Evaluation of Phenotyping and Genotyping Pattern of Resistance to Carbapenems in Pseudomonas aeruginosa and Acinetobacterbaumannii, Isolated from Educational Therapeutic Hospitals of Mazandaran University of Medical Sciences during 2017

Background and Objectives: Pseudomonas aeruginosa and Acinetobacterbaumanniiare clinically significant opportunistic humanpathogens, associated with nosocomial infections worldwide. The aim of this study was to investigate the prevalence of carbapenem resistance genes among the clinical isolates of this bacterium. Materials and Methods:In this study, 200 non-duplicated clinical isolates were collected from different clinical samples from patients admitted to the hospitals affiliated to Mazandaran University of Medical Sciences. The final identification of the bacteria was performed using biochemical tests and the API system for Non-fermenter bacteria. Combined disk test (CDT), modified Carba NP test (MCNP), and Modified Hodge Test (MHT) were used for phenotypic detection of Carbapenemase production by the clinical isolates and the prevalence of carbapenems resistance genes detected by PCR method. Results:In this study, resistance to Carbapenems was differentiated by bacteria, AcinetobacterBumene (97%) and Pseudomonas aerosinosa (43%). By using CDT, (97.9) of the isolates of Acinetobacterbaumannii and (76 .74%) were positive for Pseudomonas aeruginosa. Accordingly, the prevalence of OXA23 (84%), in Acinetobacterbaumannii and (30%) Pseudomonas aeruginosa was observed. In this study, SPM gene was not observed in any of the strains. Conclusions:This study revealed that other carbapenem resistance mechanisms such as overexpression of efflux pumps, down-regulation of outer-membrane proteins, AmpC overexpression or production of other carbapenemases genes could be effective on resistance to carbapenems among the strains of A. baumanniiand P. aeruginosa isolated in the studiedarea.