Detection of carbapenem-resistant enterobacteriaceae isolates harboring OXA-48 gene in a clinical setting

Abstract

Background Increasing frequency of blaOXA-48 gene, commonly identified in Enterobacteriaceae family, is alarming across the world. The poor hydrolytic profile of OXA-48 likely may obscure its detection in clinical isolates, complicating the treatment option. Objective To detect the prevalence of blaOXA-48 gene in carbapenem-resistant Enterobacteriaceae (CRE) isolates from patients in Al-Zahraa and Helwan University hospitals, Cairo, Egypt, and to compare the diagnostic performance of phenotypic tests for the detection of OXA-48-mediated carbapenem resistance. Patients and methods A total of 500 Enterobacteriaceae isolates were identified from different clinical specimens provided to the Microbiology Laboratory of Al-Zahraa and Helwan University hospitals, Cairo, Egypt. The identified isolates underwent antibiotic susceptibility testing. Phenotypic carbapenemase production was confirmed by the modified Hodge test, Carba Nordmann-Poirel test, and modified carbapenem inactivation method (mCIM), and the blaOXA-48 gene was detected using real-time PCR. Results Out of 500 Enterobacteriaceae isolates, 102 (20.4%) isolates showed resistance to one or more of carbapenems. Among these 102 CRE isolates, Klebsiella pneumoniae was the most common isolate. Carbapenemase production was detected in 67/102 (65.7%), 69/102 (67.6%), and 72/102 (70.1%) of isolates by modified Hodge test, Carba Nordmann-Poirel, and mCIM, respectively. Of the 102 CRE isolates, 74 (72.5%) harbored blaOXA-48 gene, and of them, 43 (58.1%) were K. pneumoniae, 25 (33.8%) were Escherichia coli, and 6 (8.1%) were Citrobacter. Conclusion blaOXA-48 gene was prevalent among Enterobacteriaceae isolates in the two hospitals, with more prevalence in K. pneumonia isolates. mCIM has the best performance in phenotypic detection of this resistance.