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Unformatted text preview: www.medfools.com 1 Medfools Bacteriology a la chart for the USMLE I Adapted from notes from UCLA., with additional corny mnemonics Staphylococcus aureus ( virulent ) (nonmotile, nonsporeforming, facultative anaerobe) Gm+ cocci Diseases Characteristics Habitat/Transmission Pathogenesis Diagnosis Treatment Prevention *Skin infections: impetigo, cellulitis, erysipelas, abcess, furuncle, carbuncle *Bacteremia/sepsis: hematogenous spread *Acute endocarditis: DESTRUCTIVE (compare to S. viridans and S. faecalis ) *Pneumonia damaging process, cavitations, empyema, effusions *Osteomyelitis/septic arthritis- hematogenous and traumatic spread *Food poisoning 1-8 hr onset, vomiting, preformed toxin *Tox shock syndrome- fever, vomiting, diarrhea, diffuse erythematous rash Gm + cocci in grapes/clusters Catalase + coagulase + Ubiquitous in environment; normal flora of skin/nose Spread through lesions, fomites Enterotoxin- vomiting, diarrhea, heat resistant, (actually released in gut) TSST-1 tampon use, wounds, superantigen Exfoliatin- scalded skin TISSUE SPREAD: Alpha toxin (lechthinase)- skin necrosis;hemolysis Hyaluronidase- degrades proteoglycans Fibrinolysin- lysis fibrin clots IMMUNE EVASION: Protein A- binds IgG-Fc, blocks opsonization and complement fixation Coagulase- activates prothrombin Hemolysin- destroys RBCs, PMNs, M0s, platelets Leukocidin- destroys WBCs Gm + cocci in grapes, Catalase differentiates from Strep. S. aureus: Beta hemolysis, coagulase, Yellow (Au) pigment (coagulase causes coagulation! ) Coagulase neg: S. epidermidis: novobiocin sensitive sensitive skin S. saprophyticus: Novobiocin resistant Beta lactamase production is common! Use methicillin, nafcillin, dicloxacillin MRSA- vancomycin none S. epidermitis: associated w/ IV catheters, damaged/prosthetic heart valves: INSIDIOUS onset, Nosocomial, LESS virulent . Blood culture Contaminant S. saprophyticus: Community acquired UTI in young women www.medfools.com 2 Streptococcus viridans ( GABHS ) (nonmotile, nonsporeforming) Gm+ cocci Diseases Characteristics Habitat/Transmission Pathogenesis Diagnosis Treatment Prevention *Pharyngitis- strep throat, erythema, tonsillar exudate, fever *Skin/soft tissue infections- impetigo, cellulitis, necrotizing fascitis *Scarlet fever- centrifugal, red rash, erythrogenic toxin, slap cheek, strawberry tongue *Tox shock syndrome- clinically like Staph TSS *Rheumatic fcver- fever, myocarditis, polyarthritis, chorea, subcutaneous nodules, erythema marginatum rash. Mitral valve disease follows pharyngitis, NOT skin infections. Abs vs. bacteria cross react w/ joint and heart antigens *Acute GN- hypertension, hematuria, edema of face/ankles....
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This note was uploaded on 06/17/2008 for the course MOD 2 taught by Professor Cunningham during the Spring '08 term at University of North Texas Health Science Center.
- Spring '08