Prevention of antibiotic resistance and preservation of available antibiotics through optimized penicillin dosing in pigs

Actinobacillus pleuropneumoniae (APP) is a major cause of respiratory infections in pigs. Symptoms range from peracute with mortalities without preceding clinical symptoms to chronic where growth rate is retarded and pleuropneumonia is seen in the routine meat inspection at slaughter. Irrespective of the clinical presentation, infections with APP cause animal suffering and
economic losses. Over the years, various preventive measures have been employed to reduce the impact of the disease but pleuropneumonia is re-emerging in Sweden as recordings of pleurisies at slaughter have increased. Commercial vaccines have had limited success in controlling infections with APP. Therefore, antibiotic treatment is required to save lives of pigs and
to reduce economic losses.

In Sweden, penicillin is the recommended first choice for treating APP infections but treatment is not always effective. The lack of clinical efficacy is not related to resistance since isolates of APP from Swedish pigs are susceptible to penicillin in vitro. Our hypothesis is that the poor clinical response is due to inappropriate dosing. Therefore this project aims at investigating if the efficacy of penicillin can be improved by revised dosage regimens for pigs employing experimental infections with APP as a model. If the efficacy of penicillin can be improved, use of other antimicrobials with greater impact on selection and spread of resistance can be avoided.