METALLO-B-LACTAMASE-PRODUCING PSEUDOMONAS AERUGINOSA WITH A PAN-RESISTANCE PROFILE IN RECIFE, PERNAMBUCO

Felipe Lira de Sá Cavalcanti (UFPE); Anna Carolina Soares Almeida (UPE); Marinalda Anselmo Vilela (UFPE); Márcia Maria Camargo de Morais (UPE); Marcos Antônio de Morais Júnior (UFPE)

Carbapenem resistance may be conferred through various mechanisms, including the expression of beta-lactamase carbapenemases. Metallo-beta-lactamases constitute the most clinically important group of carbapenemases since they hydrolyse virtually all beta-lactams antibiotics and, in some cases, also monobactams (due to other mechanisms associated), which implies in a vast reduction of therapeutic options currently available. The aim of this work was to detect the production of MBLs in the P. aeruginosa strains resistant both to imipenem and ceftazidim, to investigate the occurrence of genes bla_SPM-1 and bla_IMP-DIA and to verify the susceptibility profile of the isolates to the most used groups of antibiotics commercially available. We analyzed 12 samples of the biennium 2008/2009, identified in a teaching hospital. Antimicrobial susceptibility was performed according to criteria established by the CLSI, 2009. The indentification of MBL positives isolates followed the method of disk-diffusion proposed by Arakawa. The detection of genes bla_SPM-1 and bla_IMP-DIA was performed by PCR analysis using specific primers. The results showed that 25% (3/12) of the isolates resistant to imipenem and ceftazidim were confirmed as MBL positives by phenotypic testing. The bla_SPM-1 gene was also found in these isolates (3/3). None of the tested samples had bla_IMP-DIA gene. Regarding to the susceptibility assays, was observed that: 100% of the isolates (12/12) were resistant to gentamicin and ciprofloxacin; 91,6% (11/12) were resistant to amikacin and 8,4% (1/12) showed intermediate resistance to this aminoglycoside; 83,3% (10/12) were resistant to piperacilin/tazobactam and 16,7% (2/12) showed sensibility to it. When the two main drugs in the treatment of infections caused by MBL positive strains were analyzed, 83,3% (10/12) were resistant to aztreonam and 16,7% (2/12) had intermediate resistance. Regarding to polimixin B, all the 12 isolates were sensible. These findings suggest that the production of MBLs is still an important mechanism of resistance to carbapanems in our hospital, as confirmed by the detection of SPM genes. Moreover, the profile of pan-resistance found, also alert to the possible presence of multiple mechanisms of resistance in bacterial isolates, which demands an urgent need for surveillance strategies and improvement of infections control practices.