Tuberculin Skin Test Conversion Rate Research Articles

SHEA-CDC TB Survey, Part II: Efficacy of TB Infection Control Programs at Member Hospitals, 1992

AbstractObjective:To assess the efficacy of current Myco-bacterium tuberculosis control measures.Design:Voluntary questionnaire to members of the Society for Healthcare Epidemiology of America.Results: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.Conclusion: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.

Efficacy of control measures in preventing nosocomial transmission of multidrug-resistant tuberculosis to patients and health care workers.

To assess the efficacy of control measures in decreasing nosocomial transmission of multidrug-resistant tuberculosis. Retrospective cohort study. A teaching hospital in New York City. 40 patients hospitalized with multidrug-resistant tuberculosis (case-patients) and health care workers receiving tuberculin skin testing. Centers for Disease Control and Prevention (CDC) 1990 guidelines for preventing transmission of tuberculosis, including 1) prompt isolation and treatment of patients with tuberculosis; 2) rapid diagnostic techniques for processing Mycobacterium tuberculosis specimens; 3) negative-pressure isolation rooms; and 4) molded surgical masks for health care workers. Proportion of case-patients with nosocomially acquired tuberculosis and rate of tuberculin skin test conversion among health care workers before and after implementation of control measures. The proportion of patients with multidrug-resistant strains of M. tuberculosis decreased after the interventions (10 of 70 [14%] compared with 30 of 95 [32%] patients before the intervention; relative risk [RR], 0.5; 95% CI, 0.2 to 0.9). Before onset of multidrug-resistant tuberculosis, case-patients in the intervention period were as likely to be hospitalized on high-risk wards containing patients with tuberculosis (4 of 10 compared with 17 of 30 patients; RR, 0.7; P = 0.5) but were less likely to be exposed to another case-patient with tuberculosis (1 of 10 compared with 20 of 30 patients; RR, 0.2; P = 0.003). Tuberculin skin test conversion rates for health care workers assigned to wards housing patients with tuberculosis were lower in the intervention period than in the preintervention period (4 of 78 [5%] compared with 15 of 90 [17%] conversions; P = 0.02), decreasing to levels observed for workers assigned to other wards (4 of 78 [5%] compared with 9 of 228 [4%] conversions; P = 0.7). Implementing control measures reduced nosocomial transmission of multidrug-resistant strains to patients and health care workers.

The effect of the booster phenomenon on the tuberculin skin test conversion rate

The effect of the booster phenomenon on the tuberculin skin test conversion rate

Tuberculosis contact investigation: Two years of experience in New York City correctional facilities

Background: An increasing incidence of tuberculosis has been observed in the New York City correctional system. Methods: The diagnosis of active tuberculosis in persons within the correctional setting results in an investigation, with the identification and screening of contacts. Results: Thirty-four such investigations in the past 2 years in the New York City correctional system, where all inmates are screened for tuberculosis on admission, have resulted in an overall tuberculin skin test conversion rate of 6.74% in 1306 inmates. In 21 of these investigations the index had both smears and cultures positive for Mycobacterium tuberculosis and the conversion rate was 7.37% in 719 contacts tested. In seven investigations the index patient had a culture only positive for M. tuberculosis and the conversion rate was 6.58% in 243 inmates. In six investigations in which the index patients were subsequently found to have nontuberculous pneumonia or mycobacteria other than M. tuberculosis the conversion rate was 5.52% in 344 inmates. These rates are not statistically different. Conclusions: Whether the observed conversions in these events or in any of the contact investigations are due to intramural spread, anergy on admission, the booster phenomenon, or incubation of disease on admission is not known. The 5.5% conversion rate in those exposed to inmates confirmed not to have tuberculosis suggests the influence of booster phenomenon and consideration of two-step testing on admission.

Nosocomial transmission of multidrug-resistant Mycobacterium tuberculosis. A risk to patients and health care workers.

To determine the factors associated with the development of multidrug-resistant tuberculosis among patients at a New York City Hospital and to investigate possible nosocomial transmission. A retrospective case-control study and tuberculin skin test survey. Twenty-three patients with tuberculosis whose isolates were resistant to at least isoniazid and rifampin (case patients) were compared with patients with tuberculosis whose isolates were susceptible to all agents tested (controls). Tuberculin skin test conversion rates were compared among health care workers assigned to wards where patients with tuberculosis were frequently or rarely admitted. A large, teaching hospital in New York City. Mycobacterium tuberculosis isolates from case patients and controls were typed by restriction fragment length polymorphism analysis. Case patients were younger (median age, 34 compared with 42 years; P = 0.006), more likely to be seropositive for HIV (21 of 23 compared with 11 of 23 patients; odds ratio, 11.5; 95% CI, 1.9 to 117), and more likely to have had a previous hospital admission within 7 months before the onset of tuberculosis (19 of 23 compared with 5 of 23 patients; odds ratio, 17.1; CI, 3.3 to 97), particularly on one ward (12 of 23 compared with 0 of 23 patients; odds ratio, undefined; P = 0.002). Health care workers assigned to wards housing case patients were more likely to have tuberculin skin test conversions than were health care workers assigned to other wards (11 of 32 compared with 1 of 47 health care workers; P less than 0.001). Few (6 of 23) case patients were placed in acid-fast bacilli isolation, and no rooms tested had negative pressure. Of 16 available multidrug-resistant isolates obtained from case patients, 14 had identical banding patterns by restriction fragment length polymorphism analysis. In contrast, M. tuberculosis isolates from controls with drug-susceptible tuberculosis had patterns distinct from each other and from those of case patients. These data suggest nosocomial transmission of multidrug-resistant tuberculosis occurred from patient to patient and from patient to health care worker and underscore the need for effective acid-fast bacilli isolation facilities and adherence to published infection control guidelines in health care institutions.