Molecular characterization of NDM-1-producing Pseudomonas aeruginosa isolates from hospitalized patients in Iran.

BACKGROUND: The emergence of carbapenem-resistant Pseudomonas aeruginosa is one of the most important challenges in a healthcare setting. The aim of this study is double-locus sequence typing (DLST) typing of blaNDM-1 positive P. aeruginosa isolates. METHODS: Twenty-nine blaNDM-1 positive isolates were collected during three years of study from different cities in Iran. Modified hodge test (MHT), double-disk synergy test (DDST) and double-disk potentiation test (DDPT) was performed for detection of carbapenemase and metallo-beta-lactamase (MBL) producing blaNDM-1 positive P. aeruginosa isolates. The antibiotic resistance genes were considered by PCR method. Clonal relationship of blaNDM-1 positive was also characterized using DLST method. RESULTS: Antibiotic susceptibility pattern showed that all isolates were resistant to imipenem and ertapenem. DDST and DDPT revealed that 15/29 (51.8%) and 26 (89.7%) of blaNDM-1 positive isolates were MBL producing isolates, respectively. The presence of blaOXA-10, blaVIM-2, blaIMP-1 and blaSPM genes were detected in 86.2%, 41.4%, 34.5% and 3.5% isolates, respectively. DLST typing results revealed the main cluster were DLST 25-11 with 13 infected or colonized patients. CONCLUSIONS: The presence of blaNDM-1 gene with other MBLs encoding genes in P. aeruginosa is a potential challenge in the treatment of microorganism infections. DLST showed partial diversity among 29 blaNDM-1 positive isolates.