Mycobacterial genotype is associated with disease phenotype in children

Hesseling A.C. ; Marais B.J. ; Kirchner H.L. ; Mandalakas A.M. ; Brittle W. ; Victor T.C. ; Warren R.M. ; Schaaf H.S. (2010)


OBJECTIVE: To investigate the association between mycobacterial genotype and disease phenotype in children. METHODS: We describe hospitalised children diagnosed with culture-confirmed tuberculosis (TB) in South Africa, a high TB burden setting. Disease phenotype was classi-fied as intrathoracic or extrathoracic based on mycobacterial culture site. Mycobacterial genotyping was completed using spoligotyping. RESULTS: We analysed 421 isolates from 392 children (median age 2 years, range 0.1-12). Intrathoracic disease was present in 294 (75%) children and extrathoracic disease in 98 (25%). The Beijing genotype was the most prevalent (32.9%), followed by the Latin American Mediterranean (LAM, 28.8%), and S genotypes (6.4%). Age was significantly associated with genotype. Children with the Beijing (OR = 2.36, 95%CI 1.21-4.60) and S genotypes (OR = 3.47, 95%CI 1.26-9.56) were more likely to have extrathoracic disease compared to children infected with the LAM genotype, in analyses adjusted for age and drug resistance. CONCLUSIONS: TB genotype and disease phenotype in children were associated. Beijing and S genotypes were more frequently cultured from extrathoracic cultures, indicating potential improved ability to disseminate. Strain-related phenotypes could explain different disease spectra in geographic settings where certain strains are successful. Studies of mycobacterial human interaction should consider host immune responses, clinical and epidemiological factors. © 2010 The Union.

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