Lamiaa A Madkour1, May S Soliman2, Dina M Hassan2, Noha S Soliman2, Yasmin A ElMahdy2. 1. Microbiology and Immunology Department, Faculty of Medicine, Cairo University, 1 El-Saraya St., Kasr Al Ainy, Cairo, Egypt. Electronic address: m_l@kasralainy.edu.eg. 2. Clinical Pathology Department, Faculty of Medicine, Cairo University, Cairo, Egypt.
Abstract
OBJECTIVES: With a worrisome surge of carbapenem-resistant bacterial isolates, the diagnostic arsenal has become in dire need of affordable and timely assays to detect the rapidly transmissible carbapenemases. Employing multiplex PCR as a reference method, the purpose of the present study was to compare the performance of the carbapenem inactivation method (CIM) and the Carba NP test in the detection of carbapenemase-producers. METHODS: A panel of 203 Gram-negative bacterial isolates screened for carbapenem resistance were subjected to the CIM and Carba NP test. The results were compared with multiplex PCR targeting various carbapenemase genes. RESULTS: According to multiplex PCR, 92 (45.3%) of 203 isolates were found to harbour one or more carbapenemase genes, with blaNDM and blaKPC being the most commonly encountered. The sensitivity and specificity of the CIM were 95.7% and 95.5% respectively, whilst those of the Carba NP test were 75.0% and 99.1%, respectively. Both methods were found to be rapid and reliable in the detection of carbapenemases and showed a high agreement with multiplex PCR. CONCLUSIONS: As the list of carbapenemase genes continues to expand, the reliability of PCR has become doubtful; hence, the CIM and Carba NP test could offer promising alternatives, with the CIM being of a lower cost and less labour intensive.
OBJECTIVES: With a worrisome surge of carbapenem-resistant bacterial isolates, the diagnostic arsenal has become in dire need of affordable and timely assays to detect the rapidly transmissible carbapenemases. Employing multiplex PCR as a reference method, the purpose of the present study was to compare the performance of the carbapenem inactivation method (CIM) and the Carba NP test in the detection of carbapenemase-producers. METHODS: A panel of 203 Gram-negative bacterial isolates screened for carbapenem resistance were subjected to the CIM and Carba NP test. The results were compared with multiplex PCR targeting various carbapenemase genes. RESULTS: According to multiplex PCR, 92 (45.3%) of 203 isolates were found to harbour one or more carbapenemase genes, with blaNDM and blaKPC being the most commonly encountered. The sensitivity and specificity of the CIM were 95.7% and 95.5% respectively, whilst those of the Carba NP test were 75.0% and 99.1%, respectively. Both methods were found to be rapid and reliable in the detection of carbapenemases and showed a high agreement with multiplex PCR. CONCLUSIONS: As the list of carbapenemase genes continues to expand, the reliability of PCR has become doubtful; hence, the CIM and Carba NP test could offer promising alternatives, with the CIM being of a lower cost and less labour intensive.
Authors: Luiz F Lisboa; LeeAnn Turnbull; David A Boyd; Michael R Mulvey; Tanis C Dingle Journal: J Clin Microbiol Date: 2017-12-26 Impact factor: 5.948