Effectiveness of the BDProbeTec ET system for detection of Mycobacterium tuberculosis complex in sputum and bronchoalveolar lavage specimens

ObjectiveThe diagnostic efficacy of the BDProbeTEC ET Mycobacterium tuberculosis (MTB) complex direct detection assay (DTB) performed on bronchoalveolar lavage (BAL) specimens and sputum smears was compared with acid-fast bacilli (AFB) smear microscopy.MethodAFB smear microscopy, DTB and culture results of 286 patients with pulmonary tuberculosis were retrospectively reviewed. A total of 120 patients provided expectorated sputum samples, and 166 patients provided BAL specimens. Culture results and clinical diagnosis were used as gold standards.ResultsThe sensitivity and specificity of the DTB assay in detecting MTB in sputum specimens was significantly higher compared to AFB smear microscopy (83.7% and 82.4%, vs. 75.6%, and 41.2%, respectively). The sensitivity and specificity of the DTB assay in detecting MTB in sputum samples was 77.2% and 100% compared to clinical diagnosis, while AFB smear had a sensitivity and specificity of 70.3% and 26.3%, respectively. Compared to culture, DTB had a sensitivity and specificity of 82.8% and 93.2%, respectively, in detecting MTB from BAL specimens; AFB smear had a sensitivity and specificity of 41.9% and 87.7%, respectively. Compared to clinical diagnosis, DTB had a sensitivity and specificity of 67.2% and 100%, respectively, in detecting MTB from BAL specimens; AFB smear had a sensitivity and specificity of 34.8% and 79.5%, respectively.ConclusionsThe superior performance of the DTB assay relative to AFB smear microscopy makes it a valuable tool to enable early diagnosis of MTB, thereby improving patient care and reducing transmission.     

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.     

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.     

结核分枝杆菌/利福平耐药实时荧光定量核酸扩增检测技术诊断艾滋病患者肺结核的临床应用评价

目的:探讨结核分枝杆菌(Mycobacterium tuberculosis,MTB)/利福平耐药实时荧光定量核酸扩增检测(Xpert MTB/RIF)技术诊断艾滋病患者肺结核的应用价值。方法:回顾性分析2017年7月至2019年11月上海市(复旦大学附属)公共卫生临床中心收治的226例疑似肺结核的艾滋病患者的临床资料。分别进行痰涂片荧光染色显微镜下检查、BACTEC MGIT 960液体培养(或罗氏固体培养)和Xpert MTB/RIF检测,并分析在艾滋病患者中Xpert MTB/RIF技术诊断MTB感染和利福平耐药的灵敏度和特异度。结果:226例疑似肺结核患者中,痰培养阳性94例(41.6%),其中MTB阳性51例(54.3%),非结核分枝杆菌(nontuberculosis mycobacteria,NTM)阳性43例(45.7%)。以痰分枝杆菌培养阳性且结核分枝杆菌分泌蛋白64抗原阳性为金标准,Xpert MTB/RIF技术诊断MTB的灵敏度为72.6%[95%可信区间(confidence interval,CI)66.7%~78.4%],特异度为97.1%(95%CI 95.0%~99.3%)。Xpert MTB/RIF技术诊断痰涂片阳性患者MTB的灵敏度为76.7%(95%CI 67.7%~85.8%),特异度为90.0%(95%CI 83.6%~96.5%)。Xpert MTB/RIF技术诊断痰涂片阴性患者MTB的灵敏度为50.0%(95%CI 41.8%~58.2%),特异度为99.3%(95%CI 97.9%~100.0%)。18例患者同时检测利福平表型和基因型耐药,以表型耐药为金标准,Xpert MTB/RIF技术检测利福平基因型耐药的灵敏度为75.0%,特异度为100.0%。结论:艾滋病患者中Xpert MTB/RIF技术诊断肺结核的灵敏度和特异度均较高,且能快速区分MTB和NTM,具有较好的应用价值。     

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.     

Integration of microscopy and serodiagnostic tests to screen for active tuberculosis.

SETTING: University of California San Diego Medical Center, USA. OBJECTIVE: To create a simple screening strategy for tuberculosis (TB) that includes antibody detection assays to improve the accuracy of microscopic examination of sputum for acid-fast bacilli (AFB smear). METHODS: Serum samples were obtained from 190 patients suspected of having active TB. TB diagnosis was established by Mycobacterium tuberculosis culture. HIV status was determined by commercial serologic tests. IgG antibody levels were measured by ELISA using purified M. tuberculosis antigens. Data from 130 randomly selected patients were used to develop a screening strategy; data from the remaining 60 patients were used for validation. RESULTS: AFB smear had 70% sensitivity and 88% specificity. In algorithms integrating single or multi-antigen ELISA with AFB smear and HIV results, the sensitivity improved over each test alone. The algorithm that included a four-antigen ELISA (38 kDa antigen, lipoarabinomannan, MPT-64 and glutamine synthase) had a sensitivity of 93% and a specificity of 76%. Compared to AFB smear, the sensitivity of the algorithm was significantly higher, while the specificity was not statistically different. CONCLUSION: This study demonstrates that a screening strategy can be created by integrating multi-antigen ELISA with AFB smear and HIV testing.     

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.     

A comparison between the efficiency of the Xpert MTB/RIF assay and nested PCR in identifying Mycobacterium tuberculosis during routine clinical practice

Objectives

Polymerase chain reaction (PCR) for the detection of Mycobacterium tuberculosis (MTB) is more sensitive, specific, and rapid than the conventional methods of acid-fast bacilli (AFB) smear and culture. The aim of this study was to determine if the Xpert MTB/rifampicin (RIF) assay had additional advantages over nested PCR for the detection of MTB in a geographical area with intermediate tuberculosis (TB) incidence.

Methods

Between February and December 2013, the Xpert MTB/RIF assay and MTB nested PCR, as well as AFB smear and culture, were simultaneously performed on 198 clinical samples (160 pulmonary and 38 non-pulmonary specimens) collected from 171 patients hospitalized at Hallym University Medical Center for possible TB. The accuracy of the diagnosis of MTB culture-positive TB and the turnaround time of reporting laboratory results were calculated and compared. Rifampin resistance by the Xpert MTB/RIF assay was reviewed with that of conventional drug susceptibility testing (DST).

Results

The sensitivity, specificity, and positive and negative predictive values of the Xpert MTB/RIF assay and MTB nested PCR for diagnosis of MTB culture-positive pulmonary TB were 86.1% vs. 69.4% (P=0.1563), 97.8% vs. 94.1% (P=0.2173), 91.2% vs. 75.8% (P=0.1695), and 96.4% vs. 92.0% (P=0.2032), respectively. The median turnaround times of the Xpert MTB/RIF assay and MTB nested PCR were 0 [0-4] days and 4 [1-11] days, respectively (P<0.001). Two cases of rifampin resistance, as determined by the Xpert MTB/RIF assay, were found to be multi-drug resistant (MDR) pulmonary TB by DST.

Conclusions

The Xpert MTB/RIF assay seemed to be sensitive, specific, and comparable to nested PCR for identifying MTB among clinically suspected TB patients, and the assay can be valuable in giving a timely identification of resistance to rifampin.     

Value of smear and PCR in bronchoalveolar lavage fluid in culture positive pulmonary tuberculosis.

At present, further investigations are needed in patients with suspected pulmonary tuberculosis (TB) and either negative sputum smear or without sputum. The aim of the present study was to analyse the yield of bronchoalveolar lavage fluid (BALF) smear and PCR in patients with confirmed pulmonary TB. Patients with a positive culture for Mycobacterium tuberculosis complex in sputum or BALF were analysed over 5 yrs. In total, 90 out of 230 (39%) patients with culture-positive pulmonary TB had a positive sputum smear, and 120 patients underwent bronchoscopy. BALF smear was positive in 56 (47%), BALF PCR in 93 (78%) patients, and BALF smear and/or PCR was positive in 83%. In total, 71 patients who underwent bronchoscopy and had complete clinical records were further analysed. BALF (smear or Mycobacterium tuberculosis complex-PCR) allowed a rapid diagnosis in 10 (59%) out of 17 patients who had a negative sputum smear, and 49 (91%) out of 54 patients without sputum production. Of these 71 patients, 12 (17%) were only culture positive. Rapid diagnosis of pulmonary TB by smear and/or PCR was made in 190 out of 210 patients (90%) in sputum or BALF. In conclusion, combined use of bronchoalveolar lavage fluid smear and Mycobacterium tuberculosis complex-PCR has a good diagnostic yield in patients with sputum smear-negative tuberculosis or without sputum production.     

结核抗体IgG检测辅助诊断结核病的应用价值

目的 探讨结核抗体IgG检测(简称“IgG检测”)辅助诊断结核病的应用价值。方法 收集黑龙江省传染病防治院2015年7月至2016年5月期间,具有IgG检测、抗酸杆菌涂片(简称“涂片”)镜检、结核分枝杆菌液体培养(简称“液体培养”)、CT扫描及临床诊断等资料的住院及门诊患者,共计1494例,其中继发性肺结核1020例(肺结核组)、肺外结核54例(肺外结核组)和排除结核病的其他肺部疾病420例(其他肺病组),对比分析不同患者的临床资料。结果 1020例肺结核患者和54例肺外结核患者的IgG检测阳性率分别为73.33%(748/1020)、62.96%(34/54),高于涂片镜检[分别为43.24%(441/1020)、20.37%(11/54)]和液体培养[分别为61.37%(626/1020)、29.63%(16/54)](χ ²=190.02,P<0.001;χ ²=20.15, P<0.001; χ ²=33.18,P<0.001; χ ²=12.07,P=0.001);IgG检测肺结核与其他肺病患者的阳性率(6.90%,29/420)差异有统计学意义(χ ²=553.47,P<0.001)。IgG检测1440例肺部疾病患者的敏感度、特异度、总符合率分别为73.33%(748/1020)、93.10%(391/420)、79.10%(1139/1440)。1020例肺结核患者中,涂片镜检阳性者的IgG检测阳性率(86.85%,383/441)与涂片镜检阴性者的IgG检测阳性率(63.04%,365/579),以及液体培养阳性者的IgG检测阳性率(80.51%,504/626)与液体培养阴性者的IgG检测阳性率(61.93%,244/394)的差异均有统计学意义(χ ²值分别为72.56、42.70,P值均<0.001)。分别以涂片镜检和液体培养为标准,IgG检测1020例肺结核组患者的敏感度、特异度、总符合率分别为86.85%(383/441)和80.51%(504/626) 、36.96%(214/579)和38.07%(150/394)、58.53%(597/1020)和64.12%(654/1020)。1020例肺结核组患者中涂阴培阴(菌阴)肺结核患者为372例(36.47%),其IgG检测阳性率为61.29%(228/372),阳性患者的CT扫描表现以斑片、条索状阴影(83.77%,191/228)多见。420例其他肺病患者IgG检测假阳性率为6.90%(29/420),与肺部感染(62.07%,18/29)和肿瘤(13.79%,4/29)患者有少量交叉反应。 结论 结核抗体IgG检测具有较高的敏感度和特异度,对结核病,尤其是对菌阴肺结核和肺外结核检出具有较高的辅助诊断价值。     

支气管肺泡灌洗液行Xpert MTB/RIF检测对涂阴肺结核的诊断价值

目的评价支气管肺泡灌洗液行Xpert MTB/RIF检测对涂阴肺结核的诊断价值。方法选取从2014年11月至2015年12月徐州市传染病医院收治的3次痰涂片阴性的可疑肺结核患者110例,对所有患者行支气管镜检查进行刷检及收集BALF,进行涂片镜检找抗酸杆菌、结核分枝杆菌培养及Xpert MTB/RIF检测,同时进行诊断。分别以BALF的罗氏培养结果及临床诊断标准作为肺结核诊断的阳性标准,计算Xpert MTB/RIF诊断涂阴肺结核的敏感度、特异度、阳性预测值及阴性预测值。结果以BALF培养阳性结果作为判断肺结核的阳性标准,BALF行Xpert MTB/RIF检测对诊断涂阴肺结核的敏感度、特异度、阳性预测值、阴性预测值分别为100%、97.4%、97.8%、100%。以临床诊断标准为诊断肺结核的阳性标准,BALF行Xpert MTB/RIF检测对诊断涂阴肺结核的敏感度、特异度、阳性预测值、阴性预测值分别为81.9%、97.4%、98.3%、74.0%。以DST结果为金标准,Xpert MTB/RIF检测利福平耐药的敏感度、特异度分别为75.0%、96.0%。结论BALF行Xpert MTB/RIF检测在涂阴肺结核中的敏感度、特异度均较高,且检测快速并能判断是否利福平耐药,对涂阴肺结核的快速诊断及治疗具有较大的应用价值。     

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.     

The significance of the persistent presence of acid-fast bacilli in sputum smears in pulmonary tuberculosis.

STUDY OBJECTIVES: Identification of acid-fast bacilli (AFB) in the sputum smear at the completion of tuberculosis therapy is in some settings considered evidence of treatment failure. However, some patients with pulmonary tuberculosis (TB) will have positive smear results with negative sputum culture results at the end of therapy. The objectives of this study were to estimate the prevalence of persisting positive sputum smear results in patients with TB and to identify characteristics that distinguish patients with persistently positive sputum smear results who also had negative sputum culture results from patients identified as treatment failures. DESIGN: A population-based, historical cohort study with nested case control study. SETTING: British Columbia Division of Tuberculosis Control central case registry. PATIENTS: All 428 patients with culture-proven pulmonary TB in British Columbia over 7 years with sputum that was positive for AFB. METHODS: Review of laboratory data of all 428 patients, as well as clinical data of a subset of 30 patients with persistently positive smear results beyond 20 weeks. RESULTS: Sputum smears were positive for AFB in 205 patients (48%) at 4 weeks, in 30 patients (7%) at 20 weeks, and in 12 patients (3%) at 36 weeks. Of the patients with smear results that were persistently positive at 20 weeks, 23 (77%) had negative sputum culture results and 7 (23%) had positive sputum culture results (ie, they were treatment failures). Patients identified as treatment failures had more localized disease as shown on chest radiographs, had less radiographic improvement at follow-up, had a higher prevalence of drug resistance, and were less compliant with medications than patients with persistently positive smear results and negative culture results. No subject with a negative culture result relapsed over the 6- to 48-month observation period. CONCLUSION: Sputum that is persistently positive for AFB in patients in developed countries is more likely to be associated with negative culture results than with treatment failure.     

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.     

Childhood Tuberculosis in the Kilimanjaro region: lessons from and for the TB Programme

Objective To determine the magnitude of childhood TB and treatment outcome in Kilimanjaro region. Methods Retrospective review of registration‐based data on TB notifications in Kilimanjaro region for the period 2002–2006. Results Between 2002 and 2006, there were 1615 patients of childhood TB in Kilimanjaro region constituting 13% of total TB burden and the average case detection rate was 147/100 000 for urban and 41.8/100 000 for rural populations. Of them, 54.2% were men and 75.2% had pulmonary TB (PTB); 24.9% were tested for acid‐fast bacilli (AFB) by Ziehl‐Neelsen staining showing that 5.8% of all patients with TB were AFB smear positive. The remaining 94.2% were presumptively treated for TB. Treatment success rate was 79.9%, mortality 10.9% and default rate was 7%. Unfavourable outcome was more common among unconfirmed TB patients. HIV testing was very rare but increased after 2004 (<2% before 2005, 11–16% afterwards.) Conclusion The rate of childhood TB in Kilimanjaro region is among the highest in the world. Microbiological diagnosis for TB and AFB smear positivity is very low. Treatment outcome in this region is poor. These findings argue for specific TB control strategies to be designed for children such as more AFB testing using new tools such as induced sputum and laryngeal swabs, active case finding, HIV testing of all suspected TB children, promoting and monitoring adherence. Regular epidemiological studies are also needed.     

GeneXpert MTB/RIF for rapid diagnosis and rifampin resistance detection of endobronchial tuberculosis

Background and objective

Delayed diagnosis and treatment of tuberculosis (TB) contribute to poor outcomes, especially for endobronchial TB (EBTB), which typically leads to tracheobronchial stenosis. Finding rapid and accurate diagnostic tools for EBTB is crucial. GeneXpert Mycobacterium tuberculosis (MTB)/rifampin (RIF) was recommended by the World Health Organization (WHO) as a standard molecular biological diagnostic technique for MTB. The aim of this study was to evaluate the efficacy of GeneXpert MTB/RIF for diagnosing EBTB and for evaluating RIF resistance.

Methods

Biopsy tissue and bronchial brushings from EBTB patients were prospectively assessed with GeneXpert MTB/RIF. The diagnostic yields of auramine O‐stained sputum smears and bronchial brush smears were obtained, and the results were compared with the cultures of sputum and biopsy tissues for MTB.

Results

In 61 confirmed cases of EBTB, the sensitivities of sputum smear, bronchial brush smear, sputum culture and tissue culture to diagnose EBTB were 13.1%, 32.8%, 36.1% and 68.9%, respectively. For bronchial brushings and biopsies, our data showed sensitivities of 57.4% and 63.9%, respectively, and a specificity of 100% for GeneXpert MTB/RIF, and these results were superior to those of sputum smears, bronchial brush smears and sputum culture. GeneXpert MTB/RIF for bronchial brushings and biopsies showed complementarity in its diagnostic performance. Resistance to RIF was identified in 17.4% (8/46) of GeneXpert MTB‐positive cases.

Conclusion

GeneXpert MTB/RIF may enable more rapid EBTB diagnosis and determination of RIF resistance, which are crucial for timely treatment.

     

Microbiological validation of smear microscopy after sputum digestion with bleach; a step closer to a one-stop diagnosis of pulmonary tuberculosis

BACKGROUND: Smear microscopy is relatively insensitive for the diagnosis of TB. The digestion of sputum with household bleach prior to smear preparation has been reported to improve its sensitivity. This method has not been validated. METHODS: Seven hundred and fifty six patients with symptoms suggestive of pulmonary TB (PTB) were asked to submit 3 sputum specimens for direct microscopy. One specimen was selected at random for culture and another specimen was digested to prepare a further smear. The WHO case definition (>or=2 positive smears or one positive smear and positive culture) was used to compare the sensitivity and specificity of the smears. FINDINGS: Four hundred and fifty five (60%) patients were culture-positive. Of these, 235 (31%) had "definite" PTB and 223 (29%) "very likely" PTB (smear-negative, culture-positive). The WHO case definition identified 51% (235/458) of the patients with "definite" or "very likely" PTB. One digested smear detected 219 (93%) of the 235 patients with "definite" PTB and 10 patients with "very likely" PTB (sensitivity (95%CI) 50% (45-55%); specificity 99% (97-100%)). The positive and negative predictive values for one digested smear were 98% (95-99%) and 56% (52-60%) respectively, which were not different (p>0.5) to the WHO case definition (100% and 57%, respectively). INTERPRETATION: One bleach-digested smear is as sensitive and specific as the WHO case definition for the diagnosis of PTB.     

Number of negative acid-fast smears needed to adequately assess infectivity of patients with pulmonary tuberculosis

STUDY OBJECTIVES: To investigate the relationship between the number of negative acid-fast bacilli (AFB) smear results and infectivity of pulmonary tuberculosis (TB). DESIGN: Retrospective analysis. METHODS AND SUBJECTS: We examined 122 index cases in Harris County, TX, reported in 1998 and 1999. All cases had only negative AFB smear results during the infectious period and were categorized in two groups: group A consisted of cases with only one or two sputum specimens collected and processed, and group B consisted of cases with at least three sputum specimens or at least one bronchoscopic specimen. Tuberculin skin test (TST) results of contacts were ascertained from the results of contact investigations performed by the City of Houston Department of Health and Human Services, Tuberculosis Control Division. Univariate and multivariate analyses were done to explore index case and contact attributes associated with tuberculosis (TB) transmission using positive TST results of contacts as a measure of recent transmission. RESULTS: We found male gender and younger age of index cases along with Hispanic ethnicity of contacts to be independently associated with positive TST results, while younger contacts were less likely to be TST positive. Smear category of the index case (group A vs group B) was not independently associated with transmission. We also found that the first two sputum specimens in cases where three or more were performed yielded 90% of all positive culture results for Mycobacterium tuberculosis (MTB). CONCLUSIONS: We conclude that two sputum specimens negative for AFB stain are adequate for both assessing infectivity and for isolating MTB from patients with pulmonary TB.     

湖北省两所监狱结核病现况调查研究

目的 了解示范区监狱结核病疫情和防治工作现状。方法 对示范区2所监狱3516名在押人员进行肺结核普查和结核病知晓率问卷调查,对有肺结核可疑症状者和X线胸片异常者进行痰涂片、培养、菌型鉴定和药敏试验检查。利用结核分枝杆菌散在分布数目可变串联重复序列分析方法(MIRU-VNTR)对痰菌阳性患者进行传染源同源性分析。计算监区肺结核患病率,并与普通人群患病率进行比较。结果 共确诊肺结核患者40例,其中涂片阳性1例,涂片阳性培养阳性1例(涂片阳性1例与涂片阳性培养阳性1例为同一例患者),涂片阴性培养阳性5例,涂片阴性培养阴性34例。6例培养阳性菌株药敏试验结果显示,共有3例患者耐药,其中1例耐链霉素,1例同时耐异烟肼、利福平和乙胺丁醇,1例同时耐异烟肼、利福平、乙胺丁醇和氧氟沙星。肺结核患病率、涂阳患病率、菌阳患病率分别为1156.4/10万（40/3459）、28.9/10万（1/3459）、173.5/10万（6/3459）。其中肺结核患病率高于当地普通人群患病率338.4/10万（χ²=17.858,P＜0.01）。在押人员对3条核心信息总知晓率为61.6%（6384/10 359）,其中乙监狱67.4%（4737/7026）,甲监狱49.4%（1647/3333）,差异有统计学意义（χ²=309.1,P＜0.01）。同一监狱5例痰菌阳性患者其传染源来源不同。结论 监狱结核病疫情严重,应探索有效的监狱结核病防控模式。     

Characteristics of adults and children diagnosed with tuberculosis in Lilongwe,Malawi: findings from an integrated HIV/TB clinic

Objectives To describe initial registration characteristics of adult and paediatric TB patients at a large, public, integrated TB and HIV clinic in Lilongwe, Malawi, between January 2008 and December 2010. Methods Routine data on patient with TB category and TB type, stratified by HIV and ART status, were used to explore differences in proportions among TB only, TB/HIV co‐infected patients not on ART and TB/HIV co‐infected patients on ART using chi‐square tests. Trends over time illustrate strengths and weaknesses of integrated service provision. Results Among 10 143 adults, HIV ascertainment and ART uptake were high and increased over time. The proportion of relapse was highest among those on ART (5%). The proportion of smear‐positive pulmonary TB (PTB) was highest among HIV‐negative patients with TB (34.9%); extra‐pulmonary TB (EPTB) was lowest among TB only (16.2%). Among 338 children <15 years, EPTB and smear‐positive PTB were more common among TB‐only patients. Time trends showed significant increases in the proportion of adults with smear‐positive PTB and the proportion of adults already on ART before starting TB treatment. However, some co‐infected patients still delay ART initiation. Conclusions HIV ascertainment and ART uptake among co‐infected patients are successful and improving over time. However, delays in ART initiation indicate some weakness linking TB/HIV patients into ART during TB follow‐up care. Improved TB diagnostics and screening efforts, especially for paediatric patients, may help improve quality care for co‐infected patients. These results may aid efforts to prioritise TB and HIV prevention, education and treatment campaigns for specific populations.