Microbiology Flashcards
(27 cards)
diphtheria toxin
produced by Corynebacterium diphtheriae; AB toxin; ADP-ribosylates and inactivates EF2
exotoxin A
produced by Pseudomonas aeruginosa; AB toxin; ADP-ribosylates and inactivates EF2; leads to host cell death
shiga toxin
produced by Shigella spp.; AB toxin; ADP-ribosylates and inactivates 60S ribosome by removing adenine from rRNA; leads to dysentery, cytokine release, and HUS
shiga-like toxin
produced by EHEC; AB toxin; ADP-ribosylates and inactivates 60S ribosome by removing adenine from rRNA; leads to cytokine release and HUS
heat-labile toxin
produced by ETEC; AB toxin; ADP-ribosylates and activates adenylate cyclase; leads to increased Cl secretion into gut and water efflux (watery diarrhea)
heat-stabile toxin
produced by ETEC; overactivates guanylate cyclase; leads to decreased NaCl and water resorption from gut (watery diarrhea)
edema toxin
produced by Bacillus anthracis; ADP-ribosylating AB toxin; mimics activity of adenylate cyclase; leads to edematous borders of characteristic black eschar in cutaneous anthrax
cholera toxin
produced by Vibrio cholerae; AB toxin; overactivates adenylate cyclase by ADP-ribosylating/permanently activating Gs; leads to rice-water diarrhea
pertussis toxin
produced by Bordatella pertussis; AB toxin; ADP-ribosylates and disables Gi, leading to overactivation of adenylate cyclase; also impairs phagocytosis
tetanospasmin
produced by Clostridium tetani; ADP ribosylating AB toxin; protease that cleaves SNARE, prevents release of inhibitory neurotransmitters (GABA and glycine) from Renshaw cells in spinal cord; leads to spastic paralysis
botulinum toxin
produced by Clostridium botulinum; ADP ribosylating AB toxin; protease that cleaves SNARE, prevents release of stimulatory neurotransmitters (ACh) at neuromuscular junction; leads to flaccid paralysis
alpha toxin
produced by Clostridium perfringens; phospholipase (lecithinase) that degrades tissue and cell membranes; leads to gas gangrene and “double zone” of hemolysis
streptolysin O
produced by Streptococcus pyogenes; degrades cell membranes, lyses RBCs; leads to beta hemolysis; host antibodies are diagnostic for acute rheumatic fever
toxic shock syndrome toxin
produced by Staphylococcus aureus; cross-links MHC II and TCR outside of antigen binding site, causing overwhelming cytokine release (IL-1, IL-2, IFN-y, TNF-a) and shock
exotoxin A
produced by Streptococcus pyogenes; cross-links MHC II and TCR outside of antigen binding site, causing overwhelming cytokine release (IL-1, IL-2, IFN-y, TNF-a) and shock
Staphylococcus aureus
gram (+) cocci in clusters, catalase (+), coagulase (+)
virulence factors: Protein A (binds Fc-IgG, inhibits complement activation/phagocytosis), TSST-1, forms fibrin clot (abscess formation)
diseases: skin infection, abscesses, pneumonia, endocarditis, septic arthritis, osteomyelitis, toxic shock syndrome (associated with tampons/nasal packing), scalded skin syndrome, rapid-onset food poisoning (heat-stabile toxin)
MRSA: altered PBP, resistent to methicillin and nafcillin
Staphylococcus epidermidis
gram (+) cocci, catalase (+), coagulase (-), urease (+), novobiocin sensitive
virulence factors: biofilm formation
diseases: prosthetic and catheter infection
Staphylococcus saprophyticus
gram (+) cocci, catalase (+), coagulase (-), urease (+), novobiocin resistant
diseases: second-most common cause of uncomplicated UTI in young women
Streptococcus pneumoniae
gram (+) lancet-shaped diplococci, catalse (-), optichin sensitive, alpha-hemolytic
virulence factors: capsule, IgA protease
diseases: meningitis, otitis media, pneumonia, sinusitis
Streptococcus mutans
gram (+) cocci, catalase (-), optichin resistant, alpha-hemolytic
diseases: dental caries
Streptococcus sanguinis
gram (+) cocci, catalase (-), optichin resistant, alpha-hemolytic
diseases: subacute bacterial endocarditis at damaged heart valves (binds fibrin-platelet aggregates)
Streptococcus pyogenes
gram (+) cocci in chains, catalase (-), PYR (+), bacitracin sensitive, beta-hemolytic (group A)
virulence factors: streptolysin O (degrades cell membranes), exotoxin A (similar to TSST)
diseases: phyringitis, cellulitis, impetigo, erysipelas, scarlet fever, toxic shock syndrome (associated with skin infection), rheumatic fever, glomerulonephritis
Streptococcus agalactiae
gram (+) coccin in chains, catalase (-), hippourate (+), bacitracin resistant, beta-hemolytic (group B)
virulence factors: CAMP factor (enlarges area of hemolysis formed by S. aureus)
diseases: colonizes vagina, infantile pneumonia/meningitis/sepsis (intrapartum penicillin prophylaxis)
Enterococci (E. faecalis and E. faecium)
gram (+), group D Strep, penicillin G resistant, variable hemolysis, can grow in 6.5% NaCl and bile
diseases: normal colonic flora, UTI, biliary tract infections, subacute endocarditis (following GI/GU procedures), nosocomial infections (VRE)
