Shiga toxin-producing E. coli (STEC) are an important cause of foodborne illness in humans with infections ranging from mild non-bloody diarrhea to bloody diarrhea (BD) and hemolytic uremic syndrome (HUS). This study aimed to investigate the distribution of STEC in shellfish from coastal shores of Lake Timsah in Ismailia Governorate, Egypt and its probable hazard to seafood consumers. Samples from the external surface and tissues of shrimp (n = 45), crabs (n = 45), and oysters (n = 45) batches were examined bacteriologically for the presence of STEC and tested for their antibiotic sensitivity. Moreover, occurrence of virulence genes was determined via detection of stx1, stx2 and eaeA genes using PCR. Overall, E. coli and presumptive STEC isolates (from CHROMagar) were identified from the surface (55.6 and 5.9%) and tissues (42.2 and 8.9%) of the examined shellfish batches, respectively. Five STEC isolates had been confirmed and found belonging to O26:H11, O125:H6, O146:H21, and O159 serogroups, those were 4 isolates from tissues of the three shellfish species and one isolate from the crab surface. The STEC isolates were multi-drug resistant, showing complete resistance to; penicillins, amoxycillin/clavulanic acid, colistin, fosfomycin, ceftriaxone, ciprofloxacin, and tetracycline, however, they were sensitive to gentamycin except O159 serogroup. The current study revealed low level of contamination of shellfish from coastal shores of Lake Timsah with STEC, however, it also highlights the extreme level of antimicrobial resistance exhibited by the presumptive and confirmed STEC isolates which is very hazardous for seafood consumers in the study area.
Shiga toxin-producing Escherichia coli (STEC) is responsible for several food-borne outbreaks worldwide. In this study, tissue samples of finfish (tilapia, n = 100) and (mullet, n = 100), and twenty human hand swabs from fish sellers and fishermen were tested bacteriologically for STEC presence. Isolates were tested for their antibiotic susceptibility and examined for the presence of the eaeA, stx1, and stx2 genes. E. coli and STEC were identified from the tissues (36.5% and 12.5%) of the examined tilapia and mullet, respectively; however, E. coli and STEC from human hand swabs were as high as (60% and 40%), respectively. Of the recovered E. coli isolates, 25 presumptive STEC (17 from finfish and 8 from humans) yielded characteristic mauve-colored colonies on CHROMagar STEC medium. The highest prevalence of STEC was in mullet and tilapia from freshwater of Nile tributaries at 24% and 48%, followed by fish from freshwater fish farms at 16% and 12%, respectively. No STEC was isolated from fish from Suez Canal water and saltwater fish farms. Recovered STEC isolates from fish belonged to 14 serotypes belonging to (O121:
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