Characteristics of infants exposed to maternal tuberculosis and chemoprophylaxis using 3 months of isoniazid and rifampicin

Background: Although the clinical features of infants with congenital tuberculosis (TB) are well established, the features of infants exposed to TB in utero including those who are non-infected, are not well reported. TB-exposed infants are at risk of developing TB post-delivery, and chemoprophylaxis, usually isoniazid, is therefore recommended. Isoniazid/rifampicin combined is an alternative, but little is known about its effectiveness. Objective: To determine the clinical features of infants exposed to TB in utero and the proportion who develop TB infection and disease despite chemoprophylaxis with a 3-month course of isoniazid/rifampicin. Methods: This was a retrospective review of TB-infected women and their infants between 2007 and 2010. Features of mothers and infants at delivery, and follow-up of infants after completion of isoniazid/rifampicin are described. Results: Eighty-eight infants born to 86 TB-infected women were studied. TB diagnosis was made peri-partum in 24.4% of women, and only 46.2% of those diagnosed ante-partum were on anti-TB treatment for > 2 months. Human immunodeficiency virus (HIV) was positive in 97.7% of the TB-infected women and in 74.6% the CD4 count was < 200 cells/mm(3). Fifty-six (63.6%) infants had a low birthweight (LBW) and 45 (51.2%) were preterm. Mycobacterial culture was positive in four (4.5%) infants (three were also smear-positive) and none was diagnosed with TB on clinical or radiological findings only. At 3-month follow-up, 17 (20.2%) defaulted, and, of 67 who returned, seven (10%) did not return for tuberculin test reading, but one of 60 (1.7%) tested positive. Five infants (7.2%) were HIV PCR-positive at 6 weeks and four of their mothers were on HAART. Conclusion: The majority of TB-exposed infants were born to mothers with TB/HIV co-infection, and a high proportion were pre-term and of low birthweight. Although the high attrition rate made it difficult to assess the effectiveness of chemoprophylaxis with isoniazid/rifampicin, only one of the 60 infants who completed follow-up to 3 months was found to have tuberculous infection.