An Improved Bacteriological Method for the Detection of Sulfonamide Residues in Food

The addition of trimethoprim to Mueller-Hinton medium was found to improve the sensitivity of test bacteria towards sulfonamides by 20—50 times. Depending on the test bacteria used, the optimal concentrations of trimethoprim added to the medium are 1 μg per ml (Micrococcus luteus), 0.25 μg per ml (Bacillus stearothermophilus var. calidolactis) and 0.1 μg per ml (Bacillus megaterium). Using Micrococcus luteus or Bacillus megaterium a concentration of 0.25 μg sulfanilamide per ml may be detected, and 0.1 μg per ml may be detected when Bacillus stearothermophilus var. calidolactis is used.