Evaluation of the sensitivity of individual test organisms to residual concentrations of selected types of anticoccidial drugs

Anticoccidial drugs with antibiotic or antibacterial activity can be detected by microbiological agar diffusion methods based on the ability of certain drugs to inhibit the growth of sensitive strains of bacteria which act as test organisms and produce inhibition zones. In practice, microbiological agar diffusion methods form the basis of monitoring the residues of inhibitory substances and obtaining primary proof of the presence of residues in foods and raw materials of animal origin. The aim of the present study was to observe the sensitivity of individual test organisms to residual concentrations of selected types of anticoccidial drugs. In our study, four bacterial strains were tested by agar diffusion: Bacillus stearothermophilus var. calidolactis C 953, Bacillus subtillis BGA (at pH 6.0, pH 7.2 and pH 8.0), Micrococcus luteus ATCC 9341 and Bacillus cereus ATCC 11778. The following anticoccidial drug standards were used: amprolium, nicarbazin and furazolidone as chemical compounds, monensin and lasalocid as polyether ionophores, and sulfamethazine and sulfaquinoxaline as representatives of the sulfonamide group. The residual concentrations capable of inhibiting the growth of individual test organisms in our study were compared with maximum residual limits that have been established for these anticoccidial drugs. All anticoccidial drugs were tested using dilutions from 0.0001 mg/ml up to 1 mg/ml.