Efficacy of cartridge-based nucleic acid amplification test (CBNAAT) in comparison with line probe assay and liquid culture in the evaluation of tubercular lymph node abscess.

Background: Tuberculosis (TB) remains the number one cause of adult deaths by a curable infectious disease. Mycobacterium tuberculosis bacilli (MTB) is the most common causative organism isolated from mycobacterial lymphadenitis. Accurate and speedy diagnosis is required, especially in paucibacillary extrapulmonary TB. In this study, we compared the efficacy of CBNAAT with line probe assay and liquid culture in the evaluation of tubercular lymph node abscesses. Materials and Methods: This is a hospital-based observational cross-sectional study conducted at Gandhi Medical College and Hospital, Secunderabad, TS, in patients who presented with lymph node abscesses over a period of 18 months after obtaining clearance from the ethics committee and obtaining informed consent. Each sample was evaluated and analyzed in association with the clinical findings, AFB staining, CBNAAT, LPA, and AFB culture, and the results were compared. Results: Fifty patients with TB lymph node abscess diagnosed through FNAC were included in the present study. AFB smear was positive in 29 samples, CBNAAT was positive in 43 samples, LPA was positive in 44 samples, and liquid culture was positive in 39 samples. CBNAAT could detect TB in 16 smear-negative cases, 10 liquid culture-negative cases, and one LPA-negative case. In our study, CBNAAT was more effective in diagnosing TB lymph node abscess than AFB smear. No significant results were obtained when comparing CBNAAT with LPA and liquid culture. Conclusion: This study demonstrates excellent diagnostic accuracy of the Xpert MTB/RIF test in patients with tuberculous lymphadenitis, with a sensitivity of 86%, specificity of 83.33%, negative predictive value of 95.56%, and positive predictive value of 58.82%. Thus, it can be a rule in testing for lymph node TB. These efforts will contribute to the attainment of the TB elimination goal.

Second Time's the Charm? Assessing the Sensitivity and Yield of Inpatient Diagnostic Algorithms for Pulmonary Tuberculosis in a Low-Prevalence Setting.

Background: For persons with suspected pulmonary tuberculosis, the guidelines of the Centers for Disease Control and Prevention recommend collecting 3 respiratory specimens 8 to 24 hours apart for acid-fast bacilli (AFB) smear and culture, in addition to 1 nucleic acid amplification test (NAAT). However, data supporting this approach are limited. Our objective was to estimate the performance of 1, 2, or 3 AFB smears with or without NAATs to detect pulmonary tuberculosis in a low-prevalence setting. Methods: We conducted a retrospective study of hospitalized persons at 8 Massachusetts acute care facilities who underwent mycobacterial culture on 1 or more respiratory specimens between July 2016 and December 2022. We evaluated percentage positivity and yield on serial AFB smears and NAATs among people with growth of Mycobacterium tuberculosis on mycobacterial cultures. Results: Among 104 participants with culture-confirmed pulmonary tuberculosis, the first AFB smear was positive in 41 cases (39%). A second AFB smear was positive in 11 (22%) of the 49 cases in which it was performed. No third AFB smears were positive following 2 initial negative smears. Of 52 smear-negative cases, 36 had a NAAT performed, leading to 23 additional diagnoses. Overall sensitivity to detect tuberculosis prior to culture positivity was higher in any strategy involving 1 or 2 NAATs (74%-79%), even without AFB smears, as compared with 3 smears alone (60%). Conclusions: Tuberculosis diagnostic testing with 2 AFB smears offered the same yield as 3 AFB smears while potentially reducing laboratory burden and duration of airborne infection isolation. Use of 1 or 2 NAATs increased sensitivity to detect culture-positive pulmonary tuberculosis when added to AFB smear-based diagnostic testing alone.

Utility of nucleic acid amplification test in the detection of tuberculosis in biological fluids from suspected TB patients in a cardiovascular center in the Philippines.

BACKGROUND: TB NAAT is highly sensitive and can therefore be a helpful tool used in confirming M. tuberculosis. In a prospective study, we evaluated the utility of TB NAAT in the detection of tuberculosis in biological fluids from suspected TB patients. METHODS: We compared tuberculosis nucleic acid amplification test and acid-fast bacilli smears with Lowenstein-Jensen culture, from patients with a clinical suspicion of tuberculosis disease. We calculated the sensitivity, specificity, PPV and NPV. RESULTS: Using the Lowenstein-Jensen culture as the gold standard for detection of Mycobacterium tuberculosis, the TB-NAAT showed sensitivity of 66.67 %, specificity of 93.67 %, and gave a positive predictive value of 44.44 %. CONCLUSION: We conclude that the TB-NAAT is a quick and consistent diagnostic test for TB detection. However, due to a comparably lower sensitivity than other previous studies, the utility of TB-NAAT alone may not be sufficient in the screening of TB patients. Likewise, the TB-NAAT cannot detect non-tuberculous mycobacteria, for which additional analysis may be needed.

Comparison of treatment outcomes between intermittent and daily regimens in non-cavitary nodular bronchiectatic-type Mycobacterium avium complex pulmonary disease in relation to sputum smear results: a retrospective cohort study.

This study retrospectively analyzed the treatment outcomes of 110 patients with non-cavitary nodular bronchiectatic-type Mycobacterium avium complex pulmonary disease who received intermittent or daily treatment with a three-drug oral antibiotic regimen (i.e., a macrolide, ethambutol, and rifampin) at a tertiary referral center in South Korea. Among these patients, 36 had sputum smear positivity. Of these 36 patients, intermittent treatment led to a lower culture conversion rate than daily treatment [50.0% (8/16) vs 85.0% (17/20), P = 0.034].

The Use of Pleural Adenosine Deaminase in the Early Diagnosis and Treatment of Spinal Tuberculosis.

Spinal tuberculosis (TB) is associated with serious neurologic morbidity. It commonly presents as back pain, with or without systemic symptoms. Magnetic resonance imaging (MRI) is the most sensitive and specific imaging modality for spinal TB. The diagnosis of spinal TB is made with tissue biopsy and acid-fast bacilli (AFB) culture; however, tissue AFB smear and tissue TB deoxyribonucleic acid (DNA) polymerase chain reaction (PCR) can influence early clinical decision making. Ancillary tests such as the purified protein derivative (PPD) skin test, QuantiFERON®-TB Gold (QFT) or pleural adenosine deaminase (ADA) can be used in conjunction with radiology and clinical findings to initiate treatment while AFB tissue cultures are pending. Spinal TB responds well to early medical management and surgery is reserved for cases with neurologic complications.

Establishment and validation of a predictive model for nontuberculous mycobacterial infections in acid-fast bacilli smear-positive patients.

INTRODUCTION: Nontuberculous mycobacteria (NTM) and pulmonary tuberculosis (PTB) are difficult to distinguish in initial acid-fast bacilli (AFB) smear-positive patients. OBJECTIVES: Establish a predictive model to identify more effectively NTM infections in initial AFB patients. METHODS: Consecutive AFB smear-positive patients in the Respiratory Department of Shanghai Pulmonary Hospital from January 2019 to February 2020 were retrospectively analysed. A multivariate regression was used to determine the independent risk factors for NTM. A receiver operating characteristic (ROC) curve was used to determine the model's predictive discrimination. The model was validated internally by a calibration curve and externally for consecutive AFB smear-positive patients from March to June 2020 in this institution. RESULTS: Presenting with haemoptysis, bronchiectasis, a negative QuantiFERON tuberculosis (QFT) test and being female were characteristics significantly more common in patients with NTM (P ≤ 0.001), when compared with PTB. The involvement of right middle lobe, left lingual lobe and cystic change was more commonly seen on chest high-resolution computed tomography (HRCT) in patients with NTM (P < 0.05), compared with PTB. Multivariate regression showed female, bronchiectasis, negative test for QFT and right middle lobe lesion were independent risk factors for NTM (P < 0.05). A ROC curve showed a sensitivity and specificity of 85.9% and 93.4%, respectively, and the area under the curve (AUC) was 0.963. Moreover, internal and external validation both confirmed the effectiveness of the model. CONCLUSIONS: The predictive model would be useful for early differential diagnosis of NTM in initial AFB smear-positive patients.

Performance Assessment of Xpert MTB/RIF Assay for Detecting Pulmonary Tuberculosis and Rifampin Resistance in a Tertiary Care Hospital in Korea.

In this study, we aimed to assess the performance of the Xpert MTB/RIF assay for the detection of pulmonary tuberculosis compared to the acid-fast bacilli (AFB) smear and culture analysis, and the incidence of rifampin resistance using the drug susceptibility test. The specimens referred for AFB smear and culture analysis and Xpert MTB/RIF assay from April 2015 to March 2018 were retrospectively reviewed. The sensitivity, specificity, and mean cycle threshold (Ct) values obtained in Xpert MTB/RIF assay and for rifampin resistance were analyzed. The results of Xpert MTB/RIF assay for pulmonary tuberculosis were evaluated based on the AFB smear grade. Among 3,840 specimens, 491 were positive in Xpert MTB/RIF assay and 626 in culture analysis. The sensitivity and specificity of Xpert MTB/RIF assay were 75.6% and 99.4%, respectively. The sensitivity of Xpert MTB/RIF assay for smear-positive/culture-positive specimens was 98.6% and that of smear-negative and -trace/culture-positive specimens was 63.1%. The positivity of Xpert MTB/RIF assay for culture-positive specimens was 89.9%, 98.6%, 95.7%, 100.0%, and 100.0% for the smear grades trace, 1+, 2+, 3+, 4+, respectively. The Ct values of 491 specimens significantly decreased as the AFB smear grade increased (P < 0.0001). The Ct values of smear-positive, -trace, and -negative specimens were 21.7 ± 4.2, 26.5 ± 3.9, and 27.4 ± 3.6, respectively. Rifampin resistance evaluated using Xpert MTB/RIF assay and culture analysis exhibited a correlation of 98.3%. The region covered by probe E was the most frequently mutated region (50.0%). Xpert MTB/RIF assay demonstrated reliable performance in detecting pulmonary tuberculosis from smear-positive and culture-positive specimens; however, further improvements are still required to detect smear-negative and culture-positive specimens.

Pulmonary tuberculosis at Patan Hospital, Nepal: One year audit.

BACKGROUND: Globally, Tuberculosis (TB) is one of the top 10 causes of death. In Nepal, poverty and malnutrition aggravate the burden of TB. To identify Mycobacterium tuberculosis sputum is the best sample to identify the bacterium which is helpful for diagnosis. The aim of this study is to identify the situation, burden and challenges of pulmonary tuberculosis in low-middle income country like Nepal. METHOD: A retrospective-audit with reliable-secondary-data of one year was collected (n = 4131). Descriptive-analysis was performed using frequency, percentage and analytical using chi-square-test. Level of significance was set at p < 0.05. Ethical Approval was obtained from IRC-PAHS. RESULT: The prevalence of notified/suspected cases was highest among the patients having >60 years of age 1344(32.54%) and least among the patients with ≤15 years of age 239(5.79%). The male had 1.67 times more smear-positive pulmonary TB cases. Among the AFB-positive cases, smear 3+ was seen in most of the cases 69(38.54%) followed by smear 1+ and smear 2+ in 56(31.28%) and 54(30.16%) respectively. CONCLUSION: The prevalence of smear-positive pulmonary TB case is higher in male. Smear 3+ is seen in most of the followed by smear 1+ and smear 2+. The Burden of Pulmonary TB is more among adult and old-age-people and its control is a challenge for developing and low-middle income countries like Nepal.

Use of Xpert Contributes to Accurate Diagnosis, Timely Initiation, and Rational Use of Anti-TB Treatment Among Childhood Tuberculosis Cases in South Central Ethiopia.

BACKGROUND: Childhood tuberculosis (TB) was under-prioritized, and only 15% of childhood TB cases are microbiologically confirmed. Hence, most childhood TB diagnoses are made on a clinical basis and prone to over- or under-treatment. Xpert is a rapid method for the diagnosis of childhood TB with high sensitivity. OBJECTIVE: To assess the use of Xpert for accurate diagnosis, timely initiation, and rational use of anti-TB treatment among childhood TB. METHODS: In 2016, the hospital facilitated the installation of the Xpert machine. We reviewed data trends over four consecutive years; two years before the arrival of the machine and two years following the implementation of Xpert. Data were extracted retrospectively from electronically stored databases and medical records and entered to SPSS 21 for analysis. RESULTS: In the pre-intervention period (2014-2015), 404 cases of children presenting with symptoms or signs suggestive of TB ("presumptive TB") were evaluated using AFB microscopy. A total of 254 (62.8%) TB diagnoses were made, of which 54 (21.3%) were confirmed by smear AFB while 200 (78.7%) were treated as smear-negative TB cases. The mean waiting time to start anti-TB treatment was 6.95 days [95% CI (3.71-10.90)]. During the intervention period (2016-2017), 371 children with presumptive TB were evaluated using Xpert. A total of 199 (53.6%) childhood TB cases were notified, of which 88 (44.2%) were Xpert positive and 111 (55.8%) were treated as Xpert-negative probable TB cases. The tendency to initiate anti-TB treatment for unconfirmed TB cases was reduced by a third. Compared with smear AFB, Xpert improved accuracy of diagnosing pediatric TB cases two-fold. The average waiting time to start anti-TB treatment was 1.33 days [95% CI (0.95-1.71)]. There was a significant reduction in the waiting time to start anti-TB treatment, with a mean time difference before and during intervention of 5.62 days [95% CI (1.68-9.56)]. CONCLUSION: Xpert use was associated with a significant increase in the accuracy of identifying confirmed TB cases, reduced unnecessary anti-TB prescription, and shortened the time taken to start TB treatment.

Cost-Effectiveness Analysis of Xpert MTB/RIF for Multi-Outcomes of Patients With Presumptive Pulmonary Tuberculosis in Thailand.

OBJECTIVES: The cost-effectiveness of screening adult patients for pulmonary tuberculosis is not clear. As such, this study aims to identify the cost-effectiveness between the Xpert MTB/RIF assay and the sputum acid-fast bacilli (AFB) smear. Multi-outcomes were correct diagnosis, time to achieve correct diagnosis, and gain in quality-adjusted life-years (QALYs). METHODS: A decision tree model was constructed to reveal a possible clinical pathway of tuberculosis diagnosis. The researchers used a clinical study to establish the probability of all clinical pathways for input into this model. The sample size was calculated following the correct diagnosis. Participants were randomly divided into 2 groups. A structural questionnaire and the Thai version of quality of life (EQ-5D-5L) were used for interviewing. RESULTS: The results showed that the time to achieve the correct diagnosis for the group using Xpert MTB/RIF was shorter than that for the group using the sputum AFB smear. Both the correct diagnosis and QALYs of the base case analysis presented the Xpert MTB/RIF method as dominant. A Monte Carlo model, which analyzed the Xpert MTB/RIF method, revealed that the average number of patients who were correctly diagnosed was 673, the QALYs were 945.85 years, and the total cost was $143 110.64. For the sputum AFB smear method, the average number who received a correct diagnosis was 592, the QALYs were 940.40 years, and the total cost was $196 666.84. Probabilistic and one-way sensitivity analysis confirmed that the Xpert MTB/RIF remained dominant. CONCLUSIONS: These results provide useful information for the National Strategic Plan to screen all adult patients for pulmonary tuberculosis.

Frequency, clinical characteristics, risks, and outcomes of Paradoxical upgrading reactions during anti-tuberculosis treatment in tuberculous lymphadenitis.

OBJECTIVES: To investigate the clinical characteristics, risks and outcomes of Paradoxical upgrading reactions (PUR) during anti-tuberculosis treatment (ATT) in superficial tuberculous lymphadenitis (TBLA). METHODS: In this nested case-control study, all patients diagnosed with TBLA based on combinations of histopathology, acid-fast bacilli (AFB) microscopy, AFB culture, and GeneXpert, between February 2013 and April 2016, were enrolled. Standard ATT was given. Demographics, clinical characteristics, occurrence of PUR and outcome were recorded. RESULTS: TBLA was diagnosed and treated in 189 patients. PUR developed in 33 (17%), of which 77% developed new inflamed glands, 20.6% had increased size and inflammation of pre-existing glands and 5.9% had superficial chest wall abscesses requiring aspiration. All responded to regular NSAIDs except one, where a steroid course was effective. No change in dose or duration of ATT was required. Presence of anorexia (OR; 95%CI: 2.6; 1.003-6.74), bilateral extensive lymphadenopathy (OR; 95%CI: 2.9; 1.1-7.5) and lymph node specimen positive for AFB (OR; 95%CI: 3.2; 1.04-10.1) were significantly associated with PUR. CONCLUSION: PUR is common in TBLA. It responded to NSAIDS and does not need any modification in ATT.

Evaluation of Various Diagnostic Techniques for the Diagnosis of Pulmonary and Extra Pulmonary Tuberculosis at a Tertiary Care Center in North India.

INTRODUCTION: Tuberculosis (TB) is a one of the main causes of mortality and morbidity worldwide. Bactec MGIT (Mycobacteria Growth Indicator Tube) system is a rapid, reliable automated system for early diagnosis of pulmonary and extra pulmonary TB in setups where purchase of expensive instruments is not possible. The present study was thus carried out to evaluate AFB microscopy, culture on Lowenstein Jensen media and micro MGIT system for early and accurate diagnosis of Tuberculosis. METHODS: A total of 280 samples were processed for direct AFB smear examination, and culture on micro MGIT and LJ media. The identification of Mycobacterium tuberculosis complex in positive cultures was done by MPT64 Ag card test (BD MGIT TBC Identification Test). RESULTS: Out of the processed samples, (47.1%) 132/280 were positive for Mycobacterium spp by Micro MGIT, (35%) 98/280 on LJ medium and (25.7%) 72/280 by AFB smear. A total of (48.5%) 136 samples were positive by a combination of Micro MGIT and LJ medium. Among the total positive samples (136/280), Micro MGIT was found to be positive in 97% (132/136) of samples, LJ was positive in 72% (98/136), while 52.9% (72/136) were positive by AFB smear. CONCLUSION: Manual MGIT System is a simple and efficient, safe to use the diagnostic system. It does not require any expensive/special instrumentation other than the UV lamp for the detection of fluorescence. In areas with limited resources where the purchase of expensive instruments such as the MGIT 960 is out of scope, the use of manual MGIT for rapid susceptibility testing for MDR-TB could be an option. We would recommend testing MGIT 960 using first and secondline drugs to determine DST.

Features and Outcome of Hepatobiliary Tuberculosis among Filipino Children: Report of a Six-year Experience

Background@#The features and outcome of hepatobiliary tuberculosis (HBTB) have not been extensively reported in children.@*Objective@#To describe the clinical, biochemical, radiologic, microbiologic and histologic features and outcome of children diagnosed with HBTB. @*Methods@#Data of HBTB patients aged 0-18 years were collected by review of medical records and as they were admitted. Cases were classified as bacteriologically-confirmed (positive AFB smear, TB culture or PCR of bile/liver tissue) or clinically-diagnosed (clinical, histologic and/or radiologic evidence). @*Results@#A total of 36 patients were included (mean age: 13yrs; 64% males): three bacteriologically-confirmed and 33 clinically-diagnosed. Most common signs/symptoms were weight loss (69%), fever (67%), hepatomegaly (61%) and jaundice (53%). Of the total, 68% had hypoalbuminemia, 50% increased transaminases and 47% prolonged prothrombin time. Fifteen (42%) patients were AFB positive on various microbiologic specimens. Most common imaging finding was hepatic calcification (64%). Of 11 patients with liver biopsy, seven (64%) had chronic/ granulomatous inflammation. All 36 were managed medically. Eight were lost to follow up, six died, and 22 (61%) are alive, nine with complete resolution of liver disease. @*Conclusion@#Hepatobiliary tuberculosis presents with non-specific clinical and biochemical findings. Several investigations are necessary to confirm the diagnosis. Overall response to anti-TB treatment is satisfactory with possible resolution of liver disease.

Metformin induced autophagy in diabetes mellitus - Tuberculosis co-infection patients: A case study.

Metformin (MET) is a potential combination drug to elevate anti-TB efficacy. However, the clinical effect, especially smear reversion, during metformin applied with anti-tuberculosis and insulin in patients with type 2 DM newly TB co-infection were remain unknown. An observational clinical study was done in DM newly TB co-infection outpatients at Surabaya Paru Hospital. This study evaluated MET therapy, at least 2 months, accompanying with insulin and anti-TB regimens and compared to comparison group. The smear, microtubule-associated Protein1 Light Chain 3B (MAP1LC3B) level, as the presentation of autophagy, Superoxide Dismutase (SOD) level, Interferon (IFN)-γ and Interleukin (IL)-10 levels were evaluated twice. From 42 participants in this study, 22 participants of observation group that received additional MET therapy, 100% had sputum smear reversion after 2-months intensive phase of anti-TB therapy. Whereas 25% of 20 participants of comparison group did not undergo reversion inserts sputum smear. As conclusion, MET has the potential of being an additive combination therapy to enhance the bactericidal effect of anti-TB on DM-TB coinfection patients. Metformin enhances the effects of anti-TB and insulin therapy in increasing the smear reversion by increasing autophagy.

Effectiveness of Tuberculosis Screening Technology in the Initiation of Correct Diagnosis of Pulmonary Tuberculosis at a Tertiary Care Hospital in Thailand: Comparative Analysis of Xpert MTB/RIF Versus Sputum AFB Smear.

Pulmonary tuberculosis (PTB) is one of the top 10 causes of mortality worldwide in 2016. Early detection is very important, as it can help early treatment. This study compared 2 separate methods of diagnosing PTB among suspected patients, specifically examining correct diagnosis and the duration of receiving a correct diagnosis. It was carried out in a tertiary care public hospital in Bangkok, Thailand. Ninety patients were randomly assigned to 2 groups, one with the Xpert MTB/RIF ( Mycobacterium tuberculosis/rifampicin) and the other with sputum AFB (acid-fast bacilli) smear. The proportion of correct diagnosis was 90.9% and 83.7% for the Xpert MTB/RIF and the comparison group, respectively. The difference was not statistically significant ( P > .05). However, the time to correct diagnosis in the Xpert MTB/RIF group was significantly shorter than the comparison group (2.23 days). This could lead to early diagnosis and lower transmission rate of PTB cases. Results support the provision of Xpert MTB/RIF as the initial diagnostic test for PTB in Thailand.

Multiplex PCR as a novel method in the diagnosis of spinal tuberculosis-a pilot study.

BACKGROUND: Establishment of a reliable and rapid diagnosis is of paramount importance in spinal tuberculosis. The available gadgetry of investigations, such as AFB smear, culture of Mycobacterium tuberculosis, and Uniplex PCR, suffers from a lack of adequate sensitivity and/or a lack of rapidity. Therefore, many times a diagnosis is made either very late in the disease process or sometimes empirical therapy has to be started because a definite diagnosis could not be made. All of these are not ideal situations for a clinician. The present study was done with the aim to establish a rapid and reliable diagnosis of M. tuberculosis infection. This was established by identifying M. tuberculosis genes. METHODS: The study was done on nine consecutive patients who presented with non-traumatic spontaneous vertebral compression collapse. CT-guided aspirate from the involved vertebra was subjected to Multiplex PCR (MPCR) using three primers: IS6110, protein b, and MPB 64. The aspirate was also subjected to smear and culture. The results of MPCR were compared with the final diagnosis. RESULTS: Seven out of nine patients had a final diagnosis of tuberculosis. MPCR was positive in six of these seven patients, thus showing sensitivity of 85.7% and specificity of 100%. Results of MPCR were obtained within 24 h. CONCLUSIONS: MPCR using IS6110, protein b, and MPB64 primers has a high sensitivity and specificity in rapid diagnosis of spinal tuberculosis. To the best of our knowledge, this has not been attempted before in spinal tuberculosis. This is particularly useful for paucibacillary infections like spinal tuberculosis. However, further studies using large sample sizes are needed to confirm the practical applicability of this technique.

Diagnostic usefulness of the GenoType MTBDRplus assay for detecting drug-resistant tuberculosis using AFB smear-negative specimens with positive TB-PCR result.

BACKGROUND: The aim of this study was to evaluate the diagnostic accuracy of the GenoType MTBDRplus assay in detecting drug-resistant tuberculosis (DR-TB) by using acid-fast bacilli (AFB) smear-negative specimens with positive TB-PCR results. METHODS: The MTBDRplus assay was performed with 2 different categories of 117 samples, including AFB smear-positive specimens (n = 53) and AFB smear-negative specimens (n =64), which exhibited positive TB-PCR results, at a single institution. The results were retrospectively compared with the results of the phenotypic drug susceptibility test (DST), for reference. RESULTS: A total of 105 tests were finally analyzed. Of these, 54 tests were conducted using AFB smear-negative specimens with positive TB-PCR results. The MTBDRplus assay for these 54 samples demonstrated a sensitivity of 100%, specificity of 98%, positive predictive value (PPV) of 75%, and negative predictive value (NPV) of 100% in detecting rifampicin resistance. With these same species, the sensitivity, specificity, PPV, and NPV values for the MTBDRplus assay were 83.3%, 97.9%, 83.3%, and 97.9%, respectively, for the detection of isoniazid resistance. The overall correlation between the MTBDRplus assay and phenotypic DST demonstrated excellent agreement for detection of rifampicin resistance (κ = 0.847) and for detection of INH resistance (κ = 0.812), respectively. CONCLUSIONS: The MTBDRplus assay can be used effectively even on AFB smear-negative specimens from TB patients, when the TB-PCR is positive. This result might help clinicians to manage patients with suspected DR-TB in difficult situations.

Evaluation of three rapid assays for Mycobacterium tuberculosis complex detection in a comprehensive hospital from West China.

OBJECTIVES: To assess the capacity of rapid and accurate confirmation of the Mycobacterium tuberculosis complex (MTBC) in a Chinese clinical laboratory. DESIGN AND METHODS: This prospective study investigated three rapid assays, the Amplified Mycobacterium Tuberculosis Direct (MTD) test, real-time PCR, and acid-fast bacilli (AFB) smear, for direct detection of MTBC in a large consecutive series of different clinical specimens. Performance parameters were estimated and compared overall and for separate specimen categories using a combined reference gold standard. RESULTS: The overall sensitivities were similar for MTD and real-time PCR (62.26% vs. 58.49%), significantly higher than those of AFB smear (31.13%). Among three assays, MTD had a satisfactory sensitivity in respiratory specimen (73.33%) and a nearly perfect detection for smear-positive samples (96.97%). Real-time PCR showed a high positive rate (58.97%) in regard to nonrespiratory specimen. A combination of molecular assays with conventional methods reached marked additive diagnostic values (sensitivity up to 76.42%), higher than each method individually. All detection systems showed excellent specificities (>96.00%). CONCLUSIONS: The present study indicated that our lab had a moderate diagnostic performance for tuberculosis. Quality guarantee for specimen pretreatment, as well as combination analysis, will enable these assays to better incorporate into the routine laboratory workflow in China.

Risk factors in patients with AFB smear-positive sputum who receive inappropriate antituberculous treatment.

BACKGROUND: Acid-fast bacilli (AFB) smear-positive sputum is usually an initial clue in the diagnosis of pulmonary tuberculosis (TB); however, the test is not disease-specific. Nontuberculous mycobacterium-related colonization or lung disease often has AFB smear-positive sputum results, and physicians may prescribe unnecessary antituberculous drugs for these patients. The aim of this study was to analyze the clinical characteristics of patients with AFB smear-positive sputum who received unnecessary anti-TB treatment. METHODS AND PATIENTS: From January 2008 to July 2011, we retrospectively enrolled 97 patients with AFB smear-positive sputum who did not have pulmonary TB according to mycobacterial cultures and clinical judgment. We analyzed the clinical and radiographic features of the patients who received inappropriate and unnecessary anti-TB treatment. Preliminary analyses of chisquare and Fisher's exact tests were applied to determine factors unlikely to be associated with the independent variables. The relationship between independent covariates was then analyzed using multivariate logistic regression. RESULTS: Of the 97 enrolled patients, 25 (25.8%) were diagnosed with pulmonary TB and prescribed anti-TB drugs (mostly a combination of isoniazid, rifampicin, ethambutol, and pyrazinamide). The other 72 (74.2%) patients were not initially diagnosed with pulmonary TB and were classified as the control group. Compared to the control group, the patients who received inappropriate anti-TB treatment had more chronic cough as presentation symptom and heavy AFB Ziehl-Neelsen staining in sputum (>10/100 fields, grading 2+ to 4+). There were no significant differences in the radiographic analysis between the two groups. CONCLUSION: Among the patients with AFB smear-positive sputum that did not have pulmonary TB, chronic cough and heavy AFB staining (2+ to 4+) were risk factors for the inappropriate administration of unnecessary anti-TB treatment.

Manifestations of tuberculosis in HIV/AIDS patients and its relationship with CD4 count.

BACKGROUND: HIV/AIDS pandemic is responsible for the resurgence of TB worldwide, resulting in increased morbidity and mortality. HIV and Mycobacterium tuberculosis have a synergistic interaction; each propagates progression of the other. Coinfection with HIV infection leads to difficulties in both the diagnosis and treatment of tuberculosis, increase risk of death, treatment failure and relapse. OBJECTIVE: The aim of the present study is to study the clinical, radiological profile of pulmonary and extrapulmonary tuberculosis (EPTB) in HIV-seropositive patients and their relationship to CD4 counts. MATERIALS AND METHODS: It was a prospective study conducted over a period of 1 year in the department of medicine, Indira Gandhi Medical College, Shimla. We examined 87 HIV-infected patients with associated tuberculosis recruited from the department of medicine and antiretroviral center and were subjected to thorough clinical examination, X-ray chest, tuberculin testing and sputum examination for AFB and necessary relevant investigations for EPTB. RESULTS: Most common affected age group was 31-40 years. EPTB is the commonest form of TB in our study detected in 65 patients. Commonest EPTB was CNS tuberculosis. Disseminated tuberculosis was only found in patient with CD4 count less than 200/cmm. Majority of lymph node TB was diagnosed by fine needle aspiration cytology (FNAC) examination. All patients with AFB-positive lymph node had CD4 count below 200/cum. CONCLUSIONS: The results of this study provide information regarding the various forms of TB and their presentation in HIV-infected persons. Early diagnosis of tuberculosis and prompt institution of antitubercular treatment (ATT) reduces mortality and morbidity significantly. In resource-poor areas, the diagnosis can be established with cytological/biochemical analysis of fluid, histopathological examination and ZN staining of tissue coupled with radiological features and response to ATT. Therefore, adequate knowledge of the manifestations of tuberculosis in HIV-infected patients is absolutely necessary for optimal management and to reduce mortality and morbidity.