Question

SF medium is a selective medium, developed in the 1940s, to test for fecal contamination of milk and water. Only certain gram-positive cocci can grow in this medium. Why is it named SF? Using this medium, which genus will you culture?

Answer 1

Answer:

It is named SF for Streptococcus faecalis.

The genus Streptococcus will be cultured.

Explanation:

• A selective media is the one which allows the growth of only certain organism with selective properties to ensure that any other organisms do not grow on the media.
• Streptococcus faecalis is a gram-positive cocci which contaminates milk and water through the fecal route as it inhabits the gastrointestinal tracts of several mammals including humans.
• The media in which Streptoccous faecalis grows is termed as SF indicating the first letter of the genus and second for the species and being a selective media it can only culture the genus Streptococcus.