Validation of NG-TEST ® Acineto -5 ® for the Detection of OXA Carbapenemases, NDM, and VIM in the Acinetobacter calcoaceticus-baumannii Complex and beyond
Listed in
This article is not in any list yet, why not save it to one of your lists.Abstract
Carbapenem resistance in Acinetobacter spp. is frequently mediated by acquired carbapenemases, whose rapid detection can inform antimicrobial therapy and infection-control decisions. NG-TEST ® Acineto -5 ® is a lateral flow immunoassay designed to detect major acquired carbapenemases in Acinetobacter spp. We evaluated its performance using 433 whole-genome-sequenced isolates, including single producers of OXA-23-like (n = 126), OXA-24-like (n = 14), OXA-58-like (n = 8), OXA-143/253/542 (n = 10), VIM-like (n = 9), and NDM-like enzymes (n = 25), as well as isolates co-producing two (n = 20) or three (n = 2) carbapenemases. The collection was predominantly composed of Acinetobacter baumannii (n = 365) and Acinetobacter pittii (n = 33), with 13 additional species represented by 1 to 7 isolates each. The assay detected all targeted carbapenemases, including all tested variants and combinations, yielding 100% sensitivity. OXA-24-like, OXA-143-like, and the distantly related OXA-542 were detected by the same antibody pair, demonstrating cross-reactivity within this group. No false-positive results occurred among isolates lacking targeted carbapenemases, resulting in 100% specificity. Weak positive signals were observed in four of five A. radioresistens isolates carrying intrinsic bla OXA-23-like genes, consistent with low-level expression. Overall, NG-TEST® Acineto -5 ® enables rapid detection of major acquired carbapenemases in Acinetobacter spp., supporting infection control, epidemiological surveillance and therapeutic decision-making, as carbapenemase-producing isolates are often multidrug resistant. Detection of VIM and NDM may be particularly valuable because these enzymes are not inhibited by durlobactam and have been associated with increased cefiderocol MICs, potentially limiting treatment options.
IMPORTANCE
Carbapenem-resistant Acinetobacter spp. are important causes of healthcare-associated infections and are frequently multidrug resistant, leaving few therapeutic options. The diversity of acquired carbapenem-hydrolyzing class D β-lactamases (CHDLs) and metallo-β-lactamases (MBLs) complicates their rapid phenotypic detection. We evaluated the NG-TEST ® Acineto -5 ® lateral flow immunoassay using a large, whole-genome-sequenced collection representing diverse carbapenemase variants and clinically relevant Acinetobacter spp. The assay reliably detected all targeted carbapenemases, including OXA-23-, OXA-24-, OXA-58-, OXA-143/253/542-, VIM-, and NDM-type enzymes, as well as isolates producing multiple carbapenemases. These findings support the use of NG-TEST ® Acineto -5 ® as a rapid diagnostic tool for detecting Acinetobacter -specific carbapenemases, facilitating infection-control measures and antimicrobial therapy. This is particularly relevant with the use of novel β-lactamase inhibitors such as durlobactam in combination with sulbactam. Durlobactam inhibits class D OXA-type carbapenemases but not MBLs such as NDM and VIM; therefore, rapid identification of the underlying carbapenemase mechanism may help inform appropriate therapeutic decisions.
