Tuberculosis in Hospital Nutrition Services Workers

Background: In August 2009, the occupational health program of our medical center noted that 3 nutrition service workers who deliver food trays to patients and 1 nutrition service manager had tuberculin skin test (TST) conversions without a clear epidemiologic link beyond their work area. In our healthcare system, all employees receive a two-step TST upon hire and those who have face-to-face contact with patients undergo annual tuberculosis skin testing.

Objective: First, to identify a potential source for the increase in TST conversions among our nutrition services employees. Second, we also sought to describe the epidemiologic association for these conversions.

Methods: All hospital nutrition services employees (n=211) underwent TST testing and were interviewed using a questionnaire for signs and symptoms of tuberculosis. 75% of those employees had previously been determined not to have face-to-face contact with patients and therefore had undergone TB screening only at the time of hire. TST converters and employees with a positive signs-and-symptoms review underwent screening chest x-rays (CXR). Those with CXR abnormalities underwent medical evaluation for active TB. Those with active TB underwent contract tracing. Food preparation, storage, and associated facilities were investigated for possible environmental amplification.

Results: 19 (9.0%) employees had documented TST conversions. While none reported positive signs-and-symptoms, 3 had radiographic abnormalities. Of the 3 with radiographic changes, 2 had AFB-positive sputa that grew Mycobacterium tuberculosis. The third was considered to have culture negative TB based on compatible radiographic changes (Right hilar lymphadenopathy, infiltrate, and effusion) and lack of an alternative diagnosis. The three employees worked in food preparation; none had regular patient contact. An environmental investigation found that the kitchen had a dedicated air handling system separate from the rest of the hospital. The separate system likely prevented additional exposures in the hospital; however, the kitchen environment may have amplified the exposure rate among nutrition services employees.

Conclusions: Annual tuberculin skin testing for healthcare workers with significant (i.e. face-to-face) contact with patients is part of the CDC guidelines to prevent M. tuberculosis transmission in medical facilities. We identified 14 nutrition services employees who had TST conversions but no patient contact along with 5 employees with TST conversions and regular patient contact. Three employees had active disease. This outbreak demonstrates that transmission of M. tuberculosis can occur in medical facilities in work areas where some employees have limited or no patient contact, and these cases have the potential to place HCWs and patients at risk for TB exposure. As a result, our institution has elected to perform annual TST testing in all employees regardless of job classification