1238 infection control & hospital epidemiology october 2017, vol. 38, no. 10
table 4. Exposed Employees by Occupation Healthcare Provider Registered nurse
Nursing assistant
Patient care technician Physician
Nurse practitioner Nursing supervisor Physician assistant Unit assistant
Clinical nurse specialist Total
No. 49
30 19 16 11 8 6 6 1
146
table 5. Postexposure Testing Method for High-Risk Employees Postexposure Test
Tuberculin skin test
QuantiFERON Gold-TB In-Tube Known LTBI; assessed for active TB Total
123 17 6
146 NOTE. LTBI, latent tuberculosis infection; TB, tuberculosis.
significant exposure that met criteria for first-tier testing. Exposed HCWs included individuals from various disciplines. Among all HCWs, registered nurses, nursing assistants, and patient-care technicians assigned to the unit were exposed most often (Table 4). Baseline PPD or IGRA results were available for 142 of 146 employees; 4 employees reported negative PPD in the past. Furthermore, 50 exposed employees were foreign born with incomplete data regarding BCG vaccination status. All 146 employees received postexposure testing between 8 and 12 weeks after exposure (Table 5). Among 140 employees with negative baseline screening, all underwent testing and none were positive. In addition, 6 employees were known to have LTBI and did not report new symptoms in 3 months following exposure. Furthremore, 22 months after the exposure ended, 116 (79%) of the 146 employees had completed their annual evaluations for 2016 with negative annual testing: 99 were tested using PPD, 12 were tested using IGRA, and 5 LTBI cases were screened using a symptoms questionnaire.
patient who refused TST and IGRA after exposure. At 12 months after the exposure, 42 of 63 exposed patients were alive. No cases of active tuberculosis occurred among the exposed cohort. Healthcare workers. Among exposed coworkers, 146 had
discussion
Within healthcare facilities, transmission ofMTB fromanHCW to a highly susceptible population of immunosuppressed patients undergoing treatment for cancer has seldom been reported. It is reasonable to assume that the risk of developing
disease after exposure to MTB is higher among certain indivi- duals undergoing immunosuppressive treatment for cancer. Our investigation outlines a systematic approach using the
No. of Employees Tested
EMR to quantify exposure times based on documentation of care provided to patients during daily work hours. Defining the period of contagiousness is a key step in contact tracing and has been based on evidence-based guidelines. During the reported event, the exposed cohort on the oncology unitwas composed of a diverse mix of patients. We implemented a tiered risk assess- ment among exposed patients; an initial stratification was inde- pendent of exposure times and was based solely on host susceptibility as determined by underlying cancer and degree of immunosuppression. Next, among other susceptible patients, further breakdown of risk for acquiring TB infection was extra- polated from conservative exposure times. Individuals with a higher risk of developing disease were further tested, and symptoms were carefully scrutinized for active disease. The limitations of TST and IGRA testing among immuno- suppressed patients are well recognized.17 Due to the effects of cancer or its treatment, the results of PPD and IGRA testing may be rendered falsely negative, and symptom assessment is nonspecific (ie, cough, night sweats, and weight loss are common cancer-associated symptoms). Although we achieved a high rate of postexposure testing among exposed patients, with 51of 63 (80%) patients from the first-tier group tested, a comprehensive and targeted follow-up with radiographic assessment was pursued regardless of the results of TST and IGRA. The information gained from the electronic record enabled us to substantially shorten the list of individuals with high-risk exposure and to focus our approach. The strategy used for HCWrisk assessment was based on current TB con- trol guidelines.19 Despite the intensity and duration of the index case HCW exposure to coworkers, no cases of LTBI or active TB occurred among them. The strengths of our investigation include a high number of
HCWs and patients followed up with postexposure testing, mostly due to prompt generation of an exposure list using electronic resources. We describe host-based risk stratification criteria used in an oncologic setting to guide a postexposure work-up. In conclusion, the EMR and employee scheduling system are useful resources for conducting otherwise labor- intensive contact investigations. The widespread implementa- tion of these systems should be routinely utilized. Despite the high-risk features of our index case, a highly vulnerable immunocompromised patient population, and extended proximity with coworkers, we did not find any evidence of TB transmission after this hospital-based exposure.
acknowledgments
Financial support: No financial support was provided relevant to this article. Potential conflicts of interest: All authors report no conflicts of interest rele-
vant to this article. Address correspondence to Fabian A. Romero, 4922 Lasalle Rd, Hyattsville,
MD, 20782 (
romero.fabian.md@
gmail.com).
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