Metabolic inhibition as an index of bacterial susceptibility to drugs.

Detection of bacterial growth by measuring the release of (14)CO(2) from the metabolism of uniformly labeled (14)C-glucose has proven to be accurate, sensitive, and rapid. The inhibition of glucose metabolism by antibiotics as an index of bacterial susceptibility was evaluated based on radiometric methodology. Bacterial dose-response curves to antibiotics were defined. The susceptibility to drugs was determined within several hours after inoculation of the cultures. The pentose phosphate shunt appeared to be the major metabolic pathway involved during this period. There was a consistent relationship between the dose-response curves determined by the inhibition of glucose metabolism and the minimal inhibitory concentrations determined by a serial broth dilution technique. Inhibition of metabolism as an index of bacterial susceptibility to drugs appears to be valid, rapid, and readily applicable to available automation.