Comparison of sputum induction with fiberoptic bronchoscopy in the diagnosis of tuberculosis: experience at an acquired immune deficiency syndrome reference center in Rio de Janeiro, Brazil

Many patients with suspected pulmonary tuberculosis (PTB) do not produce sputum spontaneously or are smear-negative for acid-fast bacilli (AFB). We prospectively compared the yield of sputum induction (SI) and fiberoptic bronchoscopy with bronchoalveolar lavage (BAL) for the diagnosis of PTB in a region with a high prevalence of tuberculosis and human immunodeficiency virus (HIV) infection. Fifty seven percent (143 of 251) of patients had diagnoses of PTB, of whom 17% (25 of 143) were HIV seropositive. There were no significant differences in the yields of AFB smears or cultures whether obtained via SI or BAL. Among 207 HIV-seronegative patients, the AFB smear and mycobacterial culture results from specimens obtained by SI and BAL were in agreement in 97% (202 of 207) (kappa test = 0.92) and 90% (186 of 207) (kappa test = 0.78), respectively. Among HIV-seropositive patients the agreements between AFB smear and culture results for SI and BAL specimens were 98% (43 of 44) (kappa test = 0.93) and 86% (38 of 44) (kappa test = 0.69), respectively. We conclude that SI is a safe procedure with a high diagnostic yield and high agreement with the results of fiberoptic bronchoscopy for the diagnosis of PTB in both HIV-seronegative and HIV-seropositive patients.     

Useful clues to the presence of smear-negative pulmonary tuberculosis in a West African city.

OBJECTIVE: Tuberculosis suspects with negative sputum smears for acid-fast bacilli (AFB) may have either pulmonary tuberculosis (PTB) or some other pulmonary disease (non-PTB). The aim of this study was to improve the differentiation between PTB and non-PTB. DESIGN: We enrolled 396 tuberculosis suspects 15 years of age or older who had cough of 21 days or longer and three negative AFB smears. Non-PTB was diagnosed by clinical and radiographic responses to amoxicillin; smear-negative PTB was diagnosed by positive culture for Mycobacterium tuberculosis or response to antituberculosis chemotherapy. RESULTS: Multivariate analysis, without X-ray variables, of 79 patients with a final diagnosis of non-PTB and 110 patients with smear-negative PTB indicated that age less than 37 years, family contact with TB, never having been married, loss of weight, lack of expectoration, human immunodeficiency virus (HIV) seropositivity, and tuberculin reactivity were significantly associated with PTB. When the initial X-ray findings were included, age younger than 37 years, lack of expectoration, HIV seropositivity, and tuberculin reactivity remained in the model, and cavitation and patchy densities were significantly associated. CONCLUSION: The response to 10 days of amoxicillin and certain demographic, clinical and radiographic characteristics are useful in separating non-PTB from PTB in tuberculosis suspects with negative AFB smears.     

The role of induced sputum in the diagnosis of pulmonary tuberculosis

OBJECTIVES: To determine the sensitivity of referral guidelines for induced sputum in pulmonary tuberculosis (PTB) case detection and determine the diagnostic yield of the test. METHODS: A retrospective analysis of case notes of adult patients referred for induced sputum was carried out at the North Trent Regional Department of Infection and Tropical Medicine, the Royal Hallamshire Hospital, Sheffield, UK. Clinical characteristics were noted on patients referred during a 12-month period in 2001-2002, and of all patients with positive induced sputum results from April 1998 to March 2002. RESULTS: Over a 12-month period 114 patients were referred in our unit for induced sputum sampling. Twelve of the 114 patients had positive sputum cultures giving a positive yield for the test of 10.5%. With strict adherence to our referral guidelines, 10 of the 12 positive cases (83.3%) would have been detected. With modification to the referral guidelines, all 12 microbiologically positive cases would have been detected making the guidelines 100% sensitive in detecting microbiologically positive cases among patients referred with a clinical suspicion of PTB who are unable to self-expectorate. The positive yield for the test would have been increased to 13.2%. In the past 4 years 29 patients had positive induced sputum results. Of these, 11 patients (37.9%) had concurrent microbiological proven extra-pulmonary TB (EPTB) and 10 (34.5%) had past histories of TB infection. Seven patients had chest X-rays reported as normal. CONCLUSIONS: Induced sputum offers a relatively non-invasive investigation for patients with suspected PTB who are unable to bring up sputum. Induced sputum also offers a means of establishing a microbiological diagnosis in some cases of EPTB. An investigative algorithm is suggested.Summary. In an era of increasing drug resistant disease, establishing a microbiological diagnosis of TB is paramount. Sputum induction can be used as an alternative investigation to bronchoscopy in suspected PTB patients who are able to self-expectorate. Induced sputum is a sensitive investigation for suspected PTB patients but with a low diagnostic yield. Referral guidelines are suggested.     

Fiberoptic bronchoscopy for the rapid diagnosis of smear-negative pulmonary tuberculosis

ABSTRACT: BACKGROUND: This study was aimed to investigate the diagnostic value of fiberoptic bronchoscopy (FOB) with chest high-resolution computed tomography (HRCT) for the rapid diagnosis of active pulmonary tuberculosis (PTB) in patients suspected of PTB but found to have a negative sputum acid-fast bacilli (AFB) smear. METHODS: We evaluated the diagnostic accuracy of results from FOB and HRCT in 126 patients at Gangnam Severance Hospital (Seoul, Korea) who were suspected of having PTB. RESULTS: Of 126 patients who had negative sputum AFB smears but were suspected of having PTB, 54 patients were confirmed as having active PTB. Hemoptysis was negatively correlated with active PTB. Tree-in-bud appearance on HRCT was significantly associated with active PTB. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of FOB alone was 75.9%, 97.2%, 95.3%, and 84.3%, respectively, for the rapid diagnosis of active PTB. The combination of FOB and HRCT improved the sensitivity to 96.3% and the NPV to 96.2%. CONCLUSIONS: FOB is a useful tool in the rapid diagnosis of active PTB with a high sensitivity, specificity, PPV and NPV in sputum smear-negative PTB-suspected patients. HRCT improves the sensitivity of FOB when used in combination with FOB in sputum smear-negative patients suspected of having PTB.     

The validity of acid-fast smears of gastric aspirates as an indicator of pulmonary tuberculosis.

SETTING: A tuberculosis referral hospital in Canada. OBJECTIVE: To determine the validity of acid-fast (AFB) smears of gastric aspirates (GA) in the diagnosis of pulmonary tuberculosis, and to assess the prevalence of nontuberculous mycobacteria (NTM) in GA isolates from such patients. DESIGN: A retrospective case review of our experience with AFB smears (Kinyoun) and cultures of GA and sputum over a 3-year period. RESULTS: From 1994 to 1996 inclusive, 1155 GA were performed in 889 patients. Mycobacteria were cultured from 109 (9%) GA. Thirteen of these were positive on smear (sensitivity 19%). All GA that were positive on smear were culture positive for Mycobacterium tuberculosis. There were no false positive smears (specificity 100%). The sensitivity and specificity of the sputum smear were 45% and 99%, respectively. Of the 96 culture positive, smear negative GA, 54 grew M. tuberculosis and 42 grew an NTM. Of 13 patients who had sputum and GA studied coincidentally, and in whom the sputum was both smear and culture positive, the GA culture was positive in 13 and the smear was positive in eight (66%). CONCLUSION: AFB smear of GA is a relatively insensitive but highly specific indicator of pulmonary tuberculosis warranting institution of antituberculosis treatment. Gastric AFB smear positivity appears to reflect a high bacillary burden within the respiratory tract.     

How many sputum specimens are necessary to diagnose pulmonary tuberculosis?

The definitive diagnosis of pulmonary tuberculosis (PTB) relies on identifying or culturing Mycobacterium tuberculosis from respiratory specimens. National guidelines have recommended obtaining 3 sputum specimens from patients with suspected tuberculosis, but there has been little data on the number of specimens actually needed to support a diagnosis. We retrospectively reviewed all patients diagnosed with PTB at a public inner-city hospital and assessed the sensitivity of the acid-fast bacilli (AFB) smear and the number of smears needed to establish the diagnosis. Between January 1, 1997 and October 1, 2000, 425 patients were diagnosed with culture-proven PTB. Acid-fast bacilli (AFB) smears and cultures were performed on 951 respiratory specimens from 425 patients. The overall sensitivity of a positive AFB smear increased from 67% with 1 sputum collected to 71% and 72%, respectively, with the second and third specimens. The sensitivity of smears from 239 HIV-negative patients was 75%, 79%, and 80% with 1, 2, and 3 smears, respectively, collected compared with 57%, 61%, and 62%, respectively, for 142 HIV-positive patients. In summary, 2 respiratory specimens proved adequate in establishing a diagnosis of tuberculosis, and the third specimen added little additional diagnostic value.     

Diagnostic value of gastric aspirate smear and polymerase chain reaction in smear-negative pulmonary tuberculosis

OBJECTIVE: The aim of this study was to determine the validity of acid-fast bacilli (AFB) smear and polymerase chain reaction (PCR) from gastric aspirates for the diagnosis of smear-negative pulmonary tuberculosis. METHODOLOGY: A cross-sectional study was conducted in a university hospital. One hundred and nine patients with suspected pulmonary tuberculosis in whom either sputum smears were negative or who were not producing sputum were recruited to the study. All patients underwent gastric aspiration after an overnight fast followed by standard fibreoptic bronchoscopy. Specimens were subjected to AFB smear, culture, and pathological examination. PCR was performed on culture filtrate after 1 week of incubation. RESULTS: Eight patients did not complete the follow-up schedule. Of the 101 patients with final outcomes, a diagnosis of pulmonary tuberculosis from microbiological evidence was established in 54 patients. The gastric aspirate smear, PCR, or either one of them was positive in 34, 30, and 39 tuberculosis patients, respectively. There were 13 false positive smears from 47 non-tuberculosis patients, with five resulting from non-tuberculous mycobacteria (NTM). The PCR was falsely positive in eight patients, five of whom had previous histories of tuberculosis. The overall sensitivity, specificity, positive predictive value, and negative predictive value of gastric aspirate examination by combined smear and PCR were 72, 58, 66, and 64%, respectively. CONCLUSIONS: Gastric aspiration is a useful tool for the diagnosis of smear-negative pulmonary tuberculosis warranting institution of antituberculosis treatment. Interpretation of the results should be cautious in those who have had tuberculosis in the past or who have been at risk for acquisition of NTM.     

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.     

Occurrence of Pneumocystis carinii in HIV-positive patients with suspected pulmonary tuberculosis in Ethiopia

OBJECTIVE: To investigate the prevalence of Pneumocystis carinii in consecutive HIV-positive patients with suspected pulmonary tuberculosis (PTB) attending a university hospital in Ethiopia. METHODS: A PCR for P. carinii and an indirect immunoflorescence (IF) assay were performed on expectorated sputum samples from: 119 HIV-1-positive patients with negative smears and sputum cultures for Mycobacterium tuberculosis; 96 HIV-1-positive patients with culture-verified PTB; and 97 HIV-negative patients with negative mycobacterial cultures and 72 HIV-negative patients with culture-verified PTB, serving as controls. Outcome of PCR and IF were compared with the chest radiographic (CXR) and initial clinical diagnosis. RESULTS: In the HIV+PTB- group, P. carinii was found in 10.9% by IF, 8.4% by single PCR (sPCR) and 30.3% by nested PCR (nPCR). In the HIV+PTB+ group, 3.1% were P. carinii positive by IF and sPCR and 13.5% by nPCR. All IF- and sPCR-positive samples were nPCR positive. In the HIV-PTB+ and HIV-PTB- groups, 4.2% and 3.1% were nPCR positive, respectively. Six out of eight HIV+PTB- patients with CXR suggesting P. carinii pneumonia (PCP) were IF and/or nPCR positive for P. carinii. In the IF-positive and nested PCR-positive HIV+PTB- patients more than one-third were interpreted as PTB by CXR whereas only one patient was diagnosed with clinical PCP. CONCLUSIONS: P. carinii is prevalent in HIV-positive PTB suspects, suggesting that PCP may be an important, but not well recognized, differential diagnosis. Our findings have implications for treatment and primary prophylaxis for PCP in Ethiopia.     

Comparison of induced versus expectorated sputum for diagnosis of pulmonary tuberculosis by acid-fast smear

Objective: To evaluate the sensitivity of induced versus expectorated sputum for the diagnosis of pulmonary tuberculosis by acid-fast smear.Methods: We performed a retrospective review of data on patients with cultures from respiratory secretions that were positive for Mycobacterium tuberculosis. We analyzed data on the 114 patients with positive cultures during a 4-year period in an urban tertiary care academic medical center.Results: Sputum samples had been obtained for 103 of the 114 patients with cultures positive for tuberculosis. Forty-four of the 114 patients were HIV seropositive. Overall 33 of 79 patients (42%) had positive acid-fast smears of expectorated sputum, and 6 of 24 (25%) had positive smears of induced sputum (p = 0.21). When data were analyzed for subgroups by HIV serostatus, there was no significant difference in the results. Estimated cost of sputum induction for 1 year was approximately $45,000.Conclusions: We found sputum induction to be costly, and induced sputum offered no advantage over routine expectorated sputum for the diagnosis of pulmonary tuberculosis.     

HIV co-infection, CD4 cell counts and clinical correlates of bacillary density in pulmonary tuberculosis.

BACKGROUND: Sputum microscopy for acid-fast bacilli (AFB) is the commonest diagnostic method for pulmonary tuberculosis (PTB) in developing countries. The method is reported to be less sensitive in human immunodeficiency virus (HIV) positive compared to negative patients. We determined the bacillary density in sputum of smear-positive PTB patients and related it to the patients' HIV status, CD4 cell count, clinical and demographic characteristics. METHODS: Three sputum samples per patient were examined using microscopy before initiating therapy. The AFB density was graded according to World Health Organization recommendations. The smear with the highest density was used. High bacillary density was defined as >10 AFB/field. HIV status and CD4 cell count were determined according to the national guidelines. RESULTS: Of 844 patients, 433 (51.3%) were HIV-positive. High bacillary density was significantly less common among HIV-positive (39.0%) than -negative (75.7%) patients (prevalence ratio 0.52; 95%CI 0.45-0.59, P < 0.0001). Among HIV-positive patients, the proportion of those with high bacillary density increased progressively with CD4 cell counts (P = 0.003). CONCLUSION: HIV is associated with lower AFB concentration in sputum. The AFB density falls with falling CD4 cell count. Microscopy for AFB in sputum may be less sensitive in diagnosing PTB when HIV infection is present, especially in severely immunocompromised patients.     

Integration of tuberculosis screening at an HIV voluntary counselling and testing centre in Haiti

OBJECTIVE: To describe the integration of tuberculosis screening into the activities of an HIV voluntary counselling and testing (VCT) centre in a country with endemic tuberculosis. SETTING: An HIV VCT centre in Port au Prince, Haiti. DESIGN: All patients presenting for HIV VCT who reported cough received same-day evaluation for active tuberculosis. Of the 1327 adults presenting to the centre for the first time between January and April 1997, 263 (20%) reported cough and of these 241 (92%) were evaluated. RESULTS: Of the 241 patients evaluated for cough, 76 (32%) were diagnosed with pulmonary tuberculosis. Of the 76 patients diagnosed with pulmonary tuberculosis, 28 (37%) had a positive smear for acid-fast bacilli (AFB), 14 (18%) had a negative AFB smear but a positive sputum culture for Mycobacterium tuberculosis, and 34 (45%) had culture-negative tuberculosis. Also, 31 out of 241 (13%) VCT clients evaluated for cough were diagnosed with bacterial pneumonia. CONCLUSION: This report confirms that in areas with a high HIV and tuberculosis prevalence, a high proportion of VCT clients have active pulmonary tuberculosis. The integration of tuberculosis screening offers several benefits, including the diagnosis and treatment of large numbers of individuals with tuberculosis, a decreased risk of nosocomial tuberculosis transmission, and the opportunity to provide tuberculosis prophylaxis to HIV-positive patients in whom tuberculosis has been excluded. Future studies are needed to determine the cost-effectiveness of integrated tuberculosis and HIV VCT services, and whether integration should be recommended in all countries with high HIV and tuberculosis rates.     

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.     

The value of fiberoptic bronchoscopy in diagnosis of smear negative pulmonary tuberculosis

Although mycobacterial culture positivity is the gold standard for the diagnosis, the initial approach to the diagnosis of pulmonary tuberculosis (PTbc) is the detection of acid-fast bacilli (AFB) in respiratory specimens as recommended by the World Health Organization. But the physicians have to make a decision for the patients whose sputum smears are negative or who can not produce sputum. Waiting for culture results with radiological follow up or empirical antituberculous therapy are the standard options. In our study we aimed to assess the diagnostic yield of fiberoptic bronchoscopy in patients, suspected to have tuberculosis, whose sputum smears were negative or who could not produce sputum. Fifty six patients who suspected to have PTbc with sputum smear negative were enrolled in the study (fiberoptic bronchoscopy and selective bronchial washings were done to all patients. Bronchial washings were obtained from the affected parts). Mucosal biopsies were done in patients in where endobronchial abnormalities were noted. Transbronchial biopsies were done in selected patients from the radiological localizations. Ziehl-Nielsen staining and culture in L?wenstein-Jensen medium were the microbiological studies. Typical granulomas were expected to detect on histopathologic examination. Bronchoscopic lavage smears were positive for Mycobacterium tuberculosis in 13 (23%) patients. Twenty eight (50%) patients had positive culture. Histopathological results confirmed tuberculosis in eight of 20 patients who had undergone mucosal biopsies, four of seven of transbronchial biopsies, two of three of needle aspiration biopsies. By bronchoscopic procedures early diagnosis was performed in 27 (48.21%) patients. We concluded that fiberoptic bronchoscopy has an important role in the diagnosis of patients suspected to have tuberculosis, whose sputum smears were negative or who could not produce sputum. It is useful and necessary in selected cases.     

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.     

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.     

Clinical significance of normal chest radiographs among HIV-seropositive patients with suspected tuberculosis in Uganda

Background and objective: The frequency, aetiologies and outcomes of normal chest radiographs (CXRs) among HIV‐seropositive patients with suspected pulmonary tuberculosis (TB) have been infrequently described. Methods: Consecutive HIV‐seropositive adults hospitalized for cough of ≥2 weeks duration at Mulago Hospital (Kampala, Uganda), between September 2007 and July 2008, were enrolled. Baseline CXRs were obtained on admission. Patients with sputum smears that were negative for acid‐fast bacilli (AFB) were referred for bronchoscopy with bronchoalveolar lavage (BAL). BAL fluid was examined for mycobacteria, Pneumocystis jirovecii and other fungi. Patients were followed for 2 months after enrolment. Results: Of the 334 patients, 54 (16%) had normal CXRs. These patients were younger (median age 30 vs 34 years, P = 0.002), had lower counts of CD4+ T lymphocytes (median 13 vs 57 cells/µL, P < 0.001), and were less likely to be smear positive for AFB (17% vs 39%, P = 0.002) than those with abnormal CXRs. Pulmonary TB was the most frequent diagnosis (44%) among those with normal CXRs, followed by unknown diagnoses, pulmonary aspergillosis and pulmonary cryptococcosis. The frequency of normal CXRs was 12% among pulmonary TB patients. There was a trend towards increased 2‐month mortality among patients with normal CXRs compared to those with abnormal CXRs (40% vs 29%, P = 0.15). Conclusions: Normal CXR findings were common among HIV‐seropositive patients with suspected TB, especially those who were young, those with low CD4+ T cell counts and those with sputum smears that were negative for AFB. Mortality was high among those with normal CXRs. Normal CXR findings should not preclude further diagnostic evaluation in this population.     

Circulating antibodies to lipoarabinomannan in relation to sputum microscopy, clinical features and urinary anti-lipoarabinomannan detection in pulmonary tuberculosis

An enzyme-linked immunosorbent assay (ELISA)-based investigation of anti-lipoarabinomannan (LAM) antibody levels in the sera of patients with acid-fast bacilli (AFB)-positive pulmonary tuberculosis (PTB), AFB-negative PTB and non-TB respiratory tract symptoms was conducted. The anti-LAM results were further evaluated using urine LAM detection and a clinical diagnostic score (DS) system as references. Using sputum AFB as a reference, positive anti-LAM was found in 66.9% of 139 AFB-positive PTB, 34.4% of 61 AFB-negative PTB and 23.5% of 800 non-TB patients and in 8% of 50 healthy individuals. The positive and negative predictive values were 48.7% and 87.4%, respectively. Using the DS as a reference, the sensitivity and specificity were 50.5% and 78.3%, respectively, whereas 45.8% of urine LAM positives and 77.9% of urine LAM negatives were correctly identified by the anti-LAM ELISA. In TB endemic areas a negative anti-LAM could be of practical value, particularly when other indicators of PTB are negative. Using any of these methods as a reference, a positive anti-LAM would mislead in about one-quarter of cases. Had all the 3 methods been combined and at least 2 positive tests sufficed, 90.6% of AFB-positive PTB, 52.5% of AFB-negative PTB and 94.9% of non-TB patients would have been correctly diagnosed. Apart from the possible impact of HIV, the low accuracy of the current assay could be due to intravascular formation of LAM-anti-LAM complexes, latent TB or environmental mycobacterial infections.     

Same-day smears in the diagnosis of tuberculosis

Objective To assess the feasibility of completing the diagnosis of tuberculosis (TB) in 1 day by collecting only on‐the‐spot specimens. Methods Individuals with suspected TB attending district hospitals in Abuja submitted three sputum samples for routine diagnosis (the standard approach). One additional sample was collected 1 h after the first sputum (the same‐day approach). One sputum sample was cultured. Blood samples were tested for HIV. Results Two hundred and twenty‐four patients with chronic cough had 135/672 (20%) positive on‐the‐spot smears and 47/224 (21%) positive morning smears. The same‐day and internationally recommended approaches identified 44 and 45 of the 78 patients with positive cultures, respectively. 106/194 (55%) patients were HIV positive. Only 9–11% of their smears were positive compared with 30–32% for HIV negatives (P < 0.01). Conclusion It could be possible to diagnose TB in a single day by examining two spot specimens, but the feasibility needs to be confirmed on a larger scale.