Which of the following test will differentiate Vibrio cholerae from E.coli?
High-Yield Explanation
Answer: a) Oxidase test (PANIKER 9th EDITION P-305)ENTEROBACTER1ACEAE* Grow well in MacConkey media* Catalase positive (except Shigella dysentriae type 1)* Oxidase & Urease negative* Urease negative (except Proteus, Klebsiella, Morganella)* Motile by peritrichate flagella (except Shigella, Klebsiella, Salmonella gallinarum-pullorum)* Ferment glucose (except Shigella)VIBRIO CHOLERAE* Comma shaped, gram negative* Fish in stream appearance in stained films* Darting type of motility* Under microscope motile vibrios suggest swarm of gnats* NaCI(0.5-l%) is required for optimal growth, though higher concentrations(>6%) are inhibitory* Gelatin slab culture infundibulum (funnel shaped)or napiform(turnip shapedjliquefaction occurs* Vibrio colonies are identified by string test* Catalase +ve, Oxidase +ve, indole +ve, Urease negative* Cholera red reaction (indole formation + nitrate reduction) adding few drops of con. Sulphuric acid to alkaline peptone water cultureLactose FermentationOrganismsOccursEscherichia, Klebsiella, EnterobacterDoes not occurShigella, Salmonella; Proteus, PseudomonasOccurs slowlySerratia, Vibrio Optochin test - to differentiate S. Pneumoniae from other alpha-hemolytic streptococci. CAMP test - to identify Group B beta-hemolytic streptococcus and differentiate it from Group A streptococcus Catalase test is used to differentiate staphylococci from streptococci.