Value of loop-mediated isothermal amplification in detection of common pathogens of bacterial pneumonia

Abstract

Objective To investigate the value of loop-mediated isothermal amplification (LAMP) assay in the etiology diagnosis of bacterial pnuemonia through nucleic acid detection of common pathogens in pneumonia patients by LAMP method. Methods Sputum DNA was extracted from 75 pneumonia patients. DNA was amplified by LAMP. The fluorescence signals of products were detected by real-time PCR. The quantitative results were qualitatively analyzed at different cutoff values, and the data were compared with the results of sputum culture. Results The positive ratio of amplified products with LAMP assay at the cutoff value of 1 × 104 was 68.0% ,and the coincidence rate between LAMP assay and sputum culture was 56.0%. The positive ratio of amplified products with LAMP assay at the cutoff value of 1× 105 was 50.7%, and the coincidence rate between LAMP assay and sputum culture was 58.7%.The positive ratio of amplified products with LAMP assay at the cutoff value of 1 × 106 was 30.7%, and the coincidence rate between LAMP assay and sputum culture was 53.3%. There was no statistical significance on the positive rate between sputum culture and LAMP results at the cutoff value of 1 × 105.The detection rate of parts of bacteria by LAMP assay is higher than that by sputum culture at the cutoff value of 1 × 105 ,especially for the harsh bacteria. Conclusions DNA of common pathogens in sputum of patients with bacterial pneumonia can be easily and quickly amplified by LAMP method to identify pathogenic bacteria types. Compared with sputum culture, the bacterial detection rate is higher by LAMP assay at the cutoff value of 1 × 105. Especially for the harsh bacteria, LAMP method has significant advantages. Key words: Bacterial pneumonia; Diagnosis; Loop-mediated isothermal amplification