Rapid automated method for screening of enteric pathogens from stool specimens

Abstract

A total of 800 colonies suggestive of Salmonella, Shigella, or Yersinia species isolated on stool differential agar media were inoculated onto both conventional biochemical test media (triple sugar iron agar, urea agar, and phenylalanine agar) and Entero Pathogen Screen cards of the AutoMicrobic system (Vitek Systems, Inc., Hazelwood, Mo.). Based on the conventional tests, the AutoMicrobic system method yielded the following results: 587 true-negatives, 185 true-positives, 2 false-negatives, and 26 false-positives (sensitivity, 99%; specificity, 96%). Both true-positive and true-negative results were achieved considerably earlier than false results (P < 0.001). The Entero Pathogen Screen card method is a fast, easy, and sensitive method for screening for Salmonella, Shigella, or Yersinia species. The impossibility of screening for oxidase-positive pathogens is a minor disadvantage of this method.

Rapid fluorescence method for screening Salmonella spp. from enteric differential agars

“…More recently, this length of time for screening of Salmonella spp. and other enteric pathogens has been reduced by using new, faster methods (2,6), allowing presumptive reports within the same day.…”

“…All lactose-negative colonies were also routinely screened with triple sugar iron agar (Difco Laboratories, Detroit, Mich.) and the Enteric Pathogen Screen card (AMS; Vitek Systems, Inc., Hazelwood, Mo.) (6). Those colonies considered positive were finally identified by using urea agar, Simmons citrate agar, indole production (all available from Difco); mannitol motility agar (Institut Pasteur, Marnes La Coquette, France); lysine agar and phenylalanine agar (both from Beckton Dickinson and Co., Cockeysville, Md.…”