Prevalence of metallo-β-lactamase genes among Pseudomonas aeruginosa isolated from various clinical samples in China

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Abstract Background Pseudomonas aeruginosa is an opportunistic pathogen which is associated with nosocomial infections and causes various diseases including urinary tract infection, pneumonia, soft-tissue infection and sepsis. The emergence of P. aeruginosa-acquired metallo-β-lactamase (MBL) is most worrisome and poses a serious threat during treatment and infection control. The objective of this study was to identify antibiotic susceptibility, phenotypic detection of MBL production and to determine the prevalence of MBL genes in carbapenem-resistant P. aeruginosa isolated from different clinical samples. Methods A total of 329 non-duplicate P. aeruginosa isolated from various clinical samples from two hospitals in China between September 2017 and March 2019 were included in this study. Phenotypic detection of MBL was performed by the combined detection method using imipenem and imipenem-ethylenediaminetetraacetic acid (EDTA) discs. MBL-encoding genes including bla VIM-1 , bla VIM-2 , bla IMP-1 , bla IMP-2 , bla SPM-1 , bla SIM , bla NDM-1 and bla GIM were detected by polymerase chain reaction (PCR). Results Of the 329 P. aeruginosa, majority of the isolates were resistant to imipenem (77.5%) followed by meropenem (64.7%). Of the 270 P. aeruginosa isolates tested, 149 (55.2%) isolates were found to be positive for MBL detection. Of the different samples, 57.8% (n = 26) of P. aeruginosa isolated from blood were found to be positive for MBL production. Of the various MBL genes, bla IMP-1 (28.2%) was the most predominant gene detected followed by bla VIM-2 (18.8%), bla VIM-1 (16.1%), bla NDM-1 (9.4%), bla IMP-2 (6.7%), bla SIM (6.0%), bla SPM-1 (4.0%) and bla GIM (1.3%) genes. Conclusions The high resistance of P. aeruginosa toward imipenem and meropenem and the high prevalence of bla IMP-1 and bla VIM-2 set the alarm on the increasing, perhaps the increased, carbapenem resistance. In addition to routine antibiotic susceptibility testings, our results emphasize the importance of both the phenotypic and genotypic MBL detection methods in routine practice for early detection of carbapenem resistance and to prevent further dissemination of this resistant pathogen.