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 bla(NDM-1) positive P. aeruginosa isolates. Methods Twenty-nine bla(NDM-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 bla(NDM-1) positive P. aeruginosa isolates. The antibiotic resistance genes were considered by PCR method. Clonal relationship of bla(NDM-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 bla(NDM-1) positive isolates were MBL producing isolates, respectively. The presence of bla(OXA-10,)bla(VIM-2), bla(IMP-1) and bla(SPM) 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 bla(NDM-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 bla(NDM-1) positive isolates.

Automated summary

The study investigated 29 carbapenem-resistant Pseudomonas aeruginosa isolates carrying the bla(NDM-1) gene in different cities of Iran. The isolates showed resistance to imipenem and ertapenem and carried other MBL encoding genes. DLST typing revealed partial diversity among the isolates, with DLST 25-11 cluster having the most infected or colonized patients.