Bile esculin test is used to differentiate -

Ans. is 'b' i.e., Enterococcus fecalis * Enterococci grow in the presence of bile and hydrolyze esculine ->> bile esculin positive.Enterocococci* Enterococci were originally classified as streptococcit because organisms of the two genera share many morphologic and phenotypic characteristics. However, DNA hybridization and 16 S rRNA sequencing clearly demonstrated that enterococci should be grouped as a genus distinct from streptococci.* Thus, enterococci are not streptococci (previously they were classified as group D streptococci, along with non-enterococcal group).* Majority of the infections are caused by E. faecalis and E. faecium. Less frequently isolated species are E. gallinarum, E. durans, E. hirae and E. avium.* Enterococci are normal inhabitants of the large bowel of human adults, although they usually make up < 1% of the culturable intestinal microflora.* They are catalase negative (as all streptococci).* Their characteristic feature is that they can grow in presence of1) 40% bile2) 6.5% Sodium chloride3) At pH 9.64) At 45degC (relative heat resistant surving 60degCfor 30 minutes)5) In 0.1% methylene blue milk* They hydrolyze esculin. They grow in presence of 40% bile and hydrolyze esculin --> Bile esculin positive.* They are PYR (Pyrrolidonyl Arylamidase) positive.* They are usually non hemolytic (gamma-hemolytic), but some times may show alpha or beta hemolysis.