Interpretation Of Tuberculin Skin Test Research Articles

Predictors of positive tuberculin skin test in neonates exposed to pulmonary tuberculosis.

Neonates are at risk of nosocomial tuberculosis (TB) infection from health care workers (HCWs) in neonatal care facilities, which can progress to severe TB diseases. Tuberculin skin test (TST) is commonly used for TB diagnosis, but its accuracy in neonates is influenced by various factors, including bacilli Calmette-Guérin (BCG) vaccination. This study aimed to identify predictors of positive TSTs in neonates exposed to HCWs with pulmonary TB. A retrospective observational study was conducted to compare the frequency of predictors between TST-positive and TST-negative neonates. Demographic, epidemiological, and clinical data of neonates exposed to TB, along with that of HCW and household contacts, were collected retrospectively through contact investigations with the Korean National TB Surveillance System (KNTSS) database. TSTs using 2 tuberculin units of purified protein derivative RT23 were performed on exposed neonates at the end of preventive TB treatment. Firth logistic regression was performed to identify predictors of TST positivity. Contact investigations revealed that 152 neonates and 54 HCWs were exposed to infectious TB index cases in 3 neonatal care facilities. Of 152 exposed neonates, 8 (5.3%) had positive TST results. Age of 6 days or more at the initial exposure is a statistically significant predictor of positive TST (Firth coefficient 2.1, 95% confidence interval 0.3-3.9, P = 0.024); BCG vaccination showed no statistical significance in both univariable and multivariable analysis. Sex, prematurity, exposure duration, duration from initial exposure to contact investigation, and isoniazid preventive treatment duration were not significant predictors. Age at the initial exposure is a significant predictor of positive TST in neonates exposed to active pulmonary TB. Given the complexities of TST interpretation, including false positives due to BCG vaccination, careful risk assessment is necessary for appropriate decision-making and resource allocation in the management of neonatal TB exposure.

Optimizing the Threshold to Treat Children for Latent Tuberculosis Infection: A North-East England Experience.

We assessed the impact of the updated guidelines on tuberculin skin test interpretation in the North East of England. Data on 241 children screened for latent tuberculosis infection (LTBI) between January 2011 and July 2018 were analyzed; 12.4% of children screened under the previous guidelines were treated for LTBI, compared to 33.3% under the new ones ( P < 0.001).

Interpretation of tuberculin skin test in bacillus calmette–guerin-vaccinated children

Objective: The objective was to determine the sensitivity and specificity of tuberculin skin test (TST) in Bacillus Calmette–Guerin (BCG)-vaccinated children for diagnosis of tuberculosis (TB). Materials and Methods: This observational study was conducted at a single tertiary care center over a period of 32 months from March 2012 to November 2014. All children up to 15 years of age who had received BCG at birth, suspected of TB, and referred to pediatric TB clinic were enrolled in the study. All patients were given TST by 5 Tuberculin Unit Purified Protein Derivative-Standard. The diagnosis of TB was based on either clinical, histopathological, or bacteriological grounds. Results: Out of 371 patients, 341 (91.91%) had TB. TST was positive in 227 (61.2%) and negative in 144 (38.8%) patients. The sensitivity of TST to detect active TB was 62.8% and specificity was 56.7%. TST cutoff as ≥15 mm increased specificity of TST to 73.3%, but sensitivity decreased to 25.8%. Age, gender, and contact with TB patients did not affect TST results. Conclusion: The accuracy of TST for the diagnosis of TB is low with low sensitivity and specificity. By increasing the cutoff for positive TST to >15 mm, the number of false-positive TST can be reduced.

Effect of neonatal bacille Calmette-Guérin on the tuberculin skin test reaction in the first 2 years of life.

Latent tuberculous infection (LTBI) is an important reservoir of disease reactivation that is sufficient to generate new cases for decades. The tuberculin skin test (TST) is an important tool to diagnose LTBI; however, neonatal bacille Calmette-Guérin (BCG) vaccination may impact interpretation of TST data. To analyse the effect of the neonatal BCG vaccine on TST reaction in the first 2 years of life in children with no identified contact with tuberculosis (TB). This was a cross-sectional study in children up to 2 years of age who received neonatal BCG vaccination. In the absence of baseline comorbidities or contact with the bacillus, the children were given the TST. Seventy-nine children participated in the study. A decline in TST reactivity was observed in the first 12-24 months of age in patients who had been vaccinated with neonatal BCG but with no contact with TB. After the age of 10 months, no patient showed a TST reaction of >5 mm. BCG had low impact on the TST in children with no TB contact. This finding suggests the need to reassess the cut-off point to 5 mm of induration to improve TST specificity in LTBI identification.

46-Year-Old Man With Lower Back Pain

46-Year-Old Man With Lower Back Pain

Purified protein derivative immunotherapy for viral warts and interpretation of tuberculin skin tests and interferon gamma release assay for diagnosis of tuberculosis in India

Purified protein derivative immunotherapy for viral warts and interpretation of tuberculin skin tests and interferon gamma release assay for diagnosis of tuberculosis in India

Tuberculosis in childhood: a systematic review of national and international guidelines.

BackgroundPaediatric tuberculosis (TB) represents a major public health concern worldwide. About 1 million children aged less than 15 years develop TB each year, contributing to 3-25% of the total TB caseload. The aim of this review is to evaluate national and international guidelines concerning tuberculosis in childhood and compare them in terms of diagnosis and treatment strategies.MethodsA literature search of the Pubmed database was performed from January 2000 to August 2013, using the terms “tuberculosis” and “children”. The search was limited to guidelines and consensus conferences, human species and full text availability, with no language restrictions.ResultsTwenty-seven national and international guidelines are identified. Several discrepancies on the diagnosis workup of TB are underlined. The main points of disagreement are represented by the interpretation of tuberculin skin test (TST) result and the recommendations on the use of TST and/or interferon-gamma release assay (IGRA) for the diagnosis of TB infection. Otherwise, all guidelines are in agreement that a microbiological confirmation should always be sought. Similarly, susceptibility drug testing and genotyping should be performed whenever it is possible on the basis of resources availability. On the contrary, the use of nucleic acid amplification tests (NAATs) for the M. tuberculosis detection is still controversial. A general consensus exists, otherwise, on TB treatment and only minor discrepancies are evidenced, such as the recommendations on daily or intermittent treatment regimens.ConclusionsDespite advances in TB diagnostic tools have been reached during the last decade, a lack of uniformity in their availability, indication and interpretation has relevant consequences for clinical practice. Further studies need to be performed to clarify this issue and identify a reliable and reproducible diagnostic workup. Moreover, future studies should analyze the drug metabolism and the efficacy of intermittent dosing regimes in childhood, as well as new treatment regimens in order to improve the therapy compliance.

Detecting Tuberculosis Infection in HIV-infected Children

Accurate identification of Mycobacterium tuberculosis infection in young and HIV-infected children could guide delivery of preventive therapy, improve resource utilization and help prevent tuberculosis. We assessed the performance of the tuberculin skin test (TST) and interferon-γ release assays (IGRAs) for identifying M. tuberculosis infection in South African children presenting for outpatient care. Tuberculosis contact was quantified using a standardized measure of M. tuberculosis exposure. Logistic regression assessed the association among test positivity, age, nutritional and HIV status, while controlling for M. tuberculosis exposure, bacille Calmette-Guérin vaccination and prior tuberculosis treatment. Among 250 (130 HIV infected) children (age 0.25-14.6 years, median 39 months), the proportion positive for each test varied: 34% (TST), 21% (T-SPOT.TB) and 25% (QuantiFERON-TB Gold In-Tube). IGRAs were more likely to be positive in HIV-uninfected compared with HIV-infected children; TST positivity did not differ between these groups. Agreement between tests was good-to-excellent in HIV-uninfected children and poor-to-good in HIV-infected children. In adjusted models, TST and T-SPOT.TB were positively associated with age; this effect varied by HIV status. The QuantiFERON-TB Gold In-Tube was negatively associated with chronic malnutrition; this effect varied by HIV status. Because 93% of children had received bacille Calmette-Guérin, we could not assess the contribution of bacille Calmette-Guérin to false-positive TST results. Our findings indicate that the TST and IGRAs perform similarly for the detection of M. tuberculosis infection in well-nourished HIV-uninfected children, but test performance is differentially affected by chronic malnutrition, HIV infection and age. Similar to TST interpretation, clinicians and researchers should interpret IGRAs in children with caution taking age, nutritional and HIV status into consideration.

Tuberculin reactivity in first‐year schoolchildren in Madagascar

The tuberculin skin test (TST) is an important tool in the diagnosis of tuberculosis infection in children. However, the interpretation of TST may be complicated by prior Bacillus Calmette-Guerin (BCG) vaccination. We evaluated the effect of vaccination with BCG on TST reactivity in first-year pupils attending state schools in Antananarivo. STs were performed on 376 first-year schoolchildren, aged 6 and 7, attending two state primary schools. The relationships between epidemiological information, BCG status (vaccination, BCG scars) and TST reactivity were assessed to compare TST sensitivity between children with and without BCG vaccination and between those with and without a BCG scar. The prevalence of positive TST results of ≥5, ≥10 and ≥ 15 mm was 20.2% (76/376), 18.3% (69/376) and 11.4% (43/376), respectively. BCG vaccination was not associated with TST reactivity, whatever the threshold used: ≥5 mm (odds ratio (OR, 1.2; 95% confidence interval (CI), 0.7-2.0); ≥10 mm (OR, 0.9; 95% CI, 0.6-1.7); ≥15 mm (OR, 0.6; 95% CI, 0.3-1.2). These results suggest that in Madagascar, a positive TST result indicates TB infection (active or latent) rather than past BCG vaccination. Therefore, high BCG vaccination coverage does not appear to impair the usefulness of the TST as a tool for diagnosing tuberculosis.

Prevalence of bovine tuberculosis in cattle in the highlands of Cameroon based on the detection of lesions in slaughtered cattle and tuberculin skin tests of live cattle

&amp;nbsp; Bovine tuberculosis (TB) is an important neglected zoonosis in Cameroon, where many communities depend on their livestock for livelihood and the incidence of human TB and TB-HIV/AIDS co-infection are high and increasing annually. The aim of this study was to estimate the prevalence of bovine TB in cattle in the highlands of Cameroon. The magnitude and trend of detecting TB lesions in slaughtered cattle (1994 to 2010) and tuberculin skin tests (TST) in 2853 cattle (84 herds) of 39 livestock rearing communities were analysed. Of 129 165 slaughtered cattle inspected, 599 (0.46%; 95% CI: 0.43%&amp;ndash;0.50%) showed suspected TB lesions among a total of 983 (0.76%; 95% CI: 0.71%&amp;ndash;0.81%) identified pathologies. The monthly TB detection rates ranged from 0.30% (95% CI: 0.20%&amp;ndash;0.40%) to 0.81% (95% CI: 0.64%&amp;ndash;0.98%) and annual rates from 0.04% (95% CI: 0%&amp;ndash;0.11%) to 1.46% (95% CI: 1.22%&amp;ndash;1.69%). The rates were not affected (P &amp;lt; 0.05) by season and fluctuating peaks were also recorded. The comparative TST revealed that bovine TB was widely distributed in live cattle (4.67%; 95% CI: 3.89%&amp;ndash;5.44%) and was higher (&amp;chi;&lt;sup&gt;2&lt;/sup&gt; = 17.50, P &amp;le; 0.001) in the Western highlands than Adamawa plateaux. Comparative TST bovine TB reactors were higher (P &amp;lt; 0.05) in cattle managed in semi-intensive and beef production systems compared to the others. Animals in small herds showed higher (&amp;chi;&lt;sup&gt;2&lt;/sup&gt; = 4.283, P = 0.038) rates than those in large herds. Bovine TB prevalence in exotic/upgraded cattle was comparable to that of the Red Bororo zebu but higher than the rates in Guadali (&amp;chi;&lt;sup&gt;2&lt;/sup&gt; = 4.971, P = 0.026) and White Fulani (&amp;chi;&lt;sup&gt;2&lt;/sup&gt; = 5.6, P = 0.018) zebus. Among the indigenous zebus, the rate was higher in Red Bororo than the Guadali (&amp;chi;&lt;sup&gt;2&lt;/sup&gt; = 6.244, P = 0.012) and White Fulani (&amp;chi;&lt;sup&gt;2&lt;/sup&gt; = 6.568, P = 0.010). Sex did not influence (&amp;chi;&lt;sup&gt;2&lt;/sup&gt; = 0.410, P = 0.522) bovine TB prevalence in this study but diagnosis of the disease was higher (&amp;chi;&lt;sup&gt;2&lt;/sup&gt; = 5.787; P = 0.016) among adult/older cattle than in younger animals. Further analysis of the TST responses revealed that atypical mycobacterial infections was widespread and 6.83% of tested animals showed positive reactions at both bovine and avian tuberculin injection sites and a strong association (&amp;chi;&lt;sup&gt;2&lt;/sup&gt; = 2.512; P = 0.113) between skin responses to both tuberculins. The study confirms that bovine TB is prevalent in live cattle and meat production abattoirs in Cameroon and we recommend strict a interpretation of TST results for maximum diagnosis of the disease in the local environment. A need for comprehensive investigation of the molecular epidemiology, zoonotic risks and the public health importance of bovine TB in Cameroon cannot be overemphasised.

Interpretation of Tuberculin Skin Testing in Children vaccinated with BCG

Interpretation of Tuberculin Skin Testing in Children vaccinated with BCG

Tuberculin Skin-Test Reactions Are Unaffected by the Severity of Hyperendemic Intestinal Helminth Infections and Co-Infections

The tuberculin skin test (TST) quantifies cell-mediated immunity to tuberculosis antigens. Helminths suppress cell-mediated immunity, so we studied the effect of helminth infection and deworming on the TST in a randomized, double-blind, placebo-controlled study in an indigenous Amazon community (N = 195). Stool microscopy diagnosed helminths in 98% and co-infection with multiple species in 24% of study subjects. The TST was positive (> or = 10 mm) for 49%, and responses increased with age (P < 0.001), Bacille Calmette Guerin (BCG) vaccination (P = 0.01), and tuberculosis contact (P = 0.05). TST results had no association with helminth-egg concentrations, species, or co-infections (all P > 0.1). One month after deworming with albendazole (three daily 400-mg doses), helminths were reduced, but 63% remained infected with helminths. Albendazole did not cause a change in TST size (P = 0.8) or positivity (P = 0.9) relative to placebo. Thus, TST reactions were unaffected by albendazole therapy that partially cured intestinal helminth infections, and TST interpretation was unaffected by high-burden helminth infections and co-infection with multiple helminth species.

Use of T Cell–Based Diagnosis of Tuberculosis Infection to Optimize Interpretation of Tuberculin Skin Testing for Child Tuberculosis Contacts

Treatment of recent tuberculosis infection in children aged <2 years is essential, because of high risk of progression to disease, but diagnosis is hindered by the inaccuracy of the tuberculin skin test (TST). More-accurate T cell-based tests of infection could enhance diagnosis by optimizing interpretation of the TST results. A total of 979 child tuberculosis contacts in Istanbul underwent the TST and enzyme-linked immunospot assay. Using enzyme-linked immunospot test results as a reference standard, we assessed the effect of age and bacille Calmette-Guérin (BCG) vaccination on the sensitivity and specificity of the TST, and we computed the optimal TST cutoff points, using receiver operating characteristic curves. With a TST cutoff point of >or=10 mm, the sensitivity of the TST was 66% for children aged <2 years, which was lower than that for older children (P= .006). Specificity was 75% for BCG-vaccinated children, compared with 92% for unvaccinated children (P= .001). Optimal cutoff points improved TST specificity for children with 1 BCG scar, with little loss of sensitivity. Despite the use of optimal cutoff points, TST sensitivity remained <70% for children aged <2 years, specificity remained <87% for BCG-vaccinated children aged >or=2 years, and overall accuracy was low for children with >1 BCG scar. Negative results of the TST cannot exclude tuberculosis infection for child tuberculosis contacts aged <2 years, which supports the use of preventive therapy regardless of the TST results for this age group. In children aged >or=2 years, the accuracy of the TST can be improved by adjustment of cutoff points for BCG-vaccinated children but remains poor for children with >1 BCG scar. This methodology can define optimal TST cutoff points for diagnosis of tuberculosis infection tailored to target populations.

The effects of sex and age on phytohaemagglutinin skin-testing of deer

AIM: To determine if there are sex- or age-related differences in the increase in skinfold thickness in response to the mitogen phytohaemagglutinin (PHA) in red deer. METHODS: One dose of 250 µg PHA was injected intradermally in the right side of the neck, and phosphate buffered saline (PBS) was injected at a second site as a control, in 110 (51 males and 59 females) captive Iberian red deer (Cervus elaphus hispanicus), ranging in age from 21 months to a5 years. Skinfold thicknesses were measured immediately before and 72 h following injection. RESULTS: There was a significant effect of gender on the average increase in skinfold thickness; males had greater increases (8.8 (SEM 0.57) mm) than females (4.23 (SEM 0.39) mm) after correcting for other confounding variables. No age-related differences were evident, but differences between sexes were more marked with increasing age. CONCLUSIONS AND CLINICAL RELEVANCE: Effects of gender, probably due to differences in energetic and reproductive constraints in red deer, should be taken into account when interpreting skinfold-test data, both in ecology and in the control of tuberculosis (Tb). Males tend to have a thicker skin than females, so skinfold increase relative to the thickness of the skin, rather than skinfold increase per se, should be used as a more appropriate measure of skinfold increase. This may also have clinical relevance in the interpretation of tuberculin skin testing.

Tuberculin Skin Test Reaction and Body Mass Index in Old Age Home Residents in Hong Kong

To study the relationship between body mass index (BMI) and tuberculin skin test (TST) reaction in predicting the development of active tuberculosis (TB). A follow-up study. Old age homes. Three thousand six hundred five residents who took part in a screening program for TB and had two-step TST using two units of the tuberculin PPD-RT23. Rate of development of active TB in these residents over an average follow-up period of 2.5+/-1.25 years. After one-step and two-step testing, 46.3% and 69.6% of residents, respectively, had positive TST reactions (> or =10 mm). Thirty-four residents developed active TB (323 per 100,000 person-years) during follow-up. The only significant risk factors associated with development of active TB were positive TST according to one-step testing (adjusted odds ratio (OR)=2.91, 95% confidence interval (CI)=1.26-6.74) and a BMI less than 18.5 (adjusted OR=3.15, 95% CI=1.45-6.86). Residents with a BMI less than 18.5 and a negative TST also had greater risk of active TB than residents with a BMI greater than 18.5 and negative TST (adjusted OR=4.36, 95% CI=1.04-18.3), whereas those with a positive TST had the highest risk (adjusted OR=10.2, 95% CI=2.63-39.4). Two-step testing increased the sensitivity but reduced the specificity of TST in identifying active TB on follow-up. In the elderly population, interpretation of TST should take into consideration the BMI of the individual. A positive TST according to one-step but not two-step testing was useful in predicting the development of active TB on follow-up.

Medical Pearl: Interpretation of tuberculin skin tests in patients who have received the BCG vaccine

Medical Pearl: Interpretation of tuberculin skin tests in patients who have received the BCG vaccine

The utility and interpretation of tuberculin skin tests in the Middle East

Tuberculin skin test (TST) interpretation can be confounded by Bacillus Calmette-Guerin (BCG) vaccination and infection with nontuberculosis mycobacteria (NTM). However, a wealth of epidemiologic information has allowed the formulation of recommendations for reasonably informed interpretation of the TST in most clinical situations. In the Middle East, the TST remains a useful test. BCG vaccination is given at birth, which should have minimal effect on TST reactions in adolescents or adults. In countries of the Middle East with moderate to high incidence of active smear-positive pulmonary TB (>20 per 100,000 per year), a positive TST will almost always indicate true TB infection. However, in Middle East countries with very low incidence of active TB (<10 per 100,000 per year), a positive TST will more likely be false positive because BCG vaccination is still routinely given; until BCG vaccination is abandoned, the TST will be less useful in these countries. These findings are applicable to countries in other regions of the world, and the utility TST will also be increased where the likelihood of TB infection is higher and lowered where TB infection is unlikely, yet BCG vaccination is still given.

The influence of BCG immunisation on tuberculin reactivity and booster effect in adults in a country with a high prevalence of tuberculosis

The relationship of age and previous BCG vaccination with tuberculin skin test (TST) reactivity was investigated to assess the interpretation of TST results in the adult population of Turkey, where there is a high prevalence of tuberculosis and a routine BCG vaccination programme. The influences of age and BCG vaccine status on booster reaction were also evaluated. TST was applied (5 tuberculin units of purified protein derivative intradermally) to two healthy adult groups, namely 98 medical students and 187 elderly people in a retirement home. The TST was considered positive if an induration > or = 10 mm in diameter was produced. Subjects (41 elderly people and 39 students) with a reaction < 10 mm in diameter were retested 1 week later. There was no significant difference between the students (59.1%) and elderly subjects (58.8%) with respect to positive TST response. No influence of BCG scars on TST reactivity was observed in either group. The booster effect was seen more commonly in the elderly, but the presence of a BCG scar did not influence the booster effect in either group. It was concluded that a positive TST response and booster reaction in adults in high-prevalence countries may be caused by latent tuberculosis rather than previous vaccination.

Estudio de la infección tuberculosa en una zona de gran incidencia de tuberculosis y con un elevado porcentaje de inmigrantes

Historically the district of Ciutat Vella in Barcelona has a high incidence of tuberculosis (TB) and, more recently, it is home to a considerable proportion of immigrants. To determine the prevalence of tuberculous infection (TI) in a pediatric population from this district and evaluate the impact of immigration. Children and adolescents aged < 16 years old were screened using the tuberculin skin test (TST) mainly in visits of the healthy child program. Proportions were compared using the x2 test and adjusted odds ratios were estimated through a logistic regression model. Six hundred ninety-nine children were studied. The overall prevalence of positive TST was 3.4 % (95 % CI: 2.2 %-5.1 %). Prevalence increased with age (P 5 0.009) from 1.9 % in children aged 1-5 years old to 6.4 % in children and adolescents aged 10-15 years. A total of 88.3 % of the immigrants had been vaccinated with BCG compared with 2.5 % of autochthonous children and adolescents (P < 0.001). The prevalence ratio between immigrants and autochthonous children was 2.1 (P 5 0.07). Three cases of TB disease were detected among children, but no index case was found in children with TI. The high TI prevalence found suggest that living in the district is a risk factor, which justifies routine TST screening of all the children living there. The present criteria for the interpretation of TST in immigrants vaccinated with BCG residing in areas of high incidence are dubious.

Improving compliance with tuberculin skin test interpretation in children

Abstract Objective To evaluate the effect of a quality improvement initiative which utilized educational interventions combined with a phone follow‐up program on the rate of return for tuberculin skin test (TST) interpretation. Design Before and after trial with analysis of practice records for all TSTs placed. Setting/Sample The study was conducted in a resident and attending primary care practice in an urban children's hospital. All children (n = 1315) who had TSTs placed during August and October of 1995 and August and October of 1996 were included in the study. Intervention Medical staff were re‐educated regarding TST screening. Patients families were given written information about tuberculosis. Physicians and nursing staff discussed TST screening with the patients' families prior to TST placement. All patients received a series of three reminder telephone calls on three consecutive days to remind them to return for TST interpretation followed by a letter if necessary. The following data were collected: date of birth, age, zip code, type of provider, transit time from the hospital, type of health insurance, number of telephone calls made, and return status for TST interpretation. Return rates were compared pre‐ and post‐intervention. Results A total of 1315 TSTs were placed during the pre‐ (n = 611) and post‐(n = 704) intervention periods. Return rates increased from 6.2 to 61.5%. Attendings' patients and those with private insurance were more likely to return. There was no relationship to season, age or distance from the practice. Conclusions Targeted screening programs utilizing more effective methods for TST interpretation should be considered.