Features of development of TB infection caused by different doses of MBT

Accoding to the literature data, tuberculosis in mice develops within 2-4 weeks after infection with large doses of the pathogen (about 1 million per ml). Perhaps a smaller dose of MBT causes the human TB.The aim is to study the features of the development of tuberculosis after infection with a smaller dose of MBT.We were made and use 2 suspensions with concentration of MBT of 10-20 and 100-200 colony-forming units (cfu) per 0.1 ml. These concentrations were used to infect 2 groups of guinea pigs (age 3 weeks) by subcutaneous injection into the inguinal region. the fist group (n=12) was infected with a dose 10-20 cfu in 0.1 ml and second group (n=12) - dose of 100-200 cfu in 0.1 ml. The delayed-type hypersensitivity (DTH) responses in skin had been used. The tubercular recombinant allergen 0.1 ml (0.2 µcg) were introduced intradermally. Internal organs were studied by macroscopic and microscopic (Ziel-Neelsen) methods after euthanizing animals. Pieces of lugs and spleen were inoculated in LJ medium and studied by PCR methods.The positive reactions of DTH were detected after 2.5 months in the first group (dose 10-20 cfu) and 1.5 months in the second group (dose 100-200 cfu). MBT in smears from lung tissue were detected in the first group after 4 months, and in the second group after 1.5 months.The timing of development of TB is dose-dependent. Thus, when a dose of 10-20 cfu was infected, the delayed type hypersensitivity re4action and MBT (DNA and ARM) in the lungs were ...
Source: European Respiratory Journal - Category: Respiratory Medicine Authors: Tags: Tuberculosis Source Type: research