The distribution of Escherichia coli serovars, virulence genes, gene association and combinations and virulence genes encoding serotypes in pathogenic E. coli recovered from diarrhoeic calves, sheep and goat.

Ruminants, especially cattle, have been implicated as a principal reservoir of one of the enterovirulent Escherichia coli pathotypes. The detection of the virulence genes in diarrhoeic calves and small ruminants has not been studied in Egypt. To determine the occurrence, serotypes and the virulence gene markers, stx1, stx2, hylA, Flic(h7) , stb, F41, K99, sta, F17, LT-I, LT-II and eae, rectal swabs were taken from diarrhoeic calves, sheep and goats and subjected to bacterial culture and PCR. The E. coli prevalence rate in the diarrhoeic animals was 63.6% in calves, 27.3% in goat and 9.1% in sheep. The 102 E. coli strains isolated from the calves, goat and sheep were 100% haemolytic non-verotoxic and fitted into the Eagg group. The isolates belonged to seven O serogroups (O25, O78, O86, O119, O158, O164 and O157). The eae gene was detected in six of the strains isolated from the calves. The 102 bovine, ovine and caprine E. coli strains isolated in this study were negative for stx1, stx2, F41, LT-I and Flic(h7) genes. The highest gene combinations were found to occur in the form of 24/102 isolates (23.5%) that carried the F17 gene predominantly associated with eaeA, hylA, K99 and Stb genes in the calves, while the hylA, K99 and Sta were the only genes found to be in conjunction in both calves and goats (6/102; 5.9% each). Our data show that in Egypt, large and small ruminants could be a potential source of infection in humans.

Identification of serotypes and virulence markers of Escherichia coli isolated from human stool and urine samples in Egypt.

PURPOSE: Haemorrhagic colitis and haemolytic-uremic syndrome are associated with Shiga-toxin producing Escherichia coli (STEC). There are others DEC (Diarrhoeagenic E. coli) pathotypes responsible for outbreaks and others toxins associated to these. Most clinical signs of disease arise as a consequence of the production of Shiga toxin 1 (Stx1), Stx2 or combinations of these toxins. Other major virulence factors include E. coli haemolysin (hlyA), and intimin, the product of the eaeA gene that is involved in the attaching and effacing adherence phenotype. MATERIALS AND METHODS: In this study, the PCR assay was used to detect 12 E. coli genes associated with virulence (stx1, stx2, hylA, Flic h7 , stb, F41, K99, sta, F17, LT-I, LT-II and eaeA). RESULTS: A total of 108 E. coli strains were serotyped into 64 typable strains. The investigated strains from the stool, 8/80 (10%) strains were O 164:K, while the 56/110 strains isolated from the urine were O126:K71 (44/110, 40%) and O 86:K 61 (12/110, 11%). The distribution pattern of the detected virulence genes was observed to be in the following order: F17 (10% from the stool and 44% from the urine), Sta (10% from the stool), hylA (10% from the stool and 44% from the urine), Stb (44% from the urine) and stx1 (27% from the urine). The 8 faecal strains encoded a combination of the F17, Sta and hylA genes, while the 56 urine strains encoded a combination of the F17 0+ Stb + hylA (44/110, 40%) and Stx1 only (12/60, 20%). CONCLUSION: This is the first report on the molecular characterization of E. coli diarrhoeagenic strains in Egypt and the first report on the potential role of E. coli in diarrhoea and urinary tract infections in a localized geographic area where the people engage in various occupational activities.