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Reasons for laboratory misdiagnosis that is observed in general health care network (GHCN) and penitentiaries were studied. The clinical efficiency of the diagnosis of tuberculosis in the GHCN by the Ziehl-Neelsen method is largely determined by three major factors, each of which is fundamentally important in assessing the result. The first factor is the adequacy of making up a cohort of patients having the symptoms of productive cough in the course of 2-3 weeks or more who are to be examined for tuberculosis by laboratory studies. The second is the quality of a diagnostic material. The third is the quality of laboratory specialists' work. The paper shows it necessary to implement programs for the internal control and external assessment of the quality of laboratory studies and to optimize (centralize) the activities of laboratories under the conditions of a regional network.

The aim of the investigation was to genotype clinical Mycobacterium tuberculosis isolates circulating at the penitentiaries of the Ivanovo Region. Mycobacterial strains were genotyped by the polymorphism of the lengths of restrictive fragments containing the insertion sequence 6110 by the routine procedure. The genotypes of Mycobacterium strains were classified in accordance with the PHRI database (New York). The strains were characterized by their sensitivity to antituberculous drugs by the absolute concentration method. The investigations indicated that in terms of the IS6110 genotype there were prevalent Mycobacteria strains belonging to 2 families: a W family (62.5% of the strains) and an AI family (25%). In addition to the monocultures, genotyping also revealed 3 mixed cultures consisting of 2 strains. Determining the drug sensitivity of the genotyped strains demonstrated both drug-sensitive and drug-resistant strains, including multidrug resistance among the strains of the same genotyping family (W or AI).

The results of determination of drug medium depend on both individual cultural properties of the strains tested and the type of the medium used. The composition of a medium is of significance for some strains: the latter grow in any medium and are characterized by the same spectrum of resistance. However, most drug-resistant strains have higher feeding demands which are not fully met on the lyophilized Löwenstein-Jensen medium. The strains in the lyophilized medium show an incomplete spectrum of resistance and less grow than do those in freshly prepared Löwenstein-Yersen medium.