microbiology USMLE Flashcards
Actinomyces israeli
G+ branching rod
Anaerobic
Yellow “sulfur granules”
normal in mouth and vagina
B. anthracis
Bacillus G+ rod Spore-forming Aerobic Non-motile
Woolsorter’s Dz –> animal hinds
Polypeptide capsule!! (D-glut capsule)
B. cereus
Bacillus G+ rod Spore-forming Aerobic Motile
Food poisoning –> Reheated rice
C. botulinium
Clostridium G+ rod Anaerobic Spore-forming Motile Honey in infant or canned food Blocks ACh release at NMJ (peripheral NS) --> flaccid paralysis
C. difficile
Clostridium
G+ rod
Anaerobic
Spore-forming
Motile
Normal gut flora –> superinfxn following clindamycin
Psuedomembranous colitis –> toxic megacolon –> perforation –> death
Tx. metronidazole & oral vancomycin
C. diphtheriae
Corynebacterium G+ rod Non-spore forming Aerobic Non-motile
Grows on K. Tellurite agar (Teletubbies!)
Unimmunized child w/ psuedomembrane
C. perfringens
Clostridium
G+ rod
Anaerobic
Spore-forming
Non-motile
a-toxin (lecithinase) –>disrupts lecithin found in our cell membranes
Gas gangrene –> crepitus, bubbles, crackles
C. tetani
Clostridium G+ rod Anaerobic Spore-forming Motile Penetrating wound (found in soil, low O2) Tetanospasmin (inhibits motor neurons) --> spastic paralysis Stops Gly & GABA
Enterococcus
G+ cocci in chains
Catalase - (Strep)
a or y hemolysis
Grows in 6.5% NaCl
Listeria monocytogenes
G+ rod –> only one with LPS
Non-spore forming
Aerobic
Motile (tumbling motility)
Deli meats, Unpastuerized milk
Intracellular –> cell mediated (cytotoxic T)
Nocardia asteroidies
G+ branching rod
slightly acid fast
aerobic
–> pulmonary infxn
Non-enterococcus
G+ cocci in chains Catalase - (Strep) y hemolysis anaerobis Does not grow in 6.5% NaCl Grows in bile
S. agalactiae
GROUP B Strep G+ cocci in chains Catalase - (Strep) b hemolysis Bacitracin resistant --> colonizes vaginal tract
S. aureus
G+ cocci in clusters
Catalase + (Staph)
Coagulase +
Gold color
S. epidermidis
G+ cocci in clusters Catalase + (Staph) Coagulase - White color Novobiocin sensitive --> Causes infxns in catheters and central lines
S. pneumoniae
G+ cocci in chains Catalase - (Strep) a hemolysis CAPSULE (+ quelling reaction) bile soluble (doesn't grow) Optochin sensitive --> MCC of pneumonia >60
S. pyogenes
GROUP A Strep G+ cocci in chains Catalase - (Strep) b hemolysis Bacitracin sensitive --> M protein cleaves C3 convertase, Abs can cause rheumatic fever
S. saprophyticus
G+ cocci in clusters
Catalase + (Staph)
Coagulase +
Novobiocin resistant –> 2nd MC cause of UTIs
Viridans Strep. (S. mutans, S. Sanguis)
G+ cocci in chains Catalase - (Strep) a hemolysis No Capsule (+ quelling reaction) bile soluble (doesn't grow) Optochin resistant --> dental caries (mutans), subacute endocarditis (sanguis)
