Diagnostic value of loop-mediated isothermal amplification in detecting lower respiratory pathogens

To investigate the diagnostic value of loop-mediated thermostatic amplification (LAMP) in detecting pathogenic bacteria from bronchoalveolar lavage fluid (BALF) of patients with pulmonary disorders combined with lower respiratory tract infections (LRTI).

This cross-sectional study included patients with pulmonary disorders combined with LRTI, including chronic obstructive pulmonary disease (COPD), bronchiectasis, or lung cancer, hospitalized in Meizhou People's Hospital between January 2020 and October 2021. BALF was collected using local bronchoalveolar lavage and electronic bronchoscopy. The presence of the pathogens was confirmed using the LAMP method and the bacterial culture method.

In total, 249 patients were included (135 with COPD, 73 with bronchiectasis, and 41 with lung cancer). The proportions of Methicillin-resistant Staphylococcus aureus (4.8% vs 0.4%, p = 0.02) and Haemophilus influenzae (6.8% vs 0.4%, p < 0.001) detected by the LAMP method was higher, while the proportion of Pseudomonas aeruginosa was lower compared with that of the culture method (6.8% vs 12.4%, p = 0.034). The bacterial species with the highest agreement coefficient was Stenotrophomonas maltophilia (Kappa = 0.798, p < 0.001). Furthermore, 9 COPD patients exhibited mixed infections as determined by the LAMP method, whereas the culture method detected only 2 of these cases (1.48%) (p < 0.05).

LAMP can detect more pathogenic bacteria, notably Haemophilus influenza, Methicillin-resistant Staphylococcus aureus, and atypical pathogens in patients with clinically common pulmonary disorders combined with LRTI. LAMP may provide etiological evidence to guide the clinical use of antibiotics in primary hospitals.