Abstract
Screening for atypical mycobacteria (mycobacteria other than tubercle bacilli) were carried out in thirteen participating hospitals by using the p-nitrobenzoic acid-Ogawa egg medium. The subjects were the patients who were under hospitalization in June, September and December, 1975 and March, 1976. The isolation of mycobacteria was carried out using Ogawa egg medium which was inoculated with a sputum specimen after treatment with equal volume of a 4% (2%) NaOH solution for 15 minutes.
1. The ratio of atypical mycobacteria (including Gordona) among all mycobacteria was 7.8% in average and the ratio in senso stricto (excluding Gordona) was 7.5% in average (Table 1). The ratio was high in the hospitals located in South coast of Honshu and Shikoku islands facing Pacific Ocean (Fig. 1).
2. The kinds of species of atypical mycobacteria are shown in Table 2. The results agreed well with the results obtained by previous two studies (National Chest Hospital Group: Kekkaku, 48: 203-211, 1973; 51: 99-107, 1976).
3. The number of patients with lung disease due to atypical mycobacteria who were hospitalized in the period April, 1975 to March, 1976 was 128. Out of these, ca. 94% of the patients belonged to the disease due to M. avium-intracellulare omplex, and only 3% to that due to M. kansasii. Two cases showed the disease due to M fortuitum (Table 3). The frequency of occurrence of disease, so far observed using a ratio, the number of patients with disease due to atypical mycobacteria per the number of patients with lung disease (including tuberculosis) under hospitalization per day, as an index, was high in the hospitals located in the South coast of Honshu and Shikoku islands facing Pacific Ocean (Table 4 and Fig. 2).
4. The kinds of species isolated from sputa of patients with cavitary lung disease (mostly tuberculosis) and/or bronchiectasis were almost the same in three studies (Table 5). However, decrease in the ratio of M. nonchromogenicum was observed (1968 7.5%, 1971 4.4%, 1974 2.3%, t975 0.4%).
5. The kinds of species that caused lung disease were almost similar in our three studies (Table 6). Disease due to M. aviwn-intracellulare complex showed 94 to 96% of all atypical mycobacterioses, and disease due to M. kansasii 2 to 4% (Table 6). So far observed from the index used, the ratio of patients with lung disease due to atypical mycobacteria is increasing (Table 6). This increase has been suggested to be due to accumulation of such patients, as our another study (Kekkaku, 51: 447-451, 1976) showed that the prevalence rate of the disease among newly hospitalized patients was almost the same in recent five years (1971 to 1975).
