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112 Cards in this Set
- Front
- Back
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Pseudomonas aeruginosa
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non-lactose fermenting Gram negative rod, oxidase positive
shiny, blue-green pigment on blood agar, but shows a lack of lactose fermentation on MacConkey sweet “grape-like” odor uncommon in immune competent one of the most common in hosp patients and is a frequent cause of pneumonias, urinary infections, and bloodstream infections |
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age-related changes in the pathogens responsible for pulmonary exacerbations in pts with cystic fibrosis
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infants and younger children, S. aureus and H.influenzae
older children and adolescents, P. aeruginosa Later stages of disease are often associated with pulmonary infections due to multiple-drug resistant P. aeruginosa, other resistant grams negatives |
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Antibiotics active against P. aeruginosa
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piperacillin, 3rd and 4th gen cephalosporins, carbepenems, certain floroquinolones (like ciprofloxacin), and aminoglycosides (especially tobramycin)
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L. monocytogenes
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facultative anaerobic Gram positive bacillus
one of the leading causes of community-acquired meningitis in adults older than 60 years of age and infants younger than 1 month; less frequently in pregnant women and immunocompromised hosts |
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most common clinical manifestation of Listeriosis
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mild disease characterized by fever, nausea, vomiting, and diarrhea
associated with epidemic gastroenteritis |
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where can L. monocytogenes be found? (what should pregnant women avoid eating during their third trimester?)
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soft cheeses, processed delicatessen meats, and raw vegetables
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How do children get L. monocytogenes
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vertical transmission from mother to child during or after childbirth is likely responsible for neonatal infections
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Initial therapy for bacterial meningitis in a 67 year old woman
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steroids, vancomycin (for penicillin resistant S. pneumoniae), cetriaxone (3rd gen cephalosporin, covers S. pneumoniae & N. meningitidis), and ampicillin (for Listeria monocytogenes)
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Treatment for patient with confirmed L. monocytogenes meningitis
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ampicillin with gentamicin for synergy
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mortality rate due to L. monocytogenes meningitis
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high: approximately 30%
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What strain of Haemophilus is associated with invasive dz in children? What is the typing done by?
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Type B, a polysaccharide capsule
Hib |
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Why are infants 6 months to 3 yrs susceptible to Hib? How are they protected the first 6 months?
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Lack antibodies to b capsule.
mother passes antibodies via breast milk |
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What are the 4 things that Hib causes in infant 6 months to 3 yrs?
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Meningitis
Acute epiglottitis Septic arthritis Sepsis |
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What are some acid fast bacteria?
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mycobacteria
mycobacterium tuberculosis mycobacterium leprae |
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What are some bacteria without cell walls?
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Mycoplasma
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Where do the vast majority of bacteria in our body live?
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large intestine
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What are the four sterile places in the body?
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blood, urine, brain, and lungs
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Pathogen
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microbe capable of producing damage
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Virulence
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relative ability of a microbe to cause damage/disease in a host
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Damage f(host) with examples
Class 1 Class 2 Class 5 |
Class 1- dz in immune-compromised, beneficial in normals
(candida, staph epiderm) Class 2- dz in immune-compromised, but no benefit (pneumococcus, cryptococcus) Class 5-dz in those w/strong immune response (H1N1, SARS) |
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Serratia
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gram negative rod
bright red pigment causes UTIs, wound infections, pneumonia in nosocomial infections |
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What is the virulence factor in Candidiasis? (defies Koch's postulate)
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medical therapy(impaired barrier)/impaired host is virulence factor
normal component of human flora |
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What is the virulence factor in Legionellosis? (defies Koch's postulate)
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envt is virulence factor
true host is amoeba, transmitted via water sources |
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How does mononucleosis defy Koch's postulate?
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Epstein Barr Virus
causes three diseases mononucleosis, B-cell tumor, Burkitt's lymphoma |
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How do ulcers defy Koch's postulate?
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H. pylori causes two dieases, one of which is non-infectious
ulcers and stomach cancer |
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Defns
Sporadic Endemic Epidemic Pandemic |
Sporadic- isolated
Endemic-regionally Epidemic-anywhere, tends to affect large #s of ppl Pandemic-global |
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What microbes have the capacity to survive outside its host? What microbes dont have this ability?
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Fungi can survive outside host
Viruses cannot |
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What kind of nucleus, ribosomes, and outer surface do fungi have?
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Eukaryotic (have mitochondria)
80S (60S + 40S) Chitin |
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What kind of nucleus, ribosomes, and outer surface do bacteria have?
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Prokaryotic
70S (50S + 30S) Peptidoglycan |
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Aerobic
Anaerobic Facultative Microaerophilic |
Aerobic- need oxygen
Anaerobic- don't need oxygen Facultative- indifferent to oxygen Microaerophilic-enhanced growth with oxygen |
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What causes pneumonia in alcoholics?
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Klebsiella (aspiration pneumonia)
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What features are unique to gram positive organisms?
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teichoic acid
Cell wall |
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What features are unique to gram negative organisms?
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Endotoxin/LPS (lipid A)
Periplasmic space |
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Siderophores
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take up and transport iron to microbe
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What does a inducer do?
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binds to (inactivates) repressor
turns on transcription |
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What strategies does N. gonorrhea use to avoid detection?
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antigenic variation- make new pilin subunits
phase variation-entire protein or truncated protein via a slipped strand mispairing |
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How does yersinia avoid host cell immune response?
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YopB/D form pores allowing...
YopH to enter which has tyrosine phosphatase activity which interferes with host cell immune response |
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Aminoglycosides (kanamycin, gentamicin) mechanism?
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bind to 30s subunit to prevent binding to 50s subunit
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B-lactams (penicillin and amoxicillin) mechanism?
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inhibit synthesis of peptidoglycan
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What strategy does Salmonella typhi use to survive in host?
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cadC gene
activates lysine decarboxylase to catalyze the reaction from lysine--> cadaverine cadaverine= greater tolerance t low pH |
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What strategies does Pseudomonas aeruginosa use to survive in host?
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acquisition of iron
quorom sensing- way bacteria communicate with one another; colonize only when a certain # of bacteria in an area |
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What organism causes syphillis?
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Treponema pallidum
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How does campylobacter jejuni acoid detection?
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has sialyl transferase which is involved in glycosylation (unusual to find in bacteria); sialic acid is on RBCs
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What is the most effective strategy for controlling a toxin-mediated disease?
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Immunization against Toxin A subunit (b/c it is the active subunit, most directly involved with causing damage)
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AB Toxins
How many A? B? for.... Diptheria toxin? Cholera? Anthrax? |
Diptheria toxin? A + B
Cholera? A + 5B Anthrax? 2A + B |
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What are bacterial viruses called?
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phage
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Which toxins are stable to boiling?
Which toxins are inactivated by boiling? |
endotoxins are stable to boiling.
most exotoxins are inactivated by boiling |
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Cornyebacterium diptheriae and immunized ppl
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gram positive, non-spore forming rod
inactive toxin used for vaccine ppl can be colonized but not affected since immunized against toxin, not the bacteria |
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Mechanism of action of Cornyebacterium diptheriae toxin?
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inactivates E2F protein which is involved in elongation step of translation
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Where does Cornyebacterium diptheriae colonize and what does it form?
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colonizes the pharynx and
forms a pseudomembrane |
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What does Cornyebacterium diptheriae cause?
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damages heart and neural cells by interfering with protein synthesis (E2F) with its exotoxin rockets
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Classification of Cornyebacterium diptheriae and Listeria moncytogenes
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gram positive rods
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Classification of Bacillus (anthracis) and Clostridium (botulinum, tetani)
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gram positive, spore-forming rods
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Three bacteria most responsible for causing most meningitis by baby coming out
Later? |
Listeria monocytogenes, Group B strep, E. Coli
Later: N. meningitidis. H. influenzae |
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What are two disease that we are vaccinated against the toxin but not the microbe?
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Tetanus (Clostridium tetani)
diptheria (Cornyebacterium diptheriae) |
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How does one get Clostridium tetani?
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skin trauma by any object contaminated with spores
germinate in necrotic tissue (anaerobic) and release tetanospasmin |
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Vibrio cholera
what is cholera? how does it cause death? |
curved gram negative rod with single polar flagellum
diarrheal disease that causes rice water diarrhea Cholera causes death by dehydration |
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How does Vibrio cholera cause disease?
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bacteria attach to epithelial cell, release choleragen toxin....
choleragen has one A subunit and 5 B subunits, B binds to intestinal epithelial cell and A enters causing secretion of NaCl and prevention of NaCl reabsorption |
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What three things does Clostridium perfringens cause?
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Gas gangrene
1. Cellutis/wound infection 2. Clostridial myonecrosis: fatal, if left untreated 3. Watery diarrhea |
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What three microbes release Shiga toxin/Shiga-like toxin?
What do these toxins do? |
Shigella
Enterohemorrhagic E. Coli Enteroinvasive E. Coli inhibit 60s ribosome resulting in intestinal epithelial cell death, bloody diarrhea |
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What two microbes release heat labile toxin and cholera toxin?
What do these toxins do? |
Enterotoxigenic E. Coli and vibrio cholera
inhibit the absorption of NaCl, watery diarrhea |
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What causes Hemolytic Uremic syndrome?
What are the symptoms? |
Enterohemorrhagic E.Coli 0157:H7
anemia, thrombocytopenia, renal failure |
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Why are infants susceptible to botulism spores in honey but adults are not?
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Infants have STERILE GI tract
In adults, commensal bacteria outcompete botulism spores and is the reason when they don't get infected when eating honey |
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What is the most virulent staph specie?
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S. aureus
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What is the main reservoir for S. aureus?
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nasal mucosa
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When staph epidermidis causes disease, what is the most likely cause?
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presence of foreign body; catheter or prosthetic device
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Important facts abt staph aureus
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resistant to penicillin
propensity to invade the vascular system s. aureus bacteremia is a common complication of IVs |
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How do supeantigens work?
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bind to MHC-II receptors of monocytes-macrophages at sites distinct from classic binding groove,causin exuberant non-specific immunologic activation and release of cytokines
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Penicillin binding proteins
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crosslink peptidoglycan chains in bacterial cell walls
altered PBPs will grant resistance to penicillin |
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Beta-lactamASE
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used by bacteria to destroy the beta-lactam ring of penicillin
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What strategies does MRSA use that make it so hard to kill?
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B-lactamase AND altered PBPs
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What is the difference between CA-MRSA and hospital acquired MRSA?
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CA-MRSA is generally susceptible to a range of non-beta lactam antibiotics, but....
hospital acquired MRSA is generally broadly resistant... REMEMBER both MRSA types have B-lactamase AND altered PBPs |
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Clinical presentation of CA-MRSA
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severe skin abscesses
necrotizing pneumonia necrotizing fasciitis septic arthritis bacteremia |
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What is Panton-Valentine leukocidin (PVL)?
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crucial mediator of increase virulence in CA-MRSA
toxin that acts by damaging neutrophils causing neutrophil apoptosis and by triggering interleukin and inflammatory mediator production |
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What people have higher rates of infection for staph aureus?
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3Ds
diabetics, dialysis, drugs |
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what increases cAMP?
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Cholera, Anthrax, Monetezuma's (Enterotoxigenic E. Coli), Pertussis
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What is the microbe best at setting up distant sites of infection?
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Staph aureus
endocarditis, osteomyelitis |
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Toxins produced by Staph Aureus and diseases they can cause
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TSST-1, enterotoxin, epidermolytic toxin, membrane damaging toxin (leukocidin)
Toxic shock- multisystem Food poisoning- projectile vomiting Scalded skin syndrome- will heal w/o scarring |
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What does TSST-1 induce the release of?
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IL1, IL2, TNF
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How do superantigens work?
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binds to Antigen presenting cells and presents to T-cells in a nonspecific way
-->1 in 5 Tcells are activated and host hurts itself thru a non-specific exuberant immune reaction |
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Weird presentations of staph aureus
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Job's syndrome- neutrophil dysfunction, abscesses on skin
Botryomycosis- chronic granulomas that do damge over months to yrs |
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What will S. epidermidis have?
so what? |
altered PBPs
dont give B-lactams like penicillin, give vancomycin |
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What features distinguish enterococci (group D strep) from other strep?
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ability to grow in bile
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What features distinguish enterococcus faecalis (enterococcal group D strep) from non-enterococcal group D strep?
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enterococcus faecalis (enterococcal group D strep) can grow in NaCl, it is one of the hardiest orgs and part of normal GI flora
both grow in bile |
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Group A Strep
aka? ID Symptoms |
aka? Strep pyogenes
ID? B-hemolysis, Bacitracin susceptible Symptoms? Mom, my throat hurts, my skin is disintegrating, and my body is turning scarlet!!!" Later...Mom, I want to watch Rheumatic Fever! Mom, my urine is tea colored!!!! |
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What is the virulence factor in Group A Strep that is anti-phagocytic and can be used for typing strains?
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M protein
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What microbiological feature of enterococci (Group D strep) distinguish it from other strep?
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ability to grow in bile
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Group B strep (strep agalactiae)
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B for baby!!! B-hemolytic, CAMP positive
early onset: neonatal meningitis, pneumonia, sepsis prophylaxis helps in preventing early onset dz, but not late onset |
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Viridans strep
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Viridans = Verde =green a-hemolytic
Dental infections Endocarditis Eating heart valves slowly |
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Group D strep (Enterococci)
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normal GI flora, gamma hemolytic
able to grow in high salt and bile nosocomial pathogen UTI, bacteremia, endocarditis, wound infection |
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Red currant jelly sputum with bulging fissure sign. what bacteria? what ppl? what is it?
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Klebsiella, diabetics and alcoholics
lobar pneumonia |
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What type of pts is pseudomonas prevalent in?
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immune compromised pts
Cystic fibrosis pts nosocomial infections |
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probs with treating pseudomonas
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highly resistant so need to treat with extended spectrum beta lactams
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Proteus
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"swarming"
has urease which causes stone formation, results in high urine pH |
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Serratia
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SerREDtia
Red color hospital outbreaks |
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Klebsiella vs. Pseudomonas
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both occur in immuno compromised
both have extended spectrum resistance to beta-lactams Klebsiella- lobar pneumonia (red currant jelly) in alcoholics and diabetics Pseudomonas- CF pneumonia; BE PSEUDo |
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Strep pneumonia
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Pneumococcal warrior
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Pneumonia is to Parents what
Group B strep is to Babies |
both cause meningitis and pneumonia in their respective groups
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What can Hib cause?
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Meningitis, acute epiglottitis, septic arthritis, sepsis
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What does Hib need to grow?
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chocolate agar, factors V and X
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Neisseria meningitidis
gram shape |
gram negative diplococci
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Strep pneumonia
gram shape |
Gram positive
lancet shaped diplococci |
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Enterotoxigenic E.Coli
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traveler's diarrhea, rice water stool
Heat labile (just like cholera toxin) and heat stabile toxin Tx: anti-motility and antibiotics |
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Enteroaggregative E. Coli
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forms aggregate patterns and biofilms
destroys cells and mucus secretion pts get watery, mucoid diarrhea (1/3 bloody) Sticks arounds (17 days in children) |
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Enteropathogenic E. Coli
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occurs in infants in developing countries
causes effacement of enterocytes and pedestal formation causing malabsorption and diarrhea |
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Enterohemorrhagic E. Coli
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Hs- causes bloody diarrhea, 5Bs, 1A
Hamburger meat in industrialized world Hemolytic uremic syndrome Shiga-like toxin, inhibits 60s ribosome causing intestinal cell death DONT give anti-motility agents; want to get rid of bloody diarrhea of course! has leukocytes in stool |
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Enteroinvasive E.coli
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Like Shigella
invade epithelial cells causes immune reaction with FEVER bloody diarrhea with WBCs (like shigellosis) |
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Typhoid fever (salmonella typhi)
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infects gall bladder and biliary system
Vi capsule gives it extra virulence with pathogenicity island invades M cells (APC cells of gut), invade lymphoid tissue, invade macrophages, to multiple organ systems after 7-14d, gets into bloodstream, relative bradycardia, fever, coated tongue, petechiae |
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Salmonellea enterocolitis
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causes diarrhea
result of improper food handling in industrialized countries food poisoning assoc with picnics RUFFLES engulf organism |
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Shigella
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like enteroinvasive E. Coli
causes dysentery, bloody mucus containing stools, painful defecation and tenesmus |
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Campylobacter jejuni
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Camping bacteria (zoonotic) in jejunum with nothing better to do than cause bloody diarrhea
oxidase positive prodrome of fever and headache |
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Vibrio cholerae (cholera)
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curve shaped gram negative adheres to jejunum to colon
oxidase positive needs a large infecting dose 5B:1A toxin, increase fluid secretion just like heat labile toxin of enterotoxigenic E. Coli. rapid onset of extreme rice water diarrhea |
