Format

Send to

Choose Destination
Swiss Med Wkly. 2014 Aug 14;144:w13988. doi: 10.4414/smw.2014.13988. eCollection 2014.

Contact tracing investigation after professional exposure to tuberculosis in a Swiss hospital using both tuberculin skin test and IGRA.

Author information

1
Service de Médecine Préventive Hospitalière , CHUV, Lausanne, Switzerland; Servizio di prevenzione delle infezioni e medicina del personale, Ente Ospedaliero Cantonale, Ticino, Switzerland; Swiss Medical Society for Occupational Health in Health Care F.
2
Service de Médecine Préventive Hospitalière , CHUV, Lausanne, Switzerland; Swiss Medical Society for Occupational Health in Health Care Facilities, Switzerland.
3
Reparto di Medicina Intensiva, Ospedale Beata Vergine di Mendrisio, Switzerland.
4
Service de Médecine Préventive Hospitalière , CHUV, Lausanne, Switzerland.
5
Swiss Lung Association, Berne, Switzerland.

Abstract

SETTING:

A 950 bed teaching hospital in Switzerland.

AIM:

To describe the result of a contact investigation among health care workers (HCW) and patients after exposure to a physician with smear-positive pulmonary tuberculosis in a hospital setting using standard tuberculin skin tests (TST) and Interferon-gamma release assay (IGRA).

METHOD:

HCW with a negative or unknown TST at hiring had a TST two weeks after the last contact with the index case (T0), repeated six weeks later if negative (T6). All exposed HCW had a T-SPOT.TB at T0 and T6. Exposed patients had a TST six weeks after the last contact, and a T-SPOT.TB if the TST was positive.

RESULTS:

Among 101 HCW, 17/73 (22%) had a positive TST at T0. TST was repeated in 50 at T6 and converted from negative to positive in eight (16%). Twelve HCW had a positive T-SPOT.TB at T0 and ten converted from negative to positive at T6. Seven HCW with a positive T-SPOT.TB reverted to negative at T6 or at later controls, most of them with test values close to the cut-off. Among 27 exposed patients tested at six weeks, ten had a positive TST, five of them confirmed by a positive T-SPOT.TB.

CONCLUSIONS:

HCW tested twice after exposure to a case of smear-positive pulmonary TB demonstrated a possible conversion in 10% with T-SPOT and 16% with TST. Some T-SPOT.TB reverted from positive to negative during the follow-up, mostly tests with a value close to the cut-off. Due to the variability of the test results, it seems advisable to repeat the test with values close to the cut-off before diagnosing the presence of a tuberculous infection.

PMID:
25121477
DOI:
10.4414/smw.2014.13988
[Indexed for MEDLINE]
Free full text

Supplemental Content

Full text links

Icon for EMH Swiss Medical Publishers Ltd.
Loading ...
Support Center