Microscopic examination of stools and a latex slide agglutination test for the rapid identification of bacterial enteric infections in khmer children

Abstract

Eighty-five stools collected from 50 children with diarrhea at an evacuation site on the Thai-Kampuchean border were (1) examined microscopically for fecal leukocytes, (2) tested after 24 hr enrichment in brain/heart infusion broth by a latex slide agglutination test for detection of Salmonella and Shigella, and (3) examined with microbiological techniques to identify bacterial, viral, and parasitic pathogens. If the 65 specimens in which one or no pathogens are considered, 6 or more fecal leukocytes/hpf were found on microscopic examination of stools in both children infected with Shigella spp., the one child infected with Salmonella spp., and three of eight children infected with Campylobacter spp. Less than or equal to 5 leukocytes/hpf were found in 70% ( 7 10 ) of children infected with rotavirus, 100% ( 2 2 ) infected with Cryptosporidium, 100% ( 2 2 ) infected with Giardia, 89% ( 8 9 ) infected with enterotoxigenic Escherichia coli, and 77% ( 24 31 ) with diarrhea in whom no etiologic agent was identified. The Salmonella slide latex test had a sensitivity of 50%, a specificity of 92%, and a positive predictive value of 12%. The Shigella slide latex test had a sensitivity of 0%, a specificity of 95%, and a positive predictive value of 0%. Forty-five percent of the latex slide agglutination tests from enrichment cultures were nonspecific. Microscopic examination of diarrheal stools for fecal leukocytes, though nonspecific, appears to be the best way to differentiate Shigella spp. from rotavirus and parasitic infections. Examining stools for fecal leukocytes was less helpful in differentiating Shigella from other bacterial infections.