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Major mechanism of host resistance to Nocardia
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activated macrophages and T-lymphcytes
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what contributes to symptoms of pulmonary illness by Nocardia?
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cytokines!!!!
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Lung pathology in unconrolled infection includes
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inflammatory endobronchial masses or diffuse pneumonitis and abscess
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Is CNS involement rare with Nocardia?
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No, it is common and takes the form of one or more abscesses
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Symptoms of CNS involvement?
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headache, lethargy, confusion, seizures, and sudden onset neurologic deficit
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Tx of nocardia
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improve pt's immune status and 6-12 months of sulfonadmides (first-line of defense)
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Which Sulfonamides are preferred with nocardia?
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Trimethoprim or sulfamethoxazole
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Any vaccine for nocardia?
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Nope
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Productive cough with foul-smelling sputum is a sign of
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Actinomyces israelii (thoracic actinomycosis)
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drainage of Actinomycosis in the chest wall contains what color granules? This is practically dx of this bacteria!!!
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Yellow
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CXR of Actinomycosis
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lung infiltrates in upper lobes
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Examine what in dx for Actinocyces
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sulfur granules in pus from sinus tract
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foul-smelling sputum should reveal diff dx of
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anaerobic bacteria/abscess
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What is usually seen in immunocompromised pts?
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Nocardia
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Gram + filamentous bacteria (that may resemble fungi); anaerobic
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Actinomyces
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Are actinomyces acid fast?
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NO
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Are they spore forming?
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NO
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In tissues, actinomyces forms
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sulfur granules
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How long does it take to grow actinomyces on culture?
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Up to 4 weeks b/c they are slow-growing
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Periodontal disease is common with Ai
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True
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what type of colonies from sulfur granules from a draining sinus infection are formed with Ai...this is diagnostic!!!
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"Molar tooth"
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Where is Ai found
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oral cavity (saliva, dental suraces, and tonsillar crypts) and GI tract as normal flora
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Transmission is
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Endogenous
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Who is as risk of getting cervicofacial abscesses?
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ppl with poor oral hygiene
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Who is at risk of getting pelvic/abdominal actinomycosis?
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Women with IUDs
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How do you get Ai
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aspiration of oropharyngeal species
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The Ai is unable to cause disease on their own.. what do they require?
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synergistic presence of other commensals - fusobacterium, prevotella, prophyromanas, capnocytophaga, and actinobacillus
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So Actinomycosis is therefore a polymicrobic infection?
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True
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A chronic suppurative abscess spreads mainly by direct extension to their tissue planes involving the chest wall - drains sulfur granules
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True
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Tx of Ai
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prolonged high dose iv therapy with penicillin followed by amoxicillin for 6-12 months; surgical if severe
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How can you prevent Ai?
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good oral hygiene for lung infection
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patchy B/L infiltrates with rales and wheezing, immunocompromised by CF (or any other chronic illness) is most likely caused by which microbes?
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A. fumingatus, atypical mycobacteria, H. influena, S. aureus, B. cepacia, P. aeruginosa
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gram negative rod
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Psudomonas aeruginosa
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What other species are in the family Psudomonadaceae?
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Burkholderia, stenotrophomonas, and aeruginosa
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P. aeruginosa characteristics
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motile with one flagella, strictly aerobic, nonfermentative, oxidase positive, nonspore forming
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P. aeruginosa makes a water-soluble pigment called what?
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pyocyanin ("blue pus")
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Has a characteristic fruit odor
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P. aeruginosa
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What kind of capsule does Pa have?
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alginate capsule
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Are psudomonads nutritionally fastidious?
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nope, they are flexible int heir nutrient requirements
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Where can Pa be found in the environment?
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common inhabitants of the soil and water (tap water and ice)
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nosocomial or community acquired Pa?
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nosocomial
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What bacteria is found in disinfectants, soap, aqueous solns, ointments, eye drops, dialysis fluids, or any equipment that requires a wet body temperature environment
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Pa
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Transmission of Pa
|
by ingestion of or of contact with contaminated water or ice; aerosolization of contaminated liquids; penetration by contaminated objects and ingstion of Pseudomonas-laden foods
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What is an example of a Pseudomonas-laden food?
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tomatoes
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Receptor on tracheal epithelial cells for psudomonas pili is...
|
sialic acid
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What also serves as a surface-bound adhesin for glycolipids on respiratory epithelial cells?
|
exoenzyme S
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When does Pa undergoes a phenotypic shift?
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When they move down to the bronchi and become MUCOID (due to the alginate capsule)
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Why is Pa mucoid?
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b/c of the alginate capsule
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What composes the alginate capsule?
|
mannuronic and glucuronic acid
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Name 2 host factors what favor the colonization of Pa
|
1. impaired ability of bronchial epithelial cells to clear Pa
2. increased mucin production by bronchial epithelial cells; stimulated by Pa LPS |
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What is host defense is stimulated by the Pa LPS?
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a chronic neutrophilic inflammatory response which interferes with pulmonary function
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In CF pts infected with Pa, what is the major cause of morbidity?
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the neutrophilic inflammatory response that interferes with pulmonary function
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Is bacteremia common with infection by Pa?
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NO; very rare b/c of a high level of antibodies to antigens by Pa
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3 secreted products of Pa that cause lung damage
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elastase, phospholipase and exotoxin a
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What does exotoxin A do?
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ADP-ribosylates EF2 - results in inhibition of protein synthesis and ultimately cell death
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What does elastase do?
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hydrolyzes elastin and collagen
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What does phospholipase do?
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hydrolyze phospholipids of eukaryotic cell membranes
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How do you tx Pa?
|
extended-spectrum penacilli (piperacillin), cephalosporin (ceftazidime), or carbapenem (imipenem) AND a antipseudomonal aminoglycoside (tobramycin)
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True or false: Pa is typically resistant to many commonly used antibiotics
|
TRUE
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In Pa infection in an abnormal host (immunocompromised), what is seen that is typically RARE in a normal host and is associated with an indwelling catheter?
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UTI's - associated with a Foley catheter
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Which microbe would be responsible in an immunocompromised individual in the ICU on respirator-therapy equipment?
|
Pseudomonas aerginosa (pneumonia)
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Is there a vaccine for Pa?
|
No
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Unilateral erythematous palpebral conjunctiva, watery eye and purulent exudate is characteristic of what infection?
|
S. aureus (secondary bacterial pneumonia and concurrent acute conjunctivitis)
|
|
|
most likely to cause infiltrates in the posterior lower lobe segment?
|
S. aureus
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|
What can cause lung collapse due to mucus plugging and acute pulmonary edema
|
S. aureus
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|
|
S. aureus characteristics:
|
Gram positive cocci that occur individually, in pairs, or in grape-like clusters; nonmotile; nonspore forming; catalase positive
|
|
|
Are Sa resistant to high temperatures?
|
Yes
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|
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Are Sa resistant to high [salt]'s
|
Yes
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Are Sa resistant to drying?
|
Yes
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|
|
Describe the colonies of Sa
|
large, smooth, translucent, and pigmented (cream orange to yellow)
|
|
|
3 clinically important species of Staphlococcus?
|
1. Sa 2. S. epidermdis (coagulase negative) and 3. S. saprophyticus (coagulase negative and novobiocin resistant)
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What is coagulase activity?
|
The ability to clot plasma
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What is the most important criteria in identifying S. aureus
|
coagulase activity
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What is extracellular coagulase
|
reacts with prothrombin to form thrombin, which then turns fibrinogen to fibrin
|
|
|
Who or what is the reservoir for Sa?
|
Human nasal carriers; as well as on the surface of the skin
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|
|
Transmission of Sa?
|
endogenously or exogenously; aspiration (usually common after viral infection) or hematogenous mode (in pts with illicit IV drug use)
|
|
|
How does influenza allow for secondary bacteria infection?
|
It destroys the mucocilliary ladder, thereby destroying the ciliary defense, which normally keeps bacteria out of the lower respiratory tract
|
|
|
How does S. aureus adhere to host cells?
|
via teichoic acid
|
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|
Wat is the hallmark of S aureus infection?!?!?!?!
|
ABSCESS, which consists of a fibrin wall surrounded by inflamed tissues enclosing a central core of pus containing the organisms
|
|
|
How do you tx Sa?
|
high IV dose of antistaphlococcal penicillin (nafcillin) for a minimun of 2 weeks. Vancomycin is used in highly resistant strains
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|
Extremely low BP, low pO2, and low platelet count is associated with which infection?
|
Sin Nombre virus (hantavirus pulmonary syndrome [HPS])
|
|
|
Hantaviruses belong to which family of viruses?
|
bunyavirus family
|
|
|
bunyacirus, phlebovirus, nairovirus, tospovirus are ____ borne?
|
athropod borne
|
|
|
hantavirus is the exception of athropod borne infection; instead it is
|
rodent borne
|
|
|
Characteristics of hantavirus
|
enveloped, spherical, triple-segmented & circular (-)ss-RNA
|
|
|
how many circular, helically symmetrical nucleocapsids does hantavirus have?
|
3
|
|
|
HFRS stands for
|
hemorrhagic fever with renal syndrome - precedes pulmonary edema and DIC
|
|
|
Lab detection of HPS consists of 3 measures: what are they?
|
1. detection of hantavirus-specific IgM (even in prodrome)
2. rising-titers of hantavirus-specific IgG 3. detection of hantavirus-specific ribonucleic acid by PCR |
|
|
pan-american zoonosis
|
HPS
|
|
|
Transmission of HPS is by:
|
rodent droppings or urine that is disturbed and inhaled
|
|
|
Is HPS associated with person=to-person transmission?
|
nope, at least not in america
|
|
|
Who is at risk for HPS?
|
adult men and individuals bearing B-locus allele (B*35)
|
|
|
Can HPS be used in bioterrorism?
|
Could possibly
|
|
|
Incubation period after exposure to infective rodent droppings:
|
1-5 weeks
|
|
|
What are the cellular receptors for pathogenic hantavirus?
|
b3 integrins
|
|
|
What cytokines are involved in hantavirus?
|
TNF and IL-2
|
|
|
HPS clinically resembles what?
|
ARDS
|
|
|
The key hallmark of early hantavirus infection?
|
thrombocytopenia
|
|
|
Tx of hantavirus:
|
aggressive ventilator management and use of systemic vasopressors
|
|
|
Any vaccines for hantavirus?
|
Nope
|
|
|
Characteristics of SARS-associated coronavirus
|
large, enveloped, (+)ss-RNA, with club-shaped peplomers providing a crown-like appearance, nonsegmented
|
|
|
Longest of any RNA virus:
|
SARS-CoV
|
|
|
3 groups of coronavirus have been known to cause upper respiratory and enteric disease:
|
Groups 1 and 2 are mammalian viruses and group 3 includes only avian viruses
|
|
|
SARS-CoV belongs to which group or coronaviruses?
|
group 4
|
|
|
Mode of transmission of SARS?
|
large-droplet aerosolization; contact (direct AND fomite); and fecal-oral route
|
|
|
Incubation period for SARS
|
2-10 days
|
|
|
What is seen in the lungs of people infected with SARS?
|
pathological cytoarchitectural changes: diffuse alveolar damage (DAD) with mulinucleated giant cells with no conspicuous viral inclusions; desquamation of pneumocytes. With progression, there is increased fibrosis and squamous metaplasia.
|
|
|
How do you tx SARS?
|
supportive care
|
|
|
Are steroids helpful in SARS?
|
Nope
|
|
|
Mortality rate of SARS?
|
10.5%
|
|
|
What is of upmost importance in a potential SARS outbreak?
|
Infection control measures! airborne precautions, hand washing, contact precautions (glove and gowns) and environmental cleaning
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