Bronchoscopy with BAL and transbronchial lung biopsy (TBLB) is commonly used to evaluate pulmonary infiltrates of uncertain etiology. In addition to histopathology, TBLB specimens may be submitted for tissue culture. The yield and utility for culture of TBLB tissue is not known.
Our retrospective review of the Mayo Clinic, Rochester microbiology database from 2003 to 2008 identified 222 patients with cultures of lung tissue. Review of these cases resulted in 43 patients with culture of parenchymal lung tissue obtained via TBLB. These 43 patients all had culture of BAL/bronchial washings obtained during the same bronchoscopic procedure. The gold-standard diagnosis was determined from review of the episode of care incorporating all clinical, laboratory and treatment response data.
A total of 43 patients were included in the analysis. Of these, 35 (81%) were immunocompromised. Gold standard diagnoses were infectious (23 -53%), inflammatory (16 -37%), cancer (2 -5%), fluid overload (1), and unknown (1). Culture of TBLB tissue demonstrated the following performance characteristics; sensitivity 33%, specificity 56%, positive predictive value 40% and negative predictive value 60%. In 1 of the 23 infected patients (4%) TBLB tissue culture was the only test to identify the etiology. All other diagnoses were made through other avenues (BAL with culture, biopsy with pathology, or clinical follow up). The key diagnostic test was determined as BAL/bronchial washings in 10/43 (23.2%), both BAL/washings and TBLB culture in 4/43 patients (9.3%), histopathology from TBLB in 12/43 patients (27.9%), diagnostic imaging in 10/43 (23.2%), and clinical follow up (inconclusive diagnoses after initial diagnostic testing) in 6/43 (13.9%).
TBLB tissue culture demonstrated low sensitivity and specificity and added little new diagnostic information to traditional bronchoscopic cultures.
Culture of TBLB tissue may be appropriate to consider in highly selected cases, but the additive diagnostic yield beyond BAL and histopathology is low.
Jacob Scott, No Financial Disclosure Information; No Product/Research Disclosure Information