ANTAGONIST ACTIVITY OF THE MICROORGANISMS FROM SELECTED LOCAL DAIRY FERMENTED FOODS ON ESCHERICHIA COLI O157:H7.

Abstract

Escherichia coli O157:H7 which is a strain of the enterohaemorrhagic E. coli group is recognized as an organism whose presence in any food material can lead to serious disease outbreak. Globally, the bacterium poses a great threat to human health. This is because in addition to causing haemolytic uremic syndrome, kidney failure can also feature. Moreover, treatment of infections caused by this bacterium is difficult because this microorganism is known to be resistant to many conventional antibiotics. Therefore there is the need to search for alternative therapies. In searching for alternatives, the microorganisms present in some fermented local dairy foods; Local cheese (Warakasi), Butter milk (Oriamo) and Sour milk (Nono) were isolated, identified and investigated for antagonistic activity against Escherichia coli O157:H7 isolated from different sources which included Poultry, Clinical, apparently healthy individuals and Typed culture, using standard microbiological assays. The bacterial isolate with the highest antagonistic activity against E. coli O157:H7 was investigated for therapeutic activity in Wistar albino rats infected with the test bacteria using standard methods. Out of thefollowing bacterial species isolated from the fermented dairy products used; Lactobacillus casei,L.brevis, L.fermentum, L. plantarum,L. lactis, Streptococcus thermophilus, S.fermentum, E. coli, Micrococcus sp, Aeromonashydrophila, Bacillus cereus, Corynebacteriumsp, Klebsiellapneumoniae, Serratiasp, Staphylococcus aureus, Shigelladysentriae, Salmonella typhi, only L.casei showed greater antagonistic activity than all the conventional antibiotics used (including the fluoroquinolones) on all the isolated E. coliO157: H7 irrespective of their source. Out of the fungi isolated from the dairy foods which included Amorphotheca resinae, Aspergillus flavus, A. fumigatus, A. niger, Candida albicans, Fusarium sp., Geotrichum sp., Monilia sp., Penicillium notatum, Rhizopus stolonifer, Saccharomyces cerevisiae and Schizosaccharomyces pombe, only P. notatum, A. flavus and A. fumigatus obtained from the fermented dairy foods showed higher antagonistic activity than all the conventional antibiotics (including the fluoroquinolones) used on all the isolated E. coli O157:H7 irrespective of their source. Therefore, these organisms can be exploited as sources of novel drugs that can be employed in the treatment of infections caused by E. coli O157:H7 as an alternative to conventional antibiotics.