1967 Volume 41 Issue 8 Pages 295-302
The authors tried isolations of drug-resistant bacilli from the feces of 68 healthy persons in 1961 and 65 persons in 1965 at monthly intervals during a one-year-period respectively using the MacConkey agars, each of which contains an antibiotic, i.e. streptomycin (SM), tetracycline (TC), chloramphenicol (CP) or kanamycin (KM) of 25 mcg/ml concentration level at the lowest.
The comparison of these experiments in different two periods leads the authors to the following conclusions:
1) The number of strains which were viable on the MacConkey agars containing above mentioned antibiotics in as high as 100 mcg/ml concentration level has markedly increased in the course of four years lapse.
2) Common tendency seen in the both experiments is that the incidence of SM-resistant and TC-resistant bacilli was greater than that of CP-resistant and KM-resistant bacilli
3) In regard to SM and TC resistance, the incidence of single-drug-resistant bacilli to SM or TO was greater in 1961, whereas, that of duple-drug-resistant bacilli against the both drugs was greater in 1965.
4) Triple-drug-resistant enterobacteriaceae against SM, TO, and CP were found in far lower percentage compared with the incidence of shigella of such resistant pattern. Seventy five percent of these strains were belonging to Escherichia coli.
5) A small number of KM-resistant strains isolated in the experiment in 1965 was mostly citrobacter. These strains, however, were apt to lose the resistance within six months after the isolation.
6) In general, the incidence of drug-resistant enterobacteriaceae was greater in summer than in other seasons.
