The objective: to identify factors of a higher risk to develop tuberculosis in children exposed to tuberculosis cases resistant or sensitive to rifampicin.Subjects 161 children under 6 years old exposed to tuberculosis in their families were enrolled in the retrospective study. The children were divided into 2 groups: Group 1 (n = 92) – children free of TB; Group 2 (n = 69) – children ill with TB. In each group, two subgroups were identified: those with index cases susceptible to rifampicin (RS) 1A (n = 40) and 2A (n = 43) and those with index cases resistant to rifampicin (RR) 1Б (n = 52) and 2Б (n = 26).Results. Exposure to isoniazid resistant tuberculosis increases the risk of TB in the child by 12 times, on the opposite, drug resistance to rifampicin provides no impact on the risk to develop tuberculosis. If the child is exposed to 2 cases of tuberculosis and more, the risk to develop tuberculosis increases by 2-14 times. BCG vaccination of the child exposed to tuberculosis reduces the risk to develop tuberculosis by 2-13 times.
In high tuberculosis (TB) burden settings TB incidence in children is an actual problem especially when contact with TB adults estimated. Another difficulty is preventive treatment in presence of multi-drug resistant (MDR) TB in infectious source. Clinical recommendations in Russia for child TB contacts are following: at least 1-year surveillance after exposure, preventive treatment by 2 drugs during 3-6 months. Preventive regimen recommended is isoniazid plus pyrazinamide or ethambutol. Rifampicin is not recommended in outpatient treatment. Isoniazid preventive therapy is not desirable. It is designated that treatment may be individually modified in case of latent MDR-TB infection risk. In our research we aimed to evaluate the effectiveness of preventive measures in child household contacts. METHODS. This is a retrospective study of the children under 6 years diagnosed with tuberculosis (TB group, n=53) and healthy children (healthy group, n=71) in household contacts with M. tuberculosis expectorators. RESULTS. In TB group 13 children were not vaccinated with BCG and in healthy group only 6 were unvaccinated (OR:3.521, 95% CI:1.239-10.006). Presence of two or more TB patients in household was fixed in 12 cases in TB group versus 3 in healthy group (OR:6.634, 95% CI:1.767-24.914). Results of drug-susceptibility testing in TB group are presented: drugsusceptible TB -23 (43.40%), monoresistant -1 (1.89%), polyresistant (not MDR) -10 (18.87%), 19%), extensively drug-resistant (XDR) -3 (5.66%). The testing results in healthy group were different: drug-susceptible TB -22 (30.99%), monoresistant -2 (2.82%), polyresistant -2 (2.82%), MDR -36 (50.70%), XDR -9 (12.68%). Thus MDR (including XDR) in our study were rarer associated with child TB (OR:0.404, 95% CI: 0.183-0.893). Preventive therapy was conducted for 20 children of TB group and for 43 children of healthy group. In almost all cases the regimen was standard without considering MDR TB of infection source, except 2 children in TB group and 4 children in healthy group, who received second-line drugs (paminosalicylic acid and/or prothionamide). But because of the small number of cases with individualized regimens we cannot evaluate their effectiveness. Although children who did not receive preventive therapy at all were at the higher risk of active TB (OR:2.534, 95% CI:1.219-5.266). CONCLUSION. BCG-vaccination and preventive treatment help to prevent TB in children in household contacts without considering MDR TB of infection source. More than two TB cases presented in household increase TB risk in child 6,6 times.
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