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MLT-Staphylococcus
Microbiology
Question | Answer |
---|---|
What are the morphology and characteristics of Staphylococci? | 1.Gram positive 2.Facultatively anerobic 3.Non motile and non-spore forming 4.catalase positive 5.Can growth in presence of 10% NaCl |
Staphylococcus is divided into 2 groups by ? | 1. Coagulase 2. S.aureus, coagulase positive 3. coagulase negative Staphylococci |
What are the virulence factors for S.aureus? | 1.Coagulase: clot blood 2.Exotoxin 3.Exfoliative toxin: scalded skin 4.Enterotoxin:induce intestinal fluid secretions 5.Enterotoxin type B: A superantigen, causes Toxic Shock Syndrome |
What are the examples of coagulase negative Staphylococci? | 1.S.epidemidis, normal flora on skin 2.S.saprophyticus, normal flora female genital tract 3.S. lugdunensis, skin flora |
What are the tests for S.aures? | 1. Yellow colonies on Mannitol salt agar, it ferments mannitol. Coagulase negative Stap is Red. 2.Solid coagulase test: positive 3.Tube coagulase test(Definitive result): positive 4.Staphaurex |
How to do a tube coagulase test? | 1.Suspend organism into ½ diluted rabbit plasma 2.Incubate the tube at 37℃ 3.Observe the results at 4 hours and 24 hours |
What is Staphaurex? | Latex agglutination test, it detects both clumping factor and Protein A on the surface of S.aureus |
Is S.aures penicillin resistant? | Yes, as it produces penicillinase. |
What is the treatment for penicillin resistant S.aures? | Methicillin-group antibiotics |
What is Coagulase negative Stapylococci (CNS)? | 1.Normal flora at different body parts 2.Opportunistic pathogens |
What are the CNS? | 1.Staphylococcus epidermidis(blood culture) 2.Staphylococcus saprophyticus(UTI) 3.Staphylococcus lugdunensis(blood culture) 4.Staphylococcus intermedicus(dog-bite) |
What is Staphylococcus epidermidis? | 1.Normal skin flora 2.the mostly frequently isolated CNS from bloodstream, insufficient skin disinfection prior to blood-taking 3. Up to 95% are methicillin resistant |
What is Staphylococcus saprophyticus | 1.Normal flora in female genital tract 2.10^5CFU/ml -> UTI |
Novobiocin test is to differentiate? | 1.Staphylococcus saprophyticus: Resistant 2.Staphylococcus epidermidis: Sensitive |