Туберкульоз – напрями пізнання і вирішення проблеми

Abstract

Наведено результати багаторічної роботи з вивчення біологічних властивостей одного високовірулентного швидкорослого штаму M. bovis. Встановлено, що мікобактерії активно змінюються за пасажів (240 пересівів) через штучне живильне середовище без умісту індукуючих чинників, набуваючи невластивих для них ознак та можливість розмножуватися за температури 3 °С. З’ясовано, що, пройшовши ряд стадій, остання морфологічна форма біологічного циклу розвитку – елементарні тільця – генерує кислотостійкі паличкоподібні варіанти збудника туберкульозу. Отримані дані є підставою для перегляду окремих положень інструктивно-нормативних документів, що сприятиме підвищенню ефективності заходів профілактики та викоріненню туберкульозу тварин. Long-term studies of one epizootic strain in the dynamics of numerous sub-cultures in some cases confirmed the results of other authors in the previous decades, in other cases – have found out previously unknown properties – to multiply in conditions of low positive temperatures (3 °С). It is shown, that for passages through artificial nutrient medium with different pH, the rate of formation of colonies is significantly different. Faster colonies appear in medium with pH 6,5-6,7 in comparison with pH 7,1-7,2. The latter (7,1-7,2) after 15-20 sub-cultures reduces the activity of reproduction of mycobacteria, which defines them as slow-growing. Over time, the growth of culture varies from single colonies to continuous growth along the line of mycobacteria inoculation. Especially this phenomenon is observed by the appearance in the population of mycobacteria of adaptive (nonacid-resisting) transitional forms of the сausative agent of tuberculosis. On this background, an opportunity for mycobacteria to actively display peroxidase, catalase, dehydrogenase activity, grow on simple nutrient media with simultaneous decrease in activity to form a cord-factor and to cause the death of Guinea pigs with virtually no allergic reaction to purified protein derivative (PPD)-tuberculin for mammals. In the long-term storage of samples in the tube on the nutrient medium which practically did not have a growth of colonies (117 and 118 sub-cultures) at 37 °С cultivation and after 20 months cultivation in the conditions of 3 °С, the dissociation of avirulent clones of mycobacteria had been observed. The content of total lipids is dynamically reduced from 11,8±1,6 to 1,74±0,28 % by weight. The qualitative composition remains unchanged, although the quantitative content was changed. At the same time, the quality of free fatty acids as well as their quantitative content was changed. The content of short-chain free fatty acids increases while simultaneously is reducing the content of long chain acids. Some of the last on 150 sub-culture are not identified. In this background, the morphology of nonacid-resisting mycobacteria tends to change: for the temperature of cultivation 3 °С as the last morphological form is nonacid-resisting grains (elemental bodies), which after two passages through Guinea pigs in the isolated colony of L-forms, transforming into granular forms (after 300 days of growth at 3 °С) are reversed in typical acid-resisting bacillus of the causative agent of tuberculosis at 37 °С – acid-proof bodies. At this temperature (37 °С) mycobacteria are poorly cultivated or not cultivated. At the same time, it was found that filtration forms (elemental bodies) generate the rod-shaped variants of mycobacteria. The generalization of long-term research shows that for mycobacteria there is a biological cycle of development that determines the endlessness of the existence in the nature of the causative agent of the tuberculosis: acid-resisting bacillus → adaptive and classical L-forms (ovals with different optical density of the surface) → released from L-forms different grains (elemental bodies) → acid-resisting bodies of tuberculosis.