Phenotypic and genotypic characterization of carbapenemresistantPseudomonas aeruginosa isolates from Hamadan, Iran

Background and Aim : In recent years, the prevalence of carbapenem-resistant Pseudomonasaeruginosa isolates has become a worldwide concern. Rapid and accurate detection ofcarbapenemase-producing P. aeruginosa isolates is so important. The aim of this study was toevaluate the performance of the phenotypic methods such as Modified Hodge test (MHT),CarbaNP (CNPt), combined double-disk synergy test (CDDT), and carbapenem inactivationmethod (CIM) for rapid and accurate detection of clinical carbapenemase production of P.aeruginosa isolates.Methods : This study was performed on ۹۷ P. aeruginosa strains, which were isolated from clinicalsamples in Hamadan hospitals, western Iran in ۲۰۱۷-۲۰۱۸. Antibiotic susceptibility testing wasperformed using disk diffusion and minimum inhibitory concentration (MIC) by E-test method.We evaluated the performance of MHT, CarbaNP, CDDT, and CIM tests in comparison topolymerase chain reaction (PCR) for the detection of carbapenemase-producing isolates.Additionally, the presence of carbapenem-resistant genes was investigated using the PCR method.Results : Our findings showed that the highest resistance was to cefoxitin (۹۴.۸%). Moreover,among the carbapenem antibiotics, the highest resistance was to imipenem (۴۹.۴%). Among the۴۹ carbapenem-resistant isolates, ۴۲ (۸۵.۷%) isolates were MIC positive. The results of phenotypictests showed that CarbaNP, CIM, CDDT, and MHT tests were positive in (۴۸/۴۹, ۹۷.۹۵%), (۴۶/۴۹,۹۳.۸۷%), (۲۷/۴۹, ۵۷.۴۴%), and (۲۵/۴۹, ۵۳.۱۹%) of isolates, respectively.Conclusion : CarbaNP and CIM tests showed high sensitivity, specificity, positive predictivevalues (PPV), and negative predictive values (NPV) compared to PCR in P. aeruginosa isolates.CarbaNP and CIM tests are highly sensitive and specific tests for identifying carbapenemaseproducingP. aeruginosa isolates.

کلیدواژه ها:

Carbapenemase ، Metallo-β-Lactamases ، Pseudomonas aeruginosa