Studies on the prevalence of primary as well as acquired resistance to the primary and secondary drugs have been conducted by the Tuberculosis Research Committee, RYOKEN, every two years from 1957 to 1963 and every three years since 1963.
In 1977, after the lapse of 5 years since the last survey, the prospective study was conducted and the results were analyzed in comparison with those in the past seven surveys.
Pulmonary tuberculosis patients newly admitted to 75 institutions participating to the Committee from July 1 to December 31, 1977 with positive bacilli and the drug sensitivity tests were completed, were subjected to this study. Among them, 949 were previously untreated cases and 882 were previously treated cases.
All strains isolated from these patients admitted from July 1 to September 30, were collected to the reference laboratories of the Committee and the drug sensitivity were reexamined.
The criteria of drug resistance to the primary drugs on Ogawa's media were as follows: streptomycin-similar growth on media containing 100 and/or 10μg/ml compared with the control, or any growth on media containing 100 and 10μg/ml; isoniazid-similar growth on media containing 5 and/or 1μg/ml compared with the control, or any growth on media containing 5 and 1μg/ml; PAS-similar growth on media containing 10 and/or 1μg/ml compared with the control media, or any growth on media containing 10 and 1μg/ml.
The results were as follows:
1) The prevalence of resistance in untreated group was 9.4% for SM, 4.7% for INH and 8.6% for PAS, and in previously treated group 22.6% for SM, 31.8% for INH and 21.0% for PAS.
The prevalence of drug resistance remained unchanged in untreated group and showed decreas ing tendency in previously treated group for all three drugs.
2) The prevalence of drug resistence in untreated group was 15.4% (10.3% to one drug, 2.7% to two drugs, 2.3% to three drugs). This rate was higher than that in 1972 and lower than in 1969. Accordingly, it can be said that the rate of the primary drug resistance was almost unchanged since 1963.
The prevalence of drug resistance in previously treated cases were 46.8% (25.4% to one drug, 14.3% to two drugs and 7.1% to three drugs). The transition of the rate showed gradual decline since 1966.
3) The sensitivity was rechecked at the reference laboratory for 567 strains from untreated group and 404 strains from previously treated group.
The rate of primary drug resistance was 11.8% (9.7% to one drug, 1, 8% to two drugs and 0.4% to three drugs). The rate in previously treated group was 44.3% (26.0% to one drug, 13.4% to two drugs, 5.0% to three drugs).
4) The sensitivity tests for KM, EB and RFP were carried out at the reference laboratory for 602 strains from untreated cases and 422 strains from previously treated cases. The criteria of resistance to those drugs were similar growth on Ogawa's media containing 100μg/ml of KM, 5μg/ml of EB and 10μg/ml of RFP compared with the growth on control media.
The rate of resistance in untreated cases was 0.5% for KM, 0.7% for EB and 1.0% for RFP and in previously treated cases 5.7%, 4.5% and 17.8% respectively.
Four strains resistant to two secondary drugs were isolated from untreated cases, and strains resistant to both KM·EEB, KM·ERFP or RFP·EEB were isolated from 0.2%, 2.6% and 1.6%, respectively, in previously treated cases.
The prevalence of resistance to those secondary drugs was 1.5% in untreated cases and 22.0% in previously treated cases at the reference laboratory, and the results were almost similar to those at local institutions.
It should be noted that four new cases were resistant to two of secondary drugs, and the preva lence of resistance to RFP has been increasing in previously treated cases.

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The ultrastructure of mycobacterial cells including tubercle bacilli has been well studied with fruitful results. We have, however, little knowledge of mycobacterial nuclear chromosome and of localization of mycobacterial antigen. In this review, the results of our electron microscopic observations on the mycobacterial chromosomes and on the visualization of mycobacterial antigen were summarized.
1. Localization of mycobacterial antigen by the use of immunoferritin. technique. Highly active IgG was obtained from rabbits immunized with M. smegmatis cells. The IgG was conjugated to the ferritin particles by the aid of 0.5% glutaraldehyde. Mycobacterial cells were agglutinated with the immunoferritin molecules and the cell-immunoferritin complexes were fixed, embedded and sectioned. The immunoferritin particles were shown to be combined with the outer layer of cell walls. It was clearly shown in another experiment that the immunoferritin particles were combined with the cell wall components isolated from the sonicated bacterial cells.
2. Ultrastructure of mycobacterial chromosome. Several species of mycobacteria, including M. tuberculosis H₃₇Ra and H₃₇Rv, BCG, M. smegmatis, streptomycin-resistant strain of M. smegmatis AC-5 and drugs-resistant strain of human tubercle bacillus, were converted into spheroplasts in a medium containing glycine and lysozyme. The spheroplasts thus prepared were spread on the surface of water according to the “one-step release” procedure introduced by Kleinschmidt. Single DNA fiber of double helix was observed in many preparations.
The length of DNA was 1, 100-1, 150μm, and the estimated genome size of M. smegmatis was 2.15-2.25×10⁹ daltons. The replication forms were of E. coli type except for some strains of human tubercle bacilli. The polyribosome was observed along the active segment of DNA.

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