A decade of experience with Mycobacterium tuberculosis culture from children: A seasonal influence on incidence of childhood tuberculosis

Setting: A tertiary care hospital in the Western Cape Province of South Africa from November 1983 - October 1993. Objective: Evaluation of the source of all cultures of Mycobacterium tuberculosis from children aged < 13 years and documentation of the mean time for culture with Lowenstein-Jensen (LJ) medium and a radiometric method (Bactec). Results: One thousand six hundred and sixty cultures of M. tuberculosis were obtained from 1204 children (638 (53%) males and 566 (47%) females). The median time to a positive culture result was 65 days with LJ medium and 23 days with Bactec (P < 0.0001). Gastric aspirate provided 1298 cultures (78%) from 983 children (82%) of whom 52% were aged < 2 years. Ninety-six positive sputum specimens were from 79 children (7%) of whom 70% were > 5 years. Significantly more positive cultures were obtained during the late winter and early spring (P < 0.001), and a similar trend was found for tuberculous meningitis. Conclusion: The use of a radiometric culture method has expedited the confirmation of tuberculosis in childhood in our hospital. Even in children < 3 months of age the diagnosis of tuberculosis can often be confirmed by culture. The documented increase in childhood tuberculous disease in spring suggests an increased transmission of tuberculous infection in autumn and winter in our community.