Detection of Plasmid-Mediated AmpC Beta-lactamase Enzyme among Escherichia coli Isolates in Livestock, South Nigeria

AmpC beta-lactamases are bacterial enzymes that hydrolyse third generation extended spectrum cephalosporins and cephamycins engendering resistance to these categories of antibiotic and is a serious threat to the currently available antibiotic armory both in human and veterinary medicine. In this study, the detection of AmpC beta-lactamase-producing E. coli in some common livestock animals was studied. A total of 196 faecal samples were aseptically collected from cattle, chicken, goat and swine from different parts of Uyo Metropolis into sterile universal containers. Samples were processed by inoculating onto macConkey agar using streak plate technique and incubated at 37oC for 18-24 hours after which growth were identified using standard identification procedures. Susceptibility profile of each of the identified E. coli isolate to some antibiotics was determined using the agar disk diffusion method. Resistant E. coli isolates to third and fourth generation cephalosporins were screened to detect ESBL producers using the modified double disk synergy test while AmpC beta-lactamase production was done by the modified disk test. The result shows that out of a total number of 123 E. coli isolates, 55.68% were potential ESBL producers while 30.68% were confirmed to be AmpC producers. The highest percentage of 5.37% came from Chicken, while the least percentage of 3.23% was from Pig and Goat respectively. The result of this study shows the presence of AmpC beta-lactamase producing E. coli in all the groups of animal tested. Therefore, improved surveillance of antibiotic use and antibiotic-resistant bacteria in farm animals should be given an urgent attention. Application of bio security and hygiene programs in the livestock breeding sector should be considered as a favorable effect on the restriction transfer of antibiotic resistance.