Molecular Characterization And Evaluation of Antibiotic Susceptibility And Biofilm Forming Capacity of Pathogenic Escherichia Coli Isolated From Seafood

Abstract- The occurrence of E. coli in seafood is directly related to faecal contamination and/or unhygienic handling during processing. This pathogen also forms biofilms on food processing equipment and other food contact surfaces and thus acquire drug resistance mechanism. Hence, this study has been undertaken to investigate the presence of E. coli in seafood and to determine the antimicrobial susceptibility patterns and biofilm forming capacity of this pathogen.

In this study, 21 E. coli isolates were isolated from 43 seafood samples and were biochemically confirmed. PCR was employed to isolate pathogenic strain targeting virulent genes by using gene specific primers. The PCR results revealed that out of 21 isolates screened for the presence of pathogenic E. coli, none of them showed positive results for the presence of pathogenic strains except for rfbE gene of EHEC with specific band of 213 bp on agarose gel.

The antibiotic susceptibility pattern showed that 19 strains (90%) were resistant to trimethoprim, co-trimoxazole, gentamicin, polymyxin-B, and tetracycline whereas all the 21 isolates were sensitive to doxycycline, naladixic acid and azithromycin. The calculated multiple antibiotic resistance (MAR) index for 17 isolates (81%) were above 0.2 and the range of MAR for all the isolates was between 0.2 and 0.5 which clearly indicates that E. coli isolated from seafood are multidrug resistant (MDR). Even though all the isolates exhibited complete resistance to trimethoprim with no MIC level, the MIC observed for ciprofloxacin was found to be as low as 0.016 mcg/ml, whereas for polymyxin-B and gentamicin it was as high as 128 mcg/ml. About 72% (15 isolates) isolates obtained were found to be moderate biofilm producers by conventional tube method. Interestingly this study revealed the emergence of antibiotic resistance in biofilm forming E. coli seen associated with seafood from Cochin markets, which may pose future threat to develop control strategies in the fish processing industry and also pose significant treatment challenge to physicians.