Antibacterial Assays in Body Fluids

Antibacterial Assays in Body Fluids

Antibacterial assays are carried out to demonstrate the toxic and therapeutic level of the antibiotics in blood and other body fluids. In this method, the MIC of the antibiotic for the test organism is done first by standard broth dilution method. The test with patient’s serum is done concurrently. Serial dilutions of the patients’ serum in nutrient broth are carried out and to each a standard drop of culture is added and incubated for 18 hours. The highest dilution of serum which has inhibited growth of the assay organism is noted. This is equivalent to the MIC of the antibiotic in question. Multiplication of the MIC by the serum dilution gives the concentration of the antibiotic which was present in the patient’s undiluted serum.