Abstract

Aims: Extended-spectrum beta-lactam (ESBL) antibiotics resistance is one of the top antimicrobial threats globally. Recent evidence suggests the emergence of ESBL-positive Escherichia coli from the animal origin foods. However, information on the animal origin ESBL-positive E. coli is very limited in Bangladesh. The present study investigated the frequency and characteristics of ESBL-positive E. coli in milk samples from cows with mastitis in northern Bangladesh.
Methods: The phenotype of ESBL-positive E. coli was determined using ESBL-CHROM agar media and the antibiotic sensitivity was measured by disk diffusion method. PCR was used to detect the E. coli and ESBL-genes of the isolates.
Results: This study detected 60 E. coli isolates from 400 milk samples. Among the isolates, ESBL-positive E. coli was detected in 14 (23.33%) isolates according to the results of phenotypic confirmatory methods. Our findings further demonstrated that the most common ESBL gene was blaCTX-M (92.86%), subsequently 71.43% of the isolates had blaTEM. Most of the isolates bearing blaCTX-M gene also harbored with blaTEM gene (78.57%). Interestingly, blaSHV gene was absent in all isolated E. coli strains. Antibiogram revealed 100% of ESBL-positive isolates showed multidrug-resistant (MDR) in nature and exhibited complete resistance to ampicillin. Additionally, 92.86% were resistant to cefuroxime, cefaclor, and cefotaxime, while 85.72% showed resistance to cefpodoxime, amoxicillin-clavulanic acid, and aztreonam. Notably, all isolates were 100% sensitive to carbapenems.
Conclusion: This study provides noble evidence on the animal borne ESBL producing E. coli and raises need for vigilant antibiotic stewardship and robust infection control measures.

Key words: Escherichia coli, mastitis, antibiotic resistance, multidrug resistance