Culture-negative Tuberculosis Research Articles

Treatment for radiographically active, sputum culture-negative pulmonary tuberculosis: A systematic review and meta-analysis.

People with radiographic evidence for pulmonary tuberculosis (TB), but negative sputum cultures, have increased risk of developing culture-positive TB. Recent expansion of X-ray screening is leading to increased identification of this group. We set out to synthesise the evidence for treatment to prevent progression to culture-positive disease. We conducted a systematic review and meta-analysis. We searched for prospective trials evaluating the efficacy of TB regimens against placebo, observation, or alternative regimens, for the treatment of adults and children with radiographic evidence of TB but culture-negative respiratory samples. Databases were searched up to 18 Oct 2022. Study quality was assessed using ROB 2·0 and ROBINS-I. The primary outcome was progression to culture-positive TB. Meta-analysis with a random effects model was conducted to estimate pooled efficacy. This study was registered with PROSPERO (CRD42021248486). We included 13 trials (32,568 individuals) conducted between 1955 and 2018. Radiographic and bacteriological criteria for inclusion varied. 19·1% to 57·9% of participants with active x-ray changes and no treatment progressed to culture-positive disease. Progression was reduced with any treatment (6 studies, risk ratio [RR] 0·27, 95%CI 0·13-0·56), although multi-drug TB treatment (RR 0·11, 95%CI 0·05-0·23) was significantly more effective than isoniazid treatment (RR 0·63, 95%CI 0·35-1·13) (p = 0·0002). Multi-drug regimens were associated with significantly reduced risk of progression to TB disease for individuals with radiographically apparent, but culture-negative TB. However, most studies were old, conducted prior to the HIV epidemic and with outdated regimens. New clinical trials are required to identify the optimal treatment approach.

The diagnostic performance of endobronchial ultrasound with Xpert MTB/RIF Ultra in smear-negative pulmonary tuberculosis

ObjectiveThis study investigated the diagnostic performance of endobronchial ultrasound with Xpert MTB/RIF Ultra (Ultra) for detecting smear-negative pulmonary tuberculosis (TB).Methods143 patients suspected of sputum smear-negative pulmonary tuberculosis were enrolled in this study in Shanghai Pulmonary Hospital, China. These patients underwent endobronchial ultrasound with a guide sheath (EBUS-GS) or endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) based on their chest CT manifestations. We assessed the sensitivity and specificity of tissue specimens with Ultra in the TB group and non-TB group. Culture and clinical diagnosis were used as gold-standard for TB.ResultsAmong these 143 patients, 11 patients were culture-positive TB, 85 patients were diagnosed with culture-negative TB and 47 were with the non-TB diseases. Direct testing with microscopy (Acid-Fast Bacilli smear, AFB), liquid culture, pathology, Xpert MTB/RIF(Xpert) test and Ultra had a sensitivity of 8.3%, 11.5%, 42.7%, 64.6%, and 78.1% individually among all the TB patients. Ultra had a higher sensitivity than Xpert (P = 0.011). But Ultra had a specificity of 59.6% (95% CI 44.3–73.3), lower than that of Xpert (89.4%, 95% CI 76.1–96.0, P = 0.001). Ultra had the same sensitivity on specimens from EBUS-TBNA and EBUS-GS (P = 0.975). Ultra’s positive predictive value and negative predictive value were 79.8% and 57.1% respectively.ConclusionsTissue specimens from interventional bronchoscopy combined with Ultra provide a sensitive method for diagnosing smear-negative pulmonary tuberculosis, but its specificity was lower than Xpert.

Factors Associated With Receiving Longer Than Recommended Therapy Among Culture-Negative Pulmonary Tuberculosis Patients.

US tuberculosis (TB) guidelines recommend treatment ≥6 months with a regimen composed of multiple effective anti-TB drugs. Since 2003, a 4-month regimen for a specific subset of TB patients has also been recommended. We used 2011-2018 US National Tuberculosis Surveillance System data to characterize factors associated with 4-month (111-140 days) therapy among adult patients who had completed treatment and were potentially eligible at that time for 4-month therapy (culture-negative pulmonary-only TB, absence of certain risk factors, and initial treatment that included pyrazinamide). We used modified Poisson regression with backward elimination of main effect variables to calculate adjusted relative risks (aRRs). During 2011-2018, 63 393 adults completed TB treatment: 5560 (8.8%) were potentially eligible for 4-month therapy; of these, 5560 patients (79%) received >4-month therapy (median, 193 days or ∼6 months). Patients with cavitary disease were more likely to receive >4-month therapy (aRR, 1.10; 95% CI, 1.07-1.14) vs patients without cavitary disease. Patients more likely to receive 4-month therapy included patients treated by health departments vs private providers only (aRR, 0.94; 95% CI, 0.91-0.98), those in the South and West vs the Midwest, non-US-born persons (aRR, 0.95; 95% CI, 0.91-0.99) vs US-born persons, and aged 25-64 years vs 15-24 years. Most patients potentially eligible for 4-month therapy were treated with standard 6-month courses. Beyond clinical eligibility criteria, other patient- and program-related factors might be more critical determinants of treatment duration.

Dominant expansion of CD4+, CD8+ T and NK cells expressing Th1/Tc1/Type 1 cytokines in culture-positive lymph node tuberculosis.

Lymph node culture-positive tuberculosis (LNTB+) is associated with increased mycobacterial antigen-induced pro-inflammatory cytokine production compared to LN culture-negative tuberculosis (LNTB-). However, the frequencies of CD4+, CD8+ T cells and NK cells expressing Th1/Tc1/Type 1 (IFNγ, TNFα, IL-2), Th17/Tc17/Type 17 (IL-17A, IL-17F, IL-22) cytokines and cytotoxic (perforin [PFN], granzyme [GZE] B, CD107a) markers in LNTB+ and LNTB- individuals are not known. Thus, we have studied the unstimulated (UNS) and mycobacterial antigen-induced frequencies of CD4+, CD8+ T and NK cells expressing Th1, Th17 cytokines and cytotoxic markers using flow cytometry. The frequencies of CD4+, CD8+ T and NK cells expressing cytokines and cytotoxic markers were not significantly different between LNTB+ and LNTB- individuals in UNS condition. In contrast, upon Mtb antigen stimulation, LNTB+ individuals are associated with significantly increased frequencies of CD4+ T cells (PPD [IFNγ, TNFα], ESAT-6 PP [IFNγ, TNFα], CFP-10 PP [IFNγ, TNFα, IL-2]), CD8+ T cells (PPD [IFNγ], ESAT-6 PP [IFNγ], CFP-10 PP [TNFα]) and NK cells (PPD [IFNγ, TNFα], ESAT-6 PP [IFNγ, TNFα], CFP-10 PP [TNFα]) expressing Th1/Tc1/Type 1, but not Th17/Tc17/Type 17 cytokines and cytotoxic markers compared to LNTB- individuals. LNTB+ individuals did not show any significant alterations in the frequencies of CD4+, CD8+ T cells and NK cells expressing cytokines and cytotoxic markers compared to LNTB- individuals upon HIV Gag PP and P/I antigen stimulation. Increased frequencies of CD4+, CD8+ T and NK cells expressing Th1/Tc1/Type 1 cytokines among the LNTB+ group indicates that the presence of mycobacteria plays a dominant role in the activation of key correlates of immune protection or induces higher immunopathology.

Gene-Based Diagnosis of Tuberculosis from Oral Swabs with a New Generation Pathogen Enrichment Technique.

ABSTRACTA rapid and sensitive diagnosis is crucial for the management of tuberculosis (TB). A simple and label-free approach via homobifunctional imidoesters with a microfluidic platform (SLIM) assay showed a higher sensitivity than the Xpert MTB/RIF assay in the diagnosis of pulmonary TB (PTB). Here, we evaluated the efficacy of the SLIM assay for oral swab samples from cases of suspected PTB. Patients with clinically suspected PTB were prospectively enrolled and oral swab samples were processed using the SLIM assay and the attending physicians were blinded to the results of the SLIM assay. TB cases were defined as those treated with anti-TB chemotherapy for at least 6 months at the discretion of the specialists based on their clinical features and conventional laboratory results, including the Xpert assay. A total of 272 patients (with TB, n = 128 [47.1%]; without TB, n = 144 [52.9%]; mean age, 59.8 years) were enrolled. Overall, the sensitivity of the oral swab-based SLIM assay (65.6%) was higher than that of the sputum-based Xpert assay (43.4%; P = 0.001). Specifically, the SLIM oral swab assay showed a notably higher sensitivity in culture-negative TB cases compared with the Xpert assay (69.0% [95% CI: 49.2 to 84.7%] versus 7.4% [95% CI: 0.9 to 24.3%]; P = 0.001). The specificity of the SLIM and the Xpert assays was 86.1% (95% CI: 79.3 to 91.3%) and 100% (95% CI: 97.2 to 100%), respectively. When only culture-confirmed cases were analyzed, the SLIM oral swab was comparable to sputum Xpert in sensitivity (64.7% versus 54.3%, P = 0.26). The oral swab-based SLIM assay showed a superior sensitivity for TB diagnosis over the sputum-based Xpert assay, especially for culture-negative cases.IMPORTANCE The development of a rapid, accessible, and highly sensitive diagnostic tool is a major challenge in the control and management of tuberculosis. Gene-based diagnostics is recommended for the rapid diagnosis of pulmonary tuberculosis (PTB), but its sensitivity, such as Xpert MTB/RIF assay (Xpert), drops in cases with a low bacterial load. It can only be applied to sputum samples, and it is quite difficult for some patients to produce an adequate amount of sputum. We evaluated the clinical validity of an oral swab-based microfluidic system, i.e., the SLIM assay. The SLIM assay showed a significantly higher sensitivity than the Xpert assay, especially in smear-negative TB cases. This non-sputum-based SLIM assay can be a useful diagnostic test by overcoming the limitations of conventional sputum-based tests in pulmonary TB.

Microarray-based selection of a serum biomarker panel that can discriminate between latent and active pulmonary TB

Bacterial culture of M. tuberculosis (MTB), the causative agent of tuberculosis (TB), from clinical specimens is the gold standard for laboratory diagnosis of TB, but is slow and culture-negative TB cases are common. Alternative immune-based and molecular approaches have been developed, but cannot discriminate between active TB (ATB) and latent TB (LTBI). Here, to identify biomarkers that can discriminate between ATB and LTBI/healthy individuals (HC), we profiled 116 serum samples (HC, LTBI and ATB) using a protein microarray containing 257 MTB secreted proteins, identifying 23 antibodies against MTB antigens that were present at significantly higher levels in patients with ATB than in those with LTBI and HC (Fold change > 1.2; p < 0.05). A 4-protein biomarker panel (Rv0934, Rv3881c, Rv1860 and Rv1827), optimized using SAM and ROC analysis, had a sensitivity of 67.3% and specificity of 91.2% for distinguishing ATB from LTBI, and 71.2% sensitivity and 96.3% specificity for distinguishing ATB from HC. Validation of the four candidate biomarkers in ELISA assays using 440 serum samples gave consistent results. The promising sensitivity and specificity of this biomarker panel suggest it merits further investigation for its potential as a diagnostic for discriminating between latent and active TB.

Serum-Based Diagnosis of Pediatric Tuberculosis by Assay of Mycobacterium tuberculosis Factors: a Retrospective Cohort Study.

Diagnosis of pediatric tuberculosis (TB) is often complicated by its nonspecific symptoms, paucibacillary nature, and the need for invasive specimen collection techniques. However, a recently reported assay that detects Mycobacterium tuberculosis virulence factors in serum can diagnose various TB manifestations, including paucibacillary TB cases, in adults with good sensitivity and specificity. The current study examined the ability of this M. tuberculosis biomarker assay to diagnose pediatric TB using archived cryopreserved serum samples drawn from children ≤18 years of age who were screened for suspected TB as part of a prospective population-based active surveillance study. In this analysis, any detectable level of either of the M. tuberculosis virulence factors CFP-10 and ESAT-6 was considered direct evidence of TB. Serum samples from 105 children evaluated for TB (55 TB cases and 50 close contacts without TB) were analyzed. The results of this analysis yielded sensitivity of 85.5% (95% confidence interval [CI], 73.3 to 93.5). Similar diagnostic sensitivities were observed for culture-positive (87.5%; 95% CI, 67.6 to 97.3) and culture-negative (83.9%; 95% CI, 66.3 to 94.5) TB cases and for culture negative pulmonary (77.8%; 95% CI, 40.0 to 97.2) and extrapulmonary (86.4%; 95% CI, 65.1 to 97.1) TB cases. These results suggest that serum biomarker analysis holds significant promise for rapid and sensitive diagnosis of pediatric TB cases, including extrapulmonary or paucibacillary TB cases. The ability to use frozen samples for this analysis should also permit assays to be performed at central sites, without a requirement for strict timelines for sample analysis.

A Prospective Evaluation of Xpert MTB/RIF Ultra for Childhood Pulmonary Tuberculosis in Uganda

Xpert MTB/RIF Ultra (Xpert Ultra) has improved the sensitivity to detect pulmonary tuberculosis (TB) in adults. However, there have been limited prospective evaluations of its diagnostic accuracy in children. We enrolled children undergoing assessment for pulmonary TB in Kampala, Uganda, over a 12-month period. Children received a complete TB evaluation and were classified as Confirmed, Unconfirmed, or Unlikely TB. We calculated the sensitivity and specificity of Xpert Ultra among children with Confirmed vs Unlikely TB. We also determined the diagnostic accuracy with clinical, microbiological, and extended microbiological reference standards (MRSs). Of the 213 children included, 23 (10.8%) had Confirmed TB, 88 (41.3%) had Unconfirmed TB, and 102 (47.9%) had Unlikely TB. The median age was 3.9 years, 13% were HIV-positive, and 61.5% were underweight. Xpert Ultra sensitivity was 69.6% (95% confidence interval [CI]: 47.1-86.8) among children with Confirmed TB and decreased to 23.4% (95% CI: 15.9-32.4) with the clinical reference standard. Specificity was 100% (95% CI: 96.4-100) among children with Unlikely TB and decreased to 94.7% (95% CI: 90.5-97.4) with a MRS. Sensitivity was 52.9% (95% CI: 35.1-70.2) and specificity 95.5% (95% CI: 91.4-98.1) with the extended MRS. Of the 26 positive Xpert Ultra results, 6 (23.1%) were "Trace-positive," with most (5/6) occurring in children with Unconfirmed TB. Xpert Ultra is a useful tool for diagnosing pulmonary TB in children, but there remains a need for more sensitive tests to detect culture-negative TB.

Gene-Based Diagnosis of Tuberculosis from Oral Swabs with a New Generation Pathogen Enrichment Technique in Real-World Practice

Background: A rapid and sensitive diagnosis is crucial for the successful management of tuberculosis (TB). The SLIM assay, a novel label-free pathogen enrichment using a microfluidic system, showed a higher sensitivity than the Xpert MTB/RIF assay in the diagnosis of pulmonary TB (PTB). Here, we evaluated the efficacy of the SLIM assay for oral swab samples in the diagnosis of PTB. Methods: Patients with clinically suspected PTB were prospectively enrolled from May 2019 to October 2020. Oral swab samples were processed using the SLIM assay and the attending physicians were blinded to the results of the SLIM assay. TB cases were defined as those treated with anti-TB chemotherapy for at least 6 months at the discretion of the specialists based on clinical features and conventional laboratory results including the Xpert assay. Findings: A total of 272 patients (TB, n=128 [47·1%]; not TB, n=144 [52·9%]; mean age, 59·8 years) were enrolled. Overall, the sensitivity of the oral swab-based SLIM assay (65·6%) was higher than that of the sputum-based Xpert assay (43·4%; p=0·001). Specifically, the SLIM oral swab assay showed a notably higher sensitivity in culture-negative TB cases compared with the Xpert assay (64·7% vs 9·4%; p=0·001). The specificities of the SLIM and the Xpert were 86·1% and 100%, respectively. Interpretation: The oral swab-based SLIM assay showed a superior sensitivity for TB diagnosis over the sputum-based Xpert assay, especially for culture-negative cases. The novel non-sputum-based diagnostic method may confer a better performance in paucibacillary TB compared with the currently available sputum-based methods. Funding: This work was supported by the Korea Medical Device Development Fund grant funded by the Korean government (Project Number: 202011C07-00), the grants from Asan Institute for Life Sciences (2019-7043) and the Ministry of Science, ICT and Future Planning (MSIP) through the National Research Foundation of Korea (NRF) (2020R1A2C2007148). Declaration of Interest: None to declare. Ethical Approval: The institutional review boards of Asan Medical Center (2018-0020) and Severance hospital (4-2018-0029) approved this study, and the protocols of this study were registered in clinicaltrials.gov (NCT03423550).

SUN-166 Primary Adrenal Insufficiency Caused by Underlying Tuberculosis

IntroductionPrimary adrenal insufficiency (AI) is a rare endocrine disorder affecting 1 in 100,000 people. Primary AI is a gradual destruction of the adrenal cortex. Etiology includes autoimmune, tuberculosis, histoplasmosis, blastomycosis, adrenal metastases, primary adrenal tumors, and opportunistic infections of HIV. Since aggressive treatment of TB, the incidence of TB adrenalitis has significantly declined, now accounting for 20% of reported cases where as autoimmune causes of AI account for 70%. Most common symptoms are non-specific, and diagnosis is often delayed, with patient initially presenting with a life-threatening adrenal crisis.CasePatient is an incarcerated 65 y/o African American male with PMHx of hypothyroidism who was admitted to the hospital for AMS after being found unresponsive in his prison cell. On admission, patient was febrile, hypotensive and tachycardic. He looked disheveled, confused, and lethargic. Other exam findings were negative.Lab results revealed WBC 11.7/μL, serum sodium 116 mmol/L, serum potassium 5.2 mmol/L, serum glucose 68 mg/dL, serum osmolality 237mOsm/kg, TSH 26.3mIU/L, and random cortisol 1.6ug/dL. ACTH stimulation test revealed pre-challenge cortisol levels 5.1ug/dL, 30-minute 4.9ug/dL and 60-minute 4.5ug/dL. ACTH 1271 pg/mL (normal range 7.2-63.3pg/mL). A normal response is a stimulated cortisol level > 18ug/dl. Chest x-ray revealed left lower lobe pneumonia.Clinical signs/symptoms and labs were consistent with primary AI. Adrenal crisis was most likely precipitated by underlying pneumonia. Workup was negative for 21-Hydrolase Antibodies, HIV, CMV, and histoplasmosis. However, QuantiFERON-TB Gold Test was positive. Abdominal CT revealed bilateral enlarged non-enhancing adrenal nodules with coarse calcifications. Biopsy of right adrenal gland revealed necrotizing caseating granulomatous inflammation. Biopsy was negative for isolated aerobic, anerobic, fungal organisms, AFB, and mycobacterium PCR.Due to current findings and high suspicion of TB adrenalitis, patient is currently being treated as culture-negative tuberculosis along with PO hydrocortisone for underlying AI.DiscussionAdrenal tuberculosis is a rare cause of primary adrenal insufficiency in developed countries. There should be high suspicion for AI when a patient presents with hypotension, hyponatremia, hyperkalemia and/or hypoglycemia. In this case, although patient did not have a positive AFB culture, he did have a positive QuantiFERON-TB Gold Test along with consistent findings on CT and biopsy. Thus, case was concluded to have high suspicion of primary AI secondary to underlying untreated tuberculosis. Prompt treatment with antituberculosis medication, appropriate steroid therapy, along with monitoring of adrenal function, underlying adrenal insufficiency may be reversible if detected in early stages and decrease mortality.

Underreporting of patients diagnosed with tuberculosis in the Region of Southern Denmark.

Background: Tuberculosis (TB) is a notifiable disease in Denmark. Underreporting leads to underestimation of the disease burden and may impede disease control. To date, no other published studies have examined underreporting of TB in the Danish setting. Method: Records of patients in the Region of Southern Denmark diagnosed with TB from 2009 to 2014 in the Danish National Patient Registry (DNPR) were linked to the national notification database. Medical records of non-notified patients were reviewed, followed by statistical comparison of demographic and medical parameters with notified TB patients in the region. Results: In the study period, 28.9% (n=30) of clinically diagnosed, culture-negative TB cases were not notified, corresponding to an overall TB underreporting rate of 7.5%. Non-notified patients had fewer co-morbidities and were less likely to have had previous TB episodes. Incidentally, we found a high number (71.1%) of erroneous TB diagnoses in the DNPR. Conclusions: Accurate data based on notification is essential to understand possible needs for preventive actions in the population. Our study demonstrates the existence of underreporting of culture-negative TB cases in the Region of Southern Denmark.

MEDIASTINAL TB PRESENTING AS RIGHT MIDDLE LOBE SYNDROME WITH PIGMENTED AIRWAYS ON BRONCHOSCOPY

SESSION TITLE: Monday Fellow Case Report Posters SESSION TYPE: Fellow Case Report Posters PRESENTED ON: 10/21/2019 02:30 PM - 03:15 PM INTRODUCTION: Mediastinal tuberculous lymphadenitis (MTLD) is an uncommon manifestation of tuberculosis (TB). We describe a case of MTLD in an adult with a recent history of pleurisy, presenting as right middle lobe syndrome, found to have black mucosal discoloration on bronchoscopy. CASE PRESENTATION: A 60-year-old Afghan female was evaluated for chronic cough. She previously immigrated from Pakistan, at which time she was evaluated for a pleural effusion and positive tuberculin skin test (20mm). Thoracentesis revealed a lymphocytic effusion, normal glucose, low ADA, and negative AFB. She did not complete an isoniazid course, yet her effusion resolved. Two years later, she presented with 2 months of cough, rare hemoptysis, fatigue, night sweats, and dyspnea. She was frail, nontoxic, with a dry cough and coarse right parasternal breath sounds. CT chest showed calcified hilar and mediastinal lymphadenopathy with right middle lobe atelectasis [Figure 1]. Bronchoscopy revealed black mucosal plaques [Figure 2], with a nodular bronchus intermedius lesion obstructing the middle lobe [Figure 3]. Biopsy showed plasma cells, eosinophils, and basement membrane thickening; no malignancy or granulomas. Bronchoalveolar lavage (BAL) and stains for acid-fast and fungal organisms were all negative. She was started on isoniazid and rifampin, with marked improvement at 1 month; CT chest at 2 months showed increased right middle lobe aeration [Figure 4]. She was diagnosed with culture-negative TB, treated with 9-months of therapy. DISCUSSION: Pleurisy is common in primary TB, and often resolves spontaneously1, but one-third have reactivation2. Lymphadenopathy is characteristic of primary disease, but isolated MTLD is unusual in post-primary TB3. Yield of sputum, BAL, and transbronchial biopsy is low in MTLD due to microorganism burden4. EBUS can aid in diagnosis in 42-85%, and mediastinoscopy is an option if benefit outweighs risk5. In a patient with compatible clinical picture, culture-negative TB may be diagnosed after demonstrating response to therapy6. Black airway pigmentation is nonspecific, seen in malignancy, anthracosis, soot, and infections such as Aspergillus and Mycobacterium tuberculosis7. Mechanism is not fully understood, but may reflect rupture of lymph nodes with pigment-laden macrophages into bronchial mucosa7. Despite treatment, it is often irreversible. CONCLUSIONS: MTLD is uncommon in post-primary TB, and diagnosis is difficult due to atypical imaging findings and low organism burden. When traditional methods for diagnosis fail, procedures such as EBUS may increase diagnostic yield. Black mucosal changes can be suggestive of TB. If clinical and radiographic findings are consistent, culture-negative TB may be diagnosed based on response to antimycobacterial therapy. Reference #1: Jeon D. Tuberculous pleurisy: an update. Tuberc Respir Dis (Seoul). 2014;76(4):153-9. Reference #2: Valdés L, Álvarez D, San José E, et al. Tuberculous Pleurisy: A Study of 254 Patients. Arch Intern Med.1998;158(18):2017–2021. https://doi.org/10.1001/archinte.158.18.2017 Reference #3: Kim J, Jang Y, Kim Yo, et. Al. Mediastinal Tuberculous Lymphadenitis Diagnosed by Endosonographic Fine Needle Aspiration. Korean J Gastroenterol. 2016 Dec 25; 68 (6): 312-316. DISCLOSURES: No relevant relationships by richard blinkhorn, source=Web Response No relevant relationships by Hau Chieng, source=Web Response No relevant relationships by Shannon Murawski, source=Web Response

Clinical Evaluation of a Blood Assay to Diagnose Paucibacillary Tuberculosis via Bacterial Antigens.

The diagnosis of active tuberculosis (TB) cases primarily relies on methods that detect Mycobacterium tuberculosis (Mtb) bacilli or their DNA in patient samples (e.g., mycobacterial culture and Xpert MTB/RIF assays), but these tests have low clinical sensitivity for patients with paucibacillary TB disease. Our goal was to evaluate the clinical performance of a newly developed assay that can rapidly diagnose active TB cases by direct detection of Mtb-derived antigens in patients' blood samples. Nanoparticle (NanoDisk)-enriched peptides derived from the Mtb virulence factors CFP-10 (10-kDa culture factor protein) and ESAT-6 (6-kDa early secretory antigenic target) were analyzed by high-throughput mass spectrometry (MS). Serum from 294 prospectively enrolled Chinese adults were analyzed with this NanoDisk-MS method to evaluate the performance of direct serum Mtb antigen measurement as a means for rapid diagnosis of active TB cases. NanoDisk-MS diagnosed 174 (88.3%) of the study's TB cases, with 95.8% clinical specificity, and with 91.6% and 85.3% clinical sensitivity for culture-positive and culture-negative TB cases, respectively. NanoDisk-MS also exhibited 88% clinical sensitivity for pulmonary and 90% for extrapulmonary TB, exceeding the diagnostic performance of mycobacterial culture for these cases. Direct detection and quantification of serum Mtb antigens by NanoDisk-MS can rapidly and accurately diagnose active TB in adults, independent of disease site or culture status, and outperform Mycobacterium-based TB diagnostics.

The effectiveness of individualized treatment regimen on smear-positive retreatment pulmonary tuberculosis with mono- and poly-drug resistance

Objective: To analyze and evaluate the effectiveness of individualized treatment regimen in the therapy of smear-positive retreatment pulmonary tuberculosis with mono-and poly-drug resistance, and therefor to provide information on how to develop rational individualized regimen for retreatment tuberculosis cases with drug resistance. Methods: This was a multi-centered, prospective cohort study. Totally 254 cases of sputum positive tuberculosis with previous treatment history during the period from July 1, 2009 to August 30, 2016 were included in the analysis. All the cases were randomly divided into 3 groups and received therapy after randomization into treatment groups. After 3 months, cases with multidrug resistant tuberculosis, extensively drug-resistant tuberculosis, non-tuberculosis mycobacterial infection and those with smear-positive but culture-negative tuberculosis were excluded according to result of sputum culture and drug susceptibility test (DST). In treatment group A (individualized treatment group), 86 cases with an average age of (42.1±13.7) years for men and (38.5±12.8) years for women, were treated with individualized regimen, which allowed drug replacement on the basis of standard regimen (2SHRZE/6HRE) according to DST result. Treatment duration was recalculated after drug replacement and the total length should be 12 months or more. If the DST result did not show drug resistance, the patients would continue the 8 months' standard treatment. In treatment group B (intensified retreatment regimen group), 86 cases with an average age of (43.2±14.2) years for man and (37.9±14.1) years for women, received intensified retreatment regimen (2HL(2)EZS/2HL(2)EZS(3)/4HL(2)E). The dose for H was 0.3 g/d for patients with body weight <50 kg, and 0.4~0.5 g/d for higher body weight (≥50 kg); The doses for L(2,)E and Z were 0.6 g, 2/w; 0.75, 1/d and 0.5g, 3/d. In treatment group C (standard treatment group), 82 cases with an average of (42.5±11.9) years for man and (38.6±12.8) years for women, were treated with standardized regimen recommended by national tuberculosis program (2HREZS/6HRE). In both group B and C, the total treatment duration was 8 months and the drugs were not replaced for mono-and poly-drug resistance. Treatment outcomes of the 3 groups were analyzed, the status of drug replacement in group A was analyzed, and the adjustment of dose of H and R according to patients' body weight was observed. SPSS 19.0 was used for data analysis. Results: The treatment cure rates for group A, B and C were 73.3%(63/86), 76.7%(66/86) and 50%(41/82), and the treatment success rates were 80.2%(69/86), 84.9%(73/86) and 62.2%(51/82) respectively. Treatment failure was 8.1%(7/86), 4.7%(4/86) and 19.5%(16/82) in 3 groups. There were significant differences in the above indicators for group A and B in comparison with group C(χ(2)=13.127, P=0.001). However, there was no difference observed between group A and B(χ(2)=0.646, P=0.422). In group A, tuberculosis specialized hospitals using regular doses for R was only 38.7%(12/31). After 3 years' follow-up, no-relapse-success for group A was 66.7% (10/15). Conclusions: Inappropriate individualized treatment would increase treatment failure for retreatment tuberculosis. Higher doses of H and R and prolonged extensive therapy phase could contribute to increased treatment success.

Rapid diagnosis of new and relapse tuberculosis by quantification of a circulating antigen in HIV-infected adults in the Greater Houston metropolitan area

BackgroundHIV-associated immune defects inhibit tuberculosis (TB) diagnosis, promote development of extrapulmonary TB and paucibacillary pulmonary TB cases with atypical radiographic features, and increase TB relapse rates. We therefore assessed the diagnostic performance of a novel assay that directly quantitates serum levels of the Mycobacterium tuberculosis (Mtb) virulence factor 10-kDa culture filtrate protein (CFP-10) to overcome limitations associated with detecting Mtb bacilli in sputum or tissue biopsies.MethodsThis study analyzed HIV-positive adults enrolled in a large, population-based TB screening and surveillance project, the Houston Tuberculosis Initiative, between October 1995 and September 2004, and assigned case designations using standardized criteria. Serum samples were trypsin-digested and immunoprecipitated for an Mtb-specific peptide of CFP-10 that was quantified by liquid chromatography-mass spectrometry for rapid and sensitive TB diagnosis.ResultsAmong the 1053 enrolled patients, 110 met all inclusion criteria; they included 60 tuberculosis cases (12 culture-negative TB), including 9 relapse TB cases, and 50 non-TB controls, including 15 cases with history of TB. Serum CFP-10 levels diagnosed 89.6% (77.3–96.5) and 66.7% (34.9–90.1) of culture-positive and culture-negative TB cases, respectively, and exhibited 88% (75.7–95.5) diagnostic specificity in all non-TB controls. Serum antigen detection and culture, respectively, identified 85% (73.4–92.9) and 80.0% (67.3–88.8) of all 60 TB cases.ConclusionsQuantitation of the Mtb virulence factor CFP-10 in serum samples of HIV-infected subjects diagnosed active TB cases with high sensitivity and specificity and detected cases missed by the gold standard of Mtb culture. These results suggest that serum CFP-10 quantitation holds great promise for the rapid diagnosis of suspected TB cases in patients who are HIV-infected.

Problems in serum antibody detection of smear- and culture-negative pulmonary tuberculosis

More than 60% of active tuberculosis(TB) patients are smear- and culture-negative, constituting a prime group in the prevention and control of TB in China. In the existing laboratory testing technologies, immunological diagnosis is more advantageous than etiological diagnosis in the detection of smear- and culture-negative TB. Serum antibody detection reagents are cheap, easy to operate and time-saving, and have been widely used in China. However, these agents are not stable in sensitivity and specificity, and because of that their accuracy in the diagnosis of smear- and culture-negative TB is doubtful. In this review, we summarize some problems in the use of serum antibody detection among smear- and culture-negative pulmonary TB patients and discuss possible methods to solve these problems expecting to provide some ideas for promoting its development, application and policy formulation. Key words: Tuberculosis/diagnosis; Smear- and culture-negative pulmonary tuberculosis; Serum antibody detection

Limited value of whole blood Xpert® MTB/RIF for diagnosing tuberculosis in children

We evaluated the ability of the Xpert(®) MTB/RIF assay to detect Mycobacterium tuberculosis in whole blood of children with tuberculosis in tuberculosis endemic settings with high rates of HIV infection. From June 2011 to September 2012 we prospectively enrolled children with symptoms or signs suggestive of tuberculosis at three research centres in Tanzania and Uganda. After clinical assessment, respiratory specimens were collected for microscopy and culture, as well as whole blood for Xpert(®) MTB/RIF. Children were classified according to standardised case definitions. A total of 232 children were evaluated; 14 (6.0%) had culture-confirmed tuberculosis. The Xpert(®) MTB/RIF assay detected M. tuberculosis in 5/232 (2.2%) blood samples with 1 (0.4%) error reading and presumably 1 (0.4%) false-positive result. The sensitivity of the assay in children with culture-confirmed (1/14) versus no tuberculosis (1/117) was 7.1% (95% CI, 1.3-31.5). Three of the five Xpert(®) MTB/RIF positive patients had negative cultures, but were classified as probable tuberculosis cases. Assay sensitivity against a composite reference standard (culture-confirmed, highly probable or probable tuberculosis) was 5.4% (95% CI, 2.1-13.1). Whole blood Xpert(®) MTB/RIF demonstrated very poor sensitivity, although it may enhance the diagnostic yield in select cases, with culture-negative tuberculosis.

Diagnosis of Childhood Tuberculosis and Host RNA Expression in Africa

BackgroundImproved diagnostic tests for tuberculosis in children are needed. We hypothesized that transcriptional signatures of host blood could be used to distinguish tuberculosis from other diseases in African children who either were or were not infected with the human immunodeficiency virus (HIV).MethodsThe study population comprised prospective cohorts of children who were undergoing evaluation for suspected tuberculosis in South Africa (655 children), Malawi (701 children), and Kenya (1599 children). Patients were assigned to groups according to whether the diagnosis was culture-confirmed tuberculosis, culture-negative tuberculosis, diseases other than tuberculosis, or latent tuberculosis infection. Diagnostic signatures distinguishing tuberculosis from other diseases and from latent tuberculosis infection were identified from genomewide analysis of RNA expression in host blood.ResultsWe identified a 51-transcript signature distinguishing tuberculosis from other diseases in the South African and Malawian children (the discovery cohort). In the Kenyan children (the validation cohort), a risk score based on the signature for tuberculosis and for diseases other than tuberculosis showed a sensitivity of 82.9% (95% confidence interval [CI], 68.6 to 94.3) and a specificity of 83.6% (95% CI, 74.6 to 92.7) for the diagnosis of culture-confirmed tuberculosis. Among patients with cultures negative for Mycobacterium tuberculosis who were treated for tuberculosis (those with highly probable, probable, or possible cases of tuberculosis), the estimated sensitivity was 62.5 to 82.3%, 42.1 to 80.8%, and 35.3 to 79.6%, respectively, for different estimates of actual tuberculosis in the groups. In comparison, the sensitivity of the Xpert MTB/RIF assay for molecular detection of M. tuberculosis DNA in cases of culture-confirmed tuberculosis was 54.3% (95% CI, 37.1 to 68.6), and the sensitivity in highly probable, probable, or possible cases was an estimated 25.0 to 35.7%, 5.3 to 13.3%, and 0%, respectively; the specificity of the assay was 100%.ConclusionsRNA expression signatures provided data that helped distinguish tuberculosis from other diseases in African children with and those without HIV infection. (Funded by the European Union Action for Diseases of Poverty Program and others).

Interferon-γ release assays in the diagnosis of active tuberculosis disease in a low-incident setting: a 5-year review of data

AbstractThe role of interferon-γ release assays in the diagnosis of active tuberculosis disease is uncertain, and recent guidelines do not support their routine use. We reviewed the clinical records of 415 patients who had a QuantiFERON-TB Gold In-Tube assay between 29 June 2005 and 28 October 2010 to determine its performance in the diagnosis of active tuberculosis disease in a low prevalence setting, specifically in human immunodeficiency virus (HIV) -positive and HIV-negative patients, those of UK and non-UK origin, and those with pulmonary and extrapulmonary disease. For the diagnosis of active tuberculosis disease the overall sensitivity of QuantiFERON-TB Gold In-Tube assay was 71.4% (95% CI 59.3–81.1), specificity was 81.0% (95% CI 75.5–85.6) and negative predictive value was 92.6% (95% CI 88.2–95.5). No significant difference in sensitivity was seen in culture-positive and culture-negative tuberculosis, in pulmonary and extrapulmonary disease, or with HIV infection. Specificity and negative predictive value were significantly higher in patients of UK origin compared with those of non-UK origin (89.3% (95% CI 83.3–93.3) and 97.1% (95% CI 92.7–98.9) versus 66.3% (95% CI 55.6–75.5) and 83.3% (95% CI 72.6–90.4)). Our study suggests that there may be a role for interferon-γ release assays in excluding active tuberculosis disease, particularly extrapulmonary disease, in patients originating from areas of low tuberculosis incidence, with a negative test highly predictive of a lack of active tuberculosis disease in this group. We cannot support the use of these assays in the diagnosis of active tuberculosis infection in patients from areas of higher incidence.

Reply to Herzmann et al

To The Editor—We thank Herzmann and colleagues for their interest, comments, and description of findings related to our proposed definition for the early and asymptomatic disease state “incipient tuberculosis (TB)” [1]. Herzmann et al describe a study in which 5 of 25 individuals who were household contacts of TB patients had an interferon-gamma release assay (IGRA) result that was negative testing peripheral blood and positive testing bronchoalveolar lavage (BAL) fluid. They propose including localized immune responses in the category of “incipient TB” by expanding our definition to encompass the “presence of measurable localized M. tuberculosis specific immune responses in the absence of a generalized M. tuberculosis specific immune response” [ref Herzmann]. The intent of our characterization of a state of incipient TB was to identify, among asymptomatic immunocompetent individuals with TB exposure, a group of individuals with radiographically minimal disease who are at greater risk for progression to active TB, compared with those without radiographic abnormalities. A localized immune response, while reflecting infection after exposure, does not necessarily imply either disease or a high likelihood of progression to disease. While we acknowledge that the radiographic abnormalities in our proposed definition for incipient TB lack specificity for M. tuberculosis infection, they still suggest evidence of early disease in a person exposed to TB and are associated with histopathological changes [2]. We deliberately used the term “incipient” since it connotes “an initial stage” of something “beginning to happen or develop” (Oxford English Dictionary) to distinguish early TB from latent M. tuberculosis infection. Further, the observations substantiating the prognostic impact of radiographic abnormalities for the development of culture-positive “proven,” “active” TB have been extensively demonstrated in both isoniazid prophylaxis trials [3] and treatment trials for culture-negative TB [4]. The rationale for the diagnostic category of “culture-negative TB” in patients with compatible chest radiographic findings is based on the observed high rate of progression, radiographically and microbiologically, to culture-positive disease in the absence of treatment [5]. In both situations, the greater the radiographic abnormality, the greater the risk of progression to culture-positive disease. In conclusion, although the observations of Herzmann et al are important and very interesting, they do not provide guidance on whether to “treat or not treat.” It remains to be learned whether their observation of a localized IGRA response by pulmonary alveolar mononuclear cells from TB-exposed patients in the absence of a systemic IGRA response confers a higher or a lower likelihood of progression to active TB, compared with those without such responses. Plausibly, a vigorous local immune response, as evidenced by a locally positive IGRA result, might be protective. Furthermore, Herzmann et al do not provide data whether the localized IGRA response was associated with any radiographic abnormalities or on the local IGRA response in the remaining 15 of 40 patients with systemic positive IGRA results. For these reasons, we feel that a pulmonary M. tuberculosis–specific immune response in the absence of a systemic M. tuberculosis–specific immune response, while certainly a sign of infection, cannot be considered indicative of early TB. We look forward to follow-up clinical data on these immunologically well-characterized TB-exposed individuals from Herzmann et al and the “TB or not TB” Consortium so that we may better learn the prognostic attributes that would justify early antituberculous treatment.