Detection of Mycobacterium tuberculosis in bronchoalveolar lavage from patients with sputum smear-negative pulmonary tuberculosis using a polymerase chain reaction assay

Abstract The objective of this study was to evaluate the utility of a polymerase chain reaction (PCR) assay in detecting Mycobacterium tuberculosis in bronchoalveolar lavage (BAL) specimens of patients suspected of having active pulmonary tuberculosis (TB) but who were sputum smear-negative. Patients undergoing investigation for suspected pulmonary TB at the University Hospital, Kuala Lumpur, and who were sputum smear-negative underwent fibreoptic bronchoscopy and BAL. One portion of each lavage specimen was submitted for smear examination for acid-fast bacilli and mycobacterial culture and the other portion assayed by PCR for the presence of a 562-base pair DNA segment belonging to the insertion sequence IS986, unique to the M. tuberculosis complex. As controls, lavage specimens from patients with other lung lesions were also similarly tested. The PCR assay gave a positivity rate of 80.9% (55 of 68) compared with 8.8% of smear examination and 7.4% of culture for detecting M. tuberculosis in BAL specimens. The assay was positive in two of 45 BAL specimens from 35 control subjects. The PCR assay was more sensitive than smear and culture in detecting M. tuberculosis in BAL specimens of patients with sputum smear-negative pulmonary TB.     

纤维支气管镜检查对无痰或痰菌阴性不典型肺结核的诊断价值

目的 探讨纤维支气管镜（简称“纤支镜”）检查对无痰或痰菌阴性不典型肺结核的诊断价值。 方法 选无痰或痰菌阴性的不典型肺结核患者201例,用纤支镜在病变部位进行活检、刷检、支气管肺泡灌洗液（BALF）进行BBLMGIT(Mycobacteria Growth Indicate Tube)分枝杆菌快速培养查结核杆菌。术后进行痰涂片查抗酸杆菌、痰结核分枝杆菌快速培养。 结果201例刷检、BALF快速培养结核分枝杆菌阳性率分别是67.2%、83.6%,61例活检阳性率63.9%,201例术后痰涂片、术后痰快速培养结核分枝杆菌阳性率分别是28.9%、57.2%。 结论 纤支镜检查是确诊无痰或痰菌阴性不典型肺结核的有效方法 ,其中BALF行结核分枝杆菌快速培养具有较高的诊断价值、快速、阳性率较高。根据镜下所见采用不同的取材方法 可望提高诊断率。     

血T-SPOT.TB联合肺泡灌洗液TbDNA检测对诊断肺结核的应用价值

目的分析血T-SPOT.TB联合肺泡灌洗液(BALF)Tb DNA检测对肺结核诊断的价值。方法选择2013.3~11月86例疑似肺结核患者,经确诊后分为肺结核组46例、肺炎组40例,均行T-SPOT.TB、BALF-Tb DNA、BALF涂片、痰涂片、PPD、结核抗体检测,对各检测结果进行对比,并行T-SPOT.TB与BALFTb DNA联合检测与单用检测、涂片法、PPD、结核抗体对比分析。结果血T-SPOT.TB、BALF-Tb DNA敏感性分别为84.8%、80.4%,特异性分别为80.0%、77.5%,两者联合检测敏感性为100.0%,阳性预测值为97.1%,阴性预测值为100.0%,与单用检测对比,差异有统计学意义(P0.05),与涂片法、PPD、结核抗体对比,存在显著差异(P0.01)。结论血T-SPOT.TB与BALF-Tb DNA联合检测提高了肺结核的诊断阳性率,弥补对方不足,减少肺结核的漏诊、误诊,是一个有前途的检测方法。     

Yield of bronchoscopy for the diagnosis of tuberculosis in patients with human immunodeficiency virus infection.

The efficacy of bronchoscopy for the diagnosis of tuberculosis in patients infected with human immunodeficiency virus (HIV) has not been systematically evaluated. We therefore compared the diagnostic yield of bronchoscopy in 67 HIV-infected and 45 non-HIV-infected patients with culture-proven pulmonary tuberculosis. In all cases, acid-fast smears of sputum were negative or not obtained prior to bronchoscopy. Prebronchoscopic sputum culture yielded Mycobacterium tuberculosis in 34 (89 percent) of 38 HIV-infected patients and 26 (93 percent) of 28 non-HIV-infected patients from whom specimens were obtained. Bronchoscopy provided an early diagnosis of tuberculosis (positive acid-fast smear or granulomata on biopsy) in 23 (34 percent) of the HIV-infected patients and 20 (44 percent) of the patients without HIV infection. The sensitivities of the acid-fast smear and of mycobacterial culture of bronchoscopic specimens and postbronchoscopic sputum were similar in patients with or without HIV infection. In HIV-infected patients, granulomatous inflammation was noted on transbronchial biopsy in 11 (19 percent) of 59 patients with HIV infection, compared to 16 (43 percent) of 37 patients without HIV infection (p = 0.01). Nevertheless, transbronchial biopsy provided the exclusive means for an early diagnosis of tuberculosis in six (10 percent) of 59 HIV-infected patients. We conclude that the yield of bronchoscopy for the diagnosis of pulmonary tuberculosis in HIV-infected patients is similar to that in patients without HIV infection, and that transbronchial biopsy provides incremental diagnostic information not available from evaluation of sputum or bronchoalveolar lavage fluid.     

Combined bronchoalveolar lavage and polymerase chain reaction in the diagnosis of pulmonary tuberculosis in smear-negative patients.

SETTING: The polymerase chain reaction (PCR) may be sensitive and specific for the diagnosis of tuberculosis, but most reports are of studies conducted in well-controlled laboratories. A study to evaluate the clinical value of bronchoalveolar lavage (BAL) combined with PCR was necessary. OBJECTIVE: One hundred and thirty one patients were recruited into the study from March 1994 to February 1997. DESIGN: Patients with a positive acid-fast stain on sputum smear were recruited into group A as positive controls, patients with lung cancer and a negative acid-fast stain on sputum smear were put into group B as negative controls, and patients who had clinical symptoms of pulmonary TB without sputum or with negative smear results were the investigating group. PCR was performed on the sputum samples from group A and B patients and on the BAL fluid from those in group C. RESULTS: The sensitivity of PCR was 96% in group A, and the specificity was 100% in group B. The sensitivity of PCR in the BAL fluid from the group C patients was 36% and the specificity was 96%; the positive predictive value was 94% and the negative predictive value was 45%. CONCLUSION: BAL plus PCR is useful in the rapid diagnosis of pulmonary TB in non-productive or smear-negative patients.     

纤支镜在菌阴肺结核中的应用评估

目的 观察纤支镜在菌阴肺结核诊断中的价值.方法 分析190例入院时痰涂片和PCR分析均为阴性疑诊为肺结核患者的病例资料,从经纤支镜抗酸杆菌涂片的阳性率、PCR检测结核分枝杆菌阳性率、上皮性肉芽肿支气管活检、结核分枝杆菌的培养阳性率等四个方面进行分析.结果 190例病例中,经纤支镜取样的阳性率:42.6％(痰涂片),63.6％(PCR分析),31.2％(肉芽肿支气管活检),54.2％(痰培养),将各种检查手段联合起来,诊断率可以达到85.2％.结论 经纤支镜取样有较高阳性率,可以提供快速明确的结核诊断.     

纤支镜灌洗液的结核分支杆菌快速培养对不典型肺结核的诊断价值

目的　评价纤维支气管镜(以下简称纤支镜)支气管肺泡灌洗液(BALF)的结核分支杆菌快速培养对不典型肺结核的诊断价值。方法 选无痰或痰菌阴性的不典型肺结核患者49例行纤支镜检查,进行活检、刷检、BALF经BBLMGIT分支杆菌快速培养查结核杆菌。结果 49例经纤支镜刷检、BALF快速培养结核分支杆菌检出率分别是67.4%、83.7%,其中15例经纤支镜肺活检,10例病理证实为结核肉芽肿,检出率为66.7%。结论 纤支镜对无痰或痰菌阴性下BALF行结核分支杆菌快培对不典型肺结核具有较高的诊断价值,快速,阳性率较高。根据镜下所见采用不同的取材方法可望提高诊断率。     

支气管肺泡灌洗液多指标联合检测对不典型肺结核的诊断价值探讨

目的探讨支气管肺泡灌洗液（BALF）多指标联合检测对不典型肺结核的诊断价值。方法56例不典型肺结核患者治疗前均进行支气管镜检查,行支气管刷检涂片法、镜检后痰涂片法、BALF涂片法以及联合进行BALF涂片、BALF聚合酶链反应（BALF-PCR）、BALF结核抗原（BALF-TBAG）和BALF腺苷脱氨酶（BALF-ADA）四项指标检测方法,分析不同的检测方法对不典型肺结核诊断的阳性率。结果56例患者行支气管刷检涂片法、镜检后痰涂片法、BALF涂片法的阳性率分别为39.2%,46.4%,75.0%,联合进行BALF涂片、BALF-PCR、BALF-TBAG和BALF-ADA四项指标检测的阳性率为92.8%,与前三种检测方法相比,差异有显著性（P〈0.05）。结论BALF多指标联合检测对不典型肺结核具有较高的诊断价值,特异性高,快速,大大缩短诊断时间,可以明显提高诊断阳性率,是一项较好的组合方式。     

Role of bronchoalveolar lavage fluid and serum interleukin-27 in the diagnosis of smear-negative pulmonary tuberculosis

Background:To evaluate the value of interleukin (IL)-27 measured in serum and bronchoalveolar lavage fluid (BALF) for the diagnosis of smear-negative pulmonary tuberculosis (TB).Methods:This was a prospective study of patients planned to undergo bronchoscopy at Wuxi No.5 People''s Hospital between January 2017 and September 2018. The patients were grouped as the TB and control groups. BALF and serum IL-27 were measured by ELISA. Receiver operating characteristic (ROC) curves were used to assess the diagnostic value and calculate the optimal cutoff values.Results:There were 40 patients in the control group and 87 in the TB group. In the TB group, 20 had positive sputum smear results and 67 were negative. The area under the ROC curve (AUC) of BALF IL-27 for pulmonary TB was 0.897 (95% CI: 0.830–0.944) (P < .001). The AUC of serum IL-27 for pulmonary TB was 0.703 (95% CI: 0.616–0.781) (P < .001). In patients with negative sputum smear results, the AUCs of BALF IL-27 and serum IL-27 for pulmonary TB was 0.882 (95% confidence interval [CI]: 0.805–0.936) (P < .001) and 0.679 (95% CI: 0.601–0.782) (P < .001), respectively.Conclusions:BALF IL-27 can be used for the diagnosis of pulmonary TB, particularly in those with a negative sputum smear result. Serum IL-27 could be an auxiliary method for TB screening.     

Bronchoscopy with bronchoalveolar lavage in tuberculosis and fungal infections

STUDY OBJECTIVE: To determine the utility of bronchoscopy with bronchoalveolar lavage for diagnosing M tuberculosis and fungal infections. DESIGN: Retrospective review of patients over a six-year period. SETTING: In- and outpatients of one University hospital and affiliated Veterans Administration Medical Center. PATIENTS: Those who were subsequently found to have either M tuberculosis or fungal infections. INTERVENTIONS: Bronchoscopy with bronchoalveolar lavage specimens were compared to prebronchoscopy sputum, when available. Specimens were sent for smear and culture for both acid-fast bacilli and fungi. In the case of lavage, an aliquot also was studied for cellular differential. MEASUREMENTS AND RESULTS: For TB, sputum was smear-positive in 6/47 (34 percent) and culture positive in 24/47 (51 percent), while bronchoscopy was smear positive in 34/50 (68 percent) and culture positive in 46/50 (92 percent). For fungal infections, no sputum was smear-positive and only 1/22 (5 percent) was sputum culture-positive, while bronchoscopy was smear-positive in 14/41 (34 percent) and culture positive in 35/41 (85 percent). Bronchoscopy washings and BAL provided complementary specimens. Eighty-three patients had adequate lavages and the cellularity was significantly different from controls (lymphocytes: TB 18 +/- 11.2 percent [mean +/- SD]; fungal: 13 +/- 11.1 percent; controls 6 +/- 3.1 percent; p less than 0.001; neutrophils: TB 9 +/- 11.5 percent; fungal: 6 +/- 9.1 percent controls: 2 +/- 1.5 percent, p less than 0.01); however, there was overlap and no pattern was characteristic for TB or fungal infections. CONCLUSION: Bronchoscopy with BAL is useful in diagnosing tuberculosis and fungal infections.     

Diagnostic value of bronchoscopy in diagnosis of pulmonary tuberculosis: bronchial aspirate, bronchial washing and transbronchial lung biopsy

The diagnosis of pulmonary tuberculosis is confirmed by the detection of Mycobacterium tuberculosis in sputum. Bronchoscopy has been used for diagnosis of various pulmonary diseases. The value of bronchoscopy such as bronchial aspirate, bronchial washing and transbronchial lung biopsy in diagnosis of pulmonary tuberculosis was evaluated, and the results were as follows: 1) One hundred ninety cases were investigated bronchoscopically due to suspicion of pulmonary tuberculosis with sputum negative smear and 92 cases were confirmed to be pulmonary tuberculosis. 2) Out of 91 cases examined by bronchial aspirate and 46 cases by bronchial washing, smear positivity was 20.9% and 23.9% and culture positivity was 58.2% and 84.8%, respectively. Transbronchial lung biopsy showed positive findings of tuberculosis in 75.8% out of 33 specimens. 3) Out of 88 sputa taken before bronchoscopy and 50 sputa after bronchoscopy, smear positivity was 0% and 12%, and culture positivity was 54.5% and 40% respectively. Gastric lavage culture positivity was 29.4% in 17 cases examined. 4) Diagnosis of tuberculosis was made rapidly in 28 cases (30.4%) by smear positive results of bronchial aspirate, bronchial washing and sputa after bronchoscopy, and relatively rapidly in 20 cases (21.7%) by transbronchial lung biopsy.     

Laboratory diagnosis of pulmonary tuberculosis in TB and HIV endemic settings and the contribution of real time PCR for M. tuberculosis in bronchoalveolar lavage fluid

Background Tuberculosis (TB) in Africa is increasing because of the human immunodeficiency virus (HIV) epidemic, and in HIV/AIDS patients it presents atypically. Pulmonary tuberculosis (PTB) in Africa is mainly diagnosed clinically, by chest radiograph or by sputum smear for acid fast bacilli (AFB). Methods We evaluated in 120 HIV‐infected patients with chest infection the diagnostic accuracy of AFB smear of sputum and bronchoalveolar lavage (BAL) fluid, sputum Mycobacterium tuberculosis (MTB) culture, real‐time PCR and MycoDot^® serological test, using MTB culture of BAL fluid as gold standard. We correlated PCR cycle threshold values (C_T) to the culture results. Retrospectively, we evaluated the development of active TB in patients with positive PCR but negative culture. Results Culture of BAL fluid identified 28 patients with PTB. Fifty‐six patients could not produce adequate sputum. Sputum AFB smear and the serological test had sensitivities of 66.7% and 0%, respectively. PCR with C_T 40 was positive in 73 patients, 27 of whom were also TB culture positive (96.4% sensitivity and 52.3% specificity of PCR). PCR with C_T 32 had sensitivity of 85.7% and specificity of 90.9% to diagnose PTB in BAL. No patients with positive PCR but negative culture developed active TB during 18 months follow‐up. Conclusion In these HIV‐infected patients, AFB smear and serology had very low sensitivities. PCR of BAL with C_T value 32 had improved specificity to diagnose active PTB. A prospective follow‐up study is warranted in TB/HIV endemic settings, applying real time PCR to both sputum and BAL.     

痰与支气管肺泡灌洗液结核分枝杆菌FQ-PCR检测对涂阴肺结核诊断价值的比较

目的 探讨呼吸道痰标本和支气管肺泡灌洗液(BALF)Mtb-DNA检测对涂阴肺结核的诊断价值。方法 选择福州肺科医院2009年7月至2009年12月胸部影像学疑为肺结核但至少3份痰涂片镜检Mtb阴性,或胸部影像学无法排除肺结核需进一步检查的患者共51例,所有入选患者初诊根据临床症状、体征、胸部影像学结果分为疑似结核组（24例）和待排结核组（27例）。均行抗结核抗体、红细胞沉降率检测及PPD试验,应用实时荧光定量聚合酶链反应（FQ-PCR）定性及定量检测两组患者痰和BALF中的Mtb-DNA。结果 疑似结核组和待排结核组各有22例和2例确诊肺结核,确诊的24例中痰FQ-PCR敏感度为45.8%（11/24）,特异度为96.3%（26/27）,Youden指数42.1%;BALF FQ-PCR的敏感度为75.0%（18/24）,特异度96.3%（26/27）,Youden指数71.3%。结论 FQ-PCR检测BALF Mtb较痰更为敏感,对影像学疑诊但痰涂片阴性的结核患者有很高的实用价值,尤其适用于无痰的患者。     

四种结核分枝杆菌检测方法的临床应用评价

目的评估涂片、培养、PCR和增菌PCR检测结核分枝杆菌临床应用价值。方法对124例临床确诊的肺结核、可疑结核患者和非结核病人痰标本的涂片、培养、PCR和增菌PCR四种方法的检测结果进行比较。结果涂片、培养、PCR和4及7d的增菌PCR检测31例临床确诊的肺结核病人痰标本阳性率分别为22.5%、32.2%、54.8%、64.5%和87.1%;检测59例临床可疑肺结核病人痰标本阳性率分别为13.6%、18.6%、28.8%、37.3%和52.5%。比较四种方法的阳性检测率有显著性差异(P<0.05)。检测34例非结核病人痰标本,涂片、培养均为阴性,而PCR和增菌PCR均有1例假阳性,假阳性率2.9%。比较PCR与增菌PCR对菌阳和菌阴病人的痰标本阳性检测率,有显著性差异(P<0.05),而两种方法的假阳性率相同。结论增菌PCR检测结核分枝杆菌具有很高的敏感性和特异性,可作为结核病的有效辅助诊断方法之一。     

Impact of a Mycobacterium tuberculosis-specific interferon-γ release assay in bronchoalveolar lavage fluid for a rapid diagnosis of tuberculosis

Abstract. Jafari C, Kessler P, Sotgiu G, Ernst M, Lange C (Research Center Borstel, Borstel, Germany; Hygiene and Preventive Medicine Institute, University Sassari, Sassari, Italy; Research Center Borstel, Borstel, Germany). Impact of a Mycobacterium tuberculosis‐specific interferon‐γ release assay in bronchoalveolar lavage fluid for a rapid diagnosis of tuberculosis. J Intern Med 2011; 270 : 254–262. Objectives. Evaluation of different methods for an initial treatment decision in individuals with suspected pulmonary tuberculosis. Background. Recently, important advances regarding the diagnosis of pulmonary tuberculosis have been introduced, which influence the decision to initiate anti‐tuberculosis treatment. Methods. To evaluate the impact of different methods for the presumed diagnosis of tuberculosis, individuals with suspected tuberculosis were prospectively enrolled following a specific algorithm including initial smear microscopy and Mycobacterium tuberculosis‐specific nucleic acid amplification (NAAT) from sputum. In cases of negative initial test results, tuberculin skin testing, bronchoscopy with transbronchial biopsies and interferon‐γ release assays (IGRAs) in peripheral blood and bronchoalveolar lavage (BAL) fluid were performed. Results. Amongst 135 individuals with suspected tuberculosis, 42 had tuberculosis, 10 had nontuberculous mycobacteria pulmonary infection/colonization (one had both tuberculosis and nontuberculous mycobacteria pulmonary infection/colonization) and 84 had an alternative final diagnosis. The sensitivity and specificity were 41% and 99% [positive likelihood ratio (LR+) = 40] for sputum microscopy and 31% and 98% (LR+ = 16) for BAL nucleic acid amplification, respectively. In patients with acid‐fast bacilli smear‐negative tuberculosis (25/42, 59.5%), M. tuberculosis‐specific BAL fluid IGRA was 92% sensitive and 87% specific (LR+ = 7) for the diagnosis of tuberculosis. Conclusion. None of the microbiological or immunological methods that aim to provide a rapid diagnosis of tuberculosis whilst waiting the confirmation of the M. tuberculosis culture results is on its own accurate enough to diagnose or exclude pulmonary tuberculosis. Negative sputum microscopy and M. tuberculosis‐specific NAAT results should prompt bronchoscopy including BAL for M. tuberculosis‐specific IGRA in individuals with suspected pulmonary tuberculosis.     

Post-bronchoscopy sputum: improving the diagnostic yield in smear negative pulmonary TB

Introduction

Patients with suspected active Pulmonary Tuberculosis (PTB) who are Acid-Fast Bacilli (AFB) smear negative or non-productive of sputum may undergo bronchoalveolar lavage. However, post-bronchoscopy sputum (PBS) sampling is not routine. The aim of this study was to establish the potential diagnostic value of PBS sampling.

Methods

A retrospective study of patients attending a London University hospital with microbiologically confirmed PTB between January 2004 and December 2010. Patients who were AFB smear negative or non-productive of sputum were eligible if sputum sampling was performed within 7 days of bronchoscopy.

Results

Over the study period, 236 patients had microbiologically confirmed smear negative PTB of which 57 patients were eligible for the study. 15 patients (26.3%) were infected with HIV. 19 patients (33.3%) converted to AFB sputum smear positivity post-bronchoscopy and 5 patients (8.8%) were exclusively AFB sputum smear positive on PBS microscopy. Mycobacterium tuberculosis was cultured from the PBS of 43 patients (75.4%) and of these, 4 (7.0%) were exclusively PBS culture positive.

Conclusion

PBS analysis can provide a simple method of rapidly diagnosing pulmonary tuberculosis. In this cohort, M. tuberculosis culture yield was increased by 7% through PBS sampling. This study has important infection control implications with nearly one third of patients becoming more infectious after bronchoscopy.     

纤支镜灌洗液经变色液体培养基快速培养结核分枝杆菌对涂阴肺结核诊断价值的研究

目的评价纤维支气管镜小量肺泡灌洗液经变色液体培养基快速培养结核分枝杆菌对涂阴肺结核的诊断价值。方法对40例涂阴肺结核患者分别行纤支镜小量肺泡灌洗、刷检或活检，将灌洗液经变色液体培养基快速培养结核分枝杆菌。结果纤支镜肺泡灌洗40例，灌洗液培养出结核分枝杆菌17例，阳性率42．5％，刷检32例，阳性5例，活检8例，阳性3例，刷检＋活检阳性率20％，P〈0．05有统计学意义。快速培养检出时间平均13．5天。结论纤支镜灌洗液经变色液体培养基快速培养结核支杆菌，可提高涂阴肺结核中结核分枝杆菌的检出率，缩短了细菌培养检出时间，值得应用     

荧光定量PCR测定支气管肺泡灌洗液中TbDNA对涂阴肺结核的诊断价值

目的探讨纤支镜肺泡灌洗液中结核分枝杆菌DNA在涂阴肺结核诊断中的价值。方法应用荧光定量聚合酶链反应（FQ-PCR）技术对300例涂阴肺结核,178例菌阳肺结核及119例肺炎或肺癌患者的纤支镜肺泡灌洗液标本进行结核分枝杆菌DNA检测。结果3种病因肺泡灌洗液结核分枝杆菌DNA阳性检出率分别为：74.3%（223/300）、94.9%（169/178）、17.6%（21/119）。结论荧光定量聚合酶链反应检测肺泡灌洗液结核分枝杆菌DNA,用于肺结核诊断可提高肺结核诊断的敏感性和准确性,明显优于痰抗酸染色,亦较痰结核菌培养诊断灵敏、快速,可作为肺结核诊断较可靠指标。     

The value of bronchial lavage in patients with radiologically suggestive pulmonary tuberculosis with no sputum production and gastric lavage smear negativity

We assessed whether acid-fast bacilli (AFB) investigation in bronchial lavage (BL) contributes to diagnosis in patients with gastric lavage smear negative and radiologically suggestive of pulmonary tuberculosis. Eighty-three patients were recruited for the study, five cases were excluded due to diagnosis of inactive disease or non-tuberculosis disease. The remaining 78 patients were evaluated. All patients were unable to expectorate sputum and their gastric lavages were negative for AFB. BL was performed for the detection of Mycobacterium tuberculosis in all patients. Bronchial lavage smear were positive in 15.4%(12 patients). BL culture positivity was 58.3%(42 patients) and gastric lavage culture positivity was 33.3%(26 patients). Eighteen cases had both gastric lavage and BL culture positivity. BL culture was positive in 24 cases who had gastric lavage culture negativity. We suggest that in cases who do not produce sputum and whose gastric lavage smears are negative; BL should be performed for diagnosis of pulmonary tuberculosis.     

The role of bronchoscopy in the diagnosis of pulmonary tuberculosis in patients at risk for HIV infection.

The present study was undertaken to clarify the role of bronchoalveolar lavage (BAL) and transbronchial biopsy (TBB) in the diagnosis of pulmonary tuberculosis in patients at risk for human immunodeficiency virus (HIV) infection. We retrospectively identified 31 patients at risk for HIV who proved to have Mycobacterium tuberculosis on culture of at least one pulmonary specimen. All had pulmonary symptoms but initial sputum smears negative for acid-fast bacilli (AFB). All underwent fiberoptic bronchoscopy (FOB), including BAL and TBB; postbronchoscopy sputum was also collected in 19 patients. A specimen was considered to yield an immediate diagnosis when positive for AFB either on smear or histologic study; granulomas alone were considered positive when no other causes were identified. Overall, an immediate diagnosis was made by bronchoscopic specimens in 15 (48 percent) of 31 cases. TBB was the sole positive specimen in seven patients (23 percent). For comparison, similar specimens from 40 patients in whom M avium complex (MAC) grew on culture were also evaluated. An immediate identification of AFB was made in only four patients (10 percent). We conclude that the finding of AFB on staining of any pulmonary specimen is highly suggestive of tuberculosis, rather than MAC, and warrants institution of antituberculosis therapy. Of all bronchoscopic specimens, TBB provides the highest yield for an immediate diagnosis of tuberculosis.