Studies on the changes in intestinal flora by oral administration of Colistin.

Abstract

Effects of orally administered Colistin on intestinal flora were investigated with the strains, particularly lactose fermenting and nonfermenting ones (L+ and L-) isolated daily from stools of 26 patients suffering from acute infectious diseases of intestinal tract treated with Colistin sulphate and methansulphate.
The results were as follows:
1. By oral administration of “small dosis” of Colistin. (6, 000, 000 Unit/day), L+ was inhibited in 19 out of 21 cases (90.5%); by oral administration of “large dosis” of Colistin (18, 000, 000 24, 000, 000 Unit/day), L+ was inhibited in 4 out of 5 cases (80.0%).The L+ inhibiting effect of Colistin was similar to that of Kanamycin, Tetracycline and Kanamycin combined with Tetracycline.
2. By oral administration of small dosis of Colistin, L-was inhibited in 10 out of 21 cases (47.6%), and by large dosis of Colistin L-was inhibited in 3 out of 5 cases (60.0%). Thus, L-was not inhibited strongly by oral administration of Colistin.
3. By oral administration of Colistin, disappearance of the total intestinal microflora on the isolation media was not observed except only two out of 26 case. Therefore, Clistin did not seem to be an effective “enteric aseptic”.
4. By oral administration of Colistin, enterococci were markedly increased. Increase of enterococci was seen in 15 out of 21 cases (71.4%) by small dosis of Colistin and in 3 out of 5 cases (60.0%) by large dosis.
5. Enterococci isolated from stools were over 100γ/ml sensitive against colistin except 1 strain.
6. Staphylococcal enteritis was observed in 3 out of 32 cases (9.4%) during or immediately after oral treatment by Colistin.