To determine trends in Mycobacterium tuberculosis infection in healthcare workers, tuberculosis (TB) control measures, and compliance with the 1990 Centers for Disease Control and Prevention (CDC) guideline for preventing transmission of TB in healthcare facilities.

Voluntary questionnaire sent to all members of the Society for Healthcare Epidemiology of America, representing 359 hospitals.

Respondents’ hospitals (210 [58%]) had a median of 2,400 healthcare workers (range, 396 to 13,745), 437 beds (range, 48 to 1,250), 5.6 patients with TB per year (range, 0 to 492), and 0 multidrug-resistant (MDR) TB patients per year (range, 0 to 33). Of 166 respondents’ hospitals for which data were provided for 1989 through 1992, the number caring for MDR-TB patients increased from 10 (6%) in 1989 to 49 (30%) in 1992. Reported policies for routine healthcare worker tuberculin skin testing varied. The median skin-test positivity rate for healthcare workers at the time of hire increased from 0.54% in 1989 to 0.81% in 1992, but the median conversion rate during routine testing remained similar: 0.35% in 1989 and 0.33% in 1992. Among 196 hospitals with reported data on respiratory protection use for 1989 through 1992, the use of either surgical submicron, dust-mist, or dust-fume-mist respirators for healthcare workers increased from 9 (5%) in 1989 to 85 (43%) in 1992. Of 181 hospitals with reported data, 113 (62%) had acid-fast bacilli isolation facilities consistent with the 1990 CDC guideline (ie, a single patient room, negative air pressure relative to the hallway, air exhausted directly outside, and ≥ 6 air exchanges per hour).

While the number of surveyed hospitals caring for TB and MDR-TB patients increased during 1989 through 1992, TB infection control measures at many hospitals still did not meet the 1990 CDC guideline recommendations.

To assess the efficacy of current Myco-bacterium tuberculosis control measures.

Voluntary questionnaire to members of the Society for Healthcare Epidemiology of America.

Healthcare worker (HCW) tuberculin skin-test (TST) conversion rates were significantly higher in larger hospitals ( ≥ 437 beds) (0.9% versus 0.6%; P < 0.05), or in hospitals reporting ≥ 6 TB patients in 1992 (1.2% versus 0.6%; P < 0.05). Among larger hospitals or those hospitals surveyed reporting ≥ 6 TB patients, those without at least three of the four criteria suggested in the 1990 Centers for Disease Control and Prevention (CDC) TB guidelines for acid-fast bacilli (AFB) isolation (specifically, a single-patient room; negative pressure; and air exhausted directly outside) had significantly higher annual TST conversion rates than those with these criteria (1.8% versus 0.6%; P < 0.05). Respiratory therapist or bronchoscopist TST conversion rates were significantly lower in hospitals compliant with the exhaust criteria (1.2% versus 2.8%; P < 0.05). Regardless of hospital characteristic, HCW TST conversion rates did not differ between hospitals in which HCWs used surgical masks or used disposable particulate respirators.

Among larger hospitals or hospitals reporting ≥ 6 TB patients per year, failure to comply with the 1990 CDC TB recommendations for AFB isolation room guidelines was associated with higher HCW TST conversion rates. These data suggest that complete implementation of the 1990 CDC TB guidelines would decrease HCWs’ risk of nosocomial transmission of TB in larger hospitals or those reporting more TB patients. However, in nonoutbreak situations, disposable particulate respirators or submicron surgical masks may not offer significantly greater protection to HCWs than surgical masks.

To evaluate the efficacy of Centers for Disease Control and Prevention (CDC)-recommended infection control measures implemented in response to an outbreak of multidrug-resistant (MDR) tuberculosis (TB).

Retrospective cohort studies of acquired immunodeficiency syndrome (AIDS) patients and healthcare workers. The study period (January 1989 through September 1992) was divided into period I, before changes in infection control; period II, after aggressive use of administrative controls (eg, rapid placement of TB patients or suspected TB patients in single-patient rooms); and period III, while engineering changes were made (eg, improving ventilation in TB isolation rooms).

A New York City hospital that was the site of one of the first reported outbreaks of MDR-TB among AIDS patients in the United States.

All AIDS patients admitted during periods I and II. Healthcare workers on nine inpatient units with TB patients and six without TB patients.

The epidemic (38 patients) waned during period II and only one MDR-TB patient presented during period III. The MDR-TB attack rate among AIDS patients hospitalized on the same ward on the same days as an infectious MDR-TB patient was 8.8% (19 of 216) during period I, decreasing to 2.6% (5 of 193; P= 0.01) during period II. In a small group of healthcare workers with tuberculin skin test data, conversions during periods II through III were higher on wards with than without TB patients (5 of 29 versus 0 of 15; P= 0.15), although the difference was not statistically significant.

Transmission of MDR-TB among AIDS patients decreased markedly after enforcement of readily implementable administrative measures, ending the outbreak. However, tuberculin skin-test conversions among healthcare workers may not have been prevented by these measures. CDC guidelines for prevention of nosocomial transmission of TB should be implemented fully at all US hospitals.

To identify the tuberculosis (TB) skin-testing practices of long-term care facilities for the elderly in Toronto, Ontario.

A telephone survey using a 25-item questionnaire.

Twenty-nine nursing homes (NHs) and 26 Homes for the Aged (HFAs) in metropolitan Toronto.

Thirty-one percent of facilities (17 of 55) had no formal tuberculin skin-testing program, including 52% of NHs (15 of 29) versus 8% of HFAs (2 of 26; P= 0.001). Ninety-two percent of HFAs (24 of 26) compared with 45% of NHs (13 of 29), obtained preadmission or admission skin-test status of residents (P= 0.0005). Annual testing was performed at 46% of HFAs (12 of 26) and 27% of NHs (8 of 29; P= 0.28). Of facilities that carried out any skin testing, 64% of HFAs (16 of 25) versus 32% of NHs (6 of 19) measured induration to establish test positivity (P=0.068). Fifty-two percent of HFAs (13 of 25), compared with 21% of NHs (4 of 19), recorded the actual size of induration in the patient record (P=0.085). Only 28% of HFAs (7 of 25) and 21% of NHs (4 of 19) correctly defined a positive tuberculin skin test.

TB surveillance practices in long-term care institutions in Toronto are inadequate and often yield results that do not predict the risk of infection and cannot be used to investigate outbreaks. Tuberculin skin-testing practices were better at HFAs, which are subject to provincial legislation regarding TB surveillance, than at NHs, which are not subject to this legislation. Staff at HFAs and NHs require education regarding tuberculin skin-testing policies and procedures.

To evaluate nosocomial transmission of multidrug-resistant (MDR) tuberculosis (TB).

Outbreak investigation: review of infection control practices and skin test results of healthcare workers (HCWs); medical records of hospitalized TB patients and mycobacteriology reports; submission of specimens for restriction fragment length polymorphism (RFLP) typing; and an assessment of the air-handling system.

A teaching hospital in upstate New York.

Skin-test conversions occurred among 46 (6.6%) of 696 HCWs tested from August through October 1991. Rates were highest on two units (29% and 20%); HCWs primarily assigned to these units had a higher risk for conversion compared with HCWs tested following previous incidents of exposure to TB (relative risk [RR] = 53.4, 95% confidence interval [CI95] =6.9 to 411.1; and RR=37.4, CI95= 5.0 to 277.3, respectively). The likely source patient was the only TB patient hospitalized on both units during the probable exposure period. This patient appeared clinically infectious, was associated with a higher risk of conversion among HCWs providing direct care (RR = 2.37; CI95 = 1.05 to 5.34), and was a prison inmate with TB resistant to seven antituberculosis agents. The MDR-TB strain isolated from this patient also was isolated from other inmate and noninmate patients, and a prison correctional officer exposed in the hospital. Mycobacterium tuberculosis isolates from all of these patients had matching RFLP patterns. Infection control practices closely followed established guidelines; however, several rooms housing TB patients had marginal negative pressure with variable numbers of air changes per hour, and directional airflow was disrupted easily.

These data strongly suggest nosocomial transmission of MDR-TB to HCWs, patients, and a prison correctional officer working in the hospital. Factors contributing to transmission apparently included prolonged infectiousness of the likely source patient and inadequate environmental controls. Continued urgent attention to TB infection control is needed.

To determine the prevalence of and risk factors for having a positive tuberculin skin test (TST) result among employees at a medical examiner's office (MEO).

Cohort study, environmental investigation.

Several employees at a medical examiner's office were found to have positive TST results after autopsies were performed on persons with multidrug-resistant tuberculosis (MDR-TB).

Employees of the MEO.

Of 18 MEO employees, 5 (28%) had a positive TST result; 2 of these 5 had TST conversions. We observed a trend between TST conversion and participation in autopsies on persons with MDR-TB (2 of 2 converters versus 3 of 13 employees with negative TST; relative risk=4.3; 95% confidence interval 1.61 to 11.69; P=0.l0). The environmental investigation revealed that the autopsy room was at positive pressure relative to the rest of the MEO and that air from the autopsy room mixed throughout the facility.

A systematic approach to preventing transmission of Mycobacterium tuberculosis in autopsy suites should include effective environmental controls and routine tuberculin skin testing of employees.