Comparison of Clinical Characteristics of Pneumococcal and non-Pneumococcal Streptococcal Pneumonia

Background: Although Pneumococcal (SPN) pneumonia is the most common cause of community-acquired pneumonia, non-pneumococcal streptococcal (NSPN) pneumonia is also frequently reported. However, there are insufficient data on characteristics of NSPN pneumonia which makes it difficult to decide treatment plans or to assess the prognosis. Materials and Methods: Between March 2002 and February 2009, medical records including clinical and epidemiological data on patients aged >= 18 years with community-acquired streptococcal pneumonia were reviewed retrospectively. Clinical characteristics were compared between community-acquired NSPN pneumonia and SPN pneumonia. Results: During the 7 year study periods, 248 patients were hospitalized with community-acquired streptococcal pneumonia and 30 of them had NSPN pneumonia. There were 12 cases of Streptococcus constellatus, 7 cases of S. anginosus, 4 cases of S. mitis, 3 cases of S. pyogenes, 2 cases of S. oralis, 1 case of S. alactolyticus and 1 case of S. agalactiae. There was no difference in percentage of patients with a chronic underlying disease between SPN and NSPN pneumonia groups. The most common was chronic obstructive pulmonary disease (SPN 29.8%, NSPN 16.7%) followed by diabetes mellitus (SPN 22.0%, NSPN 13.3%). Bacteremia (SPN 7.3%, NSPN 20.0%, P=0.04) and empyema (SPN 1.4%, NSPN 53.3%, P<0.001) were more common in NSPN pneumonia. However, there was no significant difference in the CURB-65 pneumonia severity score and 30-day mortality between the two groups. According to multivariate analysis results, the significant risk factor for NSPN pneumonia was the history of frequent alcohol drinking (Adjusted OR 3.81, 95% CI 1.36 to 10.67). Conclusion: Pneumonia caused by NPSN is more commonly accompanied by bacteremia and empyema compared to SPN pneumonia, but there was no difference in the 30-day mortality between the two groups. NSPN pneumonia should be considered if a patient with a history of chronic alcoholism presents with pneumonia and pleural effusion, especially when Gram positive diplococci is seen in the sputum Gram stain.