Chest
Original ResearchChest InfectionsChallenges of Interferon-γ Release Assay Conversions in Serial Testing of Health-care Workers in a TB Control Program
Section snippets
Testing
QFT-GIT is an in vitro diagnostic test using a peptide cocktail simulating early secretory antigen target-6 (ESAT-6), culture filtrate product-10 (CFP-10), and TB7.7 proteins to stimulate cells in heparinized whole blood (Cellestis International Pty Ltd). QFT-GIT with the third TB antigen TB7.7 was used beginning March 2008. These three proteins are not present in the bacille Calmette-Guérin (BCG) strains and are absent from most nontuberculous mycobacteria, with the exception of Mycobacterium
Results
There were 7,374 IGRAs (45.3%) performed on newly hired HCWs at the Cleveland Clinic. Demographic information, history of previous BCG vaccination, and previous positive TSTs in these HCWs are shown in Table 1. Among newly hired HCWs, 486 (6.6%) had positive results, 305 (4.1%) had indeterminate results, and 6,583 (89.3%) had qualitatively negative results.
All 486 HCWs with baseline positive IGRAs were offered evaluation by an ID physician, and their management is described in Figure 1. A total
Discussion
Although IGRAs are promising for serial testing, there still are limited data available on interpreting serial testing in HCWs.13, 14 The present study provides data on IGRAs among HCWs in the United States, a low-incidence country. Because exposure is a risk factor for developing TB, the ability to treat persons with LTBI is a vital component of infection control in a hospital TB program. With the implementation of IGRA testing in 2007, the Cleveland Clinic ID department evaluated > 300 HCWs,
Acknowledgments
Author contributions: Drs Fong and Miranda had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Dr Fong: contributed to the study design, institutional review board application, data analysis, and preparation of the manuscript.
Dr Tomford: contributed to the data analysis and approval of the final manuscript.
Dr Teixeira: contributed to the study design, data analysis, and approval of the final manuscript.
Dr
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Funding/Support: The authors have reported to CHEST that no funding was received for this study.