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19 Cards in this Set
- Front
- Back
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Staph aureus 1
Metabolism / Characteristics |
Gram +
grape-like structures Catalase + Coagulase + --> bound + free DNAse + beta-Hemolytic (gold colonies on blood agar) Facultative anaerobe Yellow colonies |
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Staph. aureus 2
Antigenic structure |
Peptidoglycan + teichoic acid
Cell wall protein A --> antiphagocytic Capsule (some strains) --> antiphagocytic Bound coagulase |
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Staph. aureus 3
Virulence/Toxins |
1) Exotoxin -immunogenic; eg staphylolysins --> alpha hemolysin
2) Leuokocidin- may lyse leukocytes 3) Hyalurodinase- spreading factor --> decompose ECM; eg staphylokinase 4) DNase 5) Enterotoxins- groups A-F; food poisoning; 6 different antigenic structures. 50% SA can produce; food not heated up properly 6) Coagulase - bound + free 7) Toxic shock sydrome toxin - F-toxin 8) Exfoliative toxin- Toxin A & B; dermatitis esp. in children |
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Staph. aureus 4
Pathogenesis |
Abscesses in all organs affected. Bacteria enter via follicle/hair --> tissue necrosis --> coagulase- fibrin surrounds lesion resulting in a wall --> focal suppuration (pus) --> localized abscess or furuncle --> can be spread by lymphocytes to blood spread
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Staph. aureus 5
Clinical |
1)Lesions=abscess = suppination + pus
2)osteomyelitis - very severe and hard to treat 3)pneumonia - rare 4)empyema- bacteria between visceral and parietal pleura 5)endocarditis - rare 6)sepsis 7)impetigo (skin disease in children) acne 8)sinusitis 9)otitis media |
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Staph. aureus 6
Diagnosis |
1) Specimens - depending where bacteria is--> surface, blood, pus, CSF
2) Direct smear - NOT diagnostic- will tell you it's gram + 3) Culture: - blood agar: hemolysis, gold colonies - mannitol: yellow - DNA: transparent after add HCl 4) Coagulase test 5) Catalase test - way to differentiate staph and strept |
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Staph. aureus 7
Epidemiology & control |
- Ubiquitous human parasites
- Opportunistic infections - Sources of infections: human lesions, fomites (bed sheets, clothes), contaminated skin, resp. tract - Nose- major reservoir - Hospital staff --> WASH HANDS with hexachlrophene |
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Staph. aureus 8
Treatment |
- Penicllinase-resistant penicllins (bacteremia, endocarditis, pneumonia, chronic osteomyelitis)
- Vancomycin - Clindamycin Many are antibiotic resistant... if methicillin resistant treat with IV vancomycin |
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Staph. aureus 9
Toxic shock Syndrome |
- Strains producing Toxin F --> binds MHC-II --> massive T cell reponse --> massive cytokine production
- Fever, shock, nausea, skin rash, and in severe cases heart and renal insuffiency - Associated with tampon use for 5 straight days |
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Staph. aureus 10
2 types of coagulase |
1) Free- takes 5-6 hours to produce & secrete in presence of plasma
2) Bound- antigen on surface, rapid reponse ~30 secs. ALWAYS have both |
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Staph. epidermidis 1
Metabolism/ Characteristics |
Gram +
Catalase + Coagulase - DNase - Facultative anaerobe White colonies Normal flora of skin and throat |
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Staph. epidermidis 2
Virulence |
Generally non-virulent
Polysaccharide capsule- binds to prosthetic devices --> biofilms |
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Staph. epidermidis 3
Clinical |
1) Nosocomial infections of:
- prosthetic joints - prosthetic heart valves - sepsis from IV lines 2) frequent skin contaminant in blood cultures |
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Staph. epidermidis 4
Treatment |
- Vancomycin
(highly resistant) - Novobiocin sensitive |
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Staph. epidermidis 5
Diagnosis |
1) Gram stain- confirms gram + growing in clusters
2) Culture - Catalase + - Coagulase - - Mannitol - - DNase - |
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Staph. saprophyticus 1
Metabolism/ characteristics |
Gram +
Grows in clusters Catalase + Coagulase - DNase - facultative anaerobe |
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Staph. saprophyticus 2
Clinical |
Major cause of UTI in young women
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Staph. saprophyticus 3
Treatment |
-Penicillin
-resistant to novobiocin |
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Staph. saprophyticus 4
Diagnosis |
1) Gram stain- confirms gram + growing in clusters
2) Culture - Catalase + - Coagulase - - Mannitol - - DNase - |
