Prevalence and Geographical Distribution of blaTEM, tetA, and sul۱ Antibiotic Resistance Genes in Escherichia coli Isolated from Dairy Cattle across the Middle East: A Systematic Review (۲۰۱۵–۲۰۲۵)

Background: Antimicrobial resistance (AMR) in bovine Escherichia coli is an increasing concern across the Middle East, posing risks to both animal health and food safety. This review summarizes recent evidence on the prevalence and distribution of three key resistance genes—blaTEM, tetA, and sul۱—in E. coli isolated from dairy cattle between ۲۰۱۵ and ۲۰۲۵. Methods: A systematic search was performed in PubMed, Scopus, ScienceDirect, and Google Scholar using predefined Boolean combinations. Eligible studies were required to provide PCR- or qPCR-based detection of at least one target gene from dairy-associated isolates (milk, udder swabs, or feces). Owing to variations in study design and reporting format, the findings were synthesized descriptively. Quantitative comparison was feasible only for Iran and Egypt, while reports from Turkey and Saudi Arabia were analyzed qualitatively. Results: The reviewed literature revealed marked inter-country variation. Iranian studies frequently reported very high detection rates of blaTEM in E. coli from mastitis milk. In Egypt, a smaller dataset (n = ۱۰) found blaTEM in ۱۰۰% of isolates and tetA and sul۱ in ۵۰% each, indicating the presence of multidrug-resistant (MDR) strains despite the limited sample size. Reports from Turkey and Saudi Arabia also confirmed the coexistence of β-lactam and tetracycline resistance genes, though standardized prevalence data remain scarce. These differences likely reflect variations in antibiotic usage, diagnostic panels, and surveillance infrastructure rather than a single regional pattern. Conclusions: Resistance determinants are widespread yet inconsistently reported across Middle Eastern countries. Harmonized molecular surveillance and prudent antibiotic stewardship—under the One Health framework—are urgently needed. Future studies should employ standardized gene panels, broaden longitudinal sampling, and integrate whole-genome sequencing (WGS) to identify emerging hotspots and gene flow.

کلیدواژه ها:

Escherichia coli ، antimicrobial resistance ، blaTEM ، tetA ، sul۱ ، dairy cattle ، Middle East