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Published on: March 17, 2014
Propionibacterium acnes is the most common bacterium commensal in peripheral lung tissue and mediastinal lymph nodes
Ikuo Ishige1, Yoshinobu Eishi, Tamiko Takemura
1Department of Human Pathology, Tokyo Medical and Dental University, Tokyo, Japan.
Background:
In studies of the unknown etiology of sarcoidosis, Propionibacterium acnes (a possible agent) was found in the lungs and lymph nodes of many sarcoidosis patients and some control subjects. P. acnes might be commensal not only to the skin, conjunctivae, and intestine, but also to the lungs and lymph nodes of individuals without sarcoidosis.
Methods:
We cultured peripheral lung tissue and various lymph nodes obtained from patients with diseases other than sarcoidosis. DNA of 45 isolates of P. acnes from these patients, 67 isolates from normal skin, conjunctiva, and intestine, and 39 isolates from sarcoid lymph nodes were compared by random amplified polymorphic DNA analysis.
Results:
P. acnes was isolated from half of 43 lungs and 8 of 11 mediastinal lymph nodes, mostly in pure culture. P. acnes was isolated from half of 20 gastric and 3 of 12 intestinal lymph nodes; intestinal bacteria were also numerous. In general, fewer than 500 colony-forming units of P. acnes per gram tissue were isolated, but 4 lung tissue specimens, 2 of which had a few granulomas, had many more. P. acnes strains from a particular site (lung, lymph node, skin or conjunctivae, and intestine) were genetically similar, more than isolates obtained from different sites. Lymph-node isolates from subjects with and without sarcoidosis differed little.
Conclusion:
These results suggest that P. acnes normally resides in peripheral lung tissue and mediastinal lymph nodes and that the strains of P. acnes isolated from sarcoid lymph nodes were not specific to sarcoidosis.
Insights
Propionibacterium acnes (P. acnes) is commonly found in lung and lymph node tissues, even in individuals without sarcoidosis. Genetic analysis shows P. acnes strains from sarcoid lymph nodes are not specific to the disease.
Area of Science:
- Microbiology
- Immunology
- Pulmonology
Background:
- Sarcoidosis etiology is unknown, with Propionibacterium acnes (P. acnes) implicated.
- P. acnes may be a commensal organism in various human tissues, including lungs and lymph nodes, not just skin and gut.
Purpose of the Study:
- To investigate the presence and genetic relatedness of P. acnes in lung and lymph node tissues.
- To determine if P. acnes strains from sarcoidosis patients are distinct from those in healthy individuals.
Main Methods:
- Culturing P. acnes from peripheral lung tissue and lymph nodes of non-sarcoidosis patients.
- Comparing DNA of P. acnes isolates from various body sites (lung, lymph node, skin, conjunctiva, intestine) using random amplified polymorphic DNA analysis.
Main Results:
- P. acnes was frequently isolated from lung and mediastinal lymph nodes, often in pure culture.
- P. acnes strains from the same body site were genetically similar.
- P. acnes isolates from individuals with and without sarcoidosis showed minimal genetic differences.
Conclusions:
- P. acnes is a normal resident of peripheral lung tissue and mediastinal lymph nodes.
- The P. acnes strains found in sarcoid lymph nodes are not specific to sarcoidosis, suggesting it may not be the primary causative agent.
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