Molecular detection and patterns of multidrug resistance in Escherichia coli isolated from buffaloes

This study focused on the characterization of both phenotypic and genotypic antimicrobial resistance (AMR) in Escherichia coli isolated from buffalo. A random sampling approach was implemented in this study, leading to the collection of 400 nasal swab samples from the respiratory tract of buffaloes. The samples were subjected to analysis through conventional bacteriology and molecular techniques to isolate and identify E. coli . Resistance to 14 antimicrobial agents was evaluated using the disc diffusion method and presence of various AMR genes in the E. coli isolates was determined by polymerase chain reaction (PCR). A total of 87 E. coli isolates were identified, resulting in a prevalence of 21.75%. Buffaloes with respiratory symptoms showed significantly higher prevalence than healthy buffaloes (χ² = 28.445, p < 0.001 ). Tetracycline resistance was most prevalent (88.51%, n = 77), followed by reduced susceptibility to sulphamethoxazole–trimethoprim (36.78%, n = 32), while resistance to amoxicillin–clavulanic acid (3.45%, n = 3) and cefixime (8.05%, n = 7) remained low. At the genetic level, tetA was the dominant resistance determinant (85.06%, n = 74), followed by aac(3)-IV (68.97%, n = 60), strA (67.82%, n = 59), and sul1 (52.87%, n = 46). Notably, 80.46% of E. coli isolates were classified as multidrug-resistant (MDR). The data reveals that E. coli obtained from buffaloes exhibits resistance to multiple critical antimicrobials and possesses genes associated with AMR that have implications for human health. The findings of this study provide a foundational basis for effectively mitigating AMR within the buffalo population. In resistance surveillance programs, the inclusion of buffaloes is a critical factor that must be taken into account.