Increase in Fitness of Streptococcus pneumoniae is Associated with the Severity of Necrotizing Pneumonia.

Pediatr Infect Dis J. 2014 Dec 3. [Epub ahead of print]

Increase in Fitness of Streptococcus pneumoniae is Associated with the Severity of Necrotizing Pneumonia.

Hsieh YC1, Chi H, Chang KY, Lai SH, Mu JJ, Wong KS, Liu CC, Huang YC, Lin HC, Chang LY, Huang YC, Huang LM; for The Taiwan Pediatric Infectious Diseases Alliance.

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Abstract

BACKGROUND::

The incidence of necrotizing pneumococcal pneumonia has increased during the past two decades. We hypothothesized that increased pneumococcal load or augmented inflammatory cytokine production might lead to destructive pneumococcal lung disease.

METHODS::

This study enrolled prospectively 0-18 year-old children with a diagnosis of community-acquired pneumonia with pleural effusion admitted to 6 medical centers during 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 (RT-PCR). Pneumococcal empyema cases were further divided into four groups according to necrosis severity: 0) non-necrosis, 1) mild necrosis, 2) cavitation, and 3) bronchopleural fistula (BPF). Nasopharyngeal and pleural pneumococcal load, as well as 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 were 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 for 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 [aOR], 1.79; 95% confidence interval [CI], 1.03-3.06), and IL-8 (aOR, 2.64; 95% CI, 1.21-5.75) were independent factors associated with the severity of lung necrosis.

CONCLUSIONS::

Evolution of S. pneumoniae toward increased fitness in their interaction with host and exaggerated IL-8 expression may be responsible for the increase of necrotizing pneumococcal pneumonia.

PMID: 25461475 [PubMed - as supplied by publisher]