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Detection of OXA-23 and OXA-58 in Proteus mirabilis by immunochromatographic assays
Janina Noster-Schrader1,2, Janko Sattler3,4,5, Yvonne Stoll1
1Carl von Ossietzky University Oldenburg, Institute of Medical Microbiology and Virology, Oldenburg, Germany.
Abstract:
Proteus mirabilis is increasingly recognized as a carrier of carbapenemases, which are particularly difficult to identify, since most isolates have low carbapenem MICs. Additionally, most phenotypic tests (e.g. CARBA NP, mCIM) have insufficient sensitivity in this species. Furthermore, OXA-23 and OXA-58 are frequent in carbapenemase-producing Proteus but not included in most molecular and immunochromatographic assays for carbapenemase detection in Enterobacterales. The RESIST ACINETO lateral flow test (CORIS BioConcept) was recently developed for the detection of OXA-23, OXA-58/OXA-40, and NDM in Acinetobacter spp. The aim of this study was to investigate whether a combination of the RESIST-5 O.K.N.V.I., developed for Enterobacterales, and the RESIST ACINETO could improve the detection of carbapenemases in P. mirabilis. Ninety carbapenemase-carrying P. mirabilis isolates were analyzed by whole genome sequencing. All isolates were evaluated by the recently published carbapenemase-detection algorithm for P. mirabilis, followed by RESIST-5 and RESIST ACINETO assay. The algorithm achieved a sensitivity of 97.8%. In comparison, sensitivity/specificity among targeted carbapenemases was 96.3%/97.2% for RESIST ACINETO and 96.4%/100% for RESIST-5. In combination, a sensitivity of 97.8% was achieved. The sensitivity was excellent for OXA-23 (23/23, 100%) and NDM (18/18, 100%), but lower for OXA-58 (12/13, 92.3%) and OXA-48-like (24/25, 96.0%). The RESIST ACINETO and RESIST-5 performed well in detecting carbapenemases in P. mirabilis, particularly for the emerging OXA-23-producing P. mirabilis. The assays have the potential to improve carbapenemase detection in the routine diagnostic laboratory for this challenging species.
Importance:
OXA-23 and OXA-58 are among the most frequent carbapenemases in Proteus mirabilis but are often missed because of the difficult detection. In this article, the performance of immunochromatographic assays for the rapid and easy detection of these enzymes is assessed. The study includes a very large set of molecularly well-characterized isolates. The present work demonstrates that the notoriously challenging detection of carbapenemases in P. mirabilis can be achieved by immunochromatographic assays, enabling laboratories outside of academic centers to reliably detect these emerging carbapenemases in a short time. This will help prevent the further spread of carbapenemase-producing P. mirabilis in hospitals.
Insights
Carbapenemase detection in Proteus mirabilis is challenging due to low MICs and insensitive phenotypic tests. Combining RESIST-5 and RESIST ACINETO lateral flow assays significantly improves carbapenemase identification in P. mirabilis.
Area of Science:
- Clinical microbiology
- Antimicrobial resistance
- Molecular diagnostics
Background:
- Proteus mirabilis is a significant carrier of carbapenemases, posing diagnostic challenges due to low minimum inhibitory concentrations (MICs) and poor performance of standard phenotypic tests.
- OXA-23 and OXA-58 carbapenemases are prevalent in P. mirabilis but often missed by standard molecular and immunochromatographic assays designed for Enterobacterales.
- Existing assays lack sensitivity for detecting specific carbapenemases like OXA-23 and OXA-58 in P. mirabilis.
Purpose of the Study:
- To evaluate the combined performance of RESIST-5 O.K.N.V.I. and RESIST ACINETO lateral flow assays for detecting carbapenemases in P. mirabilis.
- To assess the utility of these immunochromatographic assays in improving carbapenemase detection for this challenging species in routine diagnostic settings.
- To determine the sensitivity and specificity of the combined assays for specific carbapenemase types, including OXA-23, OXA-58, OXA-48-like, and NDM.
Main Methods:
- Whole genome sequencing (WGS) was used to characterize 90 carbapenemase-carrying P. mirabilis isolates.
- Isolates were tested using a recently published carbapenemase-detection algorithm for P. mirabilis.
- Performance of RESIST-5 and RESIST ACINETO assays, both individually and in combination, was evaluated against WGS results.
Main Results:
- The combined use of RESIST-5 and RESIST ACINETO assays achieved an overall sensitivity of 97.8% for carbapenemase detection in P. mirabilis.
- Individual assay performance showed high sensitivity and specificity: RESIST ACINETO (96.3%/97.2%) and RESIST-5 (96.4%/100%).
- Excellent sensitivity was observed for OXA-23 (100%) and NDM (100%), with slightly lower but still high sensitivity for OXA-58 (92.3%) and OXA-48-like (96.0%).
Conclusions:
- The combination of RESIST ACINETO and RESIST-5 lateral flow assays demonstrates excellent performance for detecting carbapenemases in P. mirabilis.
- These assays are particularly effective for identifying emerging OXA-23-producing P. mirabilis, addressing a critical gap in current diagnostic capabilities.
- The study suggests these immunochromatographic assays can significantly enhance carbapenemase detection in routine laboratories, aiding in the control of carbapenemase-producing P. mirabilis spread.
