Question

Are there any tests that distinguish Enterococcus organisms from other Gram positive organisms? And what does such a test use that distinguishes them.

Answer 1

 

According to the given question-

• Enterococcus microorganism are  gram-positive, have cocci shape generally in diplococci and also sometimes in short chains, found in humans  intestines such as E. faecalis.
• Streptococcus species are also gram-positive and have similar structure as Enterococcus microorganism. so the Enterococcus microorganism are differentiated from the other gram positive microorganism by -
• Bile esculin agar used as selective and differential medium for identification of  enterococci from streptococci.
• This test is based on the ability of microorganism to hydrolyze esculin.
• Bile esculin agar contains bile salt such as oxgall which inhibit gram positive microorganisms growth except  enterococci.
• This medium also contains esculin, and ferric citrate. the microorganism which can hydrolyzes glycoside esculin which is a sugar bonded through acetyl linkage with  alcohol made up of glucose and esculetin into esculetin and dextrose.
• Then esculetin after reaction with ferric citrate form a phenolic iron complex of  dark brown or colour. This is positive result for Enterococcus microorganism.