STUDIES ON ATYPICAL MYCOBACTERIOSIS WITH SPECIAL EMPHASIS ON THE DISEASE DUE TO MYCOBACTERIUM KANSASII

Abstract

I. On the disease due to M. kansasii
The disease due to M. kansasii occupied only 2 per cent (4 cases) of the total cases (200 cases) of atypical mycobacteriosis in Japan in 1966. Therefore, it was thought that this disease was very rare in Japan. But, since then the frequency of M. kansasii increased year by year, and recently 6 to 11 cases of the infection with M. kansasii were found every year. This disease had probably been overlooked before 1966.
i) Some problems in diagnosis Photochromogenicity of M. kansasii was not found on the culture medium which was not ventilated, and yellow pigmentation of colonies did not occure if colonies were exposed to light 4 weeks after cultivation on Ogawa's medium at 37. Moreover, the colony of M. tuberculosis is more similar in shape and color to that of M. kansasii than to other atypical mycobacteria. Therefore, the laboratory technicians may misinterprete M. kansasii as M. tuberculosis, and a considerable number of strains may escape their notice.
On smear, M. kansasii looked like a long beaded rod and occured in curl-like heaps. The morphological observation of organisms may be useful for the diagnosis of the disease due to M. kansasii.
The sensitivity to rifampicin (RFP), ethionamide (TH) and cycloserine (CS) was a characteristic feature of the drug susceptibility of M. kansasii.
ii) Geographic distribution The majority (80.6%) of the patients were living in Tokyo and its vicinity, and the disease due to M. kansasii amounts to 10 percent of the total cases of atypical mycobacteriosis in this district. Therefore, it is suggested that the incidence of the infection with M. kansasii is different geographically in Japan.
iii) Clinical characteristics and chest
The majority (94.1%) of the disease occured in men. Many patients were found among younger and middle aged persons without any previous lung disease.
On the chest radiogram, cavitary lesions were found in the lung field in the majority (72.8%) of the cases of the disease due to M. kansasii, while subpleural cavitary lesions were found in many cases of the disease due to M. intracellulare.
iv) Chemotherapy
SM, PAS and INH were used most frequently. RFP, TH and CS were used in many cases.
In non-cavitary cases, bacteriological conversion occured in 4 patients (100%) by chemothe rapy excluding RFP and TH, and in 5 patients (100%) treated with the regimen containing RFP or TH. But, in cavitary cases, the negative conversion occured in 7 cases of moderate extent and 5 for advanced cases (70 or 50%) by chemotherapy excluding RFP and TH, and in 12 and 20 patients (100 or 86.9), respectively, treated with the regimen containing RFP or TH.
v) Diagnostic criteria
The diagnostic criteria for atypical mycobacteriosis established by Hibino and Yamamoto are not applicable to the disease due to M. kansasii. If there are discharge of the organism even in small amount twice and the presence of clinical symptoms which might relate to bacilli discharge, such cases are diagnosed as the disease due to M. kansasii.
II. On the disease due to M. intracellulare
As the initial radiographic changes, the pleural-thickening-like shadow and the linear shadow extending from the pleura into the lung field were found most frequently, and the appearance of the bulla and the thickening of its wall were found not rarely.
In the disease due to M. intracellulare, radiographic changes usually showed progression very slowly and the interval from the initial appearance of pulmonary changes to the cavitation was considerably long (over 2 to 4 years in many cases).
Subpleural cavitary lesions were found in many cases, but in the majority of the cases complicated with neumoconiosis, cavitary lesions were found in the lung field.