title: Gram-negative bacterial infections of the mammary gland in cows.
abstract: Naturally acquired gram-negative bacterial intramammary infections (n = 160) were studied in 99 cows over a 2-year period. Escherichia coli, Klebsiella spp, Serratia spp, Enterobacter spp, and unidentified gram-negative bacteria were isolated from 28.8, 39.4, 9.4, 5.0, and 11.2%, respectively, of infected mammary glands. A majority (61%) of intramammary infections were first detected during the nonlactating period. Gram-negative bacteria isolated during the first half of the nonlactating period were predominantly Klebsiella spp, Serratia spp, and Enterobacter spp. Onset of E coli intramammary infections was more prevalent during the second half of the nonlactating period and during the first 7 days of lactation. The majority (59%) of infections were less than 28 days in duration, but Klebsiella spp and Serratia spp infections were of significantly (P less than 0.05) greater duration than infections with E coli. The greatest percentage (47%) of gram-negative bacterial intramammary infections were first detected during the summer.
authors.affiliation: Department of Dairy Science, Ohio Agricultural Research and Development Center, Wooster.
authors.forename: D A
authors.initials: DA
authors.lastname: Todhunter
authors.forename: K L
authors.initials: KL
authors.lastname: Smith
authors.forename: J S
authors.initials: JS
authors.lastname: Hogan
authors.forename: P S
authors.initials: PS
authors.lastname: Schoenberger
mesh_terms: D000818:Animals; D001424:Bacterial Infections / Q000382:microbiology / Q000662:veterinary*; D002417:Cattle; D005260:Female; D006090:Gram-Negative Bacteria / Q000302:isolation & purification*; D007774:Lactation; D008321:Mammary Glands, Animal / Q000382:microbiology*; D008414:Mastitis, Bovine / Q000382:microbiology*; D012621:Seasons; D013997:Time Factors