# Application value of Xpert Carba-R combined with LAMP in the diagnosis and prognosis of carbapenem-resistant Gram-negative bacilli pneumonia

## TL;DR

This study shows that combining Xpert Carba-R and LAMP improves early detection of drug-resistant bacteria in pneumonia, leading to better patient outcomes.

## Contribution

The study introduces a dual-method assay combining Xpert Carba-R and LAMP for rapid detection of CR-GNB and their resistance profiles.

## Key findings

- The combined method showed 64.87% sensitivity and 94.32% specificity for detecting CR-GNB.
- Early treatment based on test results improved clinical outcomes in severe patients.
- The method achieved 81.25% clinical improvement and 56.25% microbiological eradication rates in critically ill patients.

## Abstract

Given the current global challenges posed by antimicrobial resistance, the early and accurate identification of carbapenem-resistant Gram-negative bacilli (CR-GNB) is crucial for patient outcomes. This study evaluates the combined diagnostic performance of Xpert Carba-R and Loop-mediated isothermal amplification (LAMP) in the early detection of CR-GNB in patients with hospital-acquired pneumonia (HAP) or ventilator-associated pneumonia (VAP) and investigates the effect of early treatment based on detection results on the prognosis of these patients. In this single-center prospective study, 250 HAP/VAP patients were enrolled. Respiratory specimens underwent bacterial culture, antimicrobial susceptibility testing, Xpert Carba-R, and LAMP. Diagnostic performance (sensitivity, specificity, positive predictive value [PPV], negative predictive value [NPV]) of the combined test to detect CR-GNB was assessed. Clinical utility in guiding early antibiotic therapy was evaluated. The combined method demonstrated 64.87% sensitivity (95% CI: 52.89%–75.61%) and 94.32% specificity (95% CI: 89.80%–97.24%), with perfect 100% sensitivity and specificity for detecting CR-GNB in Klebsiella pneumoniae. Patients testing positive were randomized to early or non-early treatment groups. For severe patients, the early treatment group showed significantly improved clinical outcomes, including lower acute physiology and chronic health evaluation-II (APACHE-II) scores (P < 0.05) and sequential organ failure assessment (SOFA) scores (P < 0.01) at 15 days post-treatment, along with reduced 30-day hospitalization costs (P < 0.05). Notably, among the critically ill patients, compared with the non-early treatment group, the early treatment group achieved a clinical improvement rate of 81.25% and a microbiological eradication rate of 56.25%, showing a clear advantage.

An urgent clinical need exists for rapid detection of carbapenem-resistant Gram-negative bacilli (CR-GNB) in respiratory specimens to facilitate early and precise antibiotic therapy. To address this gap, we developed an innovative dual-method assay: Xpert Carba-R to detect five major carbapenemases, and loop-mediated isothermal amplification (LAMP) to identify common Gram-negative respiratory pathogens. Integration of these methods enables simultaneous and early determination of bacterial species and their resistance profiles. We validated this assay against conventional culture-based antimicrobial susceptibility testing (AST) and assessed its clinical impact on patient outcomes. Results indicate that this integrated approach provides clinically actionable data, serving as a viable alternative to conventional diagnostic workflows.

This study is registered with the Chinese Clinical Trial Registry as ChiCTR2400090694.