Development of an immunochromatographic lateral flow assay to rapidly detect OXA-23-, OXA-40-, OXA-58- and NDM-mediated carbapenem resistance determinants in Acinetobacter baumannii

infections can be extremely challenging to treat owing to the worldwide prevalence of multidrug-resistant isolates, especially against carbapenems. Colonization with carbapenem-resistant (CRAb) requires rapid action from an infection control perspective because the organism is known for its propensity for epidemic spread There is an unmet medical need to rapidly identify CRAb to enable appropriate antimicrobial treatment and to prevent transmission Our aim was to expand the OXA-detection abilities of the rapid immunochromatographic test (ICT) OXA-23 -SeT (Coris BioConcept) to include OXA-40- and OXA-58-like carbapenemases, which together confer carbapenem resistance to more than 94 % of CRAb isolates worldwide We used hybridoma technology to generate mAbs against OXA-40 and OXA-58 and selected them for productivity and specificity against recombinant and endogenous OXA-40 and OXA-58. Combinations of the resulting mAbs were analysed in ICT format for their ability to detect recombinant rOXA-40 or rOXA-58 , respectively. Subsequently, selected antibody pairs were implemented into single-OXA-40 or single-OXA-58 prototypes and the final OXA-23/40/58/NDM ICT and were evaluated on clinical spp. isolates with well-defined carbapenem resistance mechanisms Five anti-OXA-40 and anti-OXA-58 mAbs were selected. Competition ELISA with combinations of these antibodies revealed that the anti-OXA-40 antibodies bind to one of two binding clusters on OXA-40, while anti-OXA-58 antibodies bind to one of four binding clusters on OXA-58. Direct binding to the corresponding antigen in an ICT format has left only three antibodies against rOXA-40 and rOXA-58 , respectively for the subsequent sandwich ICT selection procedure, which revealed that the anti-OXA-40 (#5) and anti-OXA-58 (#A8) mAbs in combination with the cross-reactive mAb #C8 performed best. They were implemented into single-OXA-40 and single-OXA-58 ICT prototypes and evaluated. These single ICT prototypes demonstrated 100 % specificity and sensitivity. Based on these results, an OXA-23/40/58/NDM-ICT was developed, complemented with OXA-23 and NDM-specific detection. An evaluation with selected carbapenem-resistant spp. isolates ( =34) showed 100 % specificity With this easy-to-use detection assay, one can save 12-48 h in diagnostics, which helps to treat patients earlier with appropriate antibiotics and allows immediate intervention to control transmission of CRAb