Metallobeta-lactamase enzymes and antibiotic susceptibilities in strains of Pseudomonas aeruginosa isolated from intensive care units in Turkey

Objective: The aim of this study was to determine the frequency of metallobeta-lacta- mase (MBL) enzyme in Pseudomonas aeruginosa strains resistant to carbapenem (imipenem or/and meropenem) in seven regions of Turkey and to assess the minimal inhibitory concentration (MIC) levels of drugs used in treatment such as colistin, aztreonam, polymyxin B and rifampin. Overall 186 Pseudomonas aeruginosa (P.aeruginosa) strains resistant to carbapenem from 8 provinces (Ankara, Konya, Antalya, İstanbul, İzmir, Diyarbaki{dotless}r, Van and Trabzon) representing 7 different geographical regions of Turkey were included in the study. Material and Methods: The presence of MBL in P. aeruginosa strains resistant to carbapenem was investigated by combined disk methods with imipenem and EDTA absorbed imipenem disk. The MBL positivity was determined in the strains. Additionally, susceptibility to aztreonam, colistin, polymyxin B, and rifampin was established by the E-test method. Results: MBL enzyme positivity was detected in 58 out of 186 strains (31.2%). There was statistically significant difference between regions in terms of MBL positivity, with the highest rates in Antalya (52%), and İstanbul (50%) and the lowest in Diyarbaki{dotless}r (6%). Aztreonam sensitivity was detected in 134 (72%) strains; 155 (83.3%) were sensitive to colistin and 148 (79.6%) to polymixine. No strain (0%) was sensitive to rifampin. Conclusion: In conclusion, the overall mean rate of MBL positivity was 31.2%, which is quite high. Therefore, it will be beneficial to confirm the MBL positivity of strains with molecular methods, to review regional antibiotic surveillance data at certain intervals and to share the obtained data with relevant institutions in order to prevent the regional spread of these strains. Thus, it is essential to record and monitor systematically the antibiotic surveillance data. © 2012 by Türkiye Klinikleri.