The detection of metallo-beta-laktamaz (mbl) enzyme in gram negative non fermantative bacteria by different methods and the comparison of these methods

New metallo-beta-lactamase (MBL) enzymes are identified in recent years that may be responsible for the increased number of non fermentative Gram negative(NFGN) bacilli's growing carbapenem resistance and they spread throughout the world. In this study, we aimed to investigate the production of MBL at clinicalisolates resistant to imipenem and meropenem, to test and compare phenotypicmethods that reveals the presence of these enzymes. The identification of bacteria was made with standard clinical microbiological methods and confirmed in the BD Phoenix fully automatic identification system. In vitro bacteria resistance to antibiotics determined by using disk method in accordance with CLSI recommendations and confirmed with the BD Phoenix fully automated identification device. Production of MBL were evaluated by combined disc method, double-disk synergy test, modified Hodge test and E test methods. Metallo-beta-lactamase production at meropenem resistant Acinetobacterstrains were found 95% with the combined disc method, 67.5% with MP-EDTA double-disk synergy test, 72.5% with the modified Hodge test and 97.5% with E test; at meropenem resistant Pseudomonas strains 80% with the combined disk method, 100% with MP-EDTA double-disk synergy test, the modified Hodge test and the E test with 60% and 50% respectively. Metallo-beta-lactamase producing bacteria are being resistant to all beta lactams except aztreonam and colistin, in clinical practice the lack of a suitableinhibitor for MBL, as well as presence of MBL genes together with theaminoglycoside resistance genes in genetic with epidemiologic aspect makes it very important to determine the presence of MBL. For the investigation of MBL a fast, simple, with high sensitivity and specificity good phenotypic screening method is needed. None of the screeningmethods at present are sufficient. Therefore, the molecular methods are needed to viiconfirm the screening results. Our study suggests that further research needs to be done in our hospital for identification and control of MBL producing strains. Keywords: MBL production, Pseudomonas, Acinetobacter, phenotypic methods.