A comprehensive study has determined the incidence of infection with multidrug-resistant (MDR) Mycobacterium tuberculosis (MBT) strains in children. It has first revealed the clinical and laboratory manifestations and specific features of an immune system response in children infected with MDR MBT strains. There is new evidence that impaired immunological responsiveness is similar in children infected with drug-resistant MBT strains and in those with drug-resistant tuberculosis. A rationale is provided for the use of preventive treatment with two antibacterial agents in combination with the immunomodulator licopid to prevent tuberculosis in children with drug-resistance of MBT.