Rates Of Tuberculin Skin Test Research Articles

Tuberculin reaction is not attenuated in patients with rheumatoid arthritis living in a region with intermediate burden of tuberculosis

Tuberculin reactions in patients with immunocompromised conditions have been reported to be attenuated compared with healthy controls. In the case of rheumatoid arthritis (RA), several studies have reported conflicting results. We performed this study to evaluate the tuberculin reaction in patients with RA in a region with intermediate burden of tuberculosis. Eighty-one RA patients and 104 age- and sex-matched controls who underwent tuberculin skin test (TST) at Severance Hospital in Seoul, South Korea were reviewed. TST was carried out using the Mantoux method. Indurations larger than 10 mm were considered positive. Information about risk factors for latent tuberculosis infection was acquired. The mean age of the patients with RA was 48 ± 14 years, and the median disease duration was 9 (1-203) months. The mean DAS28 was 5.22 ± 0.13. The control group consisted of healthy living donors for liver transplantation and the patients with diseases not related with immunosuppression. BCG vaccination, close contact history with active tuberculosis, and history of pulmonary tuberculosis were not different between the two groups. The positive rate of TST (34.6% vs. 38.5%) and the median skin induration size (5 mm vs. 6 mm) of the two groups were similar. Medications and DAS28 were not associated with the TST result. The tuberculin reaction of patients with RA is not attenuated compared with that of controls in South Korea.

Positive tuberculin skin tests in nursing home residents in Southern Taiwan

In Taiwan, the tuberculin skin test (TST) is not recommended as a screening test for Mycobacterium tuberculosis (TB) infections. The aim of this study is to determine the prevalence and predictors of positive tuberculin reactivity and its association with TB infections among nursing home residents in Taiwan. A cross-sectional study and review of medical records were conducted at four nursing homes in Tainan City. A one-stage TST was performed by study nurses using two tuberculin units of purified protein derivative (PPD) of the RT23 strain. An induration ≥10 mm at 72 h was considered to be a positive reaction. Chest radiographs, acid-fast stains and mycobacterial cultures of three sputum samples were performed for those with a positive TST result. Of 115 residents (66.5% participation, mean age 73.1 years) who underwent a TST, 26 (22.6%) had a positive reaction. One woman was microbiologically diagnosed to have pulmonary TB. On multivariate analysis, a Bacille Calmette-Guérin (BCG) scar and a history of myocardial infarction were significantly associated with a positive TST. In conclusions, this study shows a considerable rate of positive TST among nursing home residents in southern Taiwan. A BCG scar and a history of myocardial infarction were associated with a positive TST.

Clinical Significance of Interferon γ Release Assay for Diagnosis of Tuberculosis in Children

Purpose : The purpose of this study is to evaluate the usefulness and limitation of QuantiFERON-TB Gold (QTB) for diagnosis of latent tuberculosis in children. Methods : The medical records of 112 children who were tested by tuberculin skin test (TST) and QTB for detection of latent tuberculosis (TB) in Eulji General Hospital during the period from January 2007 to June 2009 were retrospectively reviewed. Results : Of the 112 participants, the clinical TB group included 15 (13.4%), the contact group included 43 (38.4%), and the non-contact group included 54 (48.2%). Positive rates of TST and QTB were 100% and 80% in the clinical TB group, 64% and 14% in the close contact group, 27% and 0% in the casual contact group, and 52% and 2% in the non-contact group, respectively. Sensitivity of QTB was 80.0% and specificity was 92.6%. Agreement between QTB and TST was poor (=0.209). We also confirmed that the positive rate of QTB increased as the age of the patient increased (P=0.011). A QTB indeterminate result was observed in 11 (9.8%) subjects. QTB was retested in 15 subjects. In 5 of the 6 subjects who had positive results initially, positive results persisted for a median 2.2 months after termination of treatment. Conclusion : Although QTB was associated with several problems, including low sensitivity and a high rate of indeterminate results, it had clinical importance due to its high specificity. We found good correlation with regard to exposure and QTB positivity, including that of young children under 5 years of age. However, clinical application of interferon- releasing assay for young children for diagnosis of active and latent tuberculosis will require additional prospective studies.

Use of a T Cell Interferon-γ Release Assay to Evaluate Tuberculosis Risk in Newly Qualified Physicians in Singapore Healthcare Institutions

Surveillance for latent tuberculosis in high-risk groups such as healthcare workers is limited by the nonspecificity of the tuberculin skin test (TST) in BCG-vaccinated individuals. The Mycobacterium tuberculosis antigen-specific interferon-gamma release assays (IGRAs) show promise for more accurate latent tuberculosis detection in such groups. To compare the utility of an IGRA, the T-SPOT.TB assay, with that of the TST in healthcare workers with a high rate of BCG vaccination. Two hundred seven medical students from 2 consecutive cohorts underwent the T-SPOT.TB test and the TST in their final year of study. Subjects with negative baseline test results underwent repeat testing after working for 1 year as junior physicians in Singapore's public hospitals. The baseline TST result was an induration 10 mm or greater in diameter in 177 of the 205 students who returned to have their TST results evaluated (86.3%), while the baseline T-SPOT.TB assay result was positive in 9 (4.3%) of the students. Repeat T-SPOT.TB testing in 182 baseline-negative subjects showed conversion in 9 (4.9%). A repeat TST in 18 subjects with baseline-negative TST results did not reveal any TST result conversion. The high rate of positive baseline TST results in our BCG-vaccinated healthcare workers renders the TST unsuitable as a surveillance tool in this tuberculosis risk group. Use of an IGRA has enabled the detection and treatment of latent tuberculosis in this group. Our T-SPOT.TB conversion rate highlights the need for greater tuberculosis awareness and improved infection control practices in our healthcare institutions.

Clinical Utility of the QuantiFERON TB-2G Test for Elderly Patients With Active Tuberculosis

To evaluate the response to the QuantiFERON-TB-2 Gold (QFT-2G) test (Cellestis Ltd; Carnegie, VIC, Australia) in elderly patients with active tuberculosis (TB) to determine whether the QFT-2G test might be a feasible method for diagnosing TB infection in this group of patients. The subjects were 30 elderly patients with active TB and 100 younger patients with active TB. The QFT-2G test results were analyzed in relation to combined and separate responses to early secretory antigenic target 6-kD (ESAT-6) protein and culture filtrate protein 10 (CFP-10) antigens. Of the 30 elderly patients with active TB, 27% had a positive tuberculin skin test (TST) result and 77% had a positive QFT-2G test result. Of the 100 younger patients with active TB, 70% had a positive TST result and 87% had a positive QFT-2G test result. Although there was no significant difference between the two patient groups in the positive rate for the QFT-2G test results (p = 0.185), there was a significant difference in the rates of positive TST results between the elderly and younger patients (p = 0.012). The positive test result rate for both ESAT-6 and CFP-10 antigens in the elderly patients (17%) was significantly lower than that in younger patients (37%; p = 0.038). There was an indeterminate result for the QFT-2G test in five elderly patients, and this might have been related to the presence of lymphocytopenia due to underlying disease. A negative result on the QFT-2G test was detected in two elderly patients, and this might have been related to the severity of the active TB. We confirmed that the QFT-2G test might be a more useful method of diagnosing TB infection than the TST for elderly patients if peripheral lymphocyte counts have been preserved.

Detecting a low prevalence of latent tuberculosis among health care workers in Denmark detected by M. tuberculosis specific IFN-γ whole-blood test

The study was designed to estimate prevalence of tuberculosis infection among health care workers, using the tuberculin skin test (TST) and the new M. tuberculosis specific diagnostic whole-blood test and to identify possible risk factors. Employees at 2 departments of infectious diseases in Copenhagen were invited to enter the study. All attendants completed a questionnaire, had a TST and blood drawn for detection of interferon-gamma produced after stimulation with M. tuberculosis specific antigens ESAT-6 and CFP-10 (QuantiFERON-TB-Gold, Cellestis). 47 of 139 (34%) participants had a positive TST whereas only 2 of 139 (1%) had a positive QuantiFERON TB-Gold test (QFT-TB). 42 of 106 (40%) BCG vaccinated had positive TST (> or =12 mm) compared with 2 of 27 (7%) unvaccinated persons. Among 47 persons with positive TST, 42 (89%) were BCG- vaccinated. The 2 QFT-TB positive participants as well as the remaining 45 TST positive participants showed no sign of active tuberculous disease and were allocated to 6-month clinical follow-up, without medical therapy. Today, 1.5 y later, all remain healthy. The high rate of positive TST among health care workers was most probably due to BCG vaccination and not to infection with M. tuberculosis. The overall transmission rate determined by QFT-TB was found to be very low. The QFT-TB may be useful in distinguishing persons with latent TB infection from persons with positive TST due to BCG vaccination and its use may reduce anxiety.

Nursing and Community Rates of Mycobacterium tuberculosis Infection among Students in Harare, Zimbabwe

African hospitals have experienced major increases in admissions for tuberculosis, but they are ill-equipped to prevent institutional transmission. We compared institutional rates and community rates of tuberculin skin test (TST) conversion in Harare, Zimbabwe. We conducted a cohort study of TST conversion 6, 12, and 18 months into training among 159 nursing and 195 polytechnic school students in Harare. Students had negative TST results (induration diameter, < or =9 mm) with 2-step testing at the start of training. Nursing students experienced 19.3 TST conversions (increase in induration diameter, > or =10 mm) per 100 person-years (95% confidence interval [CI], 14.2-26.2 conversions per 100 person-years), and polytechnic school students experienced 6.0 (95% CI, 3.5-10.4) conversions per 100 person-years. The rate of difference was 13.2 conversions (95% CI, 6.5-20.0) per 100 person-years. With a more stringent definition of conversion (increase in the induration diameter of > or =10 mm to at least 15 mm), which is likely to increase specificity but decrease sensitivity, conversion rates were 12.5 and 2.8 conversions per 100 person-years in nursing and polytechnic school students, respectively (rate difference, 9.7 conversions per 100 person-years; 95% CI, 4.5-14.8 conversions per 100 person-years). Nursing students reportedly nursed 20,868 inpatients with tuberculosis during 315 person-years of training. Both groups had high TST conversion rates, but the extremely high rates among nursing students imply high occupational exposure to Mycobacterium tuberculosis. Intense exposure to inpatients with tuberculosis was reported during training. Better prevention, surveillance, and management of institutional M. tuberculosis transmission need to be supported as part of the international response to the severe human immunodeficiency virus infection epidemic and health care worker crisis in Africa.

Case-Control study of Firefighters with documented positive tuberculin skin test results using Quantiferon-TB testing in comparison with Firefighters with negative tuberculin skin test results

BackgroundPhoenix Firefighters have had abnormally high rates of tuberculin skin test (TBST) results on medical surveillance. The objectives of this study were to evaluate our firefighters using QuantiFERON-TB (QFT), comparing the results to their TBST results.MethodsUsing QFT results obtained during the study, we compared previously positive TBST responders (Cases) to negative responders (Controls). We also compared both groups for QFT results for Mycobacterium avium (MA) exposure.ResultsQFT effectively monitored our working population. 12.9% of the 148 cases, and 3.2% of the 220 controls had a positive QFT result. Another 14.8% of cases and 4.5% of controls had conditionally positive QFT results. There was an unusually high rate of MA response on QFT testing in both groups.ConclusionPhoenix Firefighters have a higher than expected TBST and QFT results, which cannot be explained by the increased MA rate. The decreased level of QFT positivity in comparison to TBST results may indicate a considerable false positive TBST rate. The QFT offers many advantages as a surveillance method over TBST in exposed worker populations.

Screening Latino Adolescents for Latent Tuberculosis Infection (LTBI)

To investigate the rates of latent TB infection (LTBI) in a sample of young people in San Diego County and examine potential predictors of a positive tuberculin skin test (TST). Latino and foreign-born students from ten public middle and high schools were invited to screenings along with a random 10% sample of all other students. After obtaining parental consent, Mantoux tests were placed (N=2,698) and read (n=2,667 [98.9%]) in 48-72 hours. A positive TST was defined as > or =10 mm induration. The mean age of the sample was 14.34 years (SD=1.81); 50.1% were female (n=1,353); 78.5% were Latino (n=2,108); 35.7% were foreign-born (n=939); and 44.3% were uninsured (n=930). The positive TST rate for Latinos was 21.8% vs. 5.6% for non-Latinos, p<0.001. Foreign-born Latinos had the highest infection rate (31.3%), followed by foreign-born non-Latinos (20.4%), U.S.-born Latinos (15.4%), and U.S.-born non-Latinos (1.0%), p<0.001. Logistic regression was conducted to determine predictors of TST positivity. Being Latino (odds ratio [OR]=3.27), uninsured (OR=1.60), foreign-born (OR=3.90), and living in the south county region closest to the U.S./Mexico border (OR=2.72) were significant predictors. Results suggest that Latino youth near the California/Mexico border are at high risk for infection, for remaining undiagnosed, and for being under-treated for LTBI.

Risk of house staff tuberculin skin test conversion in an area with a high incidence of tuberculosis.

We prospectively evaluated rates of tuberculin skin test (TST) conversion from July 1992 to June 1997 among house staff in the Emory University Affiliated Hospitals Training Program following implementation of expanded infection control measures for tuberculosis at Grady Memorial Hospital (Atlanta), which cares for approximately 200 patients with tuberculosis per year. Over 5 years, documented TST conversions occurred for 52 (2.4%) of 2,144 house staff. Conversion rates decreased after the first 6 months from 5.98 to 1.09 per 100 person-years worked over the next 4.5 years (P < .001). Multivariate analysis revealed that risk factors for TST conversion included graduation from a foreign medical school and being part of the house staff in the Department of Medicine; race or ethnicity, gender, and age were not risk factors. Over the last 4.5 years, the TST conversion rate among U.S. medical school graduate house staff (n = 1,928) was 0.72 per 100 person-years worked, and there was no significant difference in conversion rates between house staff in the Department of Medicine and house staff in other departments. In summary, TST seroconversion rates decreased significantly following full implementation of expanded infection control measures for tuberculosis and were low (< 1% per year) among U.S. medical school graduates despite their caring for large numbers of patients with tuberculosis at an inner-city public hospital.

Tuberculin Skin Test Screening in Schoolchildren in the United States

To determine the current practices and results of tuberculin skin test (TST) screening of schoolchildren in the United States. Tuberculosis program staff in all states and the District of Columbia were asked about current requirements, practices, and results of school-based TST screening. Thirty-four states and the District of Columbia (69%) reported no current statewide statutes or policies for tuberculin screening of schoolchildren, and 10 (19%) reported having statewide requirements. In 6 states (12%), requirements were instituted at the local level, and 24 localities in these states were known to require screening. Of the 34 areas requiring screening, 18 (53%) screened all new entrants, 7 (21%) screened children in specific grades, and 9 (26%) used other criteria for screening. TST results were collected for 26 (76%) of 34 areas, and 6 areas collected results of follow-up evaluation of tuberculin-positive children. Additionally, 8 localities in 7 states with no screening requirements conducted tuberculin surveys. Sixteen areas provided results. In 7 of the 8 areas that collected information about birthplace, less than 2% of US-born children were tuberculin positive; foreign-born children had rates 6 to 24 times higher than US-born children. TST screening identified new cases of tuberculosis, less than 0.02% of the children screened. School-based tuberculin screening identified low rates of positive TST results in US-born children. Resources should be directed toward screening children at high risk for tuberculous infection, as recommended by the American Academy of Pediatrics and the Advisory Committee for Elimination of Tuberculosis.

Transmission of Mycobacterium tuberculosis Associated With Air Travel

To investigate potential transmission of Mycobacterium tuberculosis in aircraft from a crew member with tuberculosis. Retrospective cohort study and survey. A large US airline carrier. A total of 212 crew members and 59 passengers who were exposed to a crew member with tuberculosis during a potentially infectious period (May through October 1992). Comparison volunteer sample of 247 unexposed crew members. Positive tuberculin skin test (TST) result or tuberculosis. Rates of positive TST results were higher among foreign-born persons in all study groups. Among US-born comparisons and contacts, rates of positive TST results did not differ between comparisons and contacts exposed from May through July (5.3% vs 5.9%, respectively). However, contacts exposed from August through October had significantly higher rates of positive TST results than did contacts exposed from May through July (30% vs 5.8%, respectively; P < .001); two had documented TST conversions between September 1992 and February 1993. The risk of infection increased with increasing hours of exposure to the index case. Four (6.7%) of 59 frequent flyers were TST-positive; all flew in October. Data support the conclusion that M tuberculosis was transmitted from an infectious crew member to other crew members on an aircraft. Because of the clustering of TST-positive frequent flyers in October when the index patient was most infectious, transmission of M tuberculosis to passengers cannot be excluded.