A stool sample from a suspected case of enteric fever is inoculated first into a liquid medium to allow overgrowth of Salmonella organisms before subculture onto selective agar. Which enrichment medium is conventionally used for this purpose?
- A Thioglycollate broth
- B Selenite F broth ✓
- C Peptone water
- D Tryptic soy broth with 0.05 percent cystine
Correct answer: B. Selenite F broth
Explanation
Enrichment media contain inhibitors that suppress normal faecal flora while permitting multiplication of the target pathogen. Selenite F broth, containing sodium selenite, selectively favours Salmonella and Shigella and is the standard choice before plating on deoxycholate citrate or XLD agar. Thioglycollate broth supports anaerobes and fastidious organisms without selectivity, peptone water is a simple basal medium, and tryptic soy broth is a general non-selective nutrient base.
Reference: Ananthanarayan and Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.