title: Ceftiofur distribution in serum and milk from clinically normal cows and cows with experimental Escherichia coli-induced mastitis.
abstract: Eight Holstein cows, 4 inoculated intracisternally in 1 quarter of the mammary gland with Escherichia coli and 4 noninfected controls, were administered ceftiofur sodium (3 mg/kg of body weight, IV, q 12 hours) for 24 hours, beginning at 14 hours after inoculation of infected cows. All challenge-exposed cows became infected, with mean +/- SEM peak log10 bacterial concentration in milk of 5.03 +/- 0.69 colony-forming units/ml. The infection resulted in systemic signs (mean peak rectal temperature, 41.5 +/- 0.3 C; anorexia; signs of depression) and local inflammation (mean peak albumin concentration in milk, 7.89 +/- 1.71 mg/ml). Ceftiofur was detectable in milk from all challenge-exposed cows, compared with only 1 of 4 noninfected cows, and the mean period after inoculation that ceftiofur was detectable in milk was longer (P < 0.05) in infected (147.7 +/- 27.5 hours) than noninfected cows (1.3 +/- 1.3 hours). However, maximal ceftiofur concentration attained in milk for all cows was 0.28 microgram/ml, and was 0.20 microgram/ml or less for all but 2 milk samples collected for 10 days after challenge exposure. Mean serum concentration of ceftiofur peaked at 1.0 +/- 0.3 microgram/ml and 0.7 +/- 0.1 microgram/ml for infected and noninfected cows, respectively. After each ceftiofur dose, mean peak and trough concentrations of ceftiofur in serum did not differ between groups; however, concentration of ceftiofur in serum was higher at 7 hours after each dose in noninfected cows, suggesting more rapid clearance of the drug in infected cows.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Large Animal Surgery and Medicine, College of Veterinary Medicine, Auburn University, AL 36849, USA.
authors.forename: R J
authors.initials: RJ
authors.lastname: Erskine
authors.forename: R C
authors.initials: RC
authors.lastname: Wilson
authors.forename: J W
authors.initials: JW
authors.lastname: Tyler
authors.forename: K A
authors.initials: KA
authors.lastname: McClure
authors.forename: R S
authors.initials: RS
authors.lastname: Nelson
authors.forename: H J
authors.initials: HJ
authors.lastname: Spears
mesh_terms: D000818:Animals; D001831:Body Temperature; D002417:Cattle; D002511:Cephalosporins / Q000097:blood / Q000493:pharmacokinetics* / Q000627:therapeutic use; D004926:Escherichia coli / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000097:blood / Q000188:drug therapy / Q000378:metabolism*; D005260:Female; D008321:Mammary Glands, Animal / Q000382:microbiology; D008414:Mastitis, Bovine / Q000097:blood / Q000188:drug therapy / Q000378:metabolism*; D008657:Metabolic Clearance Rate; D008892:Milk / Q000378:metabolism* / Q000382:microbiology; D012016:Reference Values
chemical_list: D002511:Cephalosporins; C053503:ceftiofur