Prevalence and Genetic Relatedness of Extended Spectrum-β-Lactamase-Producing Escherichia coli Among Humans, Cattle, and Poultry in Pakistan

Objective: To determine the prevalence and genetic relatedness of bla CTX-M -type extended spectrum-β-lactamase (ESBL)-producing Escherichia coli at the human–animal interface in Pakistan. Materials and Methods: A total of 150 human, cattle, and poultry fecal samples (50 each) were screened for ESBL-producing E. coli using ESBL CHROMagar ® . Bacterial species confirmation as well as determination of minimum inhibitory concentrations (μg/mL) to different antibiotics was performed using the automated VITEK ® -2 compact system. Phenotypic confirmation of ESBL production was performed according to the Clinical Laboratory Standards Institute (CLSI) guidelines. Genetic analysis of bla CTX-M was carried out by PCR and DNA sequencing. Plasmids and clonal similarity of the E. coli strains were determined by PCR-based replicon typing and pulsed-field gel electrophoresis (PFGE), respectively. Results: Of 150 samples, 29 (19.3%) ESBL-producing E. coli were recovered, and majority of them originated from human ( n  = 16; 55%), followed by cattle ( n  = 9; 31%) and poultry ( n  = 4; 13.7%). bla CTX-M-15 was predominant ESBL genotype ( n  = 25; 86.2%), mainly identified from human ( n  = 15) and cattle ( n  = 9). This is also the first report of the occurrence of CTX-M-15 and CTX-M-55 in cattle and poultry E. coli isolates of Pakistan, respectively. The majority of the ESBL-producing E. coli (96.5%) showed a multidrug resistance phenotype. All isolates carried IncFII or IncFIA plasmids, and the phylogroup B1 was dominant (44.8%) followed by phylogroups A (31%), D (17.2%), and B2 (6.8%). PFGE revealed that isolates from different hosts were genetically unrelated. Conclusion: Presence of CTX-M-15-type ESBL-producing E. coli in different reservoirs is alarming and has the potential to impact both veterinary and human therapeutic treatment options.