Evaluation of tests to predict metallo--lactamase in cystic fibrosis (CF) and non-(CF) Pseudomonas

Double disks synergy test (DDST) and combined disks test (CD) were evaluated to predict the pres-ence of metallo--lactamase in 70 Pseudomonas aeruginosa isolates recovered from cystic fibrosis and non-cystic fibrosis patients. DDSTCAZ-EDTA 1 cm and CDIMP-EDTA tests showed the best accuracy (94.3%). Furthermore, for other combinations, accuracy unsatisfactory was obtained. Key words: Pseudomonas aeruginosa, metallo--lactamase, phenotypic tests. Pseudomonas aeruginosa is one of the leading nosocomial pathogens worldwide. Infections caused by P. aeruginosa are often hard to treat mainly because of the in-trinsic resistance and due to the high ability of this organ-ism to acquire resistance to antimicrobial agents, including -lactams (Giamarellou and Kanellakopoulou, 2008). Production of -lactamases is the major mechanism of acquired resistance to -lactam agents. Carbapenem-hydrolyzing enzymes, such as metallo--lactamases, ar