Background: The etiologic data of community-acquired pneumonia (CAP) is essential, but rarely available in Korea. Polymerase chain reaction (PCR) methods are more sensitive to identifying etiologic agents than traditional sputum gram stain and culture.
Objectives: To investigate the prospective and comparative etiologic data of CAP through traditional and PCR methods
Methods: Expectorated sputum was collected from patients who diagnosed as CAP in Cheju National University Hospital before administration of antimicrobials. Gram stain, bacterial culture and PCR for S. pneumonia, M. pneumoniae, C. pneumoniae, L. pneumophila, B. pertussis, and H. influenza (Seeplex○R, SeeGene, Seoul, Korea) were performed.
Results: Sputum samples from 123 patients (mean age of 65 from 21 to 81, 80 males, 45 inpatients) were examined. Eighty eight samples (71.5%) were adequate. Among adequate samples, microbes were detected in 80 samples (90.9%) by gram stain, and identified in 25 samples (28.4%) by culture and 62 (70.5%) by PCR. Gram-positive cocci were detected in 77 samples (87.5%) and gram-negative rods in 28 (31.8%) by gram stain. In bacterial culture, S. pneumoniae were identified in 13 samples (14.8%), S. aureus in 10 samples (11.4%) including 5 MRSA, P. aeruginosa in 2 samples. By PCR, S. pneumoniae were identified in 50 samples (56.8%), H. influenzae in 36 (40.9%) and M. pneumoniae in 2 (2.3%). The concordance identifying S. pneumoniae between traditional and PCR methods were 90%, but for identifying gram-negative agents, two methods showed identical.
Conclusions: The identification of etiologic agents in adult CAP depends on the methods. For identifying H. influenza and some atypical agents, PCR methods might be useful. However, gram stain and bacterial culture should be accompanied for identifying other agents.