Antibiotic Susceptibility of Shiga Toxin Producing E. coli O157:H7Isolated from Different Water Sources

Nowadays the extensive use of antibiotics for the treatment of humans and warm blooded animals has influ- enced the frequency and spread of antibiotic resistant E. coli O157:H7 in different aqueous sources. Thus, the main aim of this study was to evaluate the antibiotic susceptibilities of E. coli O157:H7 isolated from different water sources and es- tablish a correlation between the presence of virulence genes of E. coli O157:H7 with the resistance to six antibiotic groups (amoxicillin, cefixime, ciprofloxacin, tetracycline, clarithromycin and streptomycin) extensively used in Egypt. To achieve this aim 44 suspect E. coli O157:H7 isolates were confirmed by biochemical tests and were characterized for six virulence genes: fliC, stx1, stx2, eae, rfbE and hlyA using multiplex PCR. All E. coli O157:H7 isolates carrying three (stx2, eae and rfbE) or more virulence genes were resistant to amoxicillin and 77% were resistant to clarithomycin. In conclusion, it appears that the environmental E. coli O157:H7 strains develop strategies for antibiotic resistance more than reference strains.