A Study Of Bacterial Agents Associated With Diarrhoeal Cases In The Federal Capital Territory, Abuja

Abstract

One hundred and six faecal samples were analyzed to detect the sporadic involvement of E. coli O157:H7, other Enterohaemorrhagic E. coli and common bacterial pathogens in enteric infections within the Federal Capital Territory, Abuja. Enrichment culture in modified peptone water followed by immunomagnetic separation (IMS) with magnetic beads coated with an antibody against Escherichia coli O157 was used in addition to Direct culture on Sorbitol MacConkey agar and Cefixime-Tellurite Sorbitol MacConkey agar for the isolation of E. coli O157: H7. For the identification of non-O157 STEC among the Non-sorbitol fermenting E. coli isolated, PCR for virulence markers was used. Verocytotoxicity Assay was used to detect free faecal toxin in the stool samples for the identification of other Enterohaemorrhagic E. coli (EHEC) infections. Routine methods were used for the isolation of common bacterial pathogens and for identification of isolates. Antimicrobial susceptibility tests were carried out on the isolates using the disc diffusion technique while interpretation of zone sizes was done using the NCCLS interpretative chart. Stool Microscopy for ova or cyst of parasites was also done using the formol ether sedimentation technique. No E. coli O157:H7 was isolated. However, free faecal toxin was demonstrated in 16 (15.09%) of the 106 faecal samples analyzed indicating the involvement of non-O157 VTEC in diarrhoeal diseases in the Federal Capital Territory, Abuja. None of the non-sorbitol fermenting E. coli was found to be STEC. Enteric pathogens isolated from the study include V. cholerae (1.9% of the faecal sample), S. typhi (1.9%), S. paratyphi B (0.95%), S. paratyphi C (0.95%), unidentified Shigella species (0.95%), Shigella dysenteriae A1 (1.9%), Shigella flexneri (4.7%) Entamoeba histolytica (0.95%), Hookworm (0.95%), Schistosoma mansoni (0.95%) and Candida spp (6.6%). Sorbitol MacConkey agar was found to be more sensitive than the Deoxycholate Citrate agar and Selenite F enrichment broth routinely used for the isolation of Shigella flexneri. Thus, for optimal isolation of Shigella flexneri, the inclusion of MacConkey agar among the media used for routine cultures is recommended. V. cholerae isolates were 100% sensitive to tetracycline and ciprofloxacin, Shigella species were 100% resistant to tetracycline and 100% sensitive to ciprofloxacin. The Salmonella isolates were 100% sensitive to ciprofloxacin while showing varied degrees of resistance to tetracycline, chloramphenicol and trimethoprim-sulphamethoxazole. These results show the need to promote rational use of antibiotics in FCT. The results, also, suggest that the incidence of non-O157 VTEC involvement in diarrhoeal diseases may be quite common and should be considered as an agent in diarrhoeal illnesses especially among children.