Evaluation of amino penicillins in experimental infections in mice.

The therapeutic activity of bacampicillin compared to that of ampicillin and amoxycillin was evaluated against experimental infections in mice. Median curative doses (CD50) were determined in groups of animals challenged with bacterial suspensions injected intraperitoneally together with mucin and treated orally with the penicillins. When treated directly after the infection bacampicillin was slightly more active than ampicillin, whereas it was significantly more active than ampicillin and at least as active as amoxycillin when the treatment was instituted not until four hours after infection. Bacterial counts made on various organ homogenates from infected animals four hours after the infection showed that a generalized infection with high bacterial concentrations had developed. Penicillin administration caused a significant reduction in the bacterial counts and the bactericidal activity in vivo obtained after administration of bacampicillin appeared as good as that of amoxycillin.