Antibiotic treatment, intestinal aerobic microflora and experimental sarcoma L-1 growth in Balb/c-mice.

The present paper deals with the influence of a 10 days treatment with mezlocillin, piperacillin, cefotaxime, clindamycin or gentamicin on the endogenous intestinal microflora of Balb/c-mice and on the local growth of sarcoma L-1 tumor. Clindamycin and gentamicin demonstrated no influence, whereas cefotaxime and piperacillin caused the eradication of gram-negative resp. gram-positive bacteria but these antibiotics didn't produce a growth inhibition of local L-1 sarcoma tumor. The oral or parenteral application of mezlocillin (a 3 days treatment was sufficient) eradicated the complete aerobic and anaerobic intestinal microflora. This effect was significantly correlated with an increase of the cecum weight and the inhibition of local tumor growth. Possible mechanisms of these effects are discussed.