Corynebacterium accolens is a gram-positive, rod-shaped bacterium that is a common and beneficial member of the human skin and nasal microbiome. It plays a significant role in maintaining microbial balance and protecting against pathogenic bacteria, particularly in the nasal passages and on the skin surface.
Key Characteristics
C. accolens is a lipid-requiring species that lacks a fatty acid synthase, meaning it depends on exogenous sources of fatty acids for growth. This unique metabolic requirement has led to the evolution of specialized enzymes that allow it to utilize lipids found on human skin and in the nasal passages. It is non-motile, non-spore-forming, and facultatively anaerobic, allowing it to thrive in the various microenvironments of the human body.
Antimicrobial Properties
One of the most significant benefits of C. accolens is its ability to inhibit the growth of pathogenic bacteria. Research has demonstrated that C. accolens can:
- Release antipneumococcal free fatty acids from human skin surface triacylglycerols, inhibiting the growth of Streptococcus pneumoniae, a major cause of pneumonia and other respiratory infections
- Produce antimicrobial compounds that inhibit the growth of Staphylococcus aureus, including methicillin-resistant strains (MRSA)
- Modify its local habitat to create conditions unfavorable for pathogen colonization
These antimicrobial activities are primarily mediated through the action of LipS1, a triacylglycerol lipase that hydrolyzes human skin surface lipids to release free fatty acids with antimicrobial properties, particularly oleic acid.
Role in Respiratory Health
C. accolens is particularly abundant in the nasal microbiome of healthy individuals. Studies have shown that children with higher levels of nasal Corynebacterium species, including C. accolens, have lower rates of Streptococcus pneumoniae colonization. This suggests that C. accolens may play a protective role against respiratory pathogens, potentially reducing the risk of respiratory infections.
The bacterium's ability to inhibit S. pneumoniae colonization is especially significant given that pneumococcus is a leading cause of pneumonia, meningitis, and otitis media (ear infections) in children worldwide.
Skin Health Contributions
On the skin, C. accolens contributes to the overall microbial diversity and helps maintain a balanced microbiome. By competing with potential pathogens for resources and producing antimicrobial compounds, it helps prevent the overgrowth of harmful bacteria that could lead to skin infections or inflammation.
Interaction with Other Microorganisms
C. accolens engages in complex interactions with other members of the human microbiome:
- It competes with pathogenic bacteria like S. pneumoniae and S. aureus, limiting their growth and colonization
- It may work synergistically with other beneficial bacteria to maintain microbial balance
- Its lipid metabolism activities modify the local microenvironment, potentially benefiting other commensal bacteria
Potential Therapeutic Applications
The antimicrobial properties of C. accolens have sparked interest in its potential use as a probiotic or in bacteriotherapy approaches. Research is exploring whether introducing C. accolens to the nasal passages could help prevent colonization by pathogens like S. pneumoniae and S. aureus, potentially reducing the risk of respiratory infections and decreasing antibiotic use.
Additionally, understanding the mechanisms by which C. accolens inhibits pathogens could lead to the development of novel antimicrobial compounds or strategies to combat antibiotic-resistant bacteria.
Habitat and Distribution
C. accolens is primarily found in the following human body sites:
- Nasal passages and nostrils
- Skin, particularly in sebaceous (oily) areas
- Occasionally in the oral cavity
It is more abundant in pre-pubertal children than in adults, which may be related to differences in skin lipid composition across age groups.