Which of the following is catalase positive? (Repeat)
Ans: A (Staph epidermidis) Ref: Ananthanarayan, Paniker CJ. Textbook of microbiology. 8th Edition. London: John Wiley & Sons: 2009. Pg. 52, 159Explanation:Catalase test:When a bacterial colony is placed in hy drogen peroxide, if it produces catalase enzyme there will be prompt effervescence.Catalase positive organisms:Staphylococcus aureusCoagulase negative staphylococci such asS. epidermidisMicrococciPseudomonasCandidaColiformsdeg Citrobacter, Enterobacter. E.coli, Klebsiella (which are all lactose +)deg Shigella. Yersinia, Proteus and Salmonella (which are all lactose -)deg Serratia (a slow lactose fermenter)Although Shigella dysenteriae type 1 is a coliform, it is catalase negative.Streptococcus, pneumococcus and enterococcus are catalase negative.In patients with chronic granulomatous disease, a familial condition with disorder of phagocytosis, recurrent infections due to catalase positive organisms are more common as the leucocytes are unable to kill catalase positive bacteria following phagocytosis.
Staph epidermidis
Enterococcus
Streptococcus
Pneumococcus
Staphylococci