Rapid screening for carbapenemase-producing carbapenem-resistant <i>Enterobacterales</i> : clinical implementation of an immunochromatographic test using broth-enriched rectal swabs

Carbapenemase-producing carbapenem-resistant <i>Enterobacterales</i> (CP-CRE) poses a public health issue. Rapid detection of CP-CRE colonization is challenging; existing methods are either expensive or time-consuming. We evaluated an immunochromatographic test (ICT) for detecting carbapenemases directly from broth-enriched rectal swabs. One hundred intensive care patients provided 178 pairs of rectal swabs. One swab was tested using the GeneXpert Carba-R PCR assay; the other was inoculated into brain-heart infusion broth. After 4 and 6 h of incubation at 37°C, the broth was tested with the RESIST-5 O.K.N.V.I. ICT for <i>Klebsiella pneumoniae</i> carbapenemase (KPC), New Delhi metallo-β-lactamase (NDM), oxacillinase-48 (OXA-48), Verona integron-encoded metallo-β-lactamase (VIM), and imipenemase (IMP) carbapenemases. Broths were subcultured after overnight incubation, and recovered carbapenem-resistant <i>Enterobacterales</i> isolates were tested using GeneXpert Carba-R PCR. Sensitivity, specificity, and accuracy were calculated in comparison to culture positive for CP-CRE, confirmed by PCR for KPC, NDM, OXA-48, VIM, and IMP. Of the 178 swabs, 60 were culture positive for CP-CRE. After 6 h, the ICT demonstrated a sensitivity of 65%, specificity of 97.5%, and accuracy of 86.8%. Among heavily soiled swabs, sensitivity reached 81.8% for ICT after 6 h, and the specificity was 100%. The mean execution time for carbapenemase detection using ICT was reduced by 60 h compared to culture. The ICT after 6 h incubation offers reduced execution time for detecting CP-CREs. This method may serve as a valuable rapid screening tool, especially in resource-limited settings.IMPORTANCEThe rapid spread of multidrug-resistant bacteria requires innovative solutions for early detection and prevention measures. In this study, we present a simple protocol for the direct detection of carbapenemases in rectal swabs using an immunochromatographic assay. By optimizing the assay conditions, we achieved rapid and high-accuracy identification of five clinically important carbapenemases. This method can broaden access to rapid CP-CRE detection of fecal colonization-even in laboratories with limited resources-enabling the implementation of faster and more effective infection control measures, potentially reducing the spread of resistance.