Abstract

J. N. Ramalivhana *, C. L. Obi and S. R. Moyo

there is no information on the prevalence of ESBL-producing clinical Aeromonas in South African. A total of 230 isolates of Aeromonas hydrophila were isolated from 660 stool samples and 709 water samples collected in different municipalities in Limpopo province, South Africa over a period of three month. Isolates were screened for the production of ESBLs by the double disk diffusion test and for AmpC production by assessing resistance to cefoxitin. blaSHV, blaTEM , blaCTX-M and blaCMY-2 were isolated from all ESBLpositive and cefoxitin-resistant isolates. Only 21 isolates were found to be ESBL producers. All 21 isolates were screened for the production of blaSHV, blaTEM, blaCTX-M and blaCMY-2 ESBLs. Only (1/21) was found to produce blaTEM 63 and blaCMY-2. All transconjugants were resistant to amoxicillin, piperacillin, the cephalosporins and aztreonam but remained susceptible to cefoxitin and imipenem. Crude extracts of ß-lactamase-producing transconjugants were able to reduce the diameters of inhibition zones around disks containing penicillin, but had no effect on such zones around cefoxitin, imipenem and amoxicillinclavulanate disks. In conclusion, the occurrence of ESBLs in A .hydrophila emphasizes the importance of constant surveillance of clinical isolates to determine the prevalence of antibiotic resistance genes.