title: Propionibacterium acnes is the most common bacterium commensal in peripheral lung tissue and mediastinal lymph nodes from subjects without sarcoidosis.
abstract: 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Human Pathology, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Ikuo
authors.initials: I
authors.lastname: Ishige
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Eishi
authors.forename: Tamiko
authors.initials: T
authors.lastname: Takemura
authors.forename: Intetsu
authors.initials: I
authors.lastname: Kobayashi
authors.forename: Koh
authors.initials: K
authors.lastname: Nakata
authors.forename: Isao
authors.initials: I
authors.lastname: Tanaka
authors.forename: Sakae
authors.initials: S
authors.lastname: Nagaoka
authors.forename: Kazuro
authors.initials: K
authors.lastname: Iwai
authors.forename: Kunitomo
authors.initials: K
authors.lastname: Watanabe
authors.forename: Touichiro
authors.initials: T
authors.lastname: Takizawa
authors.forename: Morio
authors.initials: M
authors.lastname: Koike
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005260:Female; D016908:Gram-Positive Bacterial Infections / Q000150:complications*; D006801:Humans; D008168:Lung / Q000382:microbiology*; D008171:Lung Diseases / Q000382:microbiology; D008198:Lymph Nodes / Q000382:microbiology*; D008297:Male; D008482:Mediastinum; D008875:Middle Aged; D011425:Propionibacterium acnes / Q000302:isolation & purification* / Q000472:pathogenicity*; D012507:Sarcoidosis / Q000382:microbiology