Tuberculosis infection among health care workers in Montreal

Revisiting annual screening for latent tuberculosis infection in healthcare workers: a cost-effectiveness analysis

BACKGROUND

In North America, tuberculosis incidence is now very low and risk to healthcare workers has fallen. Indeed, recent cohort data question routine annual tuberculosis screening in this context. We compared the cost-effectiveness of three potential strategies for ongoing screening of North American healthcare workers at risk of exposure. The analysis did not evaluate the cost-effectiveness of screening at hiring, and considered only workers with negative baseline tests.

METHODS

A decision analysis model simulated a hypothetical cohort of 1000 workers following negative baseline tests, considering duties, tuberculosis exposure, testing and treatment. Two tests were modelled, the tuberculin skin test (TST) and QuantiFERON®-TB-Gold In-Tube (QFT). Three screening strategies were compared: (1) annual screening, where workers were tested yearly; (2) targeted screening, where workers with high-risk duties (e.g. respiratory therapy) were tested yearly and other workers only after recognised exposure; and (3) post exposure-only screening, where all workers were tested only after recognised exposure. Workers with high-risk duties had 1% annual risk of infection, while workers with standard patient care duties had 0.3%. In an alternate higher-risk scenario, the corresponding annual risks of infection were 3% and 1%, respectively. We projected costs, morbidity, quality-adjusted survival and mortality over 20 years after hiring. The analysis used the healthcare system perspective and a 3% annual discount rate.

RESULTS

Over 20 years, annual screening with TST yielded an expected 2.68 active tuberculosis cases/1000 workers, versus 2.83 for targeted screening and 3.03 for post-exposure screening only. In all cases, annual screening was associated with poorer quality-adjusted survival, i.e. lost quality-adjusted life years, compared to targeted or post-exposure screening only. The annual TST screening strategy yielded an incremental cost estimate of $1,717,539 per additional case prevented versus targeted TST screening, which in turn cost an incremental $426,678 per additional case prevented versus post-exposure TST screening only. With the alternate "higher-risk" scenario, the annual TST strategy cost an estimated $426,678 per additional case prevented versus the targeted TST strategy, which cost an estimated $52,552 per additional case prevented versus post-exposure TST screening only. In all cases, QFT was more expensive than TST, with no or limited added benefit. Sensitivity analysis suggested that, even with limited exposure recognition, annual screening was poorly cost-effective.

CONCLUSIONS

For most North American healthcare workers, annual tuberculosis screening appears poorly cost-effective. Reconsideration of screening practices is warranted.

Prevalence and associated risk factors of latent tuberculosis infection among undergraduate and postgraduate dental students: A retrospective study

To estimate the prevalence of latent tuberculosis (TB) infection (LTBI) in Italian dental students exposed to the same occupational risks as dental health care personnel and to evaluate potential risk factors, a cross-sectional study was conducted on undergraduate and postgraduate students. After clinical evaluation, students were given a tuberculin skin test; in those found positive, an interferon-γ release assay (IGRA) was conducted. Of the 281 students enrolled, 10 were only TST positive; 8 were TST or/and IGRA positive. We found that participants testing positive at TST and/or IGRA, a group in which the risk of false LTBI positives is minimal, were older and had been studying longer. Although the prevalence of LTBI among dental students in our study was low, a risk of acquiring a work-related infection exists even in a country with a low incidence of TB. Thus, dental students should be screened to catch LTBI early on.

Prevalência e fatores associados à infecção pelo Mycobacterium tuberculosis entre agentes comunitários de saúde no Brasil, usando-se a prova tuberculínica

Resumo Este artigo tem por objetivo determinar a prevalência e os fatores associados à infecção latente pelo Mycobacterium tuberculosis entre agentes comunitários de saúde (ACS), usando dois pontos de corte da prova tuberculínica 5mm e 10mm. Trata-se de estudo transversal, com dados coletados sobre sexo, idade, cicatriz de BCG, prova tuberculínica (PT) anterior, tempo que trabalha na profissão de ACS, atuar em unidade básica de saúde (UBS), ter tido contato intradomiciliar com tuberculose (TB), usar álcool, ser fumante e apresentar comorbidades. Para controle de variáveis de confusão e estimativa da medida de efeito (OR), foi empregada a regressão logística. Aplicou-se PT, com leitura após 48-72 horas. As prevalências foram de 57,88% e 37,3%, respectivamente, para 5mm e 10mm. Manteve-se associada à positividade para o ponto de corte de 10mm a condição de trabalhar em UBS com Programa de Controle de Tuberculose (PCT) implementado e já ter tido contato intradomiciliar com TB. Já para o ponto de corte de 5mm, trabalhar em UBS com PCT e implementado. São necessárias ações de conscientização nos municípios e fortalecimento das ações de educação permanente sobre a temática.

Evaluation of bioaerosol exposures during hospital bronchoscopy examinations

During hospital bronchoscopy examinations, aerosols emitted from the patient's during coughing can be found suspended in the ambient air. The aerosols can contain pathogenic microorganisms. Depending on their size, these microorganisms can remain in the air for a long time. The objective of this study was to measure the sizes and concentrations of the biological and non-biological particles produced during bronchoscopy examinations, and to propose preventive or corrective measures. Two bronchoscopy rooms were studied. An aerodynamic particle sizer (UV-APS) was used to establish the concentrations of the particles present and their size distributions. This instrument determines the aerodynamic diameter of the aerosols and can distinguish fluorescent (bioaerosols) and non-fluorescent particles. Reference concentrations were measured before the start of the examinations (morning background concentrations). They were used as comparison levels for the concentrations measured during and at the end of the bronchoscopies. In parallel, computational fluid dynamics (CFD) made it possible to isolate and understand different factors that can affect the concentration levels in bronchoscopy rooms. The concentrations of the non-fluorescent and fluorescent particles (bioaerosols) were significantly higher (p ≤ 0.05) during the bronchoscopy examinations than the reference concentrations. For the investigated factors, the bioaerosol concentrations were significantly higher during bronchoscope insertion tasks. The time required at the end of the day for the bioaerosols to reach the morning reference concentrations was about fifteen minutes. The average particle sizes were 2.9 μm for the fluorescent particles (bioaerosols) and 0.9 μm for the non-fluorescent particles. Our models based on computational fluid dynamics (CFD) enabled us to observe the behaviour of aerosols for the different rooms.

Prevalence of latent tuberculosis infection and associated risk factors among 3,374 healthcare students in Italy

Introduction

The risk of tuberculosis (TB) in healthcare personnel (HCP) is related to its incidence in the general population. Healthcare students involved in clinical training could be exposed to occupational risks similar to those that HCP face. The prevalence of latent tuberculosis infection (LTBI) among undergraduate healthcare students with different working seniority in Italy was analysed.

Methods

A cross-sectional study under a screening programme for LTBI among undergraduate and postgraduate students attending Medical School at the Second University of Naples was conducted between January 2012 and December 2013 with clinical evaluations, tuberculin skin testing (TST) and, in positive TST students, Interferon-γ release assays (IGRA). Putative risk factors for LTBI were assessed by means of a standardised questionnaire.

Results

3,374 students attending the Medical School of the Second University of Naples were submitted to a screening programme for TBC. 3,331 performed TST as a first-level test and 43 performed a Quantiferon test (QFT). 128 students were TST-positive and continued the diagnostic work with QFT, which was positive in 34 students. Of the 43 subjects who took the QFT as a first-level test only 1 was positive. In 35 students positive to the QFT test we formulated the diagnosis of LTBI by clinical and radiographic results. A correlation was found between age, non-Italian born persons, studying age, post-medical school status and LTBI.

Conclusions

The prevalence of LTBI among healthcare students in our study was very low. In countries with a low incidence of TB, the screening programmes of healthcare students can be useful for early identification and treatment of sporadic cases of LTBI.

Electronic supplementary material

The online version of this article (doi:10.1186/s12995-014-0034-5) contains supplementary material, which is available to authorized users.

Latent tuberculosis in nursing professionals of a Brazilian hospital

Tuberculosis (TB) is considered an occupational disease among health-care workers (HCWs). Direct contact with TB patients leads to an increased risk to become latently infected by Mycobacterium tuberculosis. The objective of this study is to estimate the prevalence of latent M. tuberculosis minfection among nursing professionals of a hospital in Rio Grande do Sul, Brazil, assessed by tuberculin skin test (TST). From November 2009 to May 2010, latent M. tuberculosis infection was assessed by TST in 55 nursing professionals. Epidemiological information was collected using a standardized questionnaire. A positive TST result (> or = 10 mm) was observed in 47.3% of the HCWs tested. There was no significant difference in TST positivity when duration of employment or professional category (technician or nurse) was evaluated. The results of this work reinforce the need for control measures to prevent latent M. tuberculosis infection among nursing professionals at the hospital where the study was conducted.

Manifestations of tuberculosis stigma within the healthcare system: the case of Sekondi-Takoradi Metropolitan district in Ghana

OBJECTIVES

To explore the manifestations of tuberculosis (TB) stigma within the healthcare system.

METHOD

Twenty-one individual interviews (16 females and 5 males) and six focus groups (1 with health managers, 1 with staff providing services for TB patients, and 4 with general staff) were conducted among healthcare workers (HCWs) and the generated data analysed using grounded theory principles and procedures.

RESULTS

TB stigma manifests in three broad and inter-related ways within the healthcare system: behaviour towards TB patients; attitudes towards TB work; and administrative procedures and policies of healthcare mangers. Healthcare workers expressed fear of infection when interacting with TB patients; a fear which intensifies after the confirmation of the diagnosis. For fear of infection, they shuned, avoided, and advocated the segregation of TB patients at home and in the hospitals. They sometimes maltreated the patients, and accused and blamed them for deliberately infecting others. Posting to TB units/wards is viewed as a punishment, with majority indicating refusal to work there or be trained as TB nurse/doctor. They maintained that those working at TB units should be given incentives. Health managers also situated TB units/wards in isolated parts of the hospital, and do not provide adequate tools, equipment, support and supervision for those offering TB services.

CONCLUSIONS

Fear of infection underlies the stigmatisation of TB by HCWs and worsen by administrative procedures and policies of healthcare managers. To help minimise TB stigma, a national guideline for the prevention of TB in HCWs should be developed as this may help protect them and alleviate their fear of infection. Rewarding and motivating HCWs involved in TB control may also improve their attitudes towards TB and those suffering from the disease. Furthermore, interventions to reduce TB stigma should be put in place, and the effects these may have on TB treatment outcomes investigated.

Occupational respiratory infections

PURPOSE OF REVIEW

In the last decade, descriptions of outbreaks of extensively drug-resistant strains of tuberculosis (TB) have increased concern about the nosocomial transmission of TB - a potentially life-threatening occupational respiratory infection. In addition, outbreaks of avian influenza caused by an H5N1 virus, severe acute respiratory syndrome caused by a coronavirus A and the recent pandemic caused by an H1N1 influenza virus have heightened concern about occupational infectious illnesses among workers in healthcare and agriculture.

RECENT FINDINGS

The last decade has witnessed extensive research into the modes, patterns, determinants and extent of transmission of these illnesses. The most important findings regarding risk, determinants and preventive measures of these occupational infections and recent guidelines are reviewed in this article.

SUMMARY

Administrative, personal and engineering measures to control respiratory infection are effective and should be implemented in healthcare facilities. The use of N95 personal respirators by healthcare workers who are caring for pulmonary TB and viral respiratory infections patients is strongly recommended. Vaccination against influenza (including H1N1) is effective and strongly recommended for healthcare workers. Ultraviolet germicidal irradiation is underused at present, despite good evidence of safety and efficacy in elimination of airborne respiratory infectious agents including TB.

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

BACKGROUND

Documentation 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.

METHODS

Retrospective 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 (> or =10 mm). Health care workers and students evaluated for reasons other than positive baseline test results were excluded.

RESULTS

630 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.

CONCLUSIONS

Only 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.

Are you prepared? Defining occupational health resource needs to prevent infectious disease transmission in the health care sector

This article discusses the extent of resource allocation to Occupational Health (OH) to prevent infectious disease exposure and transmission in British Columbia (B.C.). It also characterizes the delineation of roles and responsibilities within OH services in B.C. health care settings and highlights areas where improvements to current OH programs could be made to prevent and control occupational infections. Given the breadth of OH responsibilities, resource allocation in many health care institutions for these services is inadequate and roles and responsibilities may not be clearly delineated.

Prevalence of mycobacterium tuberculosis among professionals in a university hospital, Mato Grosso do Sul, 2004

Several studies have demonstrated an elevated prevalence amongst professionals of mycobacterium tuberculosis, both in the rate of infections and illness. This study was carried out in a School Hospital in Campo Grande, MS, Brazil, aiming to establish the prevalence of infection with Mycobacterium tuberculosis. The results of the analysis of 194 subjects showed an overall positivity for the tuberculin test of 38.7%. There was a correlation with smoking (p=0.01, RP=1. 72 (1.20-2.45- Yates's correction). The conclusion is that the establishment of a program of tuberculin screening jointly with the implementation of interventions is necessary in order to reduce the risk of nosocomial transmission.

Hospital and community acquired infection and the built environment--design and testing of infection control rooms

Negative-pressure isolation rooms are required to house patients infected with agents transmissible by the aerosol route in order to minimise exposure of healthcare workers and other patients. Housing patients in a separate room provides a barrier which minimises any physical contact with other patients. An isolation room held at negative pressure to reduce aerosol escape and a high air-change rate to allow rapid removal of aerosols can eliminate transmission of infectious aerosols to those outside the room. However, badly designed and/or incorrectly operating isolation rooms have been shown to place healthcare workers and other patients at risk from airborne diseases such as tuberculosis. Few standards are available for the design of isolation rooms and no pressure differential or air-change rates are specified. Techniques such as aerosol particle tracer sampling and computational fluid dynamics can be applied to study the performance of negative-pressure rooms and to assess how design variables can affect their performance. This should allow cost-effective designs for isolation rooms to be developed. Healthcare staff should be trained to understand how these rooms operate and there should be systems in place to ensure they are functioning correctly.

Development of an empirical model to aid in designing airborne infection isolation rooms

Airborne infection isolation rooms (AIIRs) house patients with tuberculosis, severe acute respiratory syndrome (SARS), and many other airborne infectious diseases. Currently, facility engineers and designers of heating, ventilation, and air-conditioning (HVAC) systems have few analytical tools to estimate a room's leakage area and establish an appropriate flow differential (DeltaQ) in hospitals, shelters, and other facilities where communicable diseases are present. An accurate estimate of leakage area and selection of DeltaQ is essential for ensuring that there is negative pressure (i.e., pressure differential [DeltaP]) between an AIIR and adjoining areas. National Institute for Occupational Safety and Health (NIOSH) researchers evaluated the relationship between DeltaQ and DeltaP in 67 AIIRs across the United States and in simulated AIIR. Data gathered in the simulated AIIR was used to develop an empirical model describing the relationship between DeltaQ, DeltaP, and leakage area. Data collected in health care facilities showed that the model accurately predicted the leakage area 44 of 48 times. Statistical analysis of the model and experimental validation showed that the model effectively estimated the actual leakage area from -39% to +22% with 90% confidence. The NIOSH model is an effective, cost-cutting tool that can be used by HVAC engineers and designers to estimate leakage area and select an appropriate DeltaQ in AIIRs to reduce the airborne transmission of disease.

Risk of tuberculin conversion among healthcare workers and the adoption of preventive measures

BACKGROUND

In industrialised countries, occupational tuberculosis among healthcare workers (HCWs) is re-emerging as an important public health issue. To prevent and control tuberculosis transmission, several institutions have issued and implemented recommendations and practice guidelines.

OBJECTIVES

To estimate the annual rate of tuberculosis infection (ARTI; per 100 person-years) among HCWs in Turin, the capital of the Piedmont region of Italy, to identify factors associated with variations in the ARTI and to evaluate the efficacy of the regional guidelines to prevent and control tuberculosis.

METHODS

The study was conducted between 1997 and 2004 on a cohort of HCWs. The tuberculosis infection was diagnosed through tuberculin skin testing (TST) conversion and defined as an induration increase of at least 10 mm from a previous negative TST. The ARTI and the hazard ratio for each at-risk subgroup, categorised according to working activities and settings, was estimated using exponential survival models. The efficacy of the regional guidelines was estimated by stratifying the analysis according to the moment of the implementation of the guidelines (before/after).

RESULTS

The 2182 study participants were drawn from the dynamic cohort. The overall adjusted ARTI was 1.6 (95% CI: 1.3 to 1.9)/100 person-years. Different workplaces (eg, administrative and infectious diseases inpatient services) and occupations (eg, clerical and medical workers) were associated with significantly different ARTIs, ranging between 0.62 and 2.62 and between 0.61 and 1.71, respectively, whereas the TST conversion risk differed by about 16-68% and 30-60%, respectively. The implementation of the guidelines coincided with overall ARTI reductions of 1.3/100 person-years, and concurrently the variations between ARTIs of different occupations and workplaces disappeared.

CONCLUSIONS

The occupational risk categories for targeting the surveillance and prevention of tuberculosis transmission among HCWs were identified, and the introduction of preventive measures was observed to be effective in decreasing the overall risk of tuberculosis infection among HCWs.

Review of epidemiological studies on the occupational risk of tuberculosis in low-incidence areas

This review summarizes the epidemiological evidence for occupationally acquired tuberculosis and considers the implications for the prevention of tuberculosis. The relevant epidemiological studies were identified on the basis of the Medline data bank, starting with the year 1966. The evaluation of occupational groups with an elevated tuberculosis risk is exclusively based on epidemiologic studies of good or acceptable quality, applying clearly defined criteria of methodological quality. In summary, the available epidemiological evidence suggests that the risk of tuberculosis is elevated in the following occupational groups: hospital employees in wards with tuberculosis patients; nurses in hospitals; nurses attending HIV-positive or drug-addicted patients; pathology and laboratory workers; respiratory therapists and physiotherapists; physicians in internal medicine, anaesthesia, surgery and psychiatry; non-medical hospital personnel in housekeeping and transport work; funeral home employees, and prison employees. However, the epidemiological evidence is limited for all these occupations, with the exception of the nurses, because of the lack of methodologically adequate studies that have got the statistical power to differentiate between specific work tasks. There is a need for large population-based studies with precise definition of exposure, which should include molecular epidemiologic methods in the investigation of occupational risk factors of tuberculosis.

[Epidemiological survey of a suspected nosocomial case of tuberculosis by spoligotyping]

Transmission of tuberculosis within hospitals has been increasingly recognized as a hazard for patients and health care workers. A case of pulmonary tuberculosis was detected in September 2003 in a nursing auxiliary working at Avicenne's Hospital. This 49 year-old woman was considered infected since April 2003. During this 6 months period, she worked in 23 distinct hospital units and could have contaminated patients and hospital staffs. The epidemiological survey was comprised for 1735 individuals (701 hospital staffs and 1034 patients). It encompassed clinical, para-clinical investigations and bacteriological investigations. Furthermore, between January 2003 and September 2004, a systematic comparison of 62 Mycobacterium tuberculosis strains isolated in the hospital was conducted by spoligotyping, a molecular typing method in order to access an eventual transmission. The nursing auxiliary's strain clearly showed a distinct spoligotype from the other investigated strains. This spoligotype was unique in the international spoligotype database. In this large epidemiological survey of a case of suspected nosocomial of tuberculosis, spoligotyping appeared as an interesting, easy and rapid method of molecular typing. It allowed to demonstrate that the nursing auxiliary tuberculosis case was unrelated to the others cases of tuberculosis diagnosed in the hospital during this period.

Research gaps in protecting healthcare workers from SARS and other respiratory pathogens: an interdisciplinary, multi-stakeholder, evidence-based approach

OBJECTIVE

To identify priorities for further research in protecting healthcare workers (HCWs) from severe acute respiratory syndrome (SARS) and other respiratory pathogens by summarizing the basic science of infectious bioaerosols and the efficacy of facial protective equipment; the organizational, environmental, and individual factors that influence the success of infection control and occupational health programs; and factors identified by HCWs as important.

METHOD

An extensive literature review was conducted and 15 focus groups held, mostly with frontline HCWs in Toronto. Critical gaps in knowledge were identified and prioritized.

RESULTS

Highest priority was given to organizational factors that create a climate of safety. Other priority areas included understanding aerosolization risks and practical measures to control bioaerosols at the source.

CONCLUSIONS

Further research is warranted to improve safety climate in health care and, specifically, to provide greater protection against respiratory pathogens.

Predictors of Positive Tuberculin Skin Test (TST) Results after 2‐Step TST among Health Care Workers in Manitoba, Canada

BACKGROUND

Baseline 2-step tuberculin skin testing (TST) is recommended for health care workers (HCWs) to identify cases of the "boosting phenomenon" (i.e., a negative initial TST result followed by a positive result) and to track the risk of acquiring occupational tuberculosis. However, the 2-step TST has been shown to be insufficient to identify all cases of the booster phenomenon in older adults and refugees. The objective of this study was to identify whether a history of bacille Calmette-Guérin (BCG) vaccination and foreign birth--variables that are known to be associated with the booster phenomenon--remain predictors of a positive TST result in a group of HCWs documented to have negative 2-step TST results (i.e., 2 TSTs done 7-28 days apart with indurations <10 mm in diameter).

METHODS

We performed a retrospective analysis of an employee database in a tertiary care hospital in Winnipeg, Canada. The study population was comprised of 698 HCWs with negative 2-step TST results who underwent a TST 0-2 years after completion of the 2-step procedure.

RESULTS

Forty-six HCWs (6.6%) had a positive TST result 0-2 years after the 2-step test. In a multiple logistic regression analysis controlling for age, BCG vaccination, foreign birth, sex, and work setting, only history of BCG vaccination (odds ratio [OR], 8.38; 95% confidence interval [CI], 4.04-17.4), foreign birth (OR, 3.19; 95% CI, 1.53-6.62), and high-risk work setting (OR, 2.93; 95% CI, 1.44-5.95) were associated with a positive TST result.

CONCLUSIONS

Even for HCWs with negative results of 2-step TST, foreign birth and history of BCG vaccination are associated with a positive result of a future TST. Some positive TST results in such HCWs are related to nonoccupational factors, including delayed boosting, rather than to conversion due to recent tuberculosis contact.

Survey of Tuberculin Skin Test Positivity Among Israeli Pediatric Hospital Workers

Tuberculin skin test (TST) was performed in 374 healthcare workers. TST results of induration of 10 mm or more and 20 mm or more were noted in 44.9% and 10.4%, respectively. Positive TST (> 10 mm) was found to be significantly associated with age, country of origin, and duration of employment.

Prevalência da prova tuberculínica positiva entre alunos da Faculdade de Medicina de Campos (RJ)

INTRODUÇÃO:O Hospital Ferreira Machado, utilizado em parte das atividades de treinamento clínico dos alunos da graduação da Faculdade de Medicina de Campos, admitiu 65 pacientes com tuberculose em 2001. OBJETIVO: Quantificar a resposta cutânea ao PPD e descrever a prova tuberculínica (PT) positiva entre os alunos. Identificar e analisar os fatores associados à PT positiva. Comparar as taxas de PT positiva, incluindo o efeito booster e estimar a prevalência da PT positiva nos diferentes períodos da graduação. MÉTODO: Estudo transversal de 500 alunos de medicina matriculados no primeiro semestre de 2002. Informações sobre características sócio-demográficas, vacinação pelo BCG e exposições potenciais à TB foram obtidas por meio de questionário padronizado e validado. A PT foi feita por profissional habilitado pelo Ministério da Saúde, usando-se PPD Rt23 através da técnica de Mantoux feita em dois tempos. RESULTADOS: Dos 500 alunos elegíveis, 316 (63,2%) foram incluídos. A análise mostrou taxas crescentes de positividade à PT feita em dois tempos, de acordo com o progredir das atividades práticas (4,0%, 6,4% e 13,1%) e uma tendência de associação entre o período profissional e a PT positiva. O maior percentual de PT positiva foi encontrado durante os anos de treinamento clínico, o que corresponde ao maior tempo de exposição a pacientes (1.000 horas). CONCLUSÃO: A prevalência da primeira PT positiva foi de 1,4% (5/345). Após o segundo teste, a proporção de PT positiva foi elevada (7,9%); 3). O período profissional (maior tempo de exposição a pacientes) mostrou tendência de associação com a PT positiva. A pesquisa do efeito booster mostrou-se altamente recomendável pois reduz a PT falso-negativa.

A survey of latent tuberculosis infection among laboratory healthcare workers in New York City

OBJECTIVE

To determine the prevalence of positive tuberculin skin tests (TSTs), incidence of TST conversion, risk factors for positive TSTs, and history of active TB among HCWs in microbiology laboratories in New York City.

DESIGN

Two-year survey from May 1999 to June 2001.

SETTING

Nineteen microbiology laboratories.

RESULTS

During the first year, interviews were conducted with 345 laboratory HCWs (mean, 18 HCWs per site; range, 2 to 51) to assess the prevalence of positive TSTs, but 3 (1%) could not recall their result and were excluded from further analyses. The mean age of the remaining 342 HCWs was 48 years; 68% (n = 233) were female, 54% (n = 183) received bacille Calmette-Guerin (BCG) vaccination, and 71% (n = 244) were foreign born. The prevalence of a positive TST was 57% (n = 196), but only 20% (n = 39) of the HCWs received isoniazid. The incidence of TST conversion in the second year of the study was 1% (1 of 108). Multivariate analysis identified age (odds ratio [OR] per year, 1.05; 95% confidence interval [CI95], 1.02-1.08), foreign birth (OR, 3.80; CI95, 1.98-7.28), BCG immunization (OR, 4.89; CI95, 2.72-8.80), and employment in a mycobacteriology laboratory (OR, 2.14; CI95, 1.25-3.68) as risk factors for a positive TST. Only one HCW had been treated for active TB.

CONCLUSIONS

The prevalence of positive TSTs was high among laboratory HCWs, but the TST conversion rate was low. Higher rates of treatment for latent TB infection are desirable.

Human exposure following Mycobacterium tuberculosis infection of multiple animal species in a Metropolitan Zoo

From 1997 to 2000, Mycobacterium tuberculosis was diagnosed in two Asian elephants (Elephas maximus), three Rocky Mountain goats (Oreamnos americanus), and one black rhinoceros (Diceros bicornis) in the Los Angeles Zoo. DNA fingerprint patterns suggested recent transmission. An investigation found no active cases of tuberculosis in humans; however, tuberculin skin-test conversions in humans were associated with training elephants and attending an elephant necropsy.

Risk of tuberculin skin test conversion among health care workers: occupational versus community exposure and infection

A prospective observational cohort study to assess rates of and risk factors for tuberculin skin test (TST) conversion among health care workers (HCWs) was conducted at an urban hospital located in a high tuberculosis-incidence area in 1994-1998. All hospital employees undergoing required testing every 6 months were included. A total of 69 (1.2%) of 5773 susceptible employees had a documented TST conversion (overall rate, 0.38 per 100 person-years worked). No significant difference existed in conversion rates among employees with frequent, limited, or no patient contact. HCWs with a TST conversion lived in zip codes with higher tuberculosis case rates (P< or =.05). In multivariate analysis, TST conversion was associated with history of bacille Calmette-Guérin vaccination (relative risk [RR], 11.63), annual salary <$20,000 (RR, 3.67), and increasing age. In the setting of an effective tuberculosis infection-control program, TST conversion rates were low, and risk of conversion among HCWs was associated most strongly with nonoccupational factors.

Tuberculin skin test conversion among medical students at a teaching hospital in Rio de Janeiro, Brazil

OBJECTIVE

To describe the cumulative incidence of and risk factors for tuberculosis (TB) infection among medical students.

DESIGN

In 1999, a cohort study of medical students with negative results (induration < 10 mm) on tuberculin skin test (TST) was performed. Students who had undergone two-step testing in 1998 were retested.

SETTINGS

University and teaching hospital and referral center for TB and acquired immunodeficiency syndrome, and the Health Sciences Building of the Medical School of the Federal University of Rio de Janeiro, Brazil.

PARTICIPANTS

A sample of 618 consecutive medical students with negative TST results who had been tested 12 months before were approached. Information about sociodemographic characteristics, bacille Calmette-Guérin vaccination history, and potential exposures to TB was obtained using a standardized questionnaire. Four hundred fourteen (67%) students completed the study. Students were at two different levels of their training programs (juniors = no contact with patients; seniors = intensive contact with patients).

RESULTS

Of 414 participants, 16 (3.9%; 95% confidence interval, 1.06% to 12.1%) had converted to a positive reaction after 1 year. In a multivariate logistic regression analysis, higher level of clinical training was confirmed to be an independent factor associated with TST conversion (odds ratio, 4.77; 95% confidence interval, 1.01 to 22.46; P= .048).

CONCLUSION

Senior medical students are at increased risk of Mycobacterium tuberculosis infection in this setting. Therefore, a program of routine tuberculin skin testing and specific TB infection control guidelines are needed for this population.

A meta-analysis of the effect of Bacille Calmette Guérin vaccination on tuberculin skin test measurements

BACKGROUND

The accurate diagnosis of latent tuberculosis infection (LTBI) is an important component of any tuberculosis control programme and depends largely on tuberculin skin testing. The appropriate interpretation of skin test results requires knowledge of the possible confounding factors such as previous BCG vaccination. Uncertainty about the effect of BCG vaccination on tuberculin skin testing and the strength with which recommendations are made to individual patients regarding treatment of LTBI have identified a need to analyse the available data on the effect of BCG on skin testing. A meta-analysis of the evidence for the effect of BCG vaccination on tuberculin skin testing in subjects without active tuberculosis was therefore performed.

METHODS

Medline was searched for English language articles published from 1966 to 1999 using the key words "BCG vaccine", "tuberculin test/PPD", and "skin testing". Bibliographies of relevant articles were reviewed for additional studies that may have been missed in the Medline search. Articles were considered for inclusion in the meta-analysis if they had recorded tuberculin skin test results in subjects who had received BCG vaccination more than 5 years previously and had a concurrent control group. Only prospective studies were considered. The geographical location, number of participants, type of BCG vaccine used, type of tuberculin skin test performed, and the results of the tuberculin skin test were extracted.

RESULTS

The abstracts and titles of 980 articles were identified, 370 full text articles were reviewed, and 26 articles were included in the final analysis. Patients who had received BCG vaccination were more likely to have a positive skin test (5 TU PPD: relative risk (RR) 2.12 (95% confidence interval (CI)1.50 to 3.00); 2 TU RT23: 2.65 [corrected] (95% CI 1.83 to 3.85). The effect of BCG vaccination on PPD skin test results was less after 15 years. Positive skin tests with indurations of >15 mm are more likely to be the result of tuberculous infection than of BCG vaccination.

CONCLUSIONS

In subjects without active tuberculosis, immunisation with BCG significantly increases the likelihood of a positive tuberculin skin test. The interpretation of the skin test therefore needs to be made in the individual clinical context and with evaluation of other risk factors for infection. The size of the induration should also be considered when making recommendations for treatment of latent infection.

Risk of tuberculosis among healthcare workers: can tuberculosis be considered as an occupational disease?

This study aimed to determine the incidence of tuberculosis among hospital employees in four major urban institutions, which employ nearly 90% of all hospital workers caring for adult patients in a city of 2.5 million inhabitants. It also had the objective of finding out whether this incidence changes according to the in-hospital setting, i.e. the departments, and thus, whether tuberculosis can be considered to pose an occupational risk. The study population consisted of all healthcare workers of the four hospitals between 1986 and 1998. From these, those who developed tuberculosis within this period were determined and were considered as the case group. All the remaining employees constituted the control group. Fifty-nine healthcare workers were found to have developed the disease. The annual incidence was found to range between 0.016 and 0.139%. Tuberculosis was seen 3 times more frequently among the hospital employees than the general population. The workers in departments of chest diseases were found to have a higher risk than those of other departments (OR: 6.37, CI: 3.69-11.00). Similarly, the nurses were also at a higher risk than the doctors (OR: 2.63, CI: 1.12-6.36). These findings suggest that tuberculosis can be considered as an occupational disease.

Prevalence and determinants of tuberculin reactivity among physicians in Edmonton, Canada: 1996-1997

BACKGROUND

Health care workers (HCW) have historically borne a heavy burden of tuberculosis (TB) infection and disease. Unfortunately, physicians are rarely included in HCW surveys of tuberculin exposure and infection.

METHODS

The prevalence and risk factors for tuberculin reactivity were determined for a sample of the 1732 licensed physicians in Edmonton. Stratified random sampling was used to select 554 specialists and 219 general practitioners. These physicians were contacted by means of an introductory letter and a follow-up telephone call to solicit participation. All eligible physicians were asked to complete a questionnaire and those with either no recorded positive tuberculin test or a previously negative result were two-step tuberculin skin tested.

RESULTS

In total, 560 physicians (72.4 %) participated in the study. The overall tuberculin reactivity for this population was 45.9%. Using logistic regression analysis, we determined that risk factors for reactivity were aged over 45 years, of foreign-birth, previous Bacillus Calmette-Guérin (BCG) vaccination, foreign practice experience, and being a respiratory medicine specialist.

CONCLUSION

The prevalence of tuberculin reactivity among physicians is considerably higher than estimates for the general Canadian population. This observed excess risk may be associated with factors linked to their medical practice. The high participation rate suggests physician willingness to participate in this type of research, and emphasizes the need to include them in routine HCW surveillance.

Prevalência de infecção pelo "Mycobacterium tuberculosis" entre alunos da Faculdade de Medicina da Universidade Federal do Rio de Janeiro

Introdução: O Hospital Universitário da Universidade Federal do Rio de Janeiro (HUCFF), na região Sudeste do Brasil, recebe aproximadamente 300 casos de tuberculose por ano e é nesse hospital que os alunos da Faculdade de Medicina exercem suas atividades. Objetivos: Determinar a prevalência de infecção pelo Mycobacterium tuberculosis (Mtb) entre alunos da Faculdade de Medicina da UFRJ. Desenho do estudo: Estudo transversal entre estudantes de medicina em diferentes níveis de treinamento. Informações sobre características sociodemográficas, vacinação pelo BCG e exposições potenciais à tuberculose foram obtidas através de questionário padronizado. O teste tuberculínico foi usado para determinar a prevalência de infecção pelo Mtb. Resultados: Os estudantes de medicina tiveram prevalência crescente de positividade ao teste tuberculínico de acordo com o progredir de suas atividades práticas (4,6%, 7,8%,16,2%; P = 0,002). Os riscos foram maiores durante os anos de treinamento clínico, quando os estudantes de medicina tiveram contato mais freqüente com pacientes. Conclusões: Os estudantes de medicina que desenvolvem seu treinamento no HUCFF/UFRJ podem estar sob aumentado risco de se infectar pelo Mycobacterium tuberculosis. Faz-se necessário um programa de realização de teste tuberculínico, de rotina, para confirmação de viragem tuberculínica, combinado com intervenções para reduzir o risco de transmissão nosocomial no local da prática clínica.

Hospitals in England are failing to follow guidance for tuberculosis infection control - results of a National Survey

Tuberculosis outbreaks can occur in hospitals if adequate infection control is not in place. UK guidelines on the prevention of tuberculosis transmission have recently been published. A national survey of acute NHS Trusts in England was conducted to evaluate whether tuberculosis infection control in hospitals is consistent with the new guidance. There was a 72% response rate (144 NHS Trusts). Sixty percent of Trusts had updated their tuberculosis infection control plans since the new guidance was published. Even trusts with updated plans failed to meet guidance in many areas. Thirty-five percent of Trusts had negative pressure facilities for the isolation of infectious tuberculosis patients. Depending on the risk category of the patient, 45-67% of Trusts met guidelines for isolation of infectious patients. Patients frequently left isolation for non-medical reasons. Only a minority of Trusts complied with guidance for respiratory protection of staff and visitors. These findings suggest that many Trusts remain at risk of outbreaks of tuberculosis and therefore need to re-examine infection control procedures and the availability of isolation facilities.

Tuberculosis exposure risk in emergency medicine residents

OBJECTIVES

To assess purified protein derivative (PPD) test surveillance and respiratory protection practices of emergency medicine (EM) residents, along with the prevalence of PPD test conversion and the development of active tuberculosis (TB) in EM residents.

METHODS

The study instrument was an anonymous, self-reporting, multiple-choice survey administered to U.S. and Canadian EM residents. It was distributed for voluntary completion in conjunction with the American Board of Emergency Medicine's annual in-service examination, which was administered February 25, 1998.

RESULTS

A total of 89.3% (n = 2,985) of residents eligible to complete the survey completed at least part of it. The majority of residents are PPD-tested once a year. The prevalence of PPD test conversions in EM residents was between 1.4% (36/2,575) and 2.0% (52/2,575). Of the residents who PPD test-converted, the ED was most often the perceived area of TB source exposure (n = 15). Two residents (0.08%) reported having developed active TB, including chest radiographic findings or clinical infection, which equals a 0.14% (95% CI = 0.005 to 0.31) risk of developing active TB over a three-year residency. Half of all the residents do not routinely wear National Institute for Occupational Safety and Health (NIOSH)-approved particulate filtration respirator (PFR) masks in patient encounters at risk for TB exposure. While more than a third of EM residents have not undergone fit testing for a NIOSH-approved PFR mask, the lack of routine easy availability of such masks is the most common reason they are not routinely worn by EM residents during at-risk encounters for TB transmission.

CONCLUSIONS

Most surveillance PPD testing of EM residents is performed at intervals recommended by the CDC. TB control programs at institutions sponsoring EM residencies need to improve both compliance with PFR mask fit testing by EM residents and availability of approved PFR masks in appropriate areas of the ED. Despite poor compliance with personal respiratory protection in ED patient encounters at risk for TB transmission, the risk of an EM resident's developing active TB over a three-year residency is low.

Tuberculin skin test conversion rates in New York City Emergency Medical Service health care workers

OBJECTIVE

To determine annual tuberculin skin test conversion (infection) rates for prehospital health care workers (EMTs and paramedics) in an urban environment with a high prevalence of Mycobacterium tuberculosis.

METHODS

We conducted a prospective study of prehospital health care workers for the New York City EMS, EMS Employee Health Service, and the Fire Department Bureau of Health Service to determine the tuberculin skin test conversion rates. In 1992, all current and new EMS prehospital health care workers without a known history of a positive tuberculin reaction received a baseline tuberculin purified protein derivative (PPD) skin test. Thereafter, (January 1, 1993-December 31, 1996) all EMS health care workers who had negative PPD skin test results received annual tuberculin PPD skin tests. Tuberculin skin test conversion was defined as induration of 10 mm or greater in a worker with a documented prior negative test result. The PPD skin test reaction was measured by trained professional readers.

RESULTS

A total of 7,290 PPD test results were read during this study. Compliance with annual testing was 75%. Annual tuberculin skin test conversion rates were 1.3% in 1993, .7% in 1994, .1% in 1995, and .2% in 1996 (average .5%). In a static subgroup with at least 15 years' seniority, compliance with annual testing was 100% and annual tuberculin skin test conversion rates were .5% in 1993, 0 in 1994, .5% in 1995, and 1.5% in 1996 (average .6%).

CONCLUSION

Despite the high prevalence of M tuberculosis infection in New York City and the potential for difficulty in the use of respiratory precautions during emergency response operations, EMS prehospital health care workers have an annual tuberculin conversion rate that is relatively low compared with hospital-based health care workers.

Effectiveness of a nosocomial tuberculosis control program at an urban teaching hospital

STUDY OBJECTIVE

To assess the effectiveness of a nosocomial tuberculosis (TB) program at an urban teaching hospital.

DESIGN

Retrospective review.

SETTING

An urban teaching hospital, the University of California, San Diego Medical Center (UCSD), which cares for 25 to 30 culture-proven pulmonary TB cases (>80% of which are smear-positive) per year.

STUDY POPULATION

Health-care workers.

MEASUREMENTS

(1) Purified protein derivative (PPD) conversion rates. (2) Cases of active TB among health-care workers. (3) Compliance rates with isoniazid (INH) preventive therapy.

RESULTS

The UCSD program was evaluated for the years 1993 to 1995. The PPD conversion rate among established employees was 0.6%. Of 556 employees who had an exposure, 494 (88.8%) were compliant with follow-up. Three hundred thirty-seven were skin-tested (the other 157 already had a known PPD >10 mm). Only 2 of 337 (0.6%) converted. One case of active TB, unrelated to any documented hospital exposure, was discovered in 3 years among approximately 5,000 employees per year (follow-up for convertors, 18 to 54 months). Only 48.4% of eligible employees completed at least 6 months of INH preventive therapy.

CONCLUSIONS

UCSD's TB control measures appear to be effective in the prevention of nosocomial transmission of TB. Despite poor compliance with INH preventive therapy, cases of active TB among health-care workers were rare.

Tuberculosis exposure and control in an urban emergency department

STUDY OBJECTIVE

To measure tuberculosis (TB) conversion rates among staff of an urban emergency department compared with other hospital employees (OHEs) and to evaluate the effectiveness of new TB control measures.

METHODS

A prospective interventional cohort study was performed in an academic adult 1,000-bed urban hospital, with more than 6,000 employees, and an annual ED census of 43,000. As part of a hospital-wide program, all employees were screened for tuberculin reactivity (Siebert purified protein derivative [PPD] of tuberculin) annually during a 3 1/2-year period. Additional information collected on each employee included country of birth, ethnicity, history of bacille Calmette-Gúerin (BCG) vaccination, length and site of employment, and age. At the end of the second year, TB control measures including construction of a new ED facility with TB respiratory isolation rooms, nonrecirculated air, and droplet shields for registrars were implemented. Relative risk (RR) and 95% confidence intervals (CIs) were calculated.

RESULTS

During the first screening cycle, PPD status was obtained on 5,697 hospital employees, 88 of whom worked primarily in the ED. Baseline status was 81% PPD- (induration <5 mm), 9% PPD+ (induration > or =10 mm), and 10% refused skin testing. ED staff did not differ from OHEs with regard to PPD status, age, ethnicity, BCG history, foreign birth, residing in a county with high TB prevalence, or length of employment. During the second cycle, 6 of 50 (12%) previously PPD- ED staff and 51 of 2,514 (2%) previously PPD OHEs converted to PPD+ status (RR=5.9; 95% CI 2.7,13.1). After implementing TB control measures, the conversion rate during the third year dropped to 0 for ED staff, whereas the OHEs had a conversion rate of 1.2% during that cycle.

CONCLUSION

TB conversion rates were 5.9 times greater in ED staff members than OHEs before engineering controls were implemented. The ED TB conversion rate fell dramatically in the year following new TB controls. Many EDs are high-risk sites for TB exposure and may benefit from similar measures.

Risk of tuberculin conversion according to occupation among health care workers at a New York City hospital

Concern about the risk to health care workers of occupationally acquired tuberculosis has resulted in extensive and frequently revised guidelines from the Centers for Disease Control and Prevention (CDC). Most recent studies, however, have determined that community, rather than occupational, exposure is the more significant risk for tuberculin conversion. To assess the relative contribution of community versus occupational risk, we reviewed the health records of 1,303 persons employed from 1991 to 1994 at St. Clare's Hospital in New York City, a hospital with a high tuberculosis case-rate. Demographic information included age, gender, postal zone of residence, country of birth, and BCG vaccination status, while occupations were placed into one of five groups. In multivariate analysis, occupation was significantly associated with risk of tuberculin conversion, while postal zone of residence was not. The group that included housekeeping, laundry, and security personnel and the physician-nurse group had the highest conversion rates. After implementation of CDC guidelines, there was a significant improvement in the employee tuberculin conversion rate. At our hospital, occupation was strongly associated with risk of tuberculin conversion.