Question

STUDY QUESTIONS: STAPHYLOcocc 1. Why would you perform a coagulase test on a bacterial isolate that tested positive for mannitol salt agar fermentation? 2. Would a catalase positive test always signify the presence of Staphylococci spp.? 3. What is the medical significance of a coagulase positive test result?

Answer 1

1,Mannitol salt Agar(MSA) used as a selective and differential medium to isolation and identification of staphylococcus...Coagulase positive staphylococcus produce yellow colonies and a surrounding with yellow medium..Mannitol salt agar contains peptones and beef extracts which supply the nitrogen,minerals,vitamin and aminoacids important for growth..Mannitol is the fermentable carbohydrate, fermentation of which leads to acid production by phenol red indicator..it helps to differentiate staphylococcal species for selective isolation..
2, since the catalase is nearly ubiquitone in some of the organism that can grow in the presence of oxygen..Staphylococcus is the one of the most virulent gram positive bacteria..major function of catalase within cells to prevent the accumulation of toxic levels of hydrogen peroxide formed as a by-product metabolic process-electron transport pathway..catalase useful techniques in medical microbiology to identify and differentiate between staphylococcus species..
3, staphylococci (coagulase positive result) can cause infection..it lead to superficial skin lesions and deep-seated infection like osteomylitis and endocarditis and nosocomial infection..it also make infection associated with indwelling medical devices,food poison,toxic shock syndrome,UTI etc..