Molecular epidemiology, antibiogram profile and risk factor analysis of pathogenic Escherichia coli associated with pre-weaning diarrhoea in piglets from Haryana, India.

Background: Piglet diarrhoea is a multifactorial disease with serious implications for the swine industry worldwide, including India. The Escherichia coli (E. coli) pathotypes, i.e., enterotoxigenic E. coli (ETEC) and Shiga toxin-producing E. coli (STEC) are among the major bacterial agents attributed as causative agent for piglet diarrhoea, but studies related to genetic diversity, antibiogram profile and their correlation with risk factors of these pathogens are sparse.

Material And Methods: A total of 104 faecal swab samples were collected from 32 different piggery units of Haryana, India and confirmed as E. coli by standard microbiological methods. The identified E. coli were characterized as ETEC and/or STEC using PCR assays and were studied for their genetic diversity by phylogenetic analysis of the sequences. All the isolates were subjected to antimicrobial susceptibility testing. Further, the correlation of variables with presence or absence of ETEC and/or STEC was also investigated by using Fisher's exact test.

Results: Microbiological isolation led to identification of 208 E. coli isolates. A total of 17.3% (31/208) isolates were characterized as ETEC and 4.8% (10/208) isolates as STEC, whereas 2.4% (5/208) isolates exhibited both ETEC and STEC pathotype. Of the total studied piggery units (n = 32), ETEC were isolated from fourteen and both ETEC and STEC from eight farms. The phylogenetic analysis of Stx2 gene revealed 100% homology with Stx2eA variant from Germany, while analysis of STII gene revealed a distinct nucleotide and amino acid substitution when compared with standard strains. The antibiotic susceptibility testing revealed maximum resistance to moxifloxacin (71.9%) followed by tetracycline (58.1%) and amoxicillin with a total of 41.8% (87/208) E. coli isolates designated as multi-drug resistant (MDR). The multiple antibiotic resistance index varied from 0.05 to 0.75. The statistical analysis suggested three factors viz., number of farm worker(s), frequency of using disinfectant for floor cleaning and use of antibiotic in feed as risk factors significantly associated (p < 0.05) with ETEC associated diarrhoea at piggeries under study.

Conclusion: Current study warrants a need for systematic studies on the ETEC/STEC associated diarrhea and antibiotic resistance among these isolates to understand the mechanisms of origin and dissemination of drug resistant pathogens and to design suitable prevention and control measures to curb emergence of antibiotic resistance in the farm settings.