Isolation and Culture Dependent Characterization of Escherichia coli from the Sewage Waste Water of Lahore, Pakistan

Abstract

Aims: Infectious disease haemorrhagic uremic syndrome (HUS), present in sewage water, its cross contamination with drinking water may affect the community. This study was conducted to isolate the pathogenic strain of E. coli O157 from the sewage waste water of Lahore, Pakistan. The aim of this study was to evaluate biofilm formation and antibiotic susceptibility pattern for the isolated strains. Selective Hichrome EC O157 agar media was used for the isolation of E. coli.
 Methodology: Taxonomic status of strain was confirmed by 16S rRNA gene sequencing. Serotyping of E. coli O157 strains was accomplished by ProlexTM E. coli O157 Latex Test Reagent Kit results for O157. Bacterial strains were also evaluated for biofilm formation, toxin related genes (stx1, stx2, stx2c, stx2d) and antibiotic sensitivity.
 Results: Bacterial strains showed resistance against amoxicillin, tobramycin, tetracycline and nitrofurantoin antibiotics. Maximum biofilm formation was shown by strain E124 when used as monoculture. In cocultures, strains E35 and E101 were the most efficient biofilm formers. PCR amplification recorded negative results for shiga toxin genes.
 Conclusion: Shiga toxin genes were not present in any of the E. coli strain, from which we can suggest that our environment is free of shiga toxin genes. E. coli was present in sewage water, its cross contamination with drinking water may affect the community. Therefore, waste water should be treated properly before discarding it into the common water bodies.