XXI ALAM
Resumo:273-1


Poster (Painel)
273-1Contribution of chromosomally encoded and acquired resistance mechanisms to antibiotics in nosocomial isolates of Pseudomonas aeruginosa with an extensively drug-resistant phenotype in Recife, Pernambuco
Autores:Felipe Lira de Sá Cavalcanti (CPQAM/FIOCRUZ - Centro de Pesquisas Aggeu Magalhães, Fiocruz / PPGG/UFPE - Departamento de Genética, Universidade Federal de Pernambuco / LRM/UPE - Laboratório de Resistência Microbiana, UPE) ; Anna Carolina Soares Almeida (PPGG/UFPE - Departamento de Genética, Universidade Federal de Pernambuco / LRM/UPE - Laboratório de Resistência Microbiana, UPE) ; Marinalda Anselmo Vilela (LRM/UPE - Laboratório de Resistência Microbiana, UPE) ; Tereza Cristina Leal Balbino (CPQAM/FIOCRUZ - Centro de Pesquisas Aggeu Magalhães, Fiocruz / PPGG/UFPE - Departamento de Genética, Universidade Federal de Pernambuco) ; Márcia Maria Camargo de Morais (LRM/UPE - Laboratório de Resistência Microbiana, UPE)

Resumo

Pseudomonas aeruginosa is a successful and globally important opportunistic nosocomial pathogen responsible for severe and complicated infections. This bacterium is intrinsically resistant to several drugs and can be able to become resistant to virtually all the antibiotics commercially available. The main mechanisms of resistance include the production of β-lactamases, efflux pumps overexpression and porin down-regulation. The aim of this work was to study the interaction of different mechanisms responsible for the extensively-drug resistant (XDR) phenotype in isolates of two hospitals in Recife. Furthermore, to establish the epidemiological and molecular characteristics among them. Ten samples from 2008 to 2011, obtained from two public hospitals, were analyzed. Antimicrobial susceptibility was performed according CLSI (2012). The identification of metallo-β-lactamase (MBL)-producing isolates followed the method proposed by Arakawa et al. The detection of genes encoding class B and C β-lactamases; class 1 integrase; qacEΔ1; sulI; porin (OprD) and RND family efflux systems was performed by specific PCR. The qualitative and quantitative gene expressions were evaluated by RT-PCR and qPCR, respectively. Molecular typing was carried out by PFGE. The results showed that the isolates analyzed were resistant to all drugs tested except polymyxin B, confirming the XDR phenotype. It was identified only one MBL-producing isolate, positive for the blaSPM-1 gene. The presence of class 1 integron was observed and confirmed in nine isolates (90%) by the amplification of intl1, qacEΔ1 and sulI genes. The mexB, mexY, mexD, mexF, AmpC and OprD genes were detected in all isolates. It was also observed a significant expression of genes encoding the efflux pumps MexAB-OprM and MexXY-OprM, even in the MBL positive isolate. Macrorestriction revealed distinct genotypic patterns among them. These findings indicate that a combination of different resistance determinants can coexist in these isolates, further restricting the therapeutic options and the chance of clinical successes for the patient’s treatment.


Palavras-chave:  beta-lactamases, efflux pumps, PFGE, Pseudomonas aeruginosa