INTRODUCTION: Non-fermenting Gram-negative bacilli, such as Pseudomonas aeruginosa, feature among the main microorganisms that cause nosocomial infections. The development of resistance mechanisms, such as the production of metallo-beta-lactamases (MBL), is a major concern in hospitals. OBJECTIVES: To determine the prevalence of MBL phenotype in samples of P. aeruginosa isolates from hospitals in Caxias do Sul (RS) and compare some phenotypic methods applied in this enzyme detection. MATERIAL AND METHODS: A total of 50 samples of P. aeruginosa with decreased susceptibility to ceftazidime were phenotypically evaluated as to MBL production by three tests: double-disk synergy, combined disk and MBL E-test, using different substrates and metallo-enzyme inhibitors. RESULTS: The production of MBL was detected in 15 samples (30%). The method showing higher percentage of positive results was the MBL E-test, followed by ceftazidime-EDTA disk method. CONCLUSION: The presence of MBL is an important resistance mechanism found in the studied hospitals, which substantiate the need for the detection of these enzymes in order to control the spread of resistance genes and provide appropriate therapy to the patient.
Pseudomonas aeruginosa; Metallo-beta-lactamase; Bacterial resistance
