Summary
A medRxiv preprint reports that NG-TEST Acineto-5 detected all targeted carbapenemases in a 433-isolate evaluation, with no false positives among isolates lacking them. Four of five Acinetobacter radioresistens isolates carrying an intrinsic OXA-23-like gene produced weak positive signals.
A medRxiv preprint reports that NG-TEST Acineto-5 detected all targeted carbapenemases in a validation panel of 433 whole-genome-sequenced Acinetobacter isolates. The lateral-flow immunoassay had 100% sensitivity and 100% specificity in the evaluated collection. Four of five A. radioresistens isolates carrying an intrinsic OXA-23-like gene showed weak positive signals, a finding the researchers considered consistent with low-level expression.
Carbapenemases are enzymes that can make carbapenem antibiotics ineffective. Identifying which enzyme is present can help inform treatment and infection-control decisions. NG-TEST Acineto-5 is designed to detect major acquired carbapenemases in Acinetobacter; the study tested whether it recognised several OXA enzyme groups as well as NDM and VIM.
What the isolate evaluation found
The collection was mostly Acinetobacter baumannii (365 isolates) and A. pittii (33), with 13 other species represented by one to seven isolates each. The enzyme-producing isolates included single producers of OXA-23-like (126), OXA-24-like (14), OXA-58-like (8), OXA-143/253/542 (10), VIM-like (9) and NDM-like enzymes (25). The panel also included 20 isolates producing two carbapenemases and two producing three.
The assay detected all tested target enzymes, including the tested variants and combinations. The researchers reported 100% sensitivity and no false-positive results among isolates lacking targeted carbapenemases, giving 100% specificity in this collection. OXA-24-like, OXA-143-like and OXA-542 were detected using the same antibody pair, which the study describes as cross-reactivity within this group.
The weak signals in four A. radioresistens isolates are a relevant detail because the assay detects enzyme signals, not whether the underlying gene is acquired or intrinsic. The authors link those signals to low-level expression of the species’ intrinsic blaOXA-23-like genes.
Potential use and study scope
The paper presents rapid carbapenemase detection as a possible aid to therapeutic decisions, infection control and epidemiological surveillance. It highlights NDM and VIM because these enzymes are not inhibited by durlobactam and have been associated with increased cefiderocol minimum inhibitory concentrations (MICs), which may limit treatment options. The study evaluated the assay on isolates; it did not test whether using the result to guide treatment improves patient outcomes.
The results are reported in a medRxiv preprint. The author declarations state that four coauthors were NG Biotech employees and that the company provided the kits free of charge. The authors say NG Biotech was not involved in the experimental evaluation, data analysis, interpretation or manuscript preparation.