Transmission of Mycobacterium tuberculosis from an infant

This report investigates the unusual transmission of Mycobacterium tuberculosis from a 12-week-old infant with nosocomially acquired tuberculosis (TB). Compliance with recommendations on the post-exposure management of young children is described.

Contacts of an infant case of TB were identified and recommended to undergo baseline and post-exposure tuberculin skin tests (TST) as per Canadian TB standards. TST conversion was measured at least 8 weeks post exposure. Children aged <6 years were recommended to initiate preventive treatment with isoniazid (INH) until their post-exposure TST. Information on TST results and adherence to therapy were analysed from existing medical records.

Overall, 17 TST conversions were documented among 732 contacts: both parents, two health care workers (HCWs) who provided close care, and several patients, visitors and one staff member without obvious close contact. Of 65 eligible children, 46% completed post-exposure therapy as recommended. The most common reasons for treatment failure were concern about side effects, perception of low risk and lack of physician support.

This investigation suggests that all children, including infants, with cough and numerous bacilli or extensive pulmonary disease should be considered infectious. Health care provider education is necessary to resolve the observed low compliance with current post-exposure management guidelines.