Abstract

James A. Okoro* and Benedict Osagie Oruma

Escherichia coli O157:H7 and Salmonella species have continued to cause gastrointestinal complaints in people in developing countries. 180 stool specimens from 80 undergraduates , 100 food vendors, and 86 specimens from non-human sources were screened for the presence of the pathogens. Fresh stool specimens were inoculated onto Sorbitol MacConkey Agar (Oxoid CM813), Selenite F Broth (Oxoid CM 395), Deoxycholate Citrate Agar (Oxoid CM 0227), MacConkey Agar (Oxoid CM 7) and Blood Agar (Oxoid CM 55). Colonies growing on media after 24 hours incubation at 370 C were identified biochemically. Latex agglutination test reagents (Oxoid DR 620) were used for serological identification of O157:H7 strains. One (5.6%) specimen from a food vendor yielded E.coli O157:H7. 9(5%) specimens yielded Salmonella spp. Of the 86 non-human samples, 3 (3.5%) were contaminated with E. coli O157:H7. Thirty (35%) non- O157: H7 strains were also recovered; the highest proportion of 26 (30.2%) being from hawked food items. Proteus spp (8.1%) was the next commonly isolated pathogen. Only an isolate each of Salmonella and Shigella spp were recovered from hawked foods. The incidence of E.coli O157:H7 and Salmonella spp was low in non-human samples; a possible reason for the low incidence observed in humans in this locality.