Impact of a decreased antimicrobial therapy at early stage of spontaneous bovine pneumonia cases on antimicrobial consumption and therapeutic efficacy
Résumé
Purpose Antimicrobial resistance associated with veterinary use of antimicrobials is a potential hazard for human health. In this context, it is crucial to decrease number of animals unnecessarily treated and to optimize treatments when needed. As shown in experimental models, efficacious antibiotic dosage regimen could be decreased when given at early stage of disease. We conducted a field study to evaluate at the group level antimicrobial consumption and therapeutic efficacy of such protocol to treat bovine respiratory disease (BRD). Methods In 20 barns, 217 young bulls (YBs) were randomly assigned to one of two experiment groups E2 and L10, based on detection time of BRD (Early or Late) and on dosage regimen (2 or 10 mg/kg), and follow up during the first month on feed. In the E2 group, YB temperature was continuously monitored using a ruminal temperature bolus. YBs with a ruminal temperature ≥40.2°C for more than 12h and presenting no or only slight signs of BRD were considered as Early detected and treated with 2 mg/kg of marbofloxacin, a fluoroquinolone used in Europe to treat BRD. In the L10 group, YBs with moderate or severe signs of BRD were considered as Late detected and treated with 10 mg/kg of marbofloxacin. Relapses were treated according to farmers’ habits. The treatments units [amount (mg)/ Used Daily Dose (mg/kg)] for a standard YB of 300 kg at risk were calculated and summed to determine total amount of antibiotics (TA). First line treatment and relapse rates were recorded. Results TA was decreased by 33% and marbofloxacin amount by 63% in E2 vs L10 group. A standard YB received 173 and 471 marbofloxacin units and 54 and 9 relapse treatment units in E2 and L10 groups respectively. First line treatment and relapse rates were higher in E2 (50 and 35%) vs L10 (30 and 13%). 97% and 100% of YBs treated in E2 and in L10 group were cured at the end of the study. Conclusions Our results suggest that the combination of an early detection of disease with lower antibiotic doses could be used to optimize drug consumption at the herd level without affecting treatment efficacy. Relevance Such findings evidence the possible rationalization of antimicrobial use under field conditions, to limit its impact on public health