PCR-dipstick DNA Chromatography for detection of Carbapenemase Producing Carbapenem-Resistant Enterobacteriaceae

Carbapenemase producing carbapenem-resistant Enterobacteriaceae (CP-CRE) are an epidemiologically important emerging public health threat. Early and reliable detection of CP-CRE is important for containment of these pathogens. The aim of this study was to evaluate and observe the sensitivity of polymerase chain reaction (PCR)-dipstick DNA chromatography (GeneFields CPE) for detection of carbapenemase genes (NDM, OXA-48, KPC, IMP) in comparison to conventional PCR. In this cross-sectional study, a total of 145 carbapenem resistant Enterobacteriaceae isolates were subjected to test for carbapenemase by phenotypic mCIM and genotypic- conventional PCR and PCR-dipstick DNA Chromatography method. In PCR dipstick DNA chromatography assay, after multiplex PCR a DNA-DNA hybridization-based detection system is applied where amplified products can be easily interpreted by observing a blue line in DNA strip visually within 15 minutes without gel electrophoresis. All the CP-CRE isolates (100%) were positive for either NDM or OXA-48 by PCR-dipstick DNA Chromatography assay, whereas 142 (97.9%) isolates were detected by conventional PCR. The positivity rate of NDM, OXA-48 and both NDM and OXA-48 among CP-CRE isolates were 73.8%, 51.7% and 25.5% respectively. The sensitivity, specificity of PCR-dipstick DNA Chromatography assay for detection of NDM and OXA-48 were 100.0%, 92.7% and 98.6%, 97.2% respectively. This assay showed excellent agreement with conventional PCR for detection of CP-CRE. PCR-dipstick DNA chromatography may be an excellent and robust diagnostic tool in terms of rapidity and sensitivity for the detection of CP-CRE.