keywords: Antibiotic Resistance. ESBL. Wastewater. Piggery
This study examined the occurrence of extended spectrum beta lactamase activity in Escherichia coli isolated from wastewaters of selected pig farms. Bacterial isolation was done by standard method and identification was achieved following recommended biochemical tests. Isolates obtained were tested for susceptibility to antibiotics using the Kirby Bauer disk diffusion method while phenotypic characterization to detect ESBL activity was done using the combination disc method. A total of 131 E. coli isolates were gotten from the study farms with the highest prevalence from the farm settlement. Antibiotic resistance (AR) among E. coli ranged between 0% and 89.6% to colistin and tetracycline respectively. Resistance levels were observed to be highest for ampicillin (82.1%) and tetracycline (89.6%) across sampled farms. ESBL activity among isolates ranged between 10.6% and 59.6% and all ESBL positive isolates were multiple antibiotic resistant (MAR) to at least three unrelated antibiotic classes. Predominant MAR phenotypes included ampcilin-tetracycline-cefpodoxime-sulfamethoxazole/trimethoprim-erythromycin-nalidixic acid-chloramphenicol and ampicillin-tetracycline-cefpodoxime-sulfamethoxazole/trimethoprim-erythromycin-ceftriaxone-nalidixic acid-chloramphenicol-gentamycin; found in isolates from the three farms with the highest occurrence in the farm settlement. Our study showed that piggery wastewater could be a significant reservoir of multiple antibiotic resistant bacteria with ESBL activity.