title: Penetration of ceftiofur into sterile vs. Mannheimia haemolytica-infected tissue chambers in beef calves after subcutaneous administration of ceftiofur crystalline free acid sterile suspension in the ear pinna.
abstract: The effect of Mannheimia haemolytica infection on the penetration of ceftiofur and desfuroylceftiofur metabolites into tissue chambers was studied in cattle after subcutaneous administration of ceftiofur crystalline free acid sterile suspension (CCFA-SS). Four tissue chambers were implanted subcutaneously in each of 12 calves. Approximately 45 days after implantation, two chambers were inoculated with M. haemolytica (10(6) colony-forming units per chamber) while the remaining two chambers were inoculated with sterile phosphate-buffered saline. Twenty-four hours after inoculation, CCFA-SS was administered subcutaneously in the middle third of the caudal ear pinna of each calf. Chamber fluid and blood samples were collected at predetermined times for 10 days following dosing and analyzed for ceftiofur and desfuroylceftiofur metabolites by high-performance liquid chromatography. Concentrations of ceftiofur and desfuroylceftiofur metabolites in plasma and tissue chamber fluid remained above a threshold of 0.2 microg/mL for at least 8 days. Infected tissue chamber fluid concentrations of ceftiofur and desfuroylceftiofur metabolites were significantly higher than those in non-infected tissue chamber fluid, which correlated with significantly higher total protein concentration in infected tissue chambers. These results indicate that single subcutaneous administration of CCFA-SS at 6.6 mg/kg can be expected to provide effective therapy of susceptible bacterial infections for a period of at least 1 week.
authors.affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078, USA. washbke@okstate.edu
authors.forename: K
authors.initials: K
authors.lastname: Washburn
authors.forename: R
authors.initials: R
authors.lastname: Johnson
authors.forename: C R
authors.initials: CR
authors.lastname: Clarke
authors.forename: K
authors.initials: K
authors.lastname: Anderson
authors.forename: M
authors.initials: M
authors.lastname: Lucas
authors.forename: W
authors.initials: W
authors.lastname: Bryson
authors.forename: J
authors.initials: J
authors.lastname: Robinson
authors.forename: K
authors.initials: K
authors.lastname: Dame
authors.forename: V
authors.initials: V
authors.lastname: Hubbard
authors.forename: K
authors.initials: K
authors.lastname: Callahan
authors.forename: E
authors.initials: E
authors.lastname: Robb
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D019540:Area Under Curve; D002417:Cattle; D002418:Cattle Diseases / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D002511:Cephalosporins / Q000008:administration & dosage / Q000097:blood / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics* / Q000627:therapeutic use; D002626:Chemistry, Pharmaceutical; D015194:Diffusion Chambers, Culture; D004431:Ear, External; D007279:Injections, Subcutaneous / Q000662:veterinary; D016978:Mannheimia haemolytica; D010326:Pasteurella Infections / Q000378:metabolism / Q000662:veterinary*
chemical_list: D002511:Cephalosporins; C053503:ceftiofur