Sanaz Dehbashi,1 Hamed Tahmasebi,2 Mohammad Yousef Alikhani,1 Fariba Keramat,3 Mohammad Reza Arabestani1,4 1Microbiology Department, Faculty of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran; 2Microbiology Department, Faculty of Medicine, Zahedan University of Medical Sciences, Zahedan, Iran; 3Brucellosis Research Center, Faculty of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran; 4Nutrition Health Research Center, Hamadan University of Medical Sciences, Hamadan, IranCorrespondence: Mohammad Reza ArabestaniDepartment of Microbiology, Faculty of Medicine, Hamadan University of Medical Sciences, Hamadan, IranTel kangertech subvod leaking +989 188662009Email [email protected]: There are various phenotypic methods for identifying class B and class A β-lactamase enzymes in Pseudomonas aeruginosa.The purpose of this study was to compare the sensitivity and specificity of different phenotypic methods with HRMA assay to detect β-lactamase-producing P.aeruginosa strains.
Methods: Eighty-eight of P.aeruginosa isolates were collected from different specimens.Conventional double-disk test (DDT) and EDTA-imipenem microbiological (EIM) were performed to detect ESBL and MBL-producing strains, respectively.Meanwhile, the Modified Hodge test and Carba-NP test were performed on all carbapenem-resistant strains.HRMA method and sensitivity and specificity of primers were determined based on the melt curve temperature range.
In all comparisons, PCR was considered as the gold standard.Results: Of the 402 isolates collected from different clinical specimens, 88 isolates of P.aeruginosa were identified.However, 43 strains were (48.88%) ESBL-producing, and 7 strains (7.
95%) were MBL-producing.Also, using the Modified Hodge test and Carba-NP method, 11 (12.5%) and 19 (21.59%) strains were carbapenemase-producing, respectively.The results of the HRMA test revealed that genes coding for blaSHV, blaTEM, blaKPC, blaIMP, blaVIM, and blaGES were detected in 44.
31%, 22.72%, 13.63%, 14.7%, 5.6%, and 2.
27% of P.aeruginosa isolates.Nonetheless, for blaKPC and blaGES genes, sensitivity and specificity of the Carba-NP test were junk ear warmer 90.47%, 94.87%, and 83.
36%, 94.80%, respectively.However, sensitivity and specificity of MHT was 91.66%, 98.70%, and 77.
77%, 96.42%, respectively.For blaSHV and blaTEM genes, sensitivity and specificity of DDT were 95.55%, 95.55%, and 86%, 83.
50%, respectively.However, sensitivity and specificity of EMI were 77.77%, 97.59%, and 91.66%, 97.
43% for blaVIM and blaIMP, respectively.Conclusion: The HRMA is a powerful, accurate, closed-tube, rapid method for detecting β-lactamase genes in P.aeruginosa.The high sensitivity and specificity of this method, along with phenotypic tests, play a useful role in increasing the predictive value of clinical reports.Keywords: Pseudomonas aeruginosa, high-resolution melting curve analysis, HRMA, β-lactamases, drug resistance.