Evaluation of three screening methods for detection of carbapenemase-producing enterobacteriaceae in rectal swabs

Abstract

Background: Carbapenemase-producing Enterobacteriaceae (CPE) have taken great importance on public health at global scale, which makes it necessary to implement rapid test for its prompt detection. Aim: To evaluate three screening methods to detect CPE in rectal swabs. Material and Methods: Transverse study, prospective. Seventy three rectal swabs were evaluated by three methodologies. Microorganism identification and susceptibility testing were made using automated systems. Carbapenemase production was confirmed by modified Hodge test and synergy tests using boronic acid and EDTA. Results: The method 1 (ChromID CARBA®) detected 20 positive samples (27.4%), 5 false positives (6.9 %), with concordance index of 93.2%, sensitivity 100% and specificity of 90%. Method 2 (HB&L Carbapenemase®) detected 17 positive samples (23.3%) and 3 false negatives (4.1%). The sensitivity and specificity of the assay were 85% and 100%, with concordance index of 95.9%. Method 3 (Xpert Carba-R®) detected 19 positive samples (57.5%) and 1 false negatives (3.1%), sensitivity 95%, specificity 100% and concordance index of 97%. Discussion: There is a wide variety of methodologies for rapid detection of carbapenemase-producing microorganisms. Choosing the best method must have as requirement a good sensitivity, specificity, and cost-effectiveness.