Β-lactam Resistance Genes in Gram Negative Bacteria Isolated from a Stream in Porto Alegre

The Dilúvio stream is part of an important watershed in the city of Porto Alegre, southern Brazil. It receives rain runoffs and domestic and hospital sewage, which carries a highly diverse microbial population. Some of these microorganisms may show resistance to different antimicrobials, acting as disseminators of resistance genes. This study characterizes the Gram-negative population present in the Dilúvio stream according to their antimicrobial resistance profiles, searching for the presence of β-lactams resistance genes. The resistance profile was determined according to the disk diffusion method using different classes of antimicrobials. The detection of the resistance genes blaTEM, blaSHV and blaCTX-M was carried out by PCR. Approximately 67% of the isolates from sampling points 1 and 3, and about 59% of the isolates collected from point 2 and more than 95% from site 4 were resistant to two or more antimicrobials. These strains were submitted to the PCR reaction looking for the genes blaTEM, blaSHV and blaCTX-M. The results showed a higher prevalence of blaTEM gene in 21 of the isolates. Two isolates were positive for two genes, blaTEM and blaSHV, six for blaSHV and one isolate was positive for blaCTX-M gene, revealing the transfer of different resistance genes to the environment.