Epidemiological analysis of metallo-beta-lactamase producing clinical isolates of pseudomonas aeruginosa

The emergence of acquired metallo-beta-lactamases (MBLs) especially in Pseudomonas aeruginosa is an increasing concern because of the methods used to identify MBLs which have not been standardized yet, and insufficient epidemiological data and clinical experience for these enzymes. In this study we aimed to investigate the microbiologic and epidemiologic characteristics of P. aeruginosa producing MBL. P. aeruginosa isolates that were intermediate resistant/resistant to carbapenems have been collected between 2008 and 2010 in our hospital were included in the study. The presence of MBL was investigated by a variety of phenotypic methods and Polymerase Chain Reaction (PCR). The clonally relationships of MBL positive isolates have been examined by Pulsed Field Gel Electrophoresis (PFGE). The clinical characteristics of patients were statistically analysed according to the presence of MBL positive P. aeruginosa. Of 334 isolates, were positive 21 (6.3%) with modified Hodge Test (MHT), 109 (32.6%) with imipenem/imipenem-EDTA combined disk test (CDT) and 32 (9.6%) Polymerase Chain Reaction (PCR). According to PFGE analysis, three VIM positive isolates clonnally related, which were identified from pediatric patients. Eleven VIM positive isolates were clonnally related, which were identified from adult hospitalised patients. Two VIM positive isolates were clonally related, which were identified from adult outpatient. It was detected that hospital stay was longer for the adult hospitalised patients with MBL positive P. aeruginosa (p value =0.049). In conclusion, it was observed that MBL-positive P. aeruginosa isolates could spread in the community or in the hospital, and also length of hospital stay was longer for the adult patients with MBL positive P. aeruginosa. This is the first study reporting both VIM and IMP positive P. aeruginosa in Turkey.