title: Intramammary administration of gentamicin as treatment for experimentally induced Escherichia coli mastitis in cows.
abstract: In 8 Holstein cows, 50 colony-forming units (CFU) of Escherichia coli was administered into 1 mammary gland. Infections were established in all inoculated glands. In 4 of the 8 cows, 500 mg of gentamicin sulfate was administered by intramammary infusion 14 hours after inoculation; the other 4 cows were untreated controls. Infusions of gentamicin also were given after each of the 3 successive milkings after the initial infusion, so that a total dose of 2 g of gentamicin was given to each of the treated cows. During the 33-hour treatment period and for the first milking after the last infusion of gentamicin, the treated cows had a mean gentamicin concentration of greater than or equal to 31.0 micrograms/ml in milk samples that were collected from inoculated quarters immediately before each milking. Concentrations of 0.34 and 0.69 micrograms of gentamicin/ml were detected in milk from 2 cows at 8 days after inoculation with E coli. Mean serum concentrations of gentamicin were greater than or equal to 0.37 micrograms/ml throughout the treatment period and the first 12 hours after the last infusion, with a mean peak concentration of 0.96 micrograms/ml at 24.4 hours. The range of peak concentration of gentamicin detected in urine from all treated cows was 42 to 74.4 micrograms/ml. Peak concentration of E coli in milk in the treated cows (6.08 +/- 1.02 log10 CFU/ml) did not significantly (P greater than 0.05) differ from that of the control cows (5.26 +/- 1.00 log10 CFU/ml). Similarly, mean duration of infection in the treated cows (54 hours) did not differ significantly from that of the control cows (48 hours).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Large Animal Surgery and Medicine, College of Veterinary Medicine, Auburn University, AL 36849.
authors.forename: R J
authors.initials: RJ
authors.lastname: Erskine
authors.forename: R C
authors.initials: RC
authors.lastname: Wilson
authors.forename: M G
authors.initials: MG
authors.lastname: Riddell
authors.forename: J W
authors.initials: JW
authors.lastname: Tyler
authors.forename: H J
authors.initials: HJ
authors.lastname: Spears
authors.forename: B S
authors.initials: BS
authors.lastname: Davis
mesh_terms: D000418:Albumins / Q000032:analysis; D000818:Animals; D002417:Cattle; D002452:Cell Count / Q000662:veterinary; D004350:Drug Residues / Q000032:analysis; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000662:veterinary*; D005260:Female; D005839:Gentamicins / Q000008:administration & dosage / Q000032:analysis / Q000493:pharmacokinetics / Q000627:therapeutic use*; D008414:Mastitis, Bovine / Q000188:drug therapy*; D008892:Milk / Q000032:analysis / Q000166:cytology
chemical_list: D000418:Albumins; D005839:Gentamicins