Emergence and Antimicrobial Resistance Patterns of ESBL-Producing Escherichia coli Isolated from Clinical and Subclinical Mastitis Cases in Egyptian Dairy Cattle

The emergence and global spread of ESBL-producing Enterobacteriaceae is a growing public health concern. ESBL-producing E. coli ESBL-PE poses a significant health risk, particularly with the emergence of new variants carrying blaSHV, blaTEM and blaCTX-M genes. This study looked at antibiotic susceptibility, genotyping, and gene sequencing in order to discover ESBL-PE in milk from cows with subclinical and clinical mastitis in three Egyptian governorates. 186 milk samples were analyzed in this study in order to isolate E. coli and identify which ones developed ESBL Antibiotic resistance of ESBL- PE was assessed on Mueller-Hinton agar using 10 different commercial antibiotic disks. Resistance genes were genotyped using (PCR).The obtained sequences were evaluated using Chromas pro1.7 and the maximum-likelihood phylogenetic trees were constructed using MEGA11. E. coli was found in (n. 16/57) 28.07% and (n. 27/46) 58.69 %, while (ESBL- PE) were found in (13/57) 22.8% and (7/46) 15.2% with clinical mastitis and subclinical mastitis respectively. ESBL- PE showed greater resistance to ampicillin, amoxicillin and streptomycin at percentage of 91.67% while more sensitive to azithromycin , norfloxacin , and gentamicin by 83.33%. Results indicated that 8.3%, 16.7% and 8.3% of ESBL- PE were susceptible to ciprofloxacin, tetracycline, and amoxicillin. The blaTEM gene was recorded in GenBank as PQ45739. This study detected that ESBL- PE, harboring blaSHV and blaTEM antibiotic resistance genes, were identified in mastitis milk. Consistent monitoring of ESBL- PE and proactive measures are crucial to avoiding the future lay out of resistance genes.