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Microbiology-Bacteria

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tapadebe's version from 2018-04-16 12:17

Toxins

Question Answer
B. cerus (2 + type)ENTEROTOXINS
1. Heat-stable/Emetic: Associated w/ fried rice.
• Injest TOXIN, not bacteria.
• Upper GI (toxin extent)
2. Heat-labile/Diarrheal: Stimulates adenylate cyclase-cAMP = profuse, watery diarrhea
• Due to eating actual BACTERIA (true bacterial infection)
C. tetaniblocks release of glycine, GABA from inhibitory interneurons
C. botulinuminhibits ACh release from motor neuron at NM junction
V. choleraealpha-subunit permanently on. -activates adenylate cyclase --> increased cAMP/NaCl secretion (RICE-WATER diarrhea)
ETEC (2)TRAVELERS/watery diarrhea
1. heat labile toxin: activates adenylate cyclase (increased cAMP) = *increased NaCl secretion*
2. heat stable toxin: activates guanylate cyclase = increased cGMP = *inhibits NaCl reabsorption*
EAECAggregates on mucosa b/c BIOFILM formation (sticky = path. mech.)
•Aggregations trigger inflammatory response in patient
•Aggregated layers = Persistent/longer-term watery diarrhea
•ENDEMIC *PERSISTENT DIARRHEA (BUZZ WORD)*
•aka Acute traveler's diarrhea, aka sporadic acute diarrhea
•If something aggregates, it PERSISTS.
EHEC-HEMORRHAGIC = Bloody diarrhea
-Non-invasive = no fever
-Acquired from: animal feces/petting zoo/puppies, raw meat, fruit juice.
-Ferments sorbitol
-SHIGA-LIKE: inactivates 60S (via 28s rRNA) = inhibits protein synthesis = kills intestinal epithelial cell (bloody diarrhea).
• if TOXIN into blood = Hemolytic-Uremic Syndrome
EPECPediatric – very inflammatory. EAF (path. mech.) = adherence factor = effaces mucosa = Infantile diarrhea
EIECBloody and increased leukocytes because inflammation.
*INVASIVE = causes FEVER*
•Person-to-person, fecally contaminated food (cheese).
S. aureus enterotoxinfood poisoning (diarrhea + vomiting less than 24 hrs)
B. cereus enterotoxinfood poisoning (vomiting less than 24 hrs)
S. pyogenes pyrogenic toxinactivates endogenous IL-1 production (Scarlet fever)
S. aurerus pyrogenic toxinactivates endogenous IL-1 production (TSS)
S. pyogenes (4)-Streptolysin O (oxygen-labile; ASO dx; antigenic)
-Streptolysin S (oxygen-stabile; not antigenic)
-Erythgrogenic toxin: pyrogenic (rash in SCARLETT FEVER), SUPERANTIGEN = sepsis (IL-1)
-Streptokinase: lyse blood clots
S. aureus (4)tissue invasive toxins (HEMOLYSIN), enterotoxins (heat stable), exfoliative toxin, TSST-1 (EXOtoxin, MAYONNAISE)
C. perfringens (3)-ALPHA TOXIN (phospholipase C) hydrolyzes lecithin in cell membranes --> cell death (gas gangrene)
-Heat labile enterotoxin = Watery diarhhea
B. anthracis edema factor/EF (2 things)- Edema factor (EF) inserts an adenylate cyclase = increased cAMP (EDEMA) --> impairs PMN function + causes massive edema
- Protective antigen (PA): promotes entry of EF into phagocytic cells.
B. anthracis lethal factorzinc metalloprotease INACTIVATES MAPk (protein kinase) --> induces macrophage to release TNF-alpha, IL-1 (death)
= necrosis and hypoxia
C. diphtheriaeDIPHTHERIA TOXIN – needs phage for transduction = lysogenic bacteriophage (ß-phage): Virus encoded on TOX GENE that introduces endotoxin to diphtherioid.

A-B toxin: inhibits protein synthesis via ADP ribosylation of elongation factor (EF2) --> inhibits protein *translation* (myocarditis, peripheral nerve palsies, CNS effects).
C. difficilecytotoxic to colonic epithelial cells (bloody diarrhea, fever, abdominal pain)
P. aeruginosaEXOTOXIN A (ETA)
-ADP ribosylates eEF-2 = inhibits elongation factor (EF2) --> inhibits protein translation (targets liver)
*Same as diphtheria toxin*
M. tuberculosisNO TOXIN
H. pyloriVacA cytotoxin = inflammation
•tissue destruction: produces vacuoles in epithelial cells (via IL-8)
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Classification

Question Answer
S. pyogenesgram+ coccus in chains; beta-hemolytic; bacitracin sensitive
S. agalactiaegram+ coccus; beta-hemolytic; bacitracin resistant
Enterococcusgram+ coccus; no hemolysis (normal colonic flora)
S. viridansgram+ coccus; ALPHA-hemolytic; optochin resistant; not bile soluble (normal oral flora) (VIRILE/STRONG)
S. pneumoniae (5)gram+ coccus; alpha-hemolytic; optochin sensitive; bile soluble; diplococci
S. aureusgram+ coccus in clusters; catalase +; coagulase +
S. epidermidisgram+ coccus in clusters; catalase +; coagulase -; novobiocin sensitive
S. saprophyticusgram+ coccus in clusters; catalase +; coagulase -; novobiocin resistant
B. anthracisgram+ rod; spore-forming; aerobic; non-motile
B. cereusgram+ rod; spore-forming; aerobic; motile
Clostridiumgram+ rod; spore-forming; anaerobic
Corynebacterium diphtheriaegram+ rod (CLUB-SHAPED); non spore-forming
Listeriagram+ rod; non spore-forming; tumbling motility
N. meningitisgram- coccus; maltose fermenter
N. gonorrhoaegram- coccus; matlose non-fermenter
H. influenzaegram- coccobacillus
Actinomycesgram+ rod; branching; has sulfur granules
E. coligram- rod; fast lactose fermenter; motile
K. pneumoniaegram- rod; fast lacotse fermenter; non-motile
Shigellagram- rod; lactose non-fermenter; oxidase -; non-motile
Salmonellagram- rod; lactose non-fermenter; oxidase -; motile; produce H2S
V. choleraegram- COMMA-SHAPED rod; oxidase +
C. jejunigram- comma-shaped rod; oxidase +; grows at 42 degrees C
H. pylorigram- comma-shaped rod
Bacteroidesgram- rod; anaerobic; normal gut flora
P. aeruginosagram- rod; aerobic; oxidase +
B. pertussisgram- coccobacillus
Legionellagram- rod; poorly-staining (use silver stain)
Chlamydiagram- rod; no peptidoglycan wall; obligate intracellular parasite
Rickettsiagram- rod; obligate intracellular parasite
Treponema palladiumgram -, Corkscrew-shaped
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Virulence Factors

Question Answer
S. aureus (3)tissue invasive toxins (HEMOLYSINS, streptokinase, DNAase, catalase, coagulase, hyaluronidase...), immune system defense (Protein A ["A" for Aureus]: binds Fc receptors on IgG), surface and adhesion factor (slime layer, polysaccharide capsule, clumping factor/fibrinogen-binding protein)
S. pyogenes (4 + buzzword)- M-protein: inhibits complement (adherence, anti-phagocytic, antigenic) *TYPE-2 HYPERSENSITIVITY RXNS*
- F protein (adherence)
- Hyaluronic capsule (anti-phag. = necrotizing fasciitis)
- C5a peptidase
S. pneumoniae (3)-Polysaccharide capsule (anti-phag., antigenic)
-IgA protease (mucosa; prevents IgA-mediated clearance in mucosa...RESP. = RUSTY SPUTUM)
-Pneumolysin (creates pores in cell, binds cholesterol in host membranes)
S. epidermidis (3 + buzzword)Polysaccharide capsule/Slime layer/Biofilm (PROSTHETIC DEVICES)
S. agalactiaepolysaccharide capsule (anti-phagocytic) NEONATAL MENINGITIS
B. anthracisPROTEIN capsule (unique; *all other are carbohydrate) - consists of poly-D-glutamic acid
B. cereus (3 – Be Serious MEN)MEN
- Nonencapsulated = nothing for antibodies/complement to bind to.
- Motile
- ENDOtoxins (enterotoxins) = food poisoning. Heat stabile v. Labile
Clostridiumspore
Bacillusspore
M. tuberculosis (3)- Cord factor: inhibits PMN (granulocytes) migration, encourages granuloma formation.
- Sulfatides: inhibits phagolysosome fusion.
- Facultative intracellular.
N. meningitidiscapsule, IgA protease, pili
N. gonorrhoae (2)pili (antigenic variation); IgA protease (PIaP)
E. coli (2)-pili: adhesion = UTI
-K1 capsule/K-antigen: Anti-phag., NEONATAL MENINGITIS ("K" for "K"IDS).
K. pneumoniae (2)capsule, endotoxin
Salmonellacapsule
Shigella (3 + buzz word)-Invades M-Cells = *CELLULAR RUFFLING*
-Polymerize actin = propel through cytoplasm = cell-to-cell passage
-Shiga toxin (causes fever/INVASIVE, unlike EHEC)
Y. enterocoliticasurvives refrigeration
Y. pestis (3)intracellular, coagulase +, F1 capsule
H. pylori (5)urease, CORKSCREW MOTILITY (polar flagella), CATALASE +, mucinase, VacA
H. influenzae (4)polysaccharide capsule containing PRP, *IgA protease*, pili, LPS
B. pertussiscapsule, pili
V. cholerae (3 + buzzword)-Pilus (BACTERIOPHAGE for cholera toxin and virulence factors).
-Motility (polar flagella)
-Cholera toxin = A-B toxin *ABC*
•inhibits GTPase (no GTP to GDP), keeps alpha-subunit/adenylate cyclase active = increased cAMP
*RICE WATER STOOLS*
Chlamydia trachomatiselementary body (infective); reticulate body (reproductive)
C. perfringens-ALPHA TOXIN (phospholipase C) hydrolyzes lecithin in cell membranes --> cell death (gas gangrene)
-Hyaluronidase, collagenase
-Heat labile enterotoxin = Watery diarhhea
B. cereus (2)• Toxin-mediated (heat STABLE) = No treatment/self-limiting.
• Bacteria-mediated (heat LABILE) = Resistant to penicillin (use vanco, cipro, gentamycin).
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Treatment

Question Answer
S. saprophyticusvancomycin
S. epidermidisvancomycin
MRSAvancomycin
C. botulinumantitoxin
C. tetaniantitoxin, vaccine
N. meningitidisvaccine; rifampin prophylxis in close contacts
H. pylori (3)PPI (omeprazole), macrolide, beta-lactam)
Bacteroidesmetronidazole, clindamycin
gardnerellametronidazole
Chlamydiadoxycycline (adults); erythromycin (children, pregnancy)
Rickettsiaedoxycycline
mycobacterium tuberculosisisoniazid, rifampin, ethambutol, pyrazinamide, streptomycin
T. palladiumPenicillin B
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Culture Media/Dx

Question Answer
S. pyogenes (2)-ASO (abs against streptolysin O) – Diagnostic for Strep A infection.
- PYR test: Qualitative procedure; determines ability of strep to hydrolyze L-pyrrolidonyl-ß-naphthylamide (differentiates from other Group A)
S. agalactiaeHippurate hydrolization – CAMP factor – S.aureus (b-lysin) + S.agalactiae = Zone of hemolysis between
S. pneumoniaeQuellung positive (greater refractiveness with a positive reaction; caused by capsular swelling)
C. diphtheriae (3)- Cys-Tellurite Blood Agar (CTBA): Gray-to-black colonies on PCR detect toxin gene (TOX GENE)
- Loeffler's media (coagulated serum agar to grow colonies, then methylene blue stain)
- ELEK test: Must use to test for toxin
E. coliMacConkey's agar (pink); eosin-methylene blue agar (blue-black)
INDOLE POSITIVE (RED/PINK)
Salmonella (3)-MacConkey clear (non-lactose fermenting).
-Hektoin agar = Black colony/light green w/ black (hydrolyzes urea, produces H2S).
-Acid labile/sensitive
Shigella (4)-Stool culture (never part of normal flora)
-No lactose or sorbitol ferment (diff. from EHEC with sorbitol, E.coli in general with lactose/MacConkey)
-No H2S via Hektoin (diff. from Salmonella, which is + w/ light green with black centers)
-*NON-MOTILE* (serology)
N. gonorrhoeaeThayer-Martin media (Vancomycin, Polymyxin, Nystatin)
V. choleraeTCBS (green agar) – Positive = yellow colonies over green background.
-alkaline media
C. jejunigrow media at 42 degrees C
H. influenza (3)-chocolate agar with factor V (NAD) and factor X (HEMIN) b/c hameophilii lack hemolysins *SATELLITE PHENOMENON*
-quellung positive
-G neg rods in *CSF*
Legionellacharcoal-yeast extract with Fe, cysteine
MycobacteriumZiehl Neelson Method (ACID FAST STAIN) –1º stain is Carbolfuschin
M. tuberculosis (2)1. - Auramine-rhodamine staining bacilli (FLUORESCENT GREEN APPLE): Screening test; non-specific but sensitive.
• Perform Lowenstein to confirm positive Auramine and confirm dx.
- Lowenstein-Jensen agar (specific for acid fast); grows slow.

2. PPD – (5mm HIV, 10mm HIGH, 15mm LOW) –––THEN radiograph to look for granuloma if PPD+
M. pneumoniaeEaton's agar
H. pylori (2)Serology (corkscrew motion), UREASE breath test = labeled CO2 exhaled
KlebsiellaLACTOSE FERMENTING (PINK MacConkey)
Pseudomonas aeruginosaPyocyanin (blue), Fluoroscein (green)
T. palladiumDarkfield microscopy
Leptospira interrogansDarkfield microscopy
C. perfringensNAGLER RXN (egg yolk agar)
MycoplasmaRequires cholesterol in agar; NOT SEEN ON GRAM STAIN
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Source

Question Answer
E. coli (2)Fecal-oral, UNPASTEURIZED FRUIT JUICES
B. anthracis (buzzword x2)Zoonotic; herbivores
-WOOL SORTERS DISEASE/SHEEP, POSTAL WORKER
M. lepraeARMADILLO (TEXAS, LOUISIANA)
Legionellawater sources (A/C)
Y. pestisflea bite, rodents, prairie dogs
Y. entercoliticaunpasteurized milk
Borrelia burgdorferiIxodes tick
Borrelia recurrentishuman body louse
Rickettsia rickettsiaetick
V. cholera (3)salt water, shellfish, fecal oral
V. parahaemolyticusRaw/undercooked seafood
V. vulnificusFISHERMANS WOUNDS; standing IN water
Pseudomonas aeruginosa (2)-STANDING water (as in it's not moving)
-HOT TUB
B. burgdorferiIxodes tick (CONNECTICUT, LYME DISEASE)
B. recurrentisBody louse (LICE)
Leptospira interrogansWater w/ animal urine (HAWAII)
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