A Comparative Evaluation of Fivephenotypic Methods for Identificationof Carbapenemase-Producing Enterobacteriaceae: A Modifiedcarbapenemase Detection Test Publisher Pubmed



Solgi H^{1, 2} ; Badamchi A³ ; Shahcheraghi F⁴ ; Badmasti F⁴ ; Akbari M¹ ; Behzadfar M² Show Affiliations
Source: Microbiology Spectrum Published:2024

Abstract

Rapid detection of carbapenemase-producing Enterobacteriaceae (CPE) is urgently needed to prevent their spread in healthcare settings. Here, we have evaluated the performance of the phenotypic methods for detection of carbapenemase production directly from bacterial cultures. A total of 99 clinical and rectal Enterobacteriaceae isolates were included (81 carrying known carbapenemase-encoding genes and 18 without carbapenemase production). All isolates were subjected to the fivephenotypic tests including in-house Carba NP (iCarba NP), modified-CarbaNP, E-Test MBL, modifiedHodge test (MHT), and commercial combination disk test. Test results were read at differenttime points for iCarba NP and modified-Carba(1 min, 5 min, 15 min, 1 h and 2 h). The sensitivity and specificityof the iCarba NP were 78.87% and 100%, respectively, whereas those of the modified-CarbaNP test were 95.06% and 94.44%, respectively. False-negative results were detected in four OXA-48 isolates with the use of modified-CarbaNP, whereas one non-carbapenemase isolate had false-positive results. The sensitivity/specificitywas 91.30%/100% and 80.25%/83.33% for the E-Test MBL and MHT, respectively. The sensitivity and specificityof the aminophenylboronic acid synergy test were 100% and 97.94%, respectively, whereas those of the dipicolinic acid synergy test were 82.61% and 96.23%, respectively. Rapid, simple, and reliable methods are needed for laboratory detection of CPE isolates to improve the detection and surveillance of these clinically relevant pathogens in an epidemiological context. We conclude that the modified-CarbaNP test can be one of the reliable tests for the prediction of carbapenemase-producing bacteria. © 2024 Solgi et al.