Rates Of Tuberculin Skin Test Research Articles

Clinical Characteristics and Outcomes in Chronic Kidney Disease Patients with Tuberculosis in China: A Retrospective Cohort Study.

BackgroundThe diverse manifestations of tuberculosis (TB) in chronic kidney disease (CKD) patients can cause difficulty in diagnosis, delayed treatment, even death. Therefore, this study investigated the clinical characteristics and the risk factors for mortality in CKD patients with TB.MethodsThis retrospective study included 167 patients diagnosed with active TB at two tertiary medical centers in Chongqing within six years. Clinical characteristics and outcomes of anti-TB treatment in patients with and without CKD were collected, and the predictive mortality values of variables were analyzed.ResultsOf the 167 patients, 66.7% (44/66) hemodialysis (HD), 41.1% (21/51) pre-HD, and 32.0% (16/50) non-CKD patients had extrapulmonary TB. The pleura and lymph node were the common sites in CKD patients. Clinical presentations of cough and hemoptysis in CKD patients were less common than those in non-CKD patients, 13.7% (16/117) of CKD patients even not having any clinical symptoms. The positive rates of tuberculin skin test, TB-polymerase chain reaction and acid-fast bacilli in sputum in HD patients were lower than those in pre-HD and non-CKD patients (p<0.05). CKD patients were more prone to gastrointestinal and neurological side effects during anti-TB treatment. The mortality rates of non-CKD, pre-HD and HD patients was 6.1%, 31.9% and 37.3%, respectively. Multivariate Cox analysis revealed that age≥40 years (HR: 5.871; p=0.019), hypoalbuminemia (HR:2.879; p=0.004), CKD stage 4–5 (HR:4.719; p=0.018) and HD (HR:6.13; p=0.005) were associated with mortality.DiscussionCKD patients with TB have atypical clinical manifestations and high mortality. Age, hypoalbuminemia, CKD stage 4–5, and HD were independent predictors of mortality.

Conversion Rate of Tuberculin Skin Test among Medical Students in Songklanagarind Hospital

OBJECTIVE: Airborne and Tuberculosis (TB) control measures have been implemented in Songklanagarind hospital. The infection control unit of the hospital has provided a voluntary two-step tuberculin skin test (TST) for pre-clinical medical students and serial TST for clinical medical students. This study aimed to determine the incidence of negative outcome and booster phenomenon from two-step TST as well as the TST conversion rate from serial TST among medical students in the hospital. MATERIALS AND METHODS: Percentages of negative cases and boosting phenomenon were calculated from the two-step TST records. Conversion rates of each year were calculated from serial TST data. Then the TST conversion rates were predicted based on the Jointpoint model. RESULTS: Two-step TSTs performed from 2001 to 2016 showed 40 to 100% of negative cases and zero to 14% of boosting phenomenon among 2,271 medical students. Serial TSTs from 2002 to 2016 among 665 medical students showed 60 conversion cases. Conversion rates varied from zero to 13.6%. The decline of conversion rates after the year 2006 is demonstrated in 1-Joinpoint model with statistical significance (p = 0.0129). The model corresponded with the timeline data of airborne infection control measures which were mostly implemented after 2006. CONCLUSIONS: A decline in TST conversion rate was shown after 2006. This coincided with airborne infection control measures at the institute. Keywords: tuberculin skin test, conversion rate, medical student, Songklanagarind hospital Address Correspondence to author: Sarinpant Pongpant, MD. Occupational health unit, Department of family medicine and preventive medicine, Faculty of Medicine, Prince of Songkla University, Songkhla, 90110, Thailand. email: jibpongpant@gmail.com Received: May 25, 2018 Revision received: May 31, 2018 Accepted after revision: July 3, 2018 BKK Med J 2018;14(2): 17-21. DOI: 10.31524/bkkmedj.2018.09.004

Variations of tuberculin skin test in patients with rheumatologic disorders and under anti-TNF treatment

Aim: Nowadays PPD is the most inexpensive and easy to apply modality of test in identification of latent tuberculosis infection. Isoniazid (INH) prophylaxis must be given before usage of anti-TNF-α agents for patients. We aimed to investigate the change in Tuberculin skin test (TST) levels and Isoniazid (INH) prophylaxis rates in patients with inflammatory rheumatic diseases treated with anti-tumor necrosis factor alpha (TNF-α) agents. Methods: A cross-sectional study was planned. Patients with inflammatory rheumatic diseases treated with anti-TNF agents were included in the study. Demographic data, initial TST level and INH prophylaxis had obtained from patient’s files. Control TST tests had done at tuberculosis dispensaries in different time periods such as 1-2 / 2-3 / 3-4 / ≥4 years of anti TNF treatment. INH prophylaxis rates according to initial and control TST tests were compared. The relationship between INH prophylaxis and duration of anti-TNF therapy were examined.Results: A total of 117 patients were included in the study. The mean age of the patients (81 male, 36 female) was 40.4±12.90. The control TST levels was significantly higher than initial TST (p=0.001). INH prophylaxis was given to total 99 (84.6%) of 117 patients (to 63 (53.8%) according to initial and to 36 (30.8%) according to control TST tests). There was no relationship between duration of anti TNF therapy and INH prophylaxis initiation (p=0.180). Conclusion: Anti-TNF treatments may reduce the rates of false-negative TST in patients with rheumatic diseases and latent tuberculosis (LTBI) at any stage of the treatment. Therefore, LTBI, which is not determined with initial TST tests, may be determined with TST test applied in the later stages of anti-TNF treatment, and the risk of active tuberculosis can be reduced by INH prophylaxis in this patients.

The prevalence of latent tuberculosis infection in patients with inflammatory arthritis and the diagnostic efficacy of different screening methods

Objective: To investigate the prevalence of latent tuberculosis infection (LTBI) in patients with inflammatory arthritis, and to compare the efficacy of tuberculin skin test (TST) and QuantiFERON-TB Gold (QFT) in screening for LTBI in these patients. Method: Medical records of 149 patients with inflammatory arthritis admitted to inpatient of Peking University International Hospital from December 2015 to December 2017 (diagnosis with rheumatoid arthritis, ankylosing spondylitis, sero-negative spondyloarthropathy, psoriatic arthritis, or reactive arthritis) who accepted TST or QFT were collected. The information included gender, age, history of tuberculosis infection, calcifications presence in chest X-ray or chest CT, TST result, QFT result, medication history before test, and biological treatment and all the patients were made a follow-up. Results: The positive rate of TST was 18.2%(14/77) and that of QFT was 27.1%(26/96), and the overall consistency between the two tests was fair. The rate of LTBI diagnosed by QFT was 22.9%(22/96). The positive rate of TST in patients older than 50 years was significantly higher than those younger than 50 years, but there was no significant difference between the two groups screened by QFT. The M-N values in QFT were decreased in both the patients above the age of 50 and in the patients using immunosuppressive agents. A total of 64 patients accepted biological agent therapy, and in those with a positive result of TST or QFT, only 2 cases received anti-LTBI treatment, but the other 14 cases without anti-LTBI treatment. None of them developed active tuberculosis in the following 3-24 months. Conclusion: The prevalence of LTBI in patients with inflammatory arthritis is consistent with that reported in rheumatoid patients, which is higher than in general people. In patients with inflammatory arthritis older than 50 years, especially those accepted immunosuppressive agents therapy, the immunity may be impaired and QFT is more sensitive than TST for screening LTBI.

806. 2013–2015 Nationwide Tuberculosis Contact Investigation in Childcare Centers and Schools in Korea

BackgroundThe Republic of Korea has the highest incidence rate of tuberculosis (TB) among members of the OECD, reported as 78.8/100,000 population in 2016. In response, a state-run intensive contact investigation for TB is being conducted. More effective TB control requires an epidemiologic emphasis on the diagnosis and treatment of latent TB infections in children and adolescents, compared with other age groups. Here we present an analysis of data from the childcare center and school contact investigation by the Korea Centers for Disease Control and Prevention (CDC) in 2013–2015.MethodsData collected from index patients included age, sex, occupation, disease status, results of AFB smear/culture, and chest x-ray. Data collected from contacts included age, sex, results of serial tuberculin skin test (TST), and chest x-ray. Congregate settings included childcare centers, kindergartens, elementary and secondary schools, and age groups were stratified as follows: 0–4 years, 5–12 years, and 13–18 years. TSTs were considered positive if induration ≥10 mm on the first test (TST1) or demonstrated an increase ≥6 mm over the induration of TST1 on repeat testing after 8 weeks (TST2).ResultsOf the 197,801 subjects with data collected, 173,998 were eligible and included in our analysis. TST1 results were available for 159,346 (91.6%) and when results were positive, induration was 10–14 mm in 7.6% and ≥15 mm in 1.5%. TST2 results were available for 119,797 (82.7%) of the 144,904 with negative TST1, and conversion rate was 9.0%. Altogether considering TST1 and TST2, 17.3% contacts had latent TB infections. Positive rates of TST significantly decreased with age: 20.3% in 0–4 years, 18.8% in 5–12 years, 17.1% in 13–18 years.ConclusionIn this 3-year school-setting contact investigation, 17.3% contacts were diagnosed with latent TB infection, as demonstrated by TST reactions. Positive rates of TST significantly but mildly decreased with age.Disclosures All authors: No reported disclosures.

Serial testing of healthcare workers for latent tuberculosis infection and long-term follow up for development of active tuberculosis.

BackgroundHealthcare workers (HCWs) are at high risk of tuberculosis (TB) infection due to occupational exposure. It is important to diagnose TB infections in HCWs to prevent nosocomial transmission, particularly among immunocompromised patients.ObjectiveThe aim of this study was to analyze the rate of tuberculin skin test (TST) conversion and to assess the incidence of active TB after the latent TB infection screenings in high-risk HCWs.MethodsThis retrospective cohort study involved 458 HCWs in TB-related departments between 2009 and 2013. All HCWs underwent a TST and a chest radiograph annually; an interferon-γ release assay (IGRA) was performed on the TST-converted subjects. TST-converted and IGRA-positive HCWs underwent treatment for latent TB infection.ResultsThe TST conversion rate was 30.3% from 2009 to 2011 in two years, 7.4% from 2011 to 2012, and 17.4% from 2012 to 2013. Eleven subjects out of 42 TST converters (26%) were IGRA-positive; two of them developed into active pulmonary TB during the follow-up period.ConclusionsThere was significant discordance between TST conversion and IGRA results in high-risk HCWs, and active TB developed only in TST-converted and IGRA-positive HCWs. Therefore, the combined use of TST and IGRA for periodic monitoring of TB infections in high-risk HCWs may be useful.

The prevalence of latent tuberculosis infection among Iranian sarcoidosis patients

Background: Sarcoidosis is a multisystemic disorder with unknown causes. Mycobacterium tuberculosis has been implicated as one of the possible causes of sarcoidosis. Interferon-gamma release assays are in vitro diagnostic tests for detection of the latent tuberculosis infection (LTBI) which has been replaced by tuberculin skin test (TST) in some countries. The purpose of this study was to investigate the prevalence of LTBI in Iranian sarcoidosis patients. Methods: Ninety participants with the mean age of 42.22 ± 14.55 were enrolled in this study. They were divided into three equal groups consisted of patients with active TB, patients with sarcoidosis, and controls. TST and QuantiFERON®-TB Gold (QFT) were performed according to the manufacturer's instructions and the result interpreted. Results: The positive rates of TST were 76.66%, 3.3%, and 6.66% in TB, sarcoidosis, and control groups, respectively. However, QFT was positive in 24 (96.66%) of the TB group, 6 (20%) of sarcoidosis patients, and 5 (16.66%) of the control group. The agreement between the aforementioned tests was low (Cohen's kappa coefficient (κ) = 0.24). Conclusions: The current study suggests that in an intermediate-incidence TB population such as Iran, QFT is much more accurate than TST for the diagnosis of LTBI in patients with sarcoidosis. The present finding increases the possibility of this hypothesis which states that nontuberculous mycobacteria may play a role in the etiology of sarcoidosis.

Primary tuberculosis in a nomadic Fulani population and their cattle herds in Kano, Nigeria: a one health approach

Background: Nigeria has a large population of Fulani pastoralists. Zoonotic infections like bovine tuberculosis (TB) are common among nomadic Fulani and their livestock. Close interaction between the nomads and their animals provide a critical human–animal interface with potential for transmission of zoonoses. We conducted a survey to determine the prevalence of primary TB infection among nomads and their cattle in Kano, north-western Nigeria. Materials and Methods: We performed tuberculin skin test (TST) to all inhabitants of the nomadic setting and a randomly selected population of their cattle. We obtained sociodemographic information and symptoms of pulmonary TB in both respondents and their cattle. We explore knowledge of respondents regarding risk of disease transmission between them and their livestock. We compare rates of TST among the respondents and the cattle. Participants with features of active TB were referred for further evaluation and treatment. Results: Out of 244 individuals evaluated, 103 (42.2%) were females with a median age (range) of 35 years (1–80 years). Among 167 participants who consented for and returned for TST reading, 45 (26.9%) were positive; 33 (73.3%) of which were between 20 and 50 years of age. A total of 29 (11.9%) respondents reported having cough for at least 3 weeks at the time of the study. Of the 244 participants interviewed, 51 (20.9%) reported having animals with chronic cough. A total of 26 (12.7%) of the 204 cattle tested had positive TST. Majority of the respondent (71%) were aware of potential risk of transmission of infectious diseases between them and their herds. Conclusion: High TST positivity among the nomads of economically viable age and their herds suggests that TB is prevalent in their communities with potential for animal–human transmission. TB and other infectious diseases control programs should capture nomads in their planning and implementation.

A Pulmonary Tuberculosis Cluster in an Institution in Southern Taiwan, 2012

A mental institution resident in Southern Taiwan was ill and sought medical service in March 2014; later was confirmed as pulmonary tuberculosis (TB). Two contacts were found having abnormal chest radiography at the twelfth month and were notified. In July 2013, there were six reported probable patients with pulmonary tuberculosis from the institution including the index case. Five of them were confirmed, and one was excluded. Restriction fragment length polymorphism (RFLP) molecular study done at the Research and Diagnostic Center of Taiwan CDC revealed that the five isolates belonged to the same subtype, thus, proved this cluster of patients with pulmonary tuberculosis. After two serial meetings with TB specialists, not only chest radiographies of related contacts were followed, but also extended the immunoassay from the previous existing tuberculin skin test (TST) to both interferon-gamma release assay (IGRA; QuantiFERON-TB, QFT) and TST for those identified contacts. After evaluation by physicians, the contacts who had both positive results of TST and IGRA were undergone latent tuberculosis infection (LTBI) treatment. Besides, we suggested the administrator keeping the confirmed TB patients in the isolation room on the first floor until his/her sputum was negative for acid-fast stain or TB culture, and also to isolate those suspected TB patients.Of total 85 contacted people, the positive rate of TST was 77.6% (66/85), the positive rate of QFT was 29.5% (18/61), and the positive rate for both TST and QFT was 21.2% (18/85). Twenty-four people underwent LTBI treatment, of whom 22 people completed the treatment course, and 2 people discontinued due to the adverse effects. There was not any tuberculosis patient found in the institution by October 2014.

Screening of latent tuberculosis infection by interferon-γ release assays in rheumatic patients: a systemic review and meta-analysis.

The aim of this study is to assess the diagnostic value of interferon-γ release assays (IGRAs) for latent tuberculosis infection (LTBI) in patients with rheumatic disease before receiving biologic agents. MEDLINE and EMBASE databases were used for searching studies concerning the evaluation on the performance of IGRAs [QuantiFERON-TB Gold (QFT-G), QuantiFERON-TB Gold In-Tube (QFT-GIT) and T-SPOT.TB] in rheumatic patients before biological therapy. After assessing the quality of all studies included in the review, we summarized the results in subgroups using forest plots and calculated pooled estimates if applicable. The search identified 11 studies with a total sample size of 1940 individuals. Compared with the tuberculin skin test (TST), the pooled agreements in QFT-G/GIT and T-SPOT.TB were 72 % (95 % confidence interval (CI) 65, 78 %) and 75 % (95 % CI 67, 83 %), respectively. BCG vaccination was positively correlated with positive rates of TST (pooled odds ratio (OR) 1.64, 95 % CI 1.06, 2.53). Compared with TST, IGRAs were better associated with the presentence of one or more tuberculosis (TB) risk factors. Neither steroid nor disease-modifying anti-rheumatic drugs (DMARDs) significantly affect positive IGRA results. In contrast, TST positivity was significantly impacted by the use of steroid (pooled OR 0.45, 95 % CI 0.30, 0.69), but less significantly by the use of DMARDs (pooled OR 0.78, 95 % CI 0.50, 1.21). In conclusion, in rheumatic patients with previous BCG vaccination or currently on steroid therapy, IGRAs would be the better choice to identify LTBI by decreasing the false-positivity and false-negativity rate compared with conventional TST.

Effective Tuberculosis and Hepatitis Screening Prior to Anti-TNF-α Therapy: Are We There Yet?

Anti-tumor necrosis factor-a (anti-TNF-a) drugs are widely used for the management of patients who suffer from Crohn’s disease (CD) and ulcerative colitis (UC). Screening for latent tuberculosis infection (LTBI) and hepatitis B virus (HBV) is mandatory prior to commencing therapy with anti-TNF-a drugs, due to an increased reactivation risk for these diseases. Unfortunately, in the case of LTBI, a consensus has not been reached, highlighted by the heterogeneity of current guidelines, regarding the use of the tuberculin skin test (TST) or an interferon-gamma release assay (IGRA) as parts of the initial screening strategy [1, 2]. Historically, the diagnosis of LTBI has been dependent on the TST whose mechanism relies on a delayed-type T cell mediated hypersensitivity reaction to purified protein derivative (PPD). Regrettably, the TST has well-known limitations including potential sources for false positive results, due to the non-specific nature of PPD leading to cross-reactivity with non-tuberculosis mycobacterium and individuals who have received bacillus Calmette-Guerin vaccination. Moreover, there is intrinsic test subjectivity due to induration interpretation; furthermore, two healthcare visits are required. Alternatively, the IGRAs, which measure the release of interferon-gamma post antigen exposure, have recently gained popularity as an alternative for LTBI diagnosis as their antigens are more specific for Mycobacterium tuberculosis. Nonetheless, IGRA testing is more expensive and requires appropriate infrastructure, potentially limiting its universal implementation. In this issue, van der Have et al. [3] describe a costeffectiveness analysis in patients with CD of screening strategies for LTBI and HBV: (1) traditional LTBI screening (TST and chest X-ray) versus additional IGRA testing; and (2) HBV screening versus no HBV screening. Neither extensive LTBI screening (traditional testing plus IGRA) nor HBV screening were cost-effective. Nevertheless, if LTBI prevalence was[12 % or the TST false positivity rate [20 %, cost-effectiveness of extensive testing was achieved, emphasizing the importance of the varying global prevalence of LTBI and the sensitivity and specificity of LTBI diagnostic tests. Similarly, if HBV reactivity or HBVrelated mortality were[37 and[62 %, respectively, HBV screening was cost-effective, leading the authors to conclude that although extensive LTBI screening and HBV screening are effective, their implementation should be targeted towards high-risk populations. An interesting aspect to this study was how the authors calculated probabilities for the LTBI-component of the model, which appear to be largely derived from a recent meta-analysis which analyzed TST and IGRA performance in patients with inflammatory bowel disease (IBD) [4]. Concerning the perceived false-positivity rate of TST, it appears the authors based this off an estimate of discordance between TST?/IGRAresults, which is simply the discrepancy between these two tests in a patient. IGRAs are not commonly regarded as the ‘gold standard’ in LTBI diagnostics; therefore, the discordance is potentially an inaccurate quantification of false positivity. Moreover, it was unclear how the authors established the advantage that additional IGRA testing would have over traditional LTBI screening. It appears that they may have estimated this from the alternate discordant scenario TST-/IGRA?, which would lend itself to the same limitations as the false positivity risk. N. Shahidi B. Bressler (&) Division of Gastroenterology, Department of Medicine, University of British Columbia, 770-1190 Hornby Street, Vancouver, BC V6Z 2K5, Canada e-mail: brian_bressler@hotmail.com

Optimizing Screening for Tuberculosis and Hepatitis B Prior to Starting Tumor Necrosis Factor-α Inhibitors in Crohn’s Disease

Treatment with tumor necrosis factor-α (TNF-α) inhibitors in patients with Crohn's disease (CD) is associated with potentially serious infections, including tuberculosis (TB) and hepatitis B virus (HBV). We assessed the cost-effectiveness of extensive TB screening and HBV screening prior to initiating TNF-α inhibitors in CD. We constructed two Markov models: (1) comparing tuberculin skin test (TST) combined with chest X-ray (conventional TB screening) versus TST and chest X-ray followed by the interferon-gamma release assay (extensive TB screening) in diagnosing TB; and (2) HBV screening versus no HBV screening. Our base-case included an adult CD patient starting with infliximab treatment. Input parameters were extracted from the literature. Direct medical costs were assessed and discounted following a third-party payer perspective. The main outcome was the incremental cost-effectiveness ratio (ICER). Sensitivity and Monte Carlo analyses were performed over wide ranges of probability and cost estimates. At base-case, the ICERs of extensive screening and HBV screening were €64,340 and €75,760 respectively to gain one quality-adjusted life year. Sensitivity analyses concluded that extensive TB screening was a cost-effective strategy if the latent TB prevalence is more than 12 % or if the false positivity rate of TST is more than 20 %. HBV screening became cost-effective if HBV reactivation or HBV-related mortality is higher than 37 and 62 %, respectively. Extensive TB screening and HBV screening are not cost-effective compared with conventional TB screening and no HBV screening, respectively. However, when targeted at high-risk patient groups, these screening strategies are likely to become cost-effective.

AB0363 Rate of tuberculin skin test or interferon gamma release assay conversion during anti-tumor necrosis factor therapy in rheumatic patients

BackgroundDespite negative baseline testing for tuberculosis (TB) with traditional (tuberculin skin test/TST, chest X-ray/CXR) or newer (interferon-gamma release assays/IGRAs) screening methods, a small number of patients receiving anti-tumor necrosis factor...

AB0726 Systemic review: agreement between tuberculin skin test (TST) and-gamma release assay (IGRA) blood test for latent tb screening among patients with rheumatic diseases

BackgroundThe accuracy of screening tests for latent tuberculosis infection (LTBI) such as TST and IGRAs and their agreement are varied according to study.ObjectivesWe conducted meta-analysis on the positivity of LTBI...

Screening employees of services for homeless individuals in Montréal for tuberculosis infection

The results of a tuberculin skin test (TST) screening program offered to employees of services for homeless people in Montréal from 1998 to 2005 were analyzed to assess the occupational risk of tuberculosis (TB) infection. Employees with no known contact with TB were selected among volunteer participants. They were followed in two dynamic cohorts: individuals with a negative two-step baseline TST (cohort A) and individuals with a negative single baseline TST (cohort B). We estimated the prevalences of initial positive TST, boosting effect, and conversion rate. The average age of the workers was 38.9 years. The prevalence of an initial positive TST was 12.9%. A booster effect was observed in 5.1% of workers who completed a two-step TST. The incidence of conversion was 2.3/100 person-years for cohort A (n=93) and 3.5/100 person-years for cohort B (n=221). The incidence of conversion was not significantly associated with any of the demographics or workplace factors investigated. Our findings are comparable to the rates reported among community workers, whose risk is higher than the average health worker. This suggests that there are occasional unidentified contagious cases among the homeless individuals of participating institutions.

Evaluation of Tuberculin Skin Test Results among Students of the University of Medical Sciences and Technology, Sudan

Introduction: Tuberculosis is an endemic infectious disease in Sudan and other developing countries. Healthcare workers, including students, are at a great risk of exposure and possible infection. This study is conducted to determine the pattern and prevalence of positive tuberculin skin test (TST) among students of the University of Medical Sciences and Technology during distinct periods of their training, and to study the influencing factors for positive results. Design and Setting: A cross-sectional study conducted among 100 students in the period between October 2010 to March 2011 using questionnaires, and administration of the Tuberculin Skin Test (TST) by a licensed professional. Students were divided into two groups, high risk group (medical students), and low risk group (non-medical students) according to their level of exposure. Demographics, BCG vaccination, potential exposure to TB patients and symptomatology were obtained and analyzed. Results: The overall prevalence of positive TST was 19%, 2% were strongly positive, 17% being moderately positive. The high risk group exhibited a significantly higher rate of positive TST (26%). Positive TST was found to correlate significantly with contact with TB patients (P 0.08). No significant correlation was found between positive TST and gender (P 0.834), country of residence (P 0.242), vaccination (P 0.094), presence of BCG scar (P 0.793), drinking unpasteurized milk (p 0.647), immunosuppressive therapy (P 0.674) and crowding (P 0.872). Conclusion: The TST positivity rate was high among our students; it correlates with in-hospital training stage. More attention should be paid to prevention strategies in medical students prior to and during their clinical training.

Establishment and evaluation of a Chinese rhesus model of tuberculosis

To establish and evaluate the Chinese rhesus model of tuberculosis. Twelve Chinese rhesus macaques, randomly divided into 3 groups, were inoculated with 2 different doses of Mycobacterium tuberculosis H(37) Rv strain via both bronchoscopic and intratracheal instillation into the lungs. Clinical observation and laboratory examinations were performed, including erythrocyte sedimentation rate, C-reactive protein, tuberculin skin test and X-ray examination. Histopathological assessments were performed in the 24th week postinfection. Statistical analysis was performed by ANOVA in the 3 groups. After infection all the animals manifested fever, weight lose, lack of appetite, coughing and other symptoms of tuberculosis. The temperature gradually increased and reached a peak [(40.1 ± 0.2)°C] at the 8th week postinfection. The weight decreased significantly at 24th week postinfection (-5.5 ± 5.6)%. Erythrocyte sedimentation rate elevated significantly at the 6th to 8th week postinfection (36 ± 40) mm/1 h. C-reactive protein was significantly increased at the 6th to 24th week after infection (75.8 ± 49.8) mg/L. The positive rate of tuberculin skin test was 100%. In Group I (bronchoscopic instillation, 20 CFU) the disease developed slowly, and the main manifestation of chest X-ray was patchy shadows. In group II (bronchoscopic instillation, 100 CFU) and group III (intratracheal instillation, 100 CFU) the disease developed rapidly, and the main manifestation of chest X-ray was patchy and nodular lesions during the 4th to the 12th week postinfection, but became large patchy and consolidation lesions during the 12th to the 24th week postinfection. Tuberculosis granuloma and caseous necrosis, similar to the pathological changes of human tuberculosis, were found in the lungs, mediastinal lymph nodes, kidney and spleen. The results of acid-fast stain were positive. The most serious pathological manifestations were observed in group II, followed by group III and group I. The highest bacterial load of the right lung was seen in group II, followed by group I and group III. A chinese rhesus model of tuberculosis was successfully developed via both bronchoscopic and intratracheal instillation. Their clinical manifestations, disease progression and pathological changes were similar to human primary tuberculosis and hematogenous disseminated tuberculosis.

Tuberculin reactivity in bacille calmette-guerin vaccinated individuals with sputum positive pulmonary tuberculosis

The study was carried out to assess the value of tuberculin skin test for the diagnosis of Tuberculosis (TB) in BCG vaccinated individuals and to find out the sensitivity rate of tuberculin skin test (TST) in comparison to acid fast bacilli positive pulmonary TB. Similar population with high BCG vaccination coverage having both pulmonary TB patients (n=150) and apparently healthy individuals (n=150) in eastern Nepal were enrolled in this comparative study. Sputum from all the subjects was subjected to Z-N microscopy. TST was performed on these subjects by standard Mantoux method. Among the patients (mean age 36.18±14.15 yrs) and controls (mean age 35.61±13.44 yrs), 55.33 % and 47.33 % respectively have been found to be positive PPD reactors (&gt;10mm) which is statistically not significant (P&gt;0.05). About 23% of the patients &amp; 27% of controls failed to react (anergic) to 5 TU PPD. PPD reactivity rate was high in the patients whose sputum smears were graded as 1+ in Z-N microscopy. The sensitivity of TST was highest for the induration of &gt;5mm (77.3%). Specificity increased with increasing size of induration and was highest (73.3%) with induration of &gt;15 mm. Tuberculin skin test is an all or none phenomenon. In Nepal, tuberculin test has a limited value in the diagnosis of pulmonary TB as both the apparently healthy individuals and patients with sputum smear positive pulmonary TB who had been immunized with BCG, showed almost similar rate of tuberculin reactivity. DOI: http://dx.doi.org/10.3126/jcmsn.v7i1.5970 JCMSN 2011; 7(1): 28-35

Monitoring of peptide-specific and gamma interferon-productive T cells in patients with active and convalescent tuberculosis using an enzyme-linked immunosorbent spot assay.

To establish a high-efficiency gamma interferon-specific enzyme-linked immunosorbent spot assay (IFN-γ ELISPOT assay) for detection of tuberculosis (TB), peptides (E6, E7, and C14) and peptide mixtures (E6 plus E7 and E6 plus E7 plus C14) were used to monitor peripheral blood (PBL) samples from patients with pulmonary TB (PTB), as well as control samples. The positive detection rates of the five IFN-γ ELISPOT assays were 78.38%, 74.86%, 55.83%, 90.43%, and 91.51%, respectively, and there were similar detection rates between the two combined peptide mixture IFN-γ ELISPOT assays and the tuberculin skin test (TST) (90.62% versus 95.59%). No significant difference was found between the detection rates of the two combined peptide mixture IFN-γ ELISPOT assays and the T-SPOT.TB assay for 86 patients with PTB (P > 0.05), but the median number of spot-forming cells/10(6) cells (SFP value) for positive results was higher by the former than by the latter assay (P < 0.05). In contrast, the 29.93% positive detection rate and median SFP value of 482 by the two combined peptide mixture IFN-γ ELISPOT assays were significantly higher than the corresponding values of 14.29% and 152 by T-SPOT.TB assay for the same 147 community donors (P < 0.05). For nine PTB patients tracked, the SFP value of 7 for the two peptide mixture IFN-γ ELISPOT assays began to decrease from the second month after regular treatment. A relatively low, almost normal, SFP level was reached and maintained after the third or fourth month. Two in-house IFN-γ ELISPOT assays and the T-SPOT.TB assay could reduce the false-positive and false-negative detection rates of TST and sputum acid-fast staining. Therefore, these two combined peptide mixture IFN-γ ELISPOT assays have a potential advantage, beyond their greater specificity and sensitivity, for use in screening and detection of active TB infection (TBI) and latent TB infection (LTBI) in China.

Positive Tuberculin Skin Test or Interferon-Gamma Release Assay in Patients with Radiographic Lesion Suggesting Old Healed Tuberculosis

Radiographic lesions suggesting old healed tuberculosis (TB) is considered a risk factor for the subsequent development of active TB. The aim of this study was to estimate the positive rates of tuberculin skin test (TST) and interferon-gamma release assay (IGRA) in persons with old healed TB. Participants with lesions suggesting old healed TB on chest images and controls without such lesions were prospectively enrolled between January 1, 2010, and January 31, 2011. TST and the QuantiFERON-TB Gold In-Tube test (QFT-GIT) were performed. In total, 193 participants with old healed TB and 126 controls were recruited. The rates of positive TST and QFT-GIT among patients with old healed TB were 54.6% and 77.7%, respectively. The rates of positive TST and QFT-GIT among patients without old healed TB were 38.9% and 61.9%. Sixteen percent of participants with old healed TB showed negative results by both TST and QFT-GIT. The positive rate of TST waned among participants with old healed TB who were older than 60 yr, whereas QFT-GIT positivity was unaffected by age. The positive rates of TST and IGRA among participants with radiographic lesions suggesting old healed TB was higher than without those lesions. In addition, IGRA may be more accurate than TST for the detection of latent TB infection, especially in populations of individuals older than 60 yr.