title: Bacterial isolates, antimicrobial susceptibility, and clinical characteristics of bacterial keratitis in dogs presenting to referral practice in Australia.
abstract: OBJECTIVE
  To identify clinical characteristics, bacterial isolates, and their antimicrobial susceptibility patterns in a prospective study of dogs presenting with suspected bacterial keratitis to aid selection of appropriate therapy.
  
  
  METHODS
  Seventy-one client-owned dogs presenting to two referral hospitals in Australia.
  
  
  METHODS
  Corneal swabs and clinical information were collected from dogs presenting with suspect bacterial keratitis from April 2012 to December 2014. Cytology and bacteriologic culture were performed on samples with in vitro antimicrobial susceptibility performed on bacterial isolates.
  
  
  RESULTS
  Positive cultures were obtained from 42 of the 71 ulcers sampled (59%), with 45 bacteria isolated. The most commonly isolated bacteria were β-hemolytic Streptococcus (14/45, 31%), Pseudomonas (14/45, 31%), and Staphylococcus species (8/45, 18%). β-Hemolytic Streptococcus spp. were resistant to neomycin, polymyxin B, gentamicin, framycetin and fusidic acid and >80% were resistant to ciprofloxacin but remained susceptible to chloramphenicol and cephalexin. Pseudomonas aeruginosa isolates were resistant to chloramphenicol, cephalexin, and fusidic acid; however, >90% were susceptible to ciprofloxacin, polymyxin B, and gentamicin. Brachycephalic breed (34/42, 81%), previous ocular surgery (15/42, 36%), prior use of a topical corticosteroid (13/42, 31%), and concurrent ocular surface disease (10/42, 24%) were common in dogs with bacterial keratitis.
  
  
  CONCLUSIONS
  Our study identified β-hemolytic Streptococcus and Pseudomonas spp. as the most common bacterial pathogens in canine bacterial keratitis presenting for referral. Many cases exhibited clinical factors known to influence corneal integrity that may predispose them to ulceration and infection. Based on in vitro antimicrobial susceptibility patterns and clinical outcomes, monotherapy with a fluoroquinolone may be ineffective in ulcers caused by β-hemolytic Streptococcus spp.
authors.affiliation: Veterinary Ophthalmology, Small Animal Specialist Hospital, Lvl 1, 1 Richardson Place, North Ryde, 2113, NSW, Australia. khindley@sashvets.com.
authors.forename: Kate E
authors.initials: KE
authors.lastname: Hindley
authors.affiliation: Veterinary Ophthalmology, Small Animal Specialist Hospital, Lvl 1, 1 Richardson Place, North Ryde, 2113, NSW, Australia.
authors.forename: Allyson D
authors.initials: AD
authors.lastname: Groth
authors.affiliation: Veterinary Ophthalmology, Rivergum Referral Services, Unit 1/26 Gympie Way, Willeton, 6155, WA, Australia.
authors.forename: Martyn
authors.initials: M
authors.lastname: King
authors.affiliation: Veterinary Ophthalmology, Small Animal Specialist Hospital, Lvl 1, 1 Richardson Place, North Ryde, 2113, NSW, Australia.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Graham
authors.affiliation: Veterinary Ophthalmology, Small Animal Specialist Hospital, Lvl 1, 1 Richardson Place, North Ryde, 2113, NSW, Australia.
authors.forename: F Mark
authors.initials: FM
authors.lastname: Billson
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D001315:Australia; D004283:Dog Diseases / Q000188:drug therapy / Q000382:microbiology*; D004285:Dogs; D015818:Eye Infections, Bacterial / Q000188:drug therapy / Q000382:microbiology / Q000662:veterinary*; D007634:Keratitis / Q000188:drug therapy / Q000382:microbiology / Q000662:veterinary*; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D011446:Prospective Studies; D012017:Referral and Consultation
chemical_list: D000900:Anti-Bacterial Agents
keywords: antimicrobial susceptibility; bacterial keratitis; canine; cornea; predisposing factors; resistance