Colorimetric Loop-Mediated Isothermal Amplification Assays Accurately Detect bla OXA-23-like and ISAba1 Genes from Acinetobacter baumannii in Pure Cultures and Spiked Human Sera

• Published in: Microbial drug resistance (Larchmont, N.Y.)
• Main Authors: Carascal, Mark B, Destura, Raul V, Rivera, Windell L
• Format: Journal Article
• Language: English
• Published: United States 01.10.2024
• Subjects: ISAba1; Acinetobacter baumannii; carbapenemase; loop-mediated isothermal amplification; blaOXA-23-like
• ISSN: 1931-8448
• DOI: 10.1089/mdr.2024.0075

Carbapenem resistance in is a critical global health threat attributed to transferrable carbapenemase genes. Carbapenemase genotyping using polymerase chain reaction (PCR) presents a challenge in resource-limited settings because of its technical requirements. This study designed new loop-mediated isothermal amplification (LAMP) primers using multiple sequence alignment-based workflows, validated the primer performance against multiple target variants , and developed novel LAMP assays (LAntRN-OXA23 and LAntRN-ISAba1) to detect the transferable carbapenemase genes and elements in pure cultures and -spiked serum samples. The designed LAMP primers bind to the conserved regions of their highly polymorphic targets, with their performance comparable with other published primers. The LAMP assays (using 30 PCR-profiled and 10 standard multidrug-resistant gram-negative isolates) have 100% concordance with the PCR-positive clinical samples, limits of detection as low as 1 pg/µL (200 copies/µL), and specificities of 57.89-100%. Both assays produced positive results when testing DNA samples (extracted using a commercial kit) from and PCR-positive -spiked normal human sera (five set-ups per target). In summary, the LAMP assays accurately detected the target genes and have applications in infection management, control, and point-of-care testing in resource-limited healthcare settings.