Abstract: To evaluate a Duplex PCR(DPCR)method in early diagnosis of legionella pneumonia by detecting legionella DNA in sputum samples, the sputum samples of patients from four groups, including legionella pneumonia group(n=15), clinical suspected legionella pneumonia group(n=29), ordinary pneumonia group(n=31)and pulmonary tuberculosis group(n=15)were detected with the DPCR method. Two different sets of oligonucleotide primer were stimultaneously used to amplify 386 bp 16SrRNA gene fragment and 206 bp mip gene fragment of legionella during the DPCR process. The DPCR positive rate of legionella pneumonia group(100%)was significantly higher than that of the other three groups(17.24%, 0, 0, respectively, P<0.01). The lowest detection level was 1×10³ cfu/mL for the simulated sputum sample. Primary study showed the DPCR method adopted for detecting legionella DNA in sputum samples had satisfactory sensitivity, specificity and stability. The method has its value in early diagnosis of legionella pneumonia.

Key words: duplex PCR, legionella pneumonia, sputum sample