Gram (+) Bacteria Flashcards
Streptococci
catalase (-)
non-motile
facultative or obligate anaerobles
Lancefield groupings (A,B,D)
Group A Strep.
S. pyogenes. B-hemolysis, #1 cause of bacterial pharyngitis, impetige, rheumatic fever, post-strep glomerulonephritis, necrotizing fascitis, toxic shock syndrome
Group B Strep
S. agalactiae, B-hemolysis, #1 cause of neonatal septicemia, meningitis, and pneumonia
Group D Strep
S. bovis and S. equinus. G or A-hemolysis, endocarditis, urinary tract infections
S. pneumoniae
A-hemolysis, #1 cause of bacterial pneumonia in adults, capsule, meningitis in adults, otitis media in children, optochin sensitive
S. viridans
A-hemolysis, microaerophilic, dental caries, subacute endocarditis, aspiration pneumonias and abscesses
Streptococcis virulence factors
M proteins (S. pyogenes) resists phagocytosis Capsules (S. pneumoniae, S. pyogenes, S. agalactiae) erythrogenic exotoxin (S. pyogenes) causes scarlet fever, toxic shock syndrome
Enterococci
diplococci or short chains catalase (-) G-hemolytic non-motile facultative anaerobes UTIs, bacteremia VRE=vacomycin resistant enterococci also very resistant to ampicillin
Staphylococci
catalase (+)
S. aureus
coagulase (+)
pneumonia, meningitis, acute endocarditis, osteomyelitis, TSS, food poisoning
Staphylococcus virulence factors
clumping factor
polysaccharide capsule (resists phagocytosis)
surface A protein (inhibits Igs)
exfoliative A and B toxins (scalded skin syndrome)
superantigens (TSS1 and heat stable enterotoxin)
Bacillus
aerobes to facultative anaerobes
spore-formers
B. cereus
preformed enterotoxins > food poisoning
B. anthracis
polyglutamyl capsule (survives phagocytosis) exotoxins cutaneous anthrax (95%) GI anthrax (contaminated meat > bloody diarrhea) inhalation antrax (woolsorter's disease, pneumonia, hemorrhagic mediastinitis)
Clostridia
G+ rod
spore former
obiglate anaerobes
C. tetani
racket-shaped
single exotoxin > tetenus, blocks inhibitor of neurotransmission
C. perfringens
anaerobic mixed wound infections
exotoxins
gas gangrene
C. botulinum
botulinum exotoxin > block ACh release Type A is most potent exotoxin known poorly canned foods flaccid paralysis, diplopia, dysarthria, dysphonia, dysphagia, respiratory failure infant botulism: bee honey wound botulism
C. difficile
toxin A (enterotoxin) toxin B (cytopathic agent) pseudomembranous enterocolitis Rx: oral vanco, metronidazole, bacterial recolonization
Corynebacteria
G+ rod-like, club-shaped
mycolic acid in cell wall
C. diptheriae
diptheria toxin (cytotoxin) pseudomembranous material in upper respiratory tract Rx: vaccinate, passive immunization with antitoxin
Listeria
G+ bacillus
facultative intracellular parasite
lysteryolysin O (can survive inside phagolysosome)
spread from cell to cell w/o extracellular stage
L. monocytogenes
food-borne illness
hot dogs, lunch meat, milk, cheese, raw vegetables
miscarriage/stillbirth
Gardnerella vaginalis
Gram-variable, cell wall is G+
bacterial vaginosis, clue cells, fishy odors
