Prevalence and Molecular Characterization of E. coli O157:H7 Isolated from Water Bodies in Ile-Ife and Environs

Abstract

Water is one of the crucial necessities of man since it is needed for almost all of his activities. With increase in population growth, quality water needed for consumption by man is on the decline because of environmental pollution. Thus the main aim of this study was to investigate the prevalence level of E. coli O157:H7 in water bodies in Ile-Ife and its environs which are the sources of water for man's consumption. Four hundred and fifty-one samples were investigated from five major sources of water namely; well, stream, borehole, bottled and sachet. The water samples were screened for E. coli and serologically characterized for E. coli O157:H7. The E. coli O157:H7 isolates obtained were further characterized for stx 1, stx 2 and eaeA genes. The result revealed that well water and stream water had a prevalence of 8.74% and 4.59% respectively. Antibiotic resistance profile of E. coli isolates showed that both sources harboured isolates that are resistant to three classes of antibiotics. The virulence gene distribution shows that stx 1 and stx 2 were present in all the E. coli O157:H7 investigated. In conclusion, it appears that the gastroenteritis outbreaks experienced in the study area may be due to the presence of E. coli O157:H7 in water samples.

Occurrence of Virulence Genes and Antimicrobial Resistance of E. coli O157:H7 Isolated from the Beef Carcass of Bahir Dar City, Ethiopia

“…coli O157:H7. These factors include production of at least one of two Shiga toxins ( stx1 and/or stx2 ), intimin ( eae ), and enterohemolysin (EHEC- hlyA ) [ 22 ]. In the present study, we investigated the existence of these four virulence genes in the isolated E. coli O157:H7 strains.…”

“…This finding was in agreement with studies in California [ 47 ], China [ 41 ], Egypt [ 42 ], and Modjo, Ethiopia [ 20 ]. The strains carrying stx2 are potentially more virulent than those carrying stx1 or even strains carrying both stx1 and stx2 [ 22 , 42 , 47 ]. On the contrary, 36% of the isolates do not have either of the two Shiga toxin-producing genes.…”

“…Multiple antibiotic-resistant isolates were defined as resistance to greater than or equal to three classes of the antibiotics tested. Plates were incubated at 37°C, and the diameter of the zone of growth inhibition was measured with calipers to the nearest millimeter and interpreted accordingly [ 22 , 31 ].…”

“…The sorbitol-negative isolates which were identified by latex agglutination test were examined by the polymerase chain reaction (PCR) (HiMedia Laboratories PLC.) to determine the presence of stx1 , stx2 , eae , and hlyA virulence genes [ 21 , 22 , 34 – 37 ]. PCR sequence of primers, their product size, and their amplification conditions are depicted in Table 1 .…”

“…The current accepted standard procedure for E. coli O157:H7 identification is amplification of stx1 , stx2 , eae, and hlyA by PCR [ 21 , 22 ]. PCR has gained more acceptance and use due to its ability to differentiate and reliability.…”