Beta-lactams resistance and presence of class 1 integron in Pseudomonas spp. isolated from untreated hospital effluents in Brazil
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The aim of the present study was to investigate the resistance profile, to detect the presence of beta-lactam resistance genes, phenotypic expression of efflux pump systems and class 1 integrons in Pseudomonas spp. strains obtained from untreated hospital effluents. Effluent samples were collected from four hospitals in Porto Alegre, RS, Brazil. Pseudomonas were isolated on MacConkey agar plates and the identification was confirmed by 16S rRNA PCR and biochemical tests. Susceptibility testing was determined by disk-diffusion method using 11 different beta-lactams and MIC assays were performed on isolates resistant to imipenem and ceftazidime. The beta-lactamase genes blaIMP, blaVIM, blaSPM-1, blaOXA-23-like, blaOXA-24-like, blaOXA-51-like and the intl1 gene from class 1 integron were analysed by PCR. One hundred and twenty-four isolates were recovered and the most common species was Pseudomonas pseudoalcaligenes. The resistance found among the isolates was considered high, 62 (50%) isolates were multiresistant. No isolate carrying the beta-lactamase genes tested was found among the strains. Seven isolates showed reduction of MIC for imipenem and ceftazidime in the presence of cyanide m-chlorophenylhydrazone, indicating the hyper expression of efflux pumps. From the 124 isolates, 52 (41.9%) were identified as carrying the class 1 integron gene, intI1. Untreated hospital effluents could be a source of environmental contamination due to discharge of antimicrobial resistant bacteria which can carry integron class 1 and act as a reservoir of resistance genes and have efflux pump systems.
KeywordsPseudomonas spp. Beta-lactams resistance Hospital sewage Integrons
This research was supported by CAPES (Brazilian Government Supporting Agency) and Rio Grande do Sul State Supporting Agency FAPERGS. The authors would like to thanks Dr. Ana Cristina Gales who kindly provided the strains used as positive controls in this study. The authors are also grateful to Clarissa Branco Haas, Lyvia Moreira de Oliveira and Gabriela Rosa da Cunha for the technical assistance.
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