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27 Cards in this Set
- Front
- Back
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Staphylococcus aureus/pyogenes virulence factors |
Free coagulase (clots plasma) Protein A (anti-phagocytic) Exfoliative toxins (epidermal splitting) Enterotoxin (Vomiting + d) Toxic shock syndrome toxin-1
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Clinical features of Staph aureus |
Skin & soft tissue - abscess MSS - acute hematogenous osteomyelitis Resp - tonsillitis CNS - meningitis Endovascular - infective endocarditis Toxic epidermal necrolysis - Staph Scalded Skin Syndrome SSSS Toxic shock syndrome Food poisoning |
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Why is Staph aureus food poisoning not an infection? |
Intoxication due to enterotoxin produced in food before ingestion within 4-6 hrs of eating. NB: non bloody diarrhea, no fever |
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Staph aureus lab specimen and d/x |
Specimen - depends on lesion eg pus if suppurative Smear exam - gram + cocci in clusters Catalase test - positive Coagulase test Antibiotic susceptibility test |
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Staph aureus r/x |
Drain pus + antibiotics Penicillin - if resistant i.e. 95% -> Methicillin/cloxacillin - if resistant (MRSA) -> Vancomycin, Minocycline, Teicloplanin - if resistant -> Daptomycin |
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Where does Staph aureus colonize |
Skin Mucosa of anterior nares Vagina |
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Mode of transmission of Staph aureus |
Direct contact, fomites, dust, airborne droplets |
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most common cause of post op wound infection & hospital cross infections & burn patients |
Staph aureus |
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Universal skin commensal Staph |
Staph epidermis (Staph albus) |
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Clinical significance of Staph epidermis/ albus |
Bacteremia - due to production of sticky biofilm (PS + techoic acid) on biomaterial like stitches, prosthetics, catheters, CVP line, IV line Bacterial endocarditis Stitch abscess |
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Where is Staph saprophyticus commensal? |
Skin Periurethral area GIT |
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Clinical significance of Staph saprophyticus |
UTI (esp sexually active women) Septicemia + Endocarditis (during cardiac surgery) |
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Coagulase Negative Staph r/x |
Depends on antibiotic sensitivity Severe - vancomycin |
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Most common cause of bacterial infections, food poisoning & toxic shock syndrome |
Staph aureus (Staph pyogenes) |
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Coagulase Positive Staphylococcus |
Staph aureus |
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Coagulase negative staphylococcus |
Staph epidermidis (S. Albus) Staph saprophyticus |
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Biochemical features of Staph aureus |
Coagulase + Catalase + Oxidase - Ferments mannitol Beta hemolytic colonies on BA Golden yellow pigment Susceptible to Novobiocin Produces phosphatase |
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Biochemical ID of Staph epidermidis & Staph saprophyticus |
Coagulase - No mannitol fermentation White colonies S. Epidermidis is susceptible to Novobiocin; S. saprophyticus resistant S. Epidermidis produces phosphatase not S. saprophyticus |
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Biochemical ID of micrococcus |
Coagulase negative Catalase positive Non hemolytic White colonies Bacitracin susceptible (unlike Staphylococcus spp.) |
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Clinical significance of micrococcus |
UTI Immunocompromised ppl - brain abscess, meningitis, pneumonia, cerebrospinal fluid shunt infection |
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Micrococcus of natural habitat |
Free (living in enviro) w little pathogenicity |
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Cryptococcosis- rx |
Antifungals - Amphotericin B (AMB), Flucytosine
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Cryptococcosis- rx |
Antifungals - Amphotericin B (AMB), Flucytosine
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Cryptococcosis- prophylaxis |
Conjugate vax |
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Cryptococcosis- clinical types |
Pulmonary (1o infection) Extra pul - cryptococcal meningitis is most serious, resembles TB and often in AIDS |
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Clinical features of Pulmonary Cryptococcosis |
Asymptomatic May have chronic 🫁 disease too Subclinical - only discovered by routine CXR |
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Clinical features of Extra pulmonary cryptococcosis in CNS |
Meningitis Meningoencephalitis Expanding cryptococcoma (localized solid tumor-like masses) |
