Detection and Zoonotic Implications of Shiga Toxin-Producing Escherichia coli in Black Bengal Goats in Bangladesh.

BACKGROUND

Shiga toxin-producing Escherichia coli (STEC) is an important zoonotic pathogen and a global public health concern due to its association with foodborne disease.

OBJECTIVES

This study aimed to determine the prevalence of STEC and general E. coli carriage in Black Bengal goats in Bangladesh and assess associated risk factors for zoonotic transmission.

METHODS

A total of 300 goats (200 diarrheic and 100 healthy) were sampled from the Shahedul Alam Quadary Teaching Veterinary Hospital and its surrounding areas between July 2023 and June 2024. Recto-anal junction swabs were cultured on MacConkey agar, Eosin Methylene Blue agar, and cefixime-tellurite-supplemented Sorbitol MacConkey agar. Sorbitol non-fermenting colonies were screened for uniplex PCR for stx1, stx2, hlyA and multiplex PCR for eae, ehxA, saa, and subA genes using multiplex PCR.

RESULTS

Overall, 4.3% of isolates were sorbitol non-fermenters. Molecular characterization revealed that one isolate (0.3%) from a diarrheic goat carried the stx2 and ehxA genes, while another isolate (0.3%) from a healthy goat was positive for saa and subA. No isolates carried stx1, hlyA, or eae. The isolation rate of E. coli (non-STEC) was significantly higher in diarrheic goats than in healthy ones (p = 0.001). Risk factor analysis revealed significant associations between general E. coli carriage and several factors, including frequent child-animal contact (OR = 2.45, p = 0.031), shared living spaces (OR = 2.36, p = 0.045), and farms near waterlogged areas (OR = 3.72, p = 0.008). Mixed livestock rearing and seasonal humidity also contributed to increased E. coli carriage.

CONCLUSIONS

These findings, although representing a low overall prevalence, demonstrate the presence of diverse virulence profiles in Black Bengal goats, including markers associated with severe human disease in LEE-negative strains. The detection of saa and subA suggests that these goats may serve as a reservoir for atypical STEC strains with zoonotic potential, necessitating broader surveillance strategies.