[Examination of market carps for residues of antimicrobial agents].

The residues of inhibitory substances in the muscle, hepatopancreas, bile, and pyloric caeca of 30 carps from ponds south of Brno were examined by the microbiological diffusion method. The following testing micro-organisms were used: B. cereus var. mycoides (ATCC 11778), B. subtilis (ATCC 6633), Sarcina lutea (ATCC 9341), and Micrococcus flavus (ATCC 10240). Residues of inhibitory substances were not found in any of the muscle samples tested. The rest of the tested tissues showed, in some cases, small inhibition zones which seem to be due to the presence of natural antimicrobially active substances in the bile and gastro-intestinal tract of the fish rather than to the persistence of the residues of drugs given to the fish during their life.