There have been increasing reports of mycobacterioses in man and animals caused by "atypical" or "opportunist" mycobacteria. At the present, "opportunist mycobacterioses" are not generally responsive to antituberculosis drugs, and therefore, create considerable problems with regard - to chemotherapy and control measures. In recent years studies have been made to isolate opportunist mycobacteria from soil, house-dusts and tap-water.
It seemed quite interesting to define the extent of circumstantial presence of "opportunist" mycobacteria and nocardia in the soils of school-ground of primary schools and middle-high schools. This communication is the results of pilot study to isolate and identify "opportunist" mycobacteria and nocardia from 504 soil specimens of 72 schools in Seoul City.
1. Of a total of 59 isolates from 504 soil specimens tested, 32 strains were identified as opportunist mycobacteria and 27 strains as nocardia.
2. Isolation rates of opportunist mycobacteria by the areas (of specimen collection) were as follows: 36.4% in the southern area of Han-River, 33.3% in the central area, 22.7% in the outskirt area and 16.6% in the intermediate area. There observed no apparent difference in the isolation rates both between the areas and between primary schools and middle-high schools. However, a significant´ difference was noted in the isolation rates between the places of soil sampling in-a. given school (r <0. 05), i.e., the highest was the soil of refuge heaps (15.2%), and tap-water pole area (11.1%),_ the school-lavatory entrance (9.7%), the school gate entrance (5.5%),´ and iron-bar play ground(2.7%). The soil specimens from the center of school ground and from school building entrance_ yielded none of mycobacterial isolates.
3. Isolation rates of nocardia by the areas were as follows 33.3% in the central area, 31.8% in the outskirt area, 27.3% in the southern areas of Han-River and 11. 1% in the intermediate area. As in the case of mycobacteral isolates, there observed no apparent differences in the isolation ,rates both between the areas and between primary schools and middle-high schools, but a significant difference was noted between the places of soil sampling (P4. Of the 32 strains ´of isolated mycobacteria, 15 strains were slow-growing mycobacteria and the remaining 17 strains belonged to the rapid growers. Of the 15 slow-growers, 4 strains were M. scrofulaceum-szulgai complex, 3 M. gordonae; 4 M. terrae-triviale complex, 2 M. avium-intracellulare-xenopi complex, and 2 unclassified schotochromogens. Of. the 17 strains of rapid growers, 12 were M. diernhoferi, 2 M. fortuitum-peregrinum complex, 2 M. vaccae and one M. flavescens.
5. Of the 27 strains of nocardia isolated, 11 strains were N. transvalensis, 5 N. convoluta, 5 N. erythropolis, one N. vaccinii, one N. polychromogens-paraffinae complex and 4 untypable strains of orange-pigmented nocardia spp.
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