Efficacy of sulbactam-ampicillin in an induced Pasteurella haemolytica pneumonia model in calves

Therapeutic efficacy of sulbactam, a beta-lactamase inhibitor, in combination with ampicillin was evaluated in an ampicillin-resistant Pasteurella haemolytica pneumonia model in cattle, using an IV agar emboli method of infection. Groups of cattle given vehicle (group 1, n = 19) or ampicillin (group 2, n = 8) had 74% and 50% mortality, respectively, whereas group 3 (n = 11) given sulbactam-ampicillin had no mortality. Morbidities were 100% in groups 1 and 2 and 27% in group 3. Retrospectively, mortalities and morbidities were significantly (P less than 0.001) lower for group 3 given sulbactam-ampicillin when compared with those in groups 1 and 2 given vehicle or ampicillin, respectively. Evidence of embolic pneumonic pasteurellosis was observed histologically.