Evaluation of Blue-Carba Test and ISOPLEX CRE-ART-LAMP assay for rapid screening and characterization of Carbapenemases producing Enterobacteriaceae.Sudan

Abstract

Objective: We evaluate the performance of the Blue-Carba Test (BCT) and Mast ISOPLEX ®CRE-ART-LAMP assay as quick and affordable assays for the detection of carbapenemase-producing Enterobacteriaceae clinical isolates, Khartoum State-Sudan. Methods: A total of 384 Enterobacteriaceae (122 CPE and 262 non-CPE) clinical isolates were tested for a rapid biochemical method for detection of carbapenemase activity using Blue-Carba Test (BCT), and the Loop-mediated isothermal amplification (LAMP) for carbapenemase target genes detection by MAST ISOPLEX®CRE-ART (19 CPE and 1 non-CPE). Results: The overall sensitivity, specificity and accuracy for carbapenemase detection were 100% (95% CI, 97.0%–100%), 93.9% (95% CI, 90.3%-96.5%) and 95.8 % (95% CI, 93.3%-97.6%) for BCT with 80.3% present positive blue color was appeared after 15 min of test. Interestingly, the Mast ISOPLEX CRE-ART showed specificity 100%, accuracy 96.7% (95% CI, 90.6%-99.9%), and sensitivity 94.7%(95% CI, 90.3 -98.7%) for LAMP assay for detection of the target genes and it provides rapid results with a 45-minute. Considering PCR as a standard test for CPE genes detection, the kappa value of BCT and LAMP assays were calculated to be 0.907 and 0.900 respectively, suggesting good agreement between the PCR assay and both selected tests. Conclusion: The promptness and simplicity of both assays make them suitable for inexperienced operators to readily identify carbapenemase production and characterization of major carbapenemase blagenes. Besides exhibits an almost good agreement (Kappa>0.600) emphasizing their high sensitivities and specificities with a rapid and reliable epidemiological screening of carbapenemase production in resource-limited settings.