Residual waters vs. multiresistant bacteria

Abstract

Introduction: Water is used daily in numerous domestic and industrial activities, and when discarded is considered wastewater. The self-medication, antibiotics inappropriate prescription, and the use of antibiotics in animal feed, leads to the environment being a reservoir of bacteria carrying resistance genes, allowing their dissemination among bacterial communities of water and soil. Bacteria can have several associated resistance mechanisms, giving them the ability to be resistant to different classes of antibiotics. The 3rd generation cephalosporins have an extended action spectrum and are hydrolyzed by the extended spectrum β-lactamases (ESBLs). The same bacterium can express these enzymes associated with an acetyltransferase encoded by the aac (6’)-Ib-cr gene, which confers resistance to aminoglycosides (amikacin and tobramycin) and simultaneously to Fluorquinolones. Objective: Identification of resistant genes in wastewater isolates. Materials and methods: 164 isolates from the residual water, were studied for antibiotic susceptibility and 144 were selected for identification of resistance genes by PCR reaction and sequencing. Results: The antimicrobial study of 144 strains, showed that 78% (112/144) were resistant to ciprofloxacin. The resistance to ciprofloxacin was studied by the detection of aac (6’)-Ib-cr gene, found in 26% (37/144). The remained resistant isolates could have different mechanisms, such as qnr genes plasmid-mediated quinolone resistance and/or mutations on chromosomal genes (gyrA and parC). Among the 3rd generation cephalosporin resistance, were found 35% (50/114) were found resistant to cefotaxime and 26% (37/144) to ceftazidime. After sequencing, the following enzymes were predominant: CTX-M-15 (17/55); CTX-M-14 (6/55). The enzymes CTX-M-1, CTX-M-2, CTX-M-98 were found one by each isolate. Conclusion: The existence of bacteria with resistance genes to 3rd generation cephalosporins simultaneously with fluoroquinolones and aminoglycosides constitutes a serious public health problem, with the aggravation of having the same susceptibility profile and the same genetic identity of the hospital strains.