Applications of therapy in animal models to bacterial infection in human disease

Animal models have proven to be invaluable in bridging the gap between in vitro susceptibility testing of an antibiotic and anticipating results obtained in clinical studies. Variables such as antibiotic concentration, inoculum of organism, and pharmacokinetic parameters of the drug can be carefully controlled to provide information about the principles of treating infectious diseases as well as an evaluation of specific antimicrobial agents. End points of treatment can be precisely defined (that is, CSF sterility in meningitis, vegetation counts of bacteria in endocarditis) to allow a quantitative evaluation of a new antibiotic. However, it is important to realize that there may be differences in disease pathogenesis and antibiotic pharmacokinetics between experimental infections in animal models and infections in humans. Therefore, results in animal models should be interpreted with caution and compared with results obtained with antimicrobial regimens in clinical studies. Perhaps one of the most useful features of animal models is suggesting which antimicrobials would not be expected to be of therapeutic benefit in man.