Baseline Tuberculin Skin Test Research Articles

Year in review 2012: Lung cancer, respiratory infections, tuberculosis, pleural diseases, bronchoscopic intervention and imaging

This Year in Review series addresses the most relevant articles published in Respirology and other respiratory medicine journals during 2012 concerning five specific areas that we consider to be of importance to practicing pulmonologists, namely lung cancer, respiratory infections, tuberculosis (TB), pleural diseases, and interventional pulmonology and imaging. Some important findings that will be commented on more in depth are that: 1) screening for lung cancer using low-dose computed tomography (CT) in high risk populations is promising, although not firmly established, 2) an enhanced CURB (which stands for confusion, urea, respiratory rate, blood pressure) score as well as the Japanese A-DROP (age, dehydration, respiratory failure, orientation disturbance, and pressure) prognostic scale are as accurate as the pneumonia severity index (PSI) scoring system to predict mortality in patients with community-acquired pneumonia (CAP), 3) randomized trials are urgently needed to optimize multidrug-resistant (MDR)-TB treatment, 4) the use of video-assisted thoracoscopic surgery (VATS) to quantify pleural tumor burden and, if feasible, perform an intrathoracic cytoreduction in patients with malignant effusions secondary to ovarian cancer (OC) may have a significant impact on further patient management plans, and 5) respiratory endoscopy and its different diagnostic and therapeutic modalities, is a safe procedure with overall complication rates less than 1%.

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.

Tuberculin skin test conversion among health sciences students: A retrospective cohort study

Previous studies have reported that health sciences students are at greater risk for tuberculosis infection, especially in developing countries. The objective of this study was to estimate the prevalence, incidence, and factors associated with latent tuberculosis infection among Health Sciences students in Peru. Students enrolled at private university (in Lima-Peru) are tested annually for tuberculosis infection by tuberculin skin test. Data on tuberculin skin test results between 2002 and 2009 was used in this retrospective cohort study, a total of 4842 students were included. Tuberculin skin test conversion was defined as the change of tuberculin skin test from negative (<10 mm) to positive (≥10 mm) after 48-72 h of inoculation. Baseline tuberculin skin test positivity was 1.0% (95%CI: 0.6%-1.3%), whereas tuberculin skin test conversion incidence was 12.4 per 100 person-years (95%CI: 11.8-13.0). This study showed that students from clinical careers in close contact with patients had an increased risk of tuberculosis infection in the internship, especially Medicine, Dentistry, Medical Technology and Nursing. Administrative, environmental and personal protection measures should be implemented and evaluated periodically in order to reduce the risk of exposure.

Conversion rates of an interferon-γ release assay and the tuberculin skin test in the serial monitoring of healthcare workers

Regular monitoring of latent tuberculosis (TB) infection in healthcare workers (HCWs) is recommended, but the view about the effective method and performance of serial monitoring is controversial. The aim of this study was to determine differences in conversion rates according to TB exposure risk using the tuberculin skin test (TST) and the QuantiFERON-TB Gold In-Tube (QFT-GIT), and to evaluate the reproducibility and within-subject variability of the QFT-GIT in South Korea. Fifty-three HCWs were grouped according to their risk for TB exposure: group 1, high risk (n = 21); group 2, low risk (n = 32). Baseline and follow-up TSTs and QFT-GITs were performed from June 2009 to July 2011. Enzyme-linked immunosorbent assays (ELISAs) were repeated for the second QFT-GIT and a third QFT-GIT was performed after 8 weeks when discordant results of the second TST and QFT-GIT or a conversion or reversion were observed. No difference in the QFT-GIT conversion rate was evident between the two groups (15.4 vs. 6.5 %, p = 0.57), and no TST conversion was observed. The rate of QFT-GIT positivity was higher in the high-risk group (first QFT-GIT: 38.1 vs. 3.1 %, p = 0.002; second QFT-GIT: 33.3 vs. 9.4 %, p = 0.039). The re-test reproducibility of QFT-GIT results was high (100 %), and the within-subject results of repetitive QFT-GITs were variable. Stricter prevention strategies remain necessary in HCWs at high risk of TB exposure, and serial interferon-γ release assays (IGRAs) should be interpreted with caution in HCWs.

An Outbreak of Tuberculosis Among Adults With Mental Illness

An Outbreak of Tuberculosis Among Adults With Mental Illness

Risk factors for tuberculin skin test conversion among HIV-infected patients in New York City

We assessed the incidence of and risk factors for tuberculin skin test (TST) conversion among HIV-infected adults at a New York City clinic. All adult HIV-infected patients were eligible for inclusion if they had a negative baseline TST result and at least one subsequent documented TST test result. A total of 414 HIV-infected patients had a negative baseline TST result; 288 (69.6%) were male. Among 348 patients who had a place of birth documented, 50% were born outside of mainland USA. Twenty-two (5.3%) of 414 patients had documented TST conversions, giving a crude incidence rate of 1.77 per 100 person-years. Being a foreign-born Asian individual (p=0.02), having lived in a shelter (p=0.004), and having an increase in CD4 cell count (p=0.02) while under care were independent risk factors for TST conversion. We found a high TST conversion rate among HIV-infected patients attending an urban clinic. Annual TST testing is particularly important for patients who are foreign-born from high-endemic countries, those with a history of homelessness, and those with an increase in CD4 cell count since the baseline negative TST test.

Predictive value of latent tuberculosis tests in Indian healthcare workers: a cohort study

To the Editors: Healthcare workers (HCWs) in high tuberculosis (TB)-burden countries are known to have a substantially higher risk of latent TB infection (LTBI) and TB disease [1], and this has been demonstrated repeatedly in India [2, 3]. Several studies have evaluated interferon-γ release assays (IGRAs) in HCWs [4], but no study has reported the predictive value of IGRAs in this population of HCWs at risk for TB exposure. Between January and June 2004, we had performed a cross-sectional comparison of the tuberculin skin test (TST) (1 tuberculin unit of purified protein derivation RT23) and QuantiFERON®-TB Gold In-Tube (QFT; Cellestis Ltd, Melbourne, Australia) in a cohort of 726 HCWs (719 had valid test results for both tests) at the Mahatma Gandhi Institute of Medical Sciences (Sevagram, India), with young trainees making up half the cohort [5]. A total of 360 (50%) HCWs were found to be positive using either the TST or QFT assay at baseline, and 226 (31%) were found to be positive using both tests. The prevalence estimates of TST and QFT positivity were comparable, with high concordance between test results [5]. Although isoniazid preventive therapy (IPT) was offered to HCWs with positive baseline TST or QFT results, only a small proportion had completed INH therapy. In 2010, ∼6 yrs after …

Longitudinal Analysis of QuantiFERON-TB Gold In-Tube in Children with Adult Household Tuberculosis Contact in South Africa: A Prospective Cohort Study

BackgroundQuantiFERON-TB Gold In Tube (QFT-GIT) is a tool for detecting M. tuberculosis infection. However, interpretation and utility of serial QFT-GIT testing of pediatric tuberculosis (TB) contacts is not well understood. We compared TB prevalence between baseline and 6 months follow-up using QFT-GIT and tuberculin skin testing (TST) in children who were household contacts of adults with pulmonary TB in South Africa, and explored factors associated with QFT-GIT conversions and reversions.MethodProspective study with six month longitudinal follow-up.ResultsAmong 270 enrolled pediatric contacts, 196 (73%) underwent 6-month follow-up testing. The 6-month prevalence estimate of MTB infection in pediatric contacts increased significantly from a baseline of 29% (79/270, 95%CI [24–35]) to 38% (103/270, 95% CI [32–44], p<0.001) using QFT-GIT; prevalence increased from a baseline of 28% (71/254, 95%CI [23–34]) to 33% (88/263, 95%CI [21–32], p = 0.002) using TST. Prevalence estimates were influenced by thresholds for positivity for TST, but not for QFT-GIT. Among 134 children with a negative or indeterminate baseline QFT-GIT, 24 (18%) converted to positive at follow-up; conversion rates did not differ significantly when using more stringent thresholds to define QFT-GIT conversion. Older age >10 years (AOR 8.9 95%CI [1.1–72]) and baseline TST positivity ≥5 mm (AOR 5.2 95%CI [1.2–23]) were associated with QFT-GIT conversion. Among 62 children with a positive baseline QFT-GIT, 9 (15%) reverted to negative; female gender (AOR 18.5 95%CI [1.1–321]; p = 0.04] was associated with reversion, while children with baseline positive TST were less likely to have QFT-GIT reversion (AOR 0.01 95%CI [0.001–0.24]).ConclusionAmong pediatric contacts of adult household TB cases in South Africa, prevalence estimates of TB infection increased significantly from baseline to 6 months. Conversions and reversions occurred among pediatric TB contacts using QFT-GIT, but QFT-GIT conversion rates were less influenced by thresholds used for conversions than were TST conversion rates.

Biphasic emergence of active tuberculosis in rheumatoid arthritis patients receiving TNFα inhibitors: the utility of IFNγ assay

ObjectivesThe risk of active tuberculosis increases in rheumatoid arthritis (RA) patients receiving antitumour necrosis factor alpha (TNFα) therapy. Longitudinal data concerning serial interferon γ (IFNγ) assays for detecting tuberculosis have...

Disseminated tuberculosis in human immunodeficiency virus infection: ineffective immunity, polyclonal disease and high mortality.

Disseminated tuberculosis (TB) is a major cause of death in patients with the acquired immune-deficiency syndrome (AIDS), but its pathogenesis and clinical features have not been defined prospectively. Human immunodeficiency virus (HIV) infected adults with a CD4 count ≥ 200 cells/μl and bacille Calmette-Guérin scar underwent immunologic evaluation and subsequent follow-up. Among 20 subjects who developed disseminated TB, baseline tuberculin skin tests were ≥15 mm in 14 (70%) and lymphocyte proliferative responses to Mycobacterium tuberculosis were positive in 14 (70%). At the time of diagnosis, fever ≥2 weeks plus ≥5 kg weight loss was reported in 16 (80%) patients, abnormal chest X-rays in 7/17 (41%), and positive sputum cultures in 10 (50%); median CD4 count was 30 cells/μl (range 1-122). By insertion sequence (IS) 6110 analysis, 14 (70%) blood isolates were clustered and 3/8 (37%) concurrent sputum isolates represented a different strain (polyclonal disease). Empiric TB treatment was given to eight (40%) patients; 11 (55%) died within a month. Disseminated TB in HIV occurs with cellular immune responses indicating prior mycobacterial infection, and IS6110 analysis suggests an often lethal combination of reactivation and newly acquired infection. Control will require effective prevention of both remotely and recently acquired infection, and wider use of empiric therapy in patients with advanced AIDS and prolonged fever.

The Tuberculin Skin Test versus QuantiFERON TB Gold® in Predicting Tuberculosis Disease in an Adolescent Cohort Study in South Africa

SettingThis study was conducted in a high tuberculosis (TB) burden area in Worcester, South Africa, with a notified all TB incidence rate of 1,400/100,000.Main ObjectiveTo compare the predictive value of a baseline tuberculin skin test (TST) with that of the QuantiFERON TB Gold (In-tube) assay (QFT) for subsequent microbiologically confirmed TB disease among adolescents.MethodsAdolescents aged 12–18 years were recruited from high schools in the study area. At baseline, blood was drawn for QFT and a TST administered. Participants were followed up for up to 3.8 years for incident TB disease (median 2.4 years).ResultsAfter exclusions, 5244 (82.4%) of 6,363 adolescents enrolled, were analysed. The TB incidence rate was 0.60 cases per 100 person years (pyrs) (95% CI 0.43–0.82) for baseline TST positive (≥5 mm) participants and 0.64 cases per 100 pyrs (95% CI 0.45–0.87) for baseline QFT positive participants. TB incidence rates were 0.22 per 100 pyrs (0.11–0.39) and 0.22 per 100 pyrs (0.12–0.38) among those with a negative baseline TST and QFT respectively. Sensitivity for incident TB disease was 76.9% for TST and 75.0% for QFT (p = 0.81). Positive predictive value was 1.4% for TST and 1.5% for QFT.ConclusionPositive TST and QFT tests were moderately sensitive predictors of progression to microbiologically confirmed TB disease. There was no significant difference in the predictive ability of these tests for TB disease amongst adolescents in this high burden setting. Therefore, these findings do not support use of QFT in preference to TST to predict the risk of TB disease in this study population.

Serial testing with the interferon-γ release assay in Portuguese healthcare workers

ObjectivesEvidence for the utility of the new Mycobacterium tuberculosis (MTB) specific IFN-γ release assays in diagnosing latent tuberculosis infection (LTBI) is growing. However, data concerning conversion and reversion rates in serial testing of healthcare workers (HCWs) with an interferon-γ release assay are sparse.MethodsBetween February 2007 and September 2009, 670 HCWs in the University Hospital of Porto, Portugal were tested at least twice with QuantiFERON-TB® Gold In-Tube (QFT) for LTBI. The tuberculin skin test (TST) was performed simultaneously. QFT was considered positive if INF-γ ≥0.35 IU/mL. TST conversion was defined as an increase ≥10 or ≥6 mm compared to a baseline TST <10 mm.ResultsThe second QFT was positive in 4.8% of the 376 HCWs with an INF-γ concentration at baseline below 0.1 IU/mL but in 48.8% of the 41 HCWs with an INF-γ concentration of 0.2 to <0.35 IU/mL. Out of 74 HCWs with a baseline INF-γ concentration ≥3.0 IU/mL, 4 (5.4%) reversed while 27 out of 55 HCWs (49%) with a baseline INF-γ concentration ≥0.35 to <0.7 IU/mL reversed to a negative QFT. Those 61 HCWs with TST conversion (increase ≥10 mm) were most often (78.7%) negative in both consecutive QFTs.ConclusionOur data suggests the use of an uncertainty zone between 0.2 and 0.7 IU/mL in serial testing with QFT. As long as the knowledge regarding disease progression in QFT-positive persons is limited, persons pertaining to this zone should be retested before being offered preventive chemotherapy.

Referrals for positive tuberculin tests in new health care workers and students: a retrospective cohort study

BackgroundDocumentation of test results for latent tuberculosis (TB) infection is important for health care workers and students before they begin work. A negative result provides a baseline for comparison with future tests. A positive result affords a potential opportunity for treatment of latent infection when appropriate. We sought to evaluate the yield of the referral process for positive baseline tuberculin tests, among persons beginning health care work or studies.MethodsRetrospective cohort study. We reviewed the charts of all new health care students and workers referred to the Montreal Chest Institute in 2006 for positive baseline tuberculin skin tests (≥10 mm). Health care workers and students evaluated for reasons other than positive baseline test results were excluded.Results630 health care students and workers were evaluated. 546 (87%) were foreign-born, and 443 (70%) reported previous Bacille Calmette-Guérin (BCG) vaccination. 420 (67%) were discharged after their first evaluation without further treatment. 210 (33%) were recommended treatment for latent TB infection, of whom 165 (79%) began it; of these, 115 (70%) completed adequate treatment with isoniazid or rifampin. Treatment discontinuation or interruption occurred in a third of treated subjects, and most often reflected loss to follow-up, or abdominal discomfort. No worker or student had active TB.ConclusionsOnly a small proportion of health care workers and students with positive baseline tuberculin tests were eligible for, and completed treatment for latent TB infection. We discuss recommendations for improving the referral process, so as to better target workers and students who require specialist evaluation and treatment for latent TB infection. Treatment adherence also needs improvement.

Annual Incidence of Latent Tuberculosis Infection among Newly Employed Nurses at a Tertiary Care University Hospital

To investigate the annual rate of tuberculosis (TB) infection among newly employed nurses using both tuberculin skin test (TST) and QuantiFERON-TB Gold (QFT-G; Cellestis Limited) assay. A prospective cohort study involving newly employed nurses. A tertiary care university hospital in South Korea. All participants (n = 196) were tested with the TST and QFT-G assay at baseline. After 1 year, the TST and QFT-G assay were reperformed for subjects who had negative TST results at baseline and for all subjects, respectively. The baseline TST and QFT-G assays were positive for 101 subjects (51.5%) and 28 subjects (14.3%), respectively; 22 subjects (11.2%) had positive results of both tests. Although the overall between-test agreement was 54.9% (k = 0.151) [95% confidence interval, 0.047-0.245]), agreement improved to 78.5% (k = 0.462 [95% confidence interval, 0.007-0.917]) for subjects who had not received bacille Calmette-Guérin vaccination. After 1 year, the TST yielded positive results for 16 (21.3%) of 75 nurses with negative baseline results, and the QFT-G assay yielded positive results for 21 (14.4%) of 146 subjects with negative baseline results. Collectively, 5 subjects (3.0%) experienced conversion to positive results with both tests, and 32 subjects (18.9%) experienced conversion to positive results with one of the tests. Neither the employing hospital department nor exposure to patients with TB affected test conversion status. The poor overall agreement between TST and QFT-G results may have been caused by the confounding effect of bacille Calmette-Guérin vaccination. The annual risk of TB infection among newly employed nurses was at least 3% on the basis of results of both the TST and QFT-G test. Stricter preventive strategies against TB spread should be implemented in our hospital.

Serial interferon-gamma release assays after rifampicin prophylaxis in a tuberculosis outbreak

Even though some studies have reported the results of serial interferon-gamma release assays (IGRAs) during isoniazid prophylactic treatment, serial results have not been reported after rifampicin prophylaxis. A contact investigation was conducted after a tuberculosis (TB) outbreak in an accommodation facility. The tuberculin skin test (TST) and the QuantiFERON-TB Gold In-Tube (QFT-GIT) test were performed in 214 contacts with normal chest radiographs. Rifampicin prophylaxis was initiated in TST+/QFT-GIT+ subjects, and the QFT-GIT test was repeated upon completion of 4 months of rifampicin treatment. Among the 214 contacts, the TST and QFT-GIT test results were positive in 67.7% and 56.7%, respectively, and the agreement between the two tests was fair-to-good (78.3%, kappa=0.55, p<0.001). The QFT-GIT test was positive in 77% (97/126) of contacts with positive TST results. Rifampicin prophylaxis was completed in 81 subjects with good compliance. Among 74 subjects with valid serial QFT-GIT test results, IFN-gamma levels decreased in 97.3% (72/74) of the subjects and QFT-GIT test reversion (positive to negative) was achieved in 31 subjects (41.9%). Subjects without QFT-GIT test reversion had a significantly higher baseline TST induration sizes (18.3+/-4.8 vs. 14.9+/-3.4mm, p<0.01) and IFN-gamma levels (18.6+/-17.9 vs. 3.2+/-7.5IU/mL, p<0.01) than the subjects with QFT-GIT test reversion. Thus, IGRAs may be useful in evaluating the therapeutic response to rifampicin prophylaxis in TB contacts. However, considering that this was not a controlled study, a prospective controlled study is needed to determine whether rifampicin prophylaxis truly affects QFT-GIT reversion.

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.

Interpretation of repeat tuberculin skin testing in international adoptees: conversions or boosting.

Internationally-adopted children are a unique group of Bacille Calmette-Guérin (BCG)-vaccinated children with high rates of latent tuberculosis infection (LTBI) in whom serial tuberculin skin tests (TST) are recommended. No study has measured the incidence of TST conversion in these children. Internationally-adopted children completed baseline and follow-up TST to measure the incidence of Mycobacterium tuberculosis infection and factors associated with TST conversion. Data were collected regarding age, gender, birth country, vaccination history, history of tuberculosis (TB) exposure, previous TB screening, and preadoptive environment. All children completed physical examinations including a standardized evaluation for TB, anthropometric assessment, and documentation of BCG scar. Fourteen percent of children (N = 390) had evidence of LTBI at baseline. Children were more likely to have LTBI if they were older, BCG vaccinated, or had been in the United States longer. An additional 13% of children had TST indurations > or = 10 mm at follow-up testing. Regardless of BCG vaccination status or nutritional status, children who were younger at baseline were more likely to have a TST induration > or = 10 mm at follow-up. International adoptees have significant risk of LTBI. Although our findings suggest that recent infection with M. tuberculosis led to TST conversion in some children, the increase in follow-up TST induration could also be attributed to TST boosting resulting from prior BCG vaccination. When serial TST testing is completed in young, BCG-vaccinated children, interpretation of the follow-up TST should consider baseline TST results.

Boosted Reaction on Two-Step Tuberculin Skin Test among Military Personnel in South Korea, a Setting with an Intermediate Burden of Tuberculosis and Routine Bacille Calmette-Guérin Vaccination

This study was performed to estimate the rate of boosted reaction in the two-step tuberculin skin test (TST) and to evaluate the associated factors among military personnel of South Korea, which has an intermediate burden of tuberculosis (TB) and a routine bacille Calmette-Guérin (BCG) vaccination policy. Two-step TST was performed on 264 military personnel who did not have a history of close contact to TB. Subjects with a negative reaction to the first test of <10 mm had a second TST applied 1 week later on the other forearm. A positive result (≥10 mm) on the initial TST was observed in 126 (48%) of the subjects. A boosted reaction on the second TST developed in 32 (23%) of the 124 subjects with a negative initial TST. In multiple logistic regression analysis, the size of the initial TST reaction was the only factor associated with a boosted reaction on the second TST. The high rate of boosted reaction among healthy adults in South Korea suggests that two-step TST should be performed to assess the baseline TST reactivity in settings with an intermediate burden of TB and routine BCG vaccination policy, especially among subjects with an initial TST reaction that is ≥5 mm.

Healthcare Worker-Related Tuberculosis Exposure

ISSUE: Boston Medical Center (BMC) is a 547-bed urban teaching hospital. On 6/3/05, the Boston Public Health Commission (BPHC) identified a healthcare worker (HCW) whose sputum was positive for acid fast bacillus (AFB). The HCW was immediately removed from patient care duties and empiric therapy with 4 drugs was initiated. The organism was identified as Mycobacterium tuberculosis on 6/13/05. PROJECT: BPHC determined that the HCW was potentially infectious from 12/1/04 until 6/2/05. During that time, the HCW performed clinical duties at 4 hospitals in MA. In collaboration with the MA Department of Public Health and the Centers for Diseases Control and Prevention, BPHC developed a contact investigation protocol. All institutions used the same exposure definitions and dates to identify potentially exposed patients and HCW. Data from all 4 institutions were entered into a shared database that was managed by BPHC. Within the next 6 weeks, all potentially exposed HCW had mandatory baseline tuberculin skin tests (TST) or symptom screen. Patients were offered free screening. Anyone whose last potential exposure occurred within 3 months of the baseline test was re-screened beginning in September 2005. At BMC, anyone with a positive TST or symptom screen was referred to the on-site Tuberculosis (TB) Clinic for evaluation. RESULTS: As of 12/15/05, 1514 patients, 1482 HCW had been screened at BMC. BPHC identified a small number of potentially exposed patients and HCW who met the definition for TST conversion and had no other identified risk factors. No patient or HCW developed active disease. LESSONS LEARNED: A TB exposure occurred despite having the following systems to prevent transmission of contagious infectious diseases in the workplace. 1. All HCW and students must have a baseline two-step TST upon hire and at least annually thereafter. 2. HCW with a positive TST must have a symptom screen and CXR. 3. HCW with symptoms or positive CXR are removed from patient care until evaluated by a healthcare provider with expertise in TB. 4. HCW must provide documentation of evaluation prior to being cleared for return to work. The ongoing challenge is to identify effective systems to facilitate early identification and treatment of potentially infectious HCW to prevent similar exposures in the future.

The Importance of Two-Step Tuberculin Skin Testing for Newly Employed Healthcare Workers

At the time of hire, 4059 of 6522 healthcare workers required a 2-step tuberculin skin test; 114 workers (2.8%) demonstrated a boosted reaction after the second step. Boosted reactions were significantly associated with male sex and older age. A verbal history of previous tuberculin skin test results was not a reliable indicator of baseline tuberculin skin test status at the time of hire.