PURPOSE: Sarcoidosis is an incurable, chronic granulomatous disease involving the lungs and lymph nodes of unknown etiology, treated with non-specific anti-inflammatory medicines. 25-50% of patients present with no symptoms. Persistently symptomatic patients tend to worsen with a disabling clinical course. To determine a possible infectious cause, we correlated the clinical presentation of sarcoidosis with the presence of bacterial DNA in archived mediastinal lymph nodes compared to control lymph nodes.
METHODS: We retrospectively studied formalin-fixed, paraffin-embedded, surgically resected mediastinal lymph nodes from 30 sarcoidosis patients and 31 control patients. Nodes were analyzed by extracting nucleic acids, performing rRNA PCR, sequencing the result and identifying any bacterial sequences against a library of bacterial sequences. Clinical information on sarcoidosis and control patients were correlated with results.
RESULTS: 12/30 (40.0%) of lymph nodes from sarcoidosis patients had bacteria detected: 7 Propionibacterium acnes, 3 atypical Mycobacteria species (2 chelonae, 1 mucogenicum), 1 Duganella zoogloeoides and 1 Corynebacterium propinquum. 2/31 (6.4%) of control nodes had detectable bacteria (Mycobacterium avian and Propionibacterium acnes). Of the sarcoidosis patients, 19/30 (63.3%) were symptomatic including all patients with detectable bacteria. Radiographically, there were 18 Stage I and 12 Stage II patients. All Stage II patients were symptomatic and 75% had PCR-detectable bacteria.
CONCLUSIONS: 40% of sarcoidosis lymph nodes had detectable bacteria DNA. Since formalin fixation may destroy DNA, the true number of nodes containing bacteria is likely underestimated. All patients with detectable bacteria were quite symptomatic and included most of the radiographically advanced stage patients. These findings suggest bacteria-positive, symptomatic patients have more aggressive sarcoidoisis and might benefit from specific treatment directed against a presumed chronic infection.
CLINICAL IMPLICATIONS: Persistently symptomatic sarcoidosis patients may benefit from appropriate antimicrobial treatment and should be considered for a clinical trial.
DISCLOSURE: The following authors have nothing to disclose: Lary Robinson, Prudence Smith, Dhruba SenGupta, Jennifer Prentice, Ramon Sandin
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