A urine sample of a patient suspected to have urinary tract infection(UTI) was sent to the microbiology lab. On culture, the colony shows hemolysis on blood agar, on eosin methylene blue (EMB) agar the following is seen, a positive indole test, and a positive MUG test. The most likely etiologic organism is

The above described features & colony morphology are characteristic of E.coli and help in its rapid identification. E. coli colonies show hemolysis on blood agar and iridescent sheen on differential media such as Eosin methylene blue (EMB) agar. Indole test will be positive for E.coli. More than 90% of E. coli isolates are positive for b-glucuronidase using the substrate MUG (4- methylumbelliferyl-b-glucuronide), known as the MUG test. Isolates from anatomic sites other than urine with the characteristic colony features (plus a negative oxidase test ) can be confirmed as E.coli with a positive MUG test. Reference: Ananthanarayan and Paniker&;s Textbook of Microbiology Tenth edition