Basis and results of therapy with Beta-lactam antibiotics in experimental infections.

Experimental infections in animals and their chemotherapy are dependent on a variety of experimental conditions and parameters which may be themselves interrelated; the type and number of infecting organisms, the nature of the infection, the antibiotic chosen for therapy and its administration schedule can influence the results of animal studies. One additional factor which applies to dosage of penicillins is the phenomenon of the recovery period, i. e. the period of time which surviving bacteria need to resume growth after removal of the drug. The bactericidal effect probably strongly influences the period of time which is required before the number of viable organisms reach the level present at the time of infection. Thus one can assume that it is the extent of the bactericidal effect which influences the period of time between doses rather than the recovery period. Besides these parameters the physiological state of the infecting organism may also be important. The results of penicillin therapy vary considerably depending on the bacterial growth rate. Differences in the nature of infection in experimental animals and man and the physiology of animals and man do not allow close simulation of clinical infections under experimental conditions. However the factors discussed may provide some guidelines for rational antibiotic treatment in man.