title: Cefquinome sulfate behavior after intramammary administration in healthy and infected cows.
abstract: Maintenance of adequate drug concentration at the site of infection is an important problem in mastitis antibiotic therapy, and the efficacy of intramammary β-lactams can be optimized by maintaining the drug concentration at the site of infection above the minimum inhibitory concentration (MIC) as long as possible. The most important pharmacokinetic and pharmacodynamic parameter for efficacy evaluation is time during which drug concentrations exceed the MIC (t>MIC). In this study, we assessed the pharmacokinetic profile of cefquinome (CFQ) after repeated intramammary administration in healthy cows and cows subclinically infected with Staphylococcus aureus as well as the MIC of Staph. aureus field strains. In addition, the degree of drug passage was investigated from udder to bloodstream by measuring systemic drug absorption in healthy and infected animals. Cefquinome concentrations were quantified by HPLC (UV-visible detection) in milk samples collected from quarters and from blood serum samples. The systemic drug absorption was negligible in healthy and subclinically infected animals (maximum concentration 0.09±0.02 and 0.1±0.01 μg/mL in healthy and subclinically infected animals, respectively). The MIC(90) value for CFQ in Staph. aureus field strains (n=20) was 0.24 μg/mL. The pharmacokinetic and pharmacodynamic evaluation, determined by t>MIC, showed an equal persistence of CFQ in all quarters, indicating an equivalent activity of the drug regardless of the pathological status of the udder. Moreover, with literature data regarding CFQ MIC, the t>MIC has been calculated for other bacterial species.
authors.affiliation: Università degli Studi di Milano, Department of Veterinary Sciences and Technologies for Food Safety, 20133 Milan, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Zonca
authors.forename: M
authors.initials: M
authors.lastname: Gallo
authors.forename: C
authors.initials: C
authors.lastname: Locatelli
authors.forename: S
authors.initials: S
authors.lastname: Carli
authors.forename: P
authors.initials: P
authors.lastname: Moroni
authors.forename: R
authors.initials: R
authors.lastname: Villa
authors.forename: P
authors.initials: P
authors.lastname: Cagnardi
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000493:pharmacokinetics*; D002417:Cattle; D002511:Cephalosporins / Q000008:administration & dosage / Q000493:pharmacokinetics*; D004333:Drug Administration Routes / Q000662:veterinary; D005260:Female; D007774:Lactation; D008321:Mammary Glands, Animal / Q000187:drug effects / Q000378:metabolism* / Q000382:microbiology; D008414:Mastitis, Bovine / Q000188:drug therapy* / Q000378:metabolism / Q000382:microbiology; D008826:Microbial Sensitivity Tests; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000378:metabolism / Q000382:microbiology / Q000662:veterinary; D013211:Staphylococcus aureus / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents; D002511:Cephalosporins; C068212:cefquinome