Prevalence and Characterization of Shiga-Toxin O157:H7 and Non-O157:H7 Enterohemorrhagic Escherichia Coli Isolated from Different Sources

Abstract

ABSTRACTShiga-toxin-producing Escherichia coli (STEC) is recognized as an important foodborne pathogen responsible for sporadic cases to serious outbreaks worldwide. The morbidity and mortality associated with several recent outbreaks due to STEC have highlighted the threat this organism poses to public health. This study was conducted to identify, characterize the virulence traits and antibiogram of enterohemorrhagic E. coli (EHEC) from different sources. A total of 384 samples from human, animal and environmental sources were collected from different locations in Ismailia city, Egypt. E. coli isolates (n = 283) were identified by conventional microbiology culture, and phenotypically characterized with biochemical and motility tests. Multiplex PCR (mPCR) was applied for the detection of virulence genes (stx1, stx2, eaeA, and EHEC hlyA). From the overall prevalence of E. coli isolates, 31 % (89/283) were isolated from stools of people with diarrhea; 17.3 % (49/283) were from stools of sheep, cattle and chicken with diarrhea; 16.5 % (47/283) were from urine of peple with a urinary tract infection; 17.3 % (49/283) were from fresh water; 6.4 % (18/283) from seafood; 6.02 % (17/283) from processed meat products; 3.9 % (11/283) from dairy products; and 1.1 % (3/283) from poultry products (liver). The antibiotic sensitivity pattern showed that the isolates carried a multidrug resistance (MDR) phenotype to at least four antibiotics from different classes: erythromycin (E), gentamicin (CN), cefazolin (CZ), thiampinicol (TP), vancomycin (VA), ciprofloxacin (CIP), and ampicillin (AM). Shiga toxin was identified in ten suspected EHEC by mPCR. Serotyping of these 10 E. coli isolates demonstrated the circulation of five serotypes (O157, O158, O114, O125 and O26) (10/283 [4%]): three isolates from people (serotype O157, O158), four isolates from animals (serotype O114, O26), two isolates from meat products (serotype O125, O158), and an isolate from fresh water (serotype O114). This study identified STEC O157 from human cases with diarrhea, and demonstrated that meat and water were contaminated with more than one serotype of non-O157 STEC strains. This is a cause of concern owing to their potential to cause human infections.