Abstract
The occurrence and genetic relatedness of AmpC beta-lactamase producing Enterobacteriaceae isolated from clinical environments, groundwater, beef, human and cattle faeces were investigated. One hundred seventy-seven (177) samples were collected and cultured on MacConkey agar. A total of 203 non-repetitive isolates were characterised using genus/species-specific PCRs and the identified isolates were subjected to antibiotic susceptibility testing. The production of AmpC beta-lactamases was evaluated using cefoxitin disc, confirmed by the D96C detection test and their encoding genes detected by PCR. The D64C extended-spectrum beta-lactamases (ESBL) test was also performed to appraise ESBLs/AmpC co-production. The genetic fingerprints of AmpC beta-lactamase producers were determined by ERIC-PCR. A total of 116 isolates were identified as E. coli (n = 65), Shigella spp. (n = 36) and Klebsiella pneumoniae (n = 15). Ciprofloxacin resistance (44.4-55.4%) was the most frequent and resistance against the Cephem antibiotics ranged from 15-43.1% for E. coli, 25-36.1% for Shigella spp., and 20-40% for K. pneumoniae. On the other hand, these bacteria strains were most sensitive to Amikacin (0%), Meropenem (2.8%) and Piperacillin-Tazobactam (6.7%) respectively. Nineteen (16.4%) isolates comprising 16 E. coli and 3 Shigella spp. were confirmed as AmpC beta-lactamase producers. However, only E. coli isolates possessed the corresponding resistance determinants: blaACC (73.7%, n = 14), blaCIT (26%, n = 5), blaDHA (11%, n = 2) and blaFOX (16%, n = 3). Thirty-four (27.3%) Enterobacteriaceae strains were confirmed as ESBL producers and a large proportion (79.4%, n = 27) harboured the blaTEM gene, however, only two were ESBLs/AmpC co-producers. Genetic fingerprinting of the AmpC beta-lactamase-producing E. coli isolates revealed low similarity between isolates. In conclusion, the findings indicate the presence of AmpC beta-lactamase-producing Enterobacteriaceae from cattle, beef products and hospital environments that commonly harbour the associated resistance determinants especially the blaACC gene, nonetheless, there is limited possible cross-contamination between these environments.