THE DETERMINATION of the sensitivity of bacteria to antibiotics in vitro has become a common laboratory procedure, the results of which are widely used in defining the range and relative efficacy of antibiotics against different microorganisms. The results of tests for sensitivity are also generally used in the management of the specific therapy of patients with bacterial infections. The sensitivity of any given strain of organism to an antimicrobial agent is generally defined in terms of the concentration of the agent which inhibits the growth of the organism either partially or completely, or which kills the organisms within the time limit of the test.1 Several methods of determining this value are in common use, and the results obtained with any given strain by the different methods may show wide discrepancies, depending on the details of the method and the choice of the end point.
This difficulty is well known
JACKSON GG, FINLAND M. COMPARISON OF METHODS FOR DETERMINING SENSITIVITY OF BACTERIA TO ANTIBIOTICS IN VITRO. AMA Arch Intern Med. 1951;88(4):446–460. doi:10.1001/archinte.1951.03810100030003