Antibiotic Sensitivity and Characterization of β- Lactamase Producing E. coli Isolates from Commercial Poultry

Abstract

This study was aimed at studying the antibiotic sensitivity and β-lactamase (ESBL and AmpC) production in E. coli isolated from local commercial poultry. An objective was to study the phylogenetic grouping of these isolates. Thirty E. coli isolates were recovered from the local commercial chicken and were confirmed through growth characteristics on respective medias and uidA gene PCR. Antibiotic susceptibility pattern of the E. coli isolates was determined against 13 different antibiotics. Tetracycline was found to be the least effective (80% resistance), followed by Ampicillin (76.66%) and Trimethoprim (63.3 %). On the other hand, Fosfomycin (86.66%), Gentamicin (80%) and Ceftiofur (73.3%) were found to be most effective drugs against E. coli isolates. The isolates that showed resistance to Cefpodoxime and Cefoxitin were considered potential producers of ESBLs and AmpC β-lactamases respectively. The five isolates were further tested for production of ESBLs and AmpC using a commercial D68C AmpC and ESβL Detection Disc Set (MAST Group Ltd, UK). The two isolates were positive for both AmpC and ESBL, two isolates were positive for AmpC, the remaining one was positive for ESBL only. The results of MAST kit showed agreement with the results of PCRs. bla CTX-M (ESBL gene) presented in three isolates, showed higher prevalence followed by bla-TEM in two isolates. All the isolates were negative for blaSHV gene. The AmpC genes were presented by AmpC-MOX and AmpC-FOX were present in three of isolates. A triplex PCR results depicted presence of 4 phylo-groups in the chicken E. coli isolates; most prevalent was phylo-group A (34%), followed by group B2 (23%), group D (23%) and group B1 (20%). Group A showed complete absence of ESBL and AmpC genes, while group D sowed absence of AmpC genes only. bla-TEM gene was found in isolates belonging to phylogroup D only, while bla-CTX-M was found in isolates belonging to phylogroup B2, D and B1. On the other hand, AmpC-MOX was found in phylogroup D, B2 and B1, while AmpC-FOX was found in isolates belonging to phylogroup D and B2 only. From the results of this study, it is evident that ESBL and AmpC producing E. coli in poultry meat is low as compared to other sources, so there are need for practices or xiiactions that will keep this ratio low or even disseminate it. However, resistance towards drugs such as Tetracycline, Ampicillin and Trimethoprim is quite alarming. So, there is a need to emphasize the rational use of antibiotics in poultry practice.