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Thayer-Martin (or VPN) media - Vanco inhibits gram(+) organisms, Polymyxins inhibits gram (-) organisms, and Nystatin inhibits fungal organisms.
Differentiates S. Pneumoniae (sensitive) from Viridans Streptococci (resistant)
Complete hemolysis - Group A S. pyogenes and Group B S. agalactiea. Also S. Aureus and Listeria Monocytogenes.
Maltose Fermentation test
Differentiate Neisseria species - N. Meningitidis (fermenter), N. Gonorrhoeae (non-fermenter)
Obligate anaerobes; Aminoglycosides ineffective, susceptible to oxidative damage.
Facultative Intracellular bugs
Encapsulated bacteria (+ Quellung); antiphagocytic virulence factor --> require opsonization for clearance.
H. Influenzae B
IgA protease production; used to colonize respiratory mucosa
H. influenzae B
cAMP inducers; activate host adenylate cyclase, or are themselves adenylate cyclase.
Vibrio cholerae - activates Gs
Pertussis toxin - disables Gi
E. Coli (ETEC) - heat labile toxin
Bacillus anthracis - bacterial adenylate cyclase
Bind directly to MHC II and TCRs simultaneously, activating large #'s of T cells to stimulate release of IFN-γ and IL-2 --> septic shock.
S. aureus toxins
TSST-1 = toxic shock syndrome
Enterotoxin A = food poisoning (preformed), in meat, mayo, and creamy pastry dishes; nausea and vomitting 3-6 hours after eating, little to no diarrhea.
Exfoliatin = staphylococcal scalded skin syndrome
ADP ribosylating A-B toxins
Interfere with host cell function by entering host cell and altering protein fxn from within.
Corynebacterium diphtheriae toxin
Inactivates EF-2; causes pharyngitis and pseudomembrane in throat.
Vibrio cholerae toxin
ADP ribosylation of G protein stimulates adenylyl cyclase; increases pumping of Cl⁻ into gut and decreases Na⁺ absorption. H₂O moves into gut lumen causing voluminous rice-water (secretory) diarrhea.
Heat-labile toxin stimulates Adenylate cyclase. Heat-stable toxin stimulates Guanylate cyclase. both cause watery/secretory diarrhea.
Bordatella pertussis toxin
Gram (-) aerobic bacillus, causes whooping cough (coughing, choking spells, and gasping for air);
Toxin inactivates inhibitory subunit of the G protein complex, activating adenylate cyclase, increasing cAMP in the cells of the respiratory system >> EDEMA. Toxin also causes LYMPHOCYTOSIS by blocking chemokine receptors, blocks the function of immune effector cells and increases HISTAMINE SENSITIVITY. Toxin also alters hormonal pathways regulated by cAMP, increasing insulin secretion, causing HYPOGLYCEMIA.
Bacillus Cereus Toxin
Heat-stable toxin causing vomiting. From rice in the buffet line. Onset in less than 6 hours.
Clostridium perfringens toxin
α toxin causing gas gangrene; get double zone of hemolysis on blood agar.
C. botulinum toxin
Blocks the release of ACh; causes anticholinergic symptoms, CNS flaccid paralysis, especially cranial nerves; spores found in canned food, honey (floppy baby).
Differentiate from all other anticholinergic drugs (e.g. atropine)by the presence of muscle weakness or paralysis.
Shiga toxin/verotoxin; cleaves host rRNA (inactivate 60S); enhances cytokine release, causes Hemolytic-uremic syndrome.
S. pyogenes toxin
Streptolysin O is a hemolysin; antigen for ASO antibody is used for rheumatic fever diagnosis.
Lipopolysaccharide found in outer membrane of all gram (-) bacteria (and listeria monocytogenes); Lipid A is toxic component.
Activates macrophages, alternative complement pathway, and Hageman factor to produce septic shock and DIC. Secretion of IL-1, IL-6, and TNFα
Bacterial toxins encoded on lysogenic phage
Erythrogenic toxin (S. pyogenes)
Transfer of plasmid encoded virulence factors from one bacteria to another via pilus formation.
Transfer of bacteria DNA through incorporation of DNA into bacteriophage.
Site-specific Transduction: specific sequence, error of temperate virus life-cycle.
Generalized Transduction: random bacterial DNA, error of lytic virus life-cycle.
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