Improving the detection of carbapenemase-producing organisms (CPO) in a low-prevalence setting: evaluation of four...

Carbapenemase-producing organisms (CPOs) can be resistant to almost all β-lactams and represent an increasing threat in healthcare facilities. Detection of these organisms in routine diagnostic laboratories is difficult; here we evaluate four commercially available CPO detection assays and assess their suitability for the clinical laboratory.

A panel of 95 clinical multidrug-resistant organisms (22 NDM, 24 OXA-48, 19 VIM, 4 OXA-23, 3 KPC, 4 NDM+OXA-48, 1 OXA23+NDM, 1 IMI, 1 IMP-1, 9 ESBL, 3 derepressed AmpC and 4 inducible AmpC producers) were tested by the RESIST-3 O.K.N., RapidEC CarbaNP, Acuitas Resistome and Xpert Carba-R assays.Results/Key Findings. The commercial assays performed well, with high sensitivities (96.2-100 %) and specificities (all, 100 %). The RapidEC CarbaNP and Acuitas Resistome were able to detect the broadest range of carbapenemase genotypes. The RESIST-3 O.K.N. and Xpert CarbaR had the shortest turnaround times, whilst the RapidEC CarbaNP was the only assay included in this study that could detect previously undescribed genotypes.

Using an algorithm of the RapidEC CarbaNP, followed by either the RESIST-3 O.K.N. (Enterobacteriaceae) or the Xpert Carba-R (Pseudomonas aeruginosa and Acinetobacter spp.) on suspect CPOs allowed rapid in-house detection and genotyping of a high proportion of CPOs, reducing turnaround time by up to 7 days.