Role of Fiberoptic Bronchoscopy in Diagnosis of Pulmonary Tuberculosis in Patients at Risk for AIDS

Abstract

To the Editor: We are grateful for Dr. Barnes's interest and comments on our article and appreciate the opportunity to respond to his letter. The lung is a frequent target of AIDS-related opportunistic infections, including diseases caused by bacterial, viral, protozoal, mycobacterial, and fungal pathogens. Because of this diversity and the frequency of multiple, concurrent infections, fiberoptic bronchoscopy remains a cornerstone of the diagnostic strategy in these complex cases. At our institution, when HIV-related pulmonary infection is suspected based on clinical history and examination, our practice is to perform a diagnostic bronchoscopy within 24 to 48 h of admission unless a diagnosis has been established by other means. This is justified in order to obtain a rapid and accurate diagnosis and to institute appropriate therapy. Thus, the procedure is often performed prior to availability of final results from other tests, such as the PPD skin test, serial sputum acid-fast bacilli (AFB) smear analysis, and HIV serology. We sought to determine which bronchoscopically obtained specimens were sufficient for detecting pulmonary tuberculosis. We did not intend to compare the diagnostic utility of sputum analysis alone with that of bronchoscopy for diagnosis of pulmonary tuberculosis. We agree with Dr. Barnes that bronchoscopy is not indicated for diagnosing pulmonary tuberculosis if sputum AFB smear analysis is already confirmative. However, in dealing with a population including many HIV-positive patients, there is often a clinical suspicion of pulmonary infection other than tuberculosis. In fact, a concurrent diagnosis of Pneumocystis carimi pneumonia (PCP) was found in 19 percent of our high-risk patients. This is consistent with previous reports, including a study by Dr. Barnes and his colleagues.1Golan A Ron-el R Herman A Soffer Y Weinraub Z Caspi E et al.Ovarian hyperstimulation syndrome: an update review.Obstet Gynecol Surv. 1989; 44: 430-440Crossref PubMed Scopus (729) Google Scholar They found concurrent PCP in 4 of 15 AIDS patients (27 percent) with Mycobacterium tuberculosis infection. This high frequency of concurrent infections underscores the importance of a thorough diagnostic evaluation. In our study, although only 18 of the 27 patients in the high-risk AIDS group satisfied Centers for Disease Control clinical criteria (opportunistic infections or malignancies), in all patients bronchoscopy was indicated based on an elicited history of high-risk AIDS behavior and/or other clinically typical signs. As Dr. Barnes points out, granulomatous histopathologic change detected in transbronchial biopsy (TBB) specimens provides a rapid presumptive diagnosis in the non-AIDS patient population. We similarly found a 63 percent incidence of granulomatous changes in biopsy specimens from our non-AIDS patients. However, among the high-risk group, this typical histopathologic pattern was generally absent; it was detected in only 2 of 22 (9 percent) biopsy samples analyzed. Finally, we agree that our limited sample size of six TBB specimens submitted for culture limits conclusions regarding the microbiologic contribution of this sampling tool. However, preliminary data in a prospective study from our institution similarly showed that although TBB was culture-positive in 11 of 16 (69 percent) specimens submitted, it was never the sole source of microbiologic confirmation.2Schenker JG Weinstein D Ovarian hyperstimulation syndrome: a current study.Fertil Steril. 1978; 30: 255-268Abstract Full Text PDF PubMed Google Scholar Additional information evaluating the risk-benefit ratio and complication rate from this procedure in this specific patient population would be useful in guiding clinical management. In summary, we greatly appreciate the comments made by Dr. Barnes, but contend that our conclusions regarding the limited additional value of obtaining TBB for the diagnosis of pulmonary tuberculosis in HIV-related pulmonary disorders is supported by our data. We acknowledge that our study was retrospective in nature and, therefore, represents only the initial step in evaluating the precise role of TBB in this patient population.