Carbapenemase detection by NG-Test CARBA 5-a rapid immunochromatographic assay in carbapenem-resistant diagnosis.

BACKGROUND

The global spread of carbapenem-resistant (CRE) represents a serious public health concern as these organisms are associated with limited treatment options, high mortality rate and rapid transmissibility. The identification of carbapenemase remains a challenge in microbiological laboratories as no single method is perfect when considering cost, carbapenemase coverage, accuracy, handling complexity and TATs together.

METHODS

NG-Test CARBA 5 assay and modified carbapenem inactivation method in conjunction with EDTA carbapenem inactivation method (mCIM/eCIM) were challenged with a collection of 299 molecularly characterized CRE isolates in China in order to evaluate the performance in detecting five major carbapenemases ( , , , , and ) among Enterobacterales.

RESULTS

NG-Test CARBA 5 detected all KPC-, NDM-, VIM- and OXA-48-producing isolates perfectly with a weak false-positive signal for NDM in an IMP-4 producer, which makes the specificity for NDM decreases to 99.6%. The overall specificity/sensitivity were 99.9%/100% for NG-Test CARBA 5. mCIM/eCIM achieved high specificity of 100%/100% and sensitivity of 99.6%/97.4%, with one S. marcescens isolate harboring VIM-2 undetected.

CONCLUSIONS

Both NG-Test CARBA 5 and mCIM/eCIM showed excellent results in the tested carbapenemase ( , , , , and ) detection compared with molecular genotypic test. As every assay has its own limitations, suitable methods should be combined for the establishment of the CRE diagnostic pathways.