title: Molecular analysis of sarcoidosis lymph nodes for microorganisms: a case-control study with clinical correlates.
abstract: BACKGROUND
  Sarcoidosis is an incurable, chronic granulomatous disease primarily involving the lungs and lymph nodes of unknown aetiology, treated with non-specific anti-inflammatory/immunosuppressive drugs. Persistently symptomatic patients worsen with a disabling, potentially fatal clinical course. To determine a possible infectious cause, we correlated in a case-control study the clinical information with the presence of bacterial DNA in sarcoidosis mediastinal lymph nodes compared with control lymph nodes resected during cancer surgery.
  
  
  METHODS
  We retrospectively studied formalin-fixed, paraffin-embedded, mediastinal lymph nodes from 30 patients with sarcoidosis and 30 control patients with lung cancer. Nucleic acids were extracted from nodes, evaluated by ribosomal RNA PCR for bacterial 16S ribosomal DNA and the results were sequenced and compared with a bacterial sequence library. Clinical information was correlated.
  
  
  RESULTS
  11/30 (36.7%) of lymph nodes from patients with sarcoidosis had detectable bacterial DNA, significantly more than control patient lymph nodes (2/30, 6.7%), p=0.00516. At presentation, 19/30 (63.3%) patients with sarcoidosis were symptomatic including all patients with detectable bacterial DNA. Radiographically, there were 18 stage I and 12 stage II patients. All stage II patients were symptomatic and 75% had PCR-detectable bacteria. After a mean follow-up of 52.8±32.8 months, all patients with PCR-detectable bacteria in this series were persistently symptomatic requiring treatment.
  
  
  CONCLUSIONS
  36.6% of patients with sarcoidosis had detectable bacterial DNA on presentation, all of these patients were quite symptomatic and most were radiographically advanced stage II. These findings suggest that bacterial DNA-positive, symptomatic patients have more aggressive sarcoidosis that persists long term and might benefit from antimicrobial treatment directed against this presumed chronic granulomatous infection.
authors.affiliation: Division of Thoracic Oncology, Center for Infection Research in Cancer, Moffitt Cancer Center, Tampa, Florida, USA.
authors.forename: Lary A
authors.initials: LA
authors.lastname: Robinson
authors.forename: Prudence
authors.initials: P
authors.lastname: Smith
authors.forename: Dhruba J
authors.initials: DJ
authors.lastname: Sengupta
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Prentice
authors.forename: Ramon L
authors.initials: RL
authors.lastname: Sandin
keywords: BACTERIOLOGY; MICROBIOLOGY