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TB outbreak occurs among hospital kitchen staff with minimal patient contact
Recent findings published in Infection Control and Hospital Epidemiology describe an outbreak of tuberculosis that occurred in a hospital’s food preparation area, underscoring the risk for disease transmission among employees who do not have direct patient contact.
“This outbreak demonstrates some challenges regarding the prevention of [Mycobacterium] tuberculosis transmission in medical facilities,” Kyle B. Enfield, MD, MS, assistant professor in the department of internal medicine at the University of Virginia School of Medicine, and colleagues wrote.
The CDC recommends that health care workers who are in direct contact with patients receive annual tuberculin skin test (TST) screening. However, this leaves a large number of employees with minimal or no patient care exposure who may be potential reservoirs for TB transmission untested, possibly causing widespread outbreaks in a medical facility, according to the researchers.
In August 2010, the occupational health department at the University of Virginia Medical Center identified four nutrition services staff members with TST conversions. During an investigation, the researchers interviewed and tested 224 current and former nutrition services employees to identify other potential cases. An initial evaluation revealed that 20 employees had TST conversions. Three of these patients reported signs and symptoms of active TB, all of whom had negative 2-step TSTs when hired 2 to 20 years earlier. Their symptoms may have occurred up to 4 months before the outbreak was identified.
Four years after the initial investigation, a fourth employee undergoing services for potential lung cancer who also previously tested negative for TST conversion was found to have M. tuberculosis-positive sputa, consistent with active infection. The employee had no known risks for TB exposure other than working in a medical facility. No additional active or latent infections were detected among the employee’s contacts.
Of the 21 TST conversions, 19 were linked to the kitchen, which was located in the basement of the facility and had a separate ventilation system from the rest of the hospital. This system included an air handling system that used 100% outdoor air, which may have diluted airborne bacteria, as well as a dedicated exhaust system preventing ventilated air to recirculate into patient care centers.
“Although the closed space of the kitchen facilitated the airborne spread of TB between employees, the dedicated air system may have helped prevent the spread of TB to patient care areas in the medical center,” Enfield and colleagues wrote.
They reported that 43% of all employees with TST conversions interacted with and were at risk for transmitting TB to patients. In this outbreak, the odds of TST conversion was greater among employees without patient contact than with patient contact (OR = 4; 95% CI, 1.6-10).
“As a result, our institution has elected to perform annual TST testing on all employees regardless of job classification,” Enfield and colleagues concluded. – by Stephanie Viguers
Disclosure: The researchers report no relevant financial disclosures.