Alafosfalin as a Selective Agent for Isolation of Salmonella from Clinical Samples

Abstract

ABSTRACT The selectivity of a range of culture media for the detection of Salmonella was assessed using 435 strains of gram-negative bacteria. These media showed limited ability to inhibit non- Salmonella strains found in stool samples. We report the evaluation of alafosfalin as a selective agent for isolation of Salmonella from stool samples. Susceptibility studies with this agent showed that non- typhi Salmonella strains were relatively resistant (mean MIC, 10.2 mg/liter) compared to many coliforms including Escherichia coli (mean MIC, 0.7 mg/liter). A chromogenic medium, ABC medium, was modified to incorporate alafosfalin and was compared with standard ABC medium and Hektoen enteric agar for the isolation of Salmonella from 1,000 stool samples. On direct culture, modified ABC medium showed higher recovery of Salmonella (53.6%) compared with either ABC medium (35.7%) or Hektoen enteric agar (48.2%). We conclude that alafosfalin is a useful selective agent for the isolation of Salmonella from stool samples.