Related Experiment Video
Updated: Jan 31, 2026
Following in Real Time the Impact of Pneumococcal Virulence Factors in an Acute Mouse Pneumonia Model Using Bioluminescent Bacteria
Published on: February 23, 2014
Effects of Anaerobic Culturing on Pathogenicity and Virulence-Related Gene Expression in Pneumococcal Pneumonia
Kentaro Nagaoka1, Yu Yamashita1, Hiroki Kimura1
1First Department of Internal Medicine, Hokkaido University Hospital, Hokkaido.
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.
Insights
Anaerobic Streptococcus pneumoniae culture enhances pathogenicity, leading to lower survival rates and increased bacterial load in a murine pneumonia model. This suggests a distinct invasive mechanism compared to aerobic conditions.
Area of Science:
- Microbiology
- Infectious Diseases
- Pathogenesis
Background:
- The pathogenicity of Streptococcus pneumoniae under anaerobic conditions is not well understood.
- This study investigates the virulence of S. pneumoniae cultured anaerobically in a mouse model of pneumococcal pneumonia.
Purpose of the Study:
- To compare the pathogenicity of S. pneumoniae grown under anaerobic versus aerobic conditions.
- To analyze the effect of anaerobic culture on virulence gene expression (lytA/ply) in vitro and in vivo.
Main Methods:
- Mice were infected with S. pneumoniae cultured under anaerobic or aerobic conditions.
- Pathogenic effects were compared in vivo, focusing on the lower airway tract.
- Quantitative real-time PCR was used to analyze lytA/ply transcript levels.
Main Results:
- Anaerobically cultured S. pneumoniae led to significantly lower survival rates and higher bacterial loads in lungs and blood compared to aerobically cultured bacteria.
- Aerobically cultured S. pneumoniae in early log phase also induced severe pneumonia.
- Transcript levels of ply/gyrB were significantly elevated in lungs infected with anaerobically grown S. pneumoniae.
- In vitro, anaerobic culture promoted greater S. pneumoniae proliferation and sustained bacterial concentrations for 24 hours without lytA upregulation.
Conclusions:
- S. pneumoniae grown anaerobically can cause severe invasive bacteremic pneumococcal pneumonia through a mechanism distinct from aerobic growth.
- Understanding anaerobic growth conditions is crucial for comprehending S. pneumoniae pathogenesis.
Related Concept Videos
01:42What is Gene Expression?
Gene expression is the process in which DNA directs the synthesis of functional products, that is, proteins. Cells can regulate gene expression at various stages. It allows organisms to generate different cell types and enables cells to adapt to internal and external factors.
Genetic Information Flows from DNA to RNA to Protein
A gene is a stretch of DNA that serves as the blueprint for functional RNAs and proteins. Since DNA is made up of nucleotides and proteins consist of amino...
01:36What is Gene Expression?
01:58Cell Specific Gene Expression
01:58Cell Specific Gene Expression
02:35Chromatin Position Affects Gene Expression
Topologically Associated Domains (TADs)
The 3-dimensional positioning of chromatin in the nucleus influences the...
02:51mRNA Stability and Gene Expression
Cis-acting Elements involved in mRNA stability