Increase in fitness of streptococcus pneumoniae is associated with the severity of necrotizing pneumonia
Date of Original Version
Background: The incidence of necrotizing pneumococcal pneumonia has increased during the past 2 decades. We hypothesized that increased pneumococcal load or augmented inflammatory cytokine production might lead to destructive pneumococcal lung disease. Methods: This study enrolled prospectively 0- to 18-year-old children with a diagnosis of community-acquired pneumonia with pleural effusion admitted to 6 medical centers from March 2010 to April 2012. Children were diagnosed with pneumococcal empyema if the pleural fluid tested positive for quantitative pneumococcal (lytA) detection by real-time polymerase chain reaction. Pneumococcal empyema cases were further divided into 4 groups according to necrosis severity: (0) nonnecrosis, (1) mild necrosis, (2) cavitation and (3) bronchopleural fistula. Nasopharyngeal and pleural pneumococcal load, as well as levels of proinflammatory cytokines (TNF-α, IL-1β, IL-6, IL-8), Th1-(IL-2, IFN-γ), Th2-(IL-4, IL-10) and Th17-cytokines (IL-17), in the pleural fluid was measured. Results: Serotypes 19A and 3 accounted for 69.4% and 12.5%, respectively, of 72 cases of pneumococcal empyema. Pleural pneumococcal load was significantly higher in serotypes 19A and 3 infection than in the other strains causing infection (P = 0.006). There was a correlation between nasopharyngeal and pleural pneumococcal load (ρ = 0.35; P = 0.05). In multivariate ordinal logistic regression analysis, pleural pneumococcal load (adjusted odds ratio: 1.79; 95% confidence interval: 1.03-3.06) and IL-8 (adjusted odds ratio: 2.64; 95% confidence interval: 1.21-5.75) were independent factors associated with the severity of lung necrosis. Conclusions: Evolution of Streptococcus pneumoniae toward increased fitness in their interaction with host and exaggerated IL-8 expression may be responsible for the increase of necrotizing pneumococcal pneumonia.
Publication Title, e.g., Journal
Pediatric Infectious Disease Journal
Hsieh, Yu Chia, Hsin Chi, Kuang Yi Chang, Shen Hao Lai, Jung Jung Mu, Kin Sun Wong, Ching Chuan Liu, Yi Chuan Huang, Hsiao Chuan Lin, Luan Yin Chang, Yhu Chering Huang, and Li Min Huang. "Increase in fitness of streptococcus pneumoniae is associated with the severity of necrotizing pneumonia." Pediatric Infectious Disease Journal 34, 5 (2015): 499-505. doi: 10.1097/INF.0000000000000631.