Evaluation of the RESIST ACINETO multiplex immunochromatographic assay for detection of OXA-23-like, OXA-40/58-like, and NDM carbapenemase production in Acinetobacter baumannii

Acinetobacter baumannii is a major cause of hospital-acquired infections. Due to its ability to rapidly accumulate antimicrobial resistance traits, multidrug-resistant isolates have been reported worldwide. Carbapenemase-resistant A. baumannii (CRAB) are a concern, as only few therapeutic options, including colistin, tigecycline/eravacycline, and cefiderocol, are currently available. Rapid diagnostics is crucial to prevent the dissemination of CRAB and to determine best antibiotic treatments. In this study, we evaluate the performance of “RESIST ACINETO” lateral flow immunoassay (Coris BioConcept, Belgium) for the detection of the most prevalent acquired carbapenemases in A. baumannii. Hundred-thirty-two A. baumannii clinical isolates were characterized using whole-genome-sequencing and carbapenemases were determined. “RESIST ACINETO” was performed on overnight cultures according to the manufacturer's instructions. The strain collection comprised 25 carbapenemase-negative and 107 carbapenemase-producing isolates. Ninety two isolates produced an OXA-type carbapenemase (72 OXA-23, 17 OXA-72, and three OXA-58), while three showed a combination of two oxacillinases (two OXA-23/OXA-58 and one OXA-23/OXA-72). Four isolates produced NDM-1, one NDM-2, while the remainders a combination of NDM-1 and an oxacillinase (two NDM-1/OXA-23, three NDM-1/OXA-72, and one NDM-1/OXA-58). The isolates represented 34 different STs, ST-2 was the most prevalent (47/132, 36%). “RESIST ACINETO” LFIA correctly identified all six different carbapenemase variants in all strains, including those producing two carbapenemases (sensitivity 100%). OXA-72 was correctly detected as OXA-40 variant. No false positive result, also possibly due to cross-reactivity with one of the 24 detected different intrinsic oxacillinases, was observed (specificity 100%). “RESIST ACINETO” shows a high and reliable performance for the detection of most prevalent carbapenemases in A. baumannii.