Effects of anaerobic culturing on pathogenicity and virulence-related gene expression in pneumococcal pneumonia

Kentaro Nagaoka, Yu Yamashita, Hiroki Kimura, Masaru Suzuki, Satoshi Konno, Tatsuya Fukumoto, Koji Akizawa, Yoshitomo Morinaga, Katsunori Yanagihara, Masaharu Nishimura

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Background: The pathogenicity of Streptococcus pneumoniae under anaerobic conditions remains largely unknown. We examined the pathogenicity of S. pneumoniae cultured under anaerobic conditions in a murine model of pneumococcal pneumonia. Methods: Mice were infected with S. pneumoniae grown under anaerobic or aerobic conditions. The pathogenic effects in vivo in the lower airway tract were then compared. The effect of anaerobic culture on lytA/ply transcript levels in vitro and in vivo were analyzed by quantitative real-time polymerase chain reaction. Results: Mice inoculated with anaerobically cultured S. pneumoniae exhibited significantly lower survival rates and higher bacterial loads in the lungs and blood as compared to those infected with aerobically cultured S. pneumoniae. Aerobically cultured S. pneumoniae in the early log phase of growth was also able to induce severe pneumonia at levels equivalent to those of anaerobic S. pneumoniae. However, ply/gyrB transcript levels were significantly increased in the lungs of mice infected with anaerobically grown S. pneumoniae. In vitro, S. pneumoniae grown under anaerobic culture conditions demonstrated greater proliferation than S. pneumoniae grown under aerobic culture conditions, and bacterial concentrations were maintained for 24 hours without detectable upregulation of lytA messenger RNA. Conclusions: S. pneumoniae grown under anaerobic conditions had the potential to induce severe invasive bacteremic pneumococcal pneumonia in a manner different from that of S. pneumoniae grown under aerobic conditions.

Original languageEnglish (US)
Pages (from-to)1545-1553
Number of pages9
JournalJournal of Infectious Diseases
Issue number10
StatePublished - May 1 2019


  • Anaerobic culture
  • Autolysin
  • Pneumolysin
  • Streptococcus pneumoniae

ASJC Scopus subject areas

  • Immunology and Allergy
  • Infectious Diseases


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