Comparative Evaluation of Phenotypic Synergy Tests versus RESIST-4 O.K.N.V. and NG Test Carba 5 Lateral Flow Immunoassays for the Detection and Differentiation of Carbapenemases in Enterobacterales and Pseudomonas aeruginosa.

The spread of carbapenem-resistant Pseudomonas aeruginosa and carbapenemase-producing Enterobacterales (CPE) has dramatically impacted morbidity and mortality. COVID-19 pandemic has favored the selection of these microorganisms because of the excessive and prolonged use of broad-spectrum antibiotics and the outbreaks related to patient transfer between hospitals and inadequate personal protective equipment. Therefore, early CPE detection is considered essential for their control. We aimed to compare conventional phenotypic synergy tests and two lateral flow immunoassays for detecting carbapenemases in Enterobacterales and P. aeruginosa. We analyzed 100 carbapenem-resistant Gram-negative bacilli isolates, 80 Enterobacterales, and 20 P. aeruginosa (86 isolates producing KPC, NDM, OXA-48, IMP, and VIM carbapenemases and 14 non-carbapenemase-producing isolates). We performed a modified Hodge test, boronic acid and ethylenediaminetetraacetic acid (EDTA) synergy tests, and two lateral flow immunoassays: RESIST-4 O.K.N.V. (Coris Bioconcept) and NG Test Carba 5 (NG Biotech). In total, 76 KPC, seven VIM, one NDM, one OXA-48, and one isolate coproducing KPC + NDM enzymes were included. The concordance of different methods estimated by the Kappa index was 0.432 (standard error: 0.117), thus showing a high variability with the synergy tests with boronic acid and EDTA and reporting 16 false negatives that were detected by the two immunochromatographic methods. Co-production was only detected using immunoassays. Conventional phenotypic synergy tests with boronic acid and EDTA for detecting carbapenemases are suboptimal, and their routine use should be reconsidered. These tests depend on the degree of enzyme expression and the distance between disks. Lateral flow immunoassay tests are a rapid and cost-effective tool to detect and differentiate carbapenemases, improving clinical outcomes through targeted therapy and promoting infection prevention measures. IMPORTANCE Infections due to multidrug-resistant pathogens are a growing problem worldwide. The production of carbapenemases in Pseudomonas aeruginosa and Enterobacterales cause a high impact on the mortality of infected patients. Therefore, it is of great importance to have methods that allow the early detection of these multi-resistant microorganisms, achieving the confirmation of the type of carbapenemase present, with high sensitivity and specificity, with the aim of improving epidemiological control, dissemination, the clinical course to through targeted antibiotic therapy and promoting infection control in hospitals.

Detección rápida de Enterobacterias productoras de carbapenemasas en hisopados rectales de pacientes neonatos colonizados / Rapid detection of carbapenemase-producing Enterobacteriaceae in rectal swabs of colonized neonatal patients

Resumen Objetivo: Detectar la presencia de Enterobacterias productoras de carbapenemasas en hisopados rectales de neonatos mediante técnica de nefelometría láser y caracterización del tipo de carbapenemasa mediante test inmunocromatográfico. Materiales y Métodos: Estudio descriptivo de corte transversal. Fueron incluidos 57 neonatos, tamizados al ingreso a UCI, mediante hisopado rectal, procesado por nefelometría laser HB&L Carbapenemase (Alifax®) y caracterización del tipo de carbapenemasa por inmunocromatografía rápida RESIST-3 (Coris BioConcept®). Resultados: Encontramos un alto porcentaje de colonización rectal (22.9%) correspondiente a 13 hisopados positivos y 44 (77.1%) fueron negativos por nefelometría láser. Por VITEK 2® se obtuvo identificación de Klebsiella pneumoniae resistente a carbapenémicos en los 13 aislamientos y el test inmunocromatográfico reveló la presencia de carbapenemasas blaKPC en estos aislamientos. Discusión: Estudios evidencian el aumento de la colonización por microorganismos productores de carbapenemasas en neonatos. Los resultados de este estudio demuestran que un porcentaje significativo de neonatos que ingresan a las Unidades de Cuidado Neonatal se encuentran colonizados con Enterobacterias productoras de carbapenemasas en tracto intestinal. Lo anterior constituye un riesgo potencial para su diseminación y posterior desarrollo de brotes, en donde surge la importancia de implementar estrategias de vigilancia activa como la tamización rectal para la detección oportuna de neonatos colonizados.

Abstract Objective: To detect the presence of carbapenemase-producing Enterobacteriaceae in rectal swabs of neonates by means of laser nephelometry technique and characterization of the type of carbapenemase by immunochromatographic test. Materials and Methods: Descriptive cross-sectional study. 57 neonatal patients were included; They underwent rectal screening upon admission to the ICU, using swabs which were processed by HB&L Carbapenemase laser nephelometry (Alifax®) and characterization of the type of carbapenemase by RESIST-3 rapid immu nochromatography (Coris BioConcept®). Results: We found a high percentage of rectal colonization (22.9%) corresponding to 13 positive swabs and 44 samples (77.1%) were negative by laser nephelome try. Identification of carbapenem-resistant Klebsiella pneumoniae was obtained by VITEK 2® in the 13 isolates and the immunochromatographic test revealed the presence of blaKPC carbapenemases in these isolates. Discussion: Studies show increased colonization by carbapenemase-producing microorganisms in neonates. The results of this study demonstrate that a significant percentage of neonates who enter Neonatal Care Units are colonized with Enterobacteriaceae that produce carbapenemases in the intestinal tract. This constitu tes a potential risk for its spread and subsequent development of outbreaks, where the importance of implementing active surveillance strategies such as rectal screening for the timely detection of colonized neonates arises.