Biomedical subjects
Publications and source records attributed to M Tsukamura.
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Numerical classification of slowly growing mycobacteria, including 159 strains received as Mycobacterium tuberculosis, M. bovis, M. africanum, and M. microti, was carried out using 88 characters, and the following results were obtained. 1) All 159 strains received as M. tuberculosis, M. bovis, M. africanum, and M. microti formed one cluster, and no clear-cut differentiation among four species was achieved. These four species should be reduced to one species, M. tuberculosis. 2) Within the cluster, two subclusters appeared, with a number of strains located outside the subclusters. One subcluster was composed, except for two strains, of only M. tuberculosis strains, and another of M. bovis and M. africanum strains only. The subclusters were regarded as subspecies tuberculosis and subspecies bovis, respectively. M. africanum was regarded as a synonym of M. bovis, i.e., a niacin-positive variety of M. bovis (subsp. bovis). 3) An intermediate subcluster was observed outside the M. tuberculosis and M. bovis subclusters. This may be regarded as intermediate between the two subspecies, tuberculosis and bovis. 4) In the last two decades, the characteristics of M. tuberculosis strains isolated from patients seemed to be approaching those of M. bovis strains. The recently isolated strains showed stronger arylsulfatase activity and lower resistance to thiophene-2-carboxylic acid hydrazide than the strains isolated 16 to 19 years ago.
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Numerical identification using the range of a species defined as (M +/- 2s)% was shown to be suitable for the identification of slowly growing mycobacteria. In the formula, M is the mean matching coefficient for individual strains of each species to the hypothetical median organism pattern of their own species and s is the standard deviation.
A new antituberculosis agent, ofloxacin (DL8280), inhibited the growth of Mycobacterium tuberculosis at concentrations of 0.63 to 1.25 micrograms/ml. There were no cross-resistance relationships between this agent and other antituberculosis agents. The agent delayed the growth rate of M. tuberculosis (strain H37Rv) at concentrations of 0.2 to 0.5 microgram/ml. It showed considerable bactericidal activity at concentrations a little higher than the growth-inhibitory concentration. The combined effect with other antituberculosis agents seemed to be additive. The pattern of resistance that developed with this agent was the obligatory two-step pattern, and there were 2 resistant phenotypes.
A new antibacterial substance, ofloxacin (DL8280), was used in the treatment of pulmonary tuberculosis. The agent was given to 19 patients with chronic cavitary lung tuberculosis as single doses of 300 mg daily for 6 to 8 months. A decrease in the amount of tubercle bacilli in the sputum was observed in almost all patients, and negative conversion occurred in 5. Resistance of tubercle bacilli to the agent appeared in patients who did not show negative conversion. No side effects were observed during the administration period. The agent was considered useful in lung tuberculosis therapy.
Ofloxacin (DL 8280) is rapidly eliminated from mouse organs. It disappears quickly from the lungs and the spleen and more slowly from the liver and the kidneys. The antituberculosis activity of this agent was shown in mice when the agent was given intraperitoneally at daily doses of 1 mg per mouse (approximately 42 mg/kg). The number of viable bacteria of Mycobacterium tuberculosis strain H37Rv contained in the liver decreased markedly in the mice treated with ofloxacin, and the inhibitory effect of the agent seemed to appear when the tubercle bacilli actively multiplied.
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