Background: Community-acquired pneumonia (CAP) is a major infectious disease with significant morbidity and mortality worldwide. Streptococcus pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae, Chlamydophila pneumoniae, Legionella pneumophila, and Bordetella pertussis are common pathogens of CAP; however, the conventional methods used to detect these agents, including culturing, lack sensitivity and are time-consuming. We evaluated a recently developed multiplex PCR assay which can test these agents simultaneously. 

Methods: One hundred patients with pneumonia and 99 healthy adults were tested using the Seeplex Pneumobacter ACE Detection assay (Seegene, Inc., Seoul, Korea). Culture and urinary antigen tests were also performed. 

Results: In patients with pneumonia, the positive detection rates of PCR for S. pneumoniae and H. influenzae were 52.0% (52/100) and 30.0% (30/100), respectively, those of M. pneumoniae and L. pneumophila were 2.0% (2/100) and 1.0% (1/100), respectively, and B. pertussis and C. pneumoniae were not detected. In healthy adults, the detection rates of S. pneumoniae and H. influenzae revealed similar results, 53.5% (53/101) and 40.4% (40/101), respectively, and the other four pathogens were not detected. The sensitivity and specificity of PCR for S. pneumoniae in pneumonia patients were 100% (95% confidence interval [CI], 87.9∼100%) and 65.7% (95% CI, 55.2∼76.5%), respectively, according to the urinary antigen test and cultures of the respiratory samples and blood. 

Conclusion: Differentiating S. pneumoniae and H. influenzae colonization from infection was difficult using the PCR assay. Therefore, the use of this assay is inappropriate for the diagnosis of pneumonia due to these agents, although multiplex PCR assay would be useful for the detection of M. pneumoniae and L. pneumophila. (Korean J Clin Microbiol 2010;13:40-46)