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132 Cards in this Set
- Front
- Back
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harsh, brassy, bark-like cough, upper airway narrowing (steeple sign), low-grade fever, inspiratory stridor (retractions)
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croup
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organisms which cause croup
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PIV or other respiratory viruses including RSV
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family, and genetic unit of PIV
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paramyxovirus, ssRNA (negative sense)
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risk factor for croup
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usually occurs in children 6 or younger
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PIV virulence factors
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H protein (hemeagglutinin), F protein (fusion protein)
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tx for croup
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humidification, epinephrine via nebulizer, glucocorticoids
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paroxysmal cough (sudden/violent), prolonged duration of sx (at least 14 days), in an unimmunized pt
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B. pertussis
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morphology of B. pertussis
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small, aerobic gram neg. rods (or coccobacilli
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B. pertussis virulence factors
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pertussis toxin, filamentous hemeagglutinin, agglutinogens, adenyl cyclase, tracheal cytotoxin
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effect of pertussis toxin
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incativates G-protein complex via ADP ribosylation, which leads to a rise in cAMP
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what is the earliest a child would receive the DTaP vaccine
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6 months
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atypical pneumonia typically presenting with GI sx and severe headache
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Legionella
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atypical pneumonia typically presenting without clinial pulmonary findings and/or prolonged cough
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Mycoplasma pneumonia
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morphological characteristics of M. pneumonia
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wall-less (no mucopolysaccharide cell wall), three-layer outer membraine containing cholesterol, do not gram stain
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four most important characteristics of atypical pneumonia
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1) nonproductive cough 2) variable CXR (patchy, diffuse infiltrates) 3) no bacteria on smear 4) no response to beta-lactam abx
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agar used for M. pneumoniae (with difficulty)
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Eaton's agar
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risk factors for M. pneumoniae
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age 5-20 most common, crowded military and institutional settings
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organism causing pneumonia which produces hydrogen peroxide
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M. pneumoniae
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DOC for M. pneumoniea
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erythromycin or doxycycline
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organism which commonly produces atypical pneumoniae but my also cause complications or sx including: ARDS, hemolytic anemia (associated with cold agglutinin IgM), Stevens-Johnson syn., and neurologic complications (eg encephalitis)
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M. pneumoniae
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What is mycoplasma pneumonia also known as?
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Primary atypical or "walking pneumonia"
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Describe the clinical features of tracheobronchitis
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Non productive cough, fever, malaise and pharyngitis
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How does M. pneumoniae colognize between cilia within the respiratory epithelium?
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Host sialoglycoconjugates and sulfated glycolpids.
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a four-fold rise in IgG antibody titers taken from a pt w/tracheobronchitis during the acute phase and then 2-3 weeks later is diagnostic of what?
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M. pneumoniea
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41 year old, high fever, dry cough, HA, muscle aches, confusion. Chain smoker. Works in a show room with whirlpools and spas.
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Legionella pneumophila (legionellosis)
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What does the PE reveal in a pt with Legionella pneumophila?
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Distressed patient, inspiratory rales. Cough that's productive of scantly, clear sputum.
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What three organisms are associated with exposure to birds, pigs or environmental factors?
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Chlamdia psittaci, coxiella burnetti, legionella.
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Purulent sputum is seen in what disease?
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S. pneumoniae (cause of typical pneumonia)
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Legionalla is associated with what clincail presentation?
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High fever, diarrhea, confusion and headache
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How can legionella be detected?
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Direct fluorescence antibody (DFA) staining of bronchoscopic Direct antigen in urine (Legionella pneumophila serogroup 1). Cultures of sputum, Serology and PCR for viruses (chlamydophila pneumoniae, mycoplasma pmenumonia)
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Describe the microbiologic properties of Legionella.
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Motile, flagellated, pleomorphic, strictly intracellular rods with gram negative cell wall structures
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How does legionella stain with Gram staining?
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Stain faintly
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stain of tissue used to visualise L. pneumophilia
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Dieterle silver stains
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cultural requirements for L. pneumophila
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buffered charcoal yeast extract supplemented with cystine and iron
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Legionella: When does the community-aquired disease most offten occur?
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Summertime.
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What are the primary sources of ifxn for legionella?
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Environement (showers, AC units, cooling towers, humidifiers, whilrpools, spas). Aerosolizing equipmenet (nebulizers, humidifers, water facutes). Aspiration (from contaminated water or via nasogastric tubes).
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What is a natural reservoir for the legionella organism?
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Freshwater amebae
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How is legionella spread?
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Living in water, they're aerosolized and spread via airborne routes. The organism isn't transmitted person to person.
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What is the risk group for legionella?
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Over 50 yo, somkers, alcoholics, COPD/malignancy patients, immunocompromised with organ transplants, pt on corticosteriods
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virulence factors for L. pneumophila
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flagella, pili, outer membrane protein which binds C3 favoring opsonization, dot gene products prevent phago-lysosome fusion, other gene products prevent acidification of the phagosome, toxin production including phospholipase and metalloproteases
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DOC for legionella
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macrolide (erythromycin, azythromycin, or clarithromycin) or newer quinolone (levofloxacin or gatafloxacin) or doxycycline
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organism which causes Pontiac fever
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L. pneumophila
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sx of Legionnaires' disease
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severe form of legionellosis occuring 2-10 days after exposure, acute severe fibrinopurulent pneumonis with alveolitis and bronchiolitis, Hyponatremia and Hypophosphatemia are common, infection my include extrapulmonary sites, and recovery is slow
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sx of Pontiac fever
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acute onset flu-like illness occuring w/in hours to 2 days of exposure to L. pneumophila
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myalgias are usually seen in what type of pneumonia
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viral
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genomic unit of influenza
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ssRNA (negative sense)
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surface antigens found on influenza
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H (hemagglutinin) and N (neuraminidase)
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influenza A human subtypes
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A(H1N1) and A(H3N2)
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influenza incubation period
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18-72 hours (average 48 hrs)
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binding of influenza occurs via what receptor
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H antigen to sialic acid receptors on ciliated epithelial cells
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describe the difference between antigenic drift and antigenic shift
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shift: is a complete change in epitope and results in generation of new strains, drift: is usually just a point mutation resulting in a change in the configuration of an epitope
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systemic symptoms of influenza are caused by:
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cytokines released from damaged leukocytes (NOT from disseminated infection)
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what is Reye syndrome?
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childhood hepatoencephalopathy associated with use of salicylates (asprin) and influenza B
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predisposing factor commonly seen in S. aureus pneumonia
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prior influenza or other viral infection
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DOC for influenza A
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amantadine or rimantadine, zanamivir and oseltamivir is effective but more expensive
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DOC for influenza B
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zanamivir or oseltamivir
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sx of bronchiolitis
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wheezes and hyperinflation
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risk foactors for RSV
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2-6 months old, winter months
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family, and genetic unit of RSV
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paramyxovirus (genus: pneumovirus), ssRNA (negative sense)
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morphologic characteristic which distinguishes RSV from PIV and influenza viruses
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RSV does not have a hemagglutinin protein
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incubation period of RSV
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2-8 days
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RSV virulence factors
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F (fusion) and G glycoproteins
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tx for fever in children
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acetaminophen
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tx for RSV
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Contact isolation, infection is usually self limited (8-15 days), but for severe infection ribavirin, oxygen, and immune globulin has been used
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what are koplik spots
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clustered, white lesions with red base, on the buccal mucosa found in measles (rubeola)
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family and genetic unit of measles (rubeola)
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paramyxovirus (genus: morbillivirus), ssRNA (neg. sense)
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sx of measles other than rash
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cough, conjunctivitis, coryza, occasionally croup, bronchiolitis, and pneumonia
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incubation period of measles
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7-8 days (preceding rash)
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tx for measles
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none
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complications of measles seen more often in HIV pts
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giant cell pneumonia, subacute sclerosing panencephalitis (SSPE)-fatal and seen years after primary infection
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type of vaccine given for mumps, measles (rubeola), and rubella
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live attenuated
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contraindications for MMR vaccine
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immunosupressed pts and pregnant women
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clinical differences between measles and rubella
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w/ rubella pts are less sick and koplik spots are absent
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oral lesion seen in scarlet fever
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red papilla on toungue
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lesion seen in typhoid fever
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rose spots on torso
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3 yo boy, low-grade fever, swollen lymph nodes, 3 day rash. No vaccinations. Family friend was sick with similar illness 2 weeks earlier.
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Rubella (german measles)
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What does the PE look like in a patient with rubella?
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Diffuse maculopapular rash over trunk and extremities. No lesions in the mouth. Cervical lymphadenopathy.
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What's the difference between patients with Rubella and measles?
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Rubella: Pt is less sick, Koplik spots not present.
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What would the diagnostic workup include if considering Rubella?
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Isolation of virus from throat and urine. Serology: IgM and IgG titer >4x increase
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What family does the Rubella virus belong to?
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Togavirus family.
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What does the Rubella virus look like genetically?
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Virus: central icosahedral nucleocapsid core and is covered externally by a lipid-containing envelope. ssRNA, surface spikes on the envelope contain hemagglutinin.
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How many antigenic (sero) types exist for rubella?
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One
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Where can the rubella virus be cultivated from?
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Throat, nasopharynx and urine
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Rubella and epidemiology
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2005: eradicated in US. Disease can still be imported.
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What's the natural host for rubella?
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Humans
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How can the rubella virus be spread in unvaccinated individuals?
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Droplet spread or by direct contact
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What is congenital rubella syndrome?
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Fetal damage or birth defects associated with seronegative women contracts rubella in early pregnancy
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Describe the pathogenesis of rubella?
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Virus enters/infects nasopharynx & lungs, attaches to and invades respiratory epithelium. Spreads hematogenously (1* viremia) --> lymphatics/replicates in reticuloendothelial system --> Virus-specific T cells attack virus-infected vascular endothelial cells of dermal capillaries causing skin rash.
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In rubella, what may contribute to febrile exanthem illness?
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antigen-antibody complex
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When does the Rubella rash occur and how long does it last for?
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Rash follows prodromic febrile stage and lasts for 3 days.
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What's the treatmeent of rubella?
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none
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Who is the rubella virus vaccine contraindicated in?
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Immunocompromised patients, because it's a live vaccine
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How does the rubella vaccine work?
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It induces a respiratory mucosal IgA response, thus interrupting the spread of virulent virus by nasal carriage.
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What should the rubella immunity screen in pregnant woman be greater than or equal to?
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1:8 titer of IgG antibody indicates immunity and consequent protection fo the fetus
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How does rubella manifest?
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diffuse punctate and maculopapular rash. The lesions are less intnesly red than those of measles.
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How can a rubella be confirmed in pregnant women?
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Fourfold rise in specific antibody titer between acute- and convalescent-phase serum specibimens by ELISA. Amniocentesis and rubella culture may reveal whether there is rubella virus in amniotic cluid.
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How may Congenital Rubella Syndrome (CRS) be diagnosed in a newborn?
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Presence of specific IgM antibody in a single specimen taken between 2 weeks and 3 mo of age
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complications of fetuses infected by rubella
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congenital malformations and possibly death occurs from vertical transmission in 90% of women who aquire rubella during pregnancy
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55 year old, woman, burning pain over her left forearm. Sudden onset. Several vesicles developed in a band-like distribution on her arm, new ones were erputing daily. No known allergies.
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VZV; zoser or shingles. Varicella-zoser virus
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What type of diagnostic workup would be included if VZV was considered?
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Tzanck smear of the base of a lesion, Viral antigen demonstration by direct fluorescent antibody; Virus cultivation from skin lesion
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Describe the genome of VZV
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Member of herpesvirus group. Enveloped, double stranded DNA genome. It has a single serotype.
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How may a presumtive idenfication of the VZV virus be made?
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Characteristic appearance of eosinophilic intranuclear inclusion and multinucleated giant cells in infected human fetal diploid kidney cells (3-7 days)
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What is the key biologic feature of the virus, as is found in other viruses in the herpes virus family?
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Latency
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VZV causes what diseases?
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Varicella (chickenpox in children) and herpes zoster (shingles in adults)
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Describe chickenpox
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Febrile rash disease. Sudden onset of slight fever. Skin rash: Maculopapular for a few hours, progressing to vesicular then to pustular for 3-4 days, finally crusting over. Vesicles collapse on puncture. Lesions occur in crops (several stages of lesion maturity are observed on same pt).
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Where are the chickenpox lesions most abundent?
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scalp, high in the axilla, mucous membrane of mouth and upper respiratory tract.
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What is the reservoir for VZV
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Humans
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What time of the year does chickenpox occur?
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In temperate zones, chickenpox occurs in late winter and early spring.
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How and when is varicella transmitted?
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Inhalation of airborne respiratory aerosol from patient 1-2 days before the onset of rash, which makes this infection higly contagious.
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How does Zoster occur?
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It occurs sporadically as a reactivation of latent VZV and occurs most commonly in individuals above 50 YOA.
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Where does VZV primarily infect in children and how does it culminate into the typical vesicular rash?
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VZV primarily infects the mucosa of the upper respiratory tract and spreads via the blood to the skin, where the typical vesicular rash occurs. Incubation period is 2-3 weeks (15 days median).
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Where may VZV lay dormant?
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Dorsal root ganglia (sensory nerve roots) for life.
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How can the latent virus be activated?
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Medication, illness, or malnutrition or from the natural decline in immune function with aging, causing zoster (shingles).
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What is postherpetic neuralgia?
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Patients experience pain in the vzv rash distribution. The reactivated virus causes the vesicular skin lesion and nerve pain of zoster due to damage to the peripheral nerves.
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How does VZV form clusters of blister-like lesions in a strpi-like pattern on one side of the body?
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The virus progresses down the axon to mucocutaneous sites; local spread and replication occur.
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Where can multinucleated giant cells be found in VZV?
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Multinucleated giant cells with intranuclear inclusions are seen in the base of the skin lesions. Histopathology may also reveal hemorrhage, edema and lymphocytic infiltration.
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What complications can arise from VZV?
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In immunocompromised patients, there maybe hematogenous spread of the virus to the lung causing interstitial pneumonia and to the CNS casuing encephalitis.
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After influenza B in children, primary varicella is the second most common viral antecedent for what syndrome?
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Reye syndrome
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How can VZV be treated?
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Acyclovir. ACV shortens the duration of symptoms and pain of zoster in the normal older patient. Corticosteriods maybe helpful in older adults with zoster. Famciclovir and valacyclovir may also be effective and maybe taken less often than acyclovir.
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How may VZV be prevented?
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Varivax, a live attenuated varicella virus vaccine. It's recommended in all children over 12 months.
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How does VZV vaccine enhance the immune system?
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engances VZV-specific IgG antibodies and T-cell immunity. VZIG (varicella zoster immune globulin) is effective in preventing disease if given within 96 hours after exposure of the virus in high risk individuals.
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papulovesicular lesion prominent on face and extremities (including palms and soles) bumpy lesion filled with opaque fluid, lesions appear to be at similar stage of development
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small pox (variola)
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large complex DNA virus with dumbell-shaped core and more than 100 membraine proteins
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small pox (variola)
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genomic unit of variola virus
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linear dsDNA
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transmission of variola:
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inhalation of respiratory droplets or direct contact of body fluids
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incubation period of variola
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7-17 days presenting with flu-like symptoms and the lesions appear on oropharyngeal mucosa and face after 3 more days (most infectious when lesions are present)
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tx for small pox
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none
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describe the stages of small pox disease
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prodrome (2-4 days)= fever, malaise, head & body aches; early rash (4 days)= small red spots on tongue and mouth, as mouth sores break down rash appears on face and spreads to arms, legs, hands and feet, spreading to all parts w/in 24 hrs, rash is raised red bumps until 4th day when bumps fill with opaque fluid (often with a depression); pustular rash (5 days)= bumps become sharply raised firm pustules; pustules and scabs (5 days)= pustules form crust and then scab, occurs about 2 weeks after inital rash; resolving scabs (~6 days)= scabs begin to fall off leaving pitted scars; scabs resolved= all scabs have fallen off and the pt is no longer contagious
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during what stage is variola most contagious
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during the early rash
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what is a "Jennerian vesicle"
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painful pustule, sign of a successful variola vaccination
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contraindications for variola vaccine
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"contraindications to vaccination are eczema, immunocompromised, or close, unavoidable contact with someone who has eczema or is immunocompromised or is pregnant"
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how long is someone held in isolation after exposure to small pox if they refuse the vaccine
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at least 18 days
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