title: First identification of methicillin-resistant Staphylococcus pseudintermedius strains among coagulase-positive staphylococci isolated from dogs with otitis externa in Trinidad, West Indies.
abstract: BACKGROUND
  Otitis externa is a common inflammatory ear disease in dogs caused by a variety of pathogens, and coagulase-positive staphylococci are frequently isolated from such infections.
  
  
  OBJECTIVE
  To identify antimicrobial susceptibility profiles and methicillin-resistant strains among coagulase-positive staphylococci isolated from otitis externa in dogs.
  
  
  METHODS
  A cross-sectional study was performed over 2 years on 114 client-owned dogs presented to the Veterinary Teaching Hospital with a primary complaint of ear infections. Swabs were obtained from both ears and cultured for staphylococci which were subsequently confirmed as coagulase-positive using rabbit plasma. Antimicrobial susceptibility assays were assessed on all isolates followed by subsequent genetic analysis for species identification and detection of the mecA gene.
  
  
  RESULTS
  Sixty-five coagulase-positive staphylococci were isolated from 114 client-owned dogs. The isolates exhibited resistance against neomycin (58.5%), streptomycin (49.2%), penicillin (49.2%), polymyxin B (44.6%), tetracycline (36.9%), sulphamethoxazole/trimethoprim (33.8%), kanamycin (33.8%), doxycycline (32.3%), norfloxacin (23.1%), amoxicillin/clavulanate (20%), ciprofloxacin (20%), enrofloxacin (18.5%), gentamicin (16.9%), and cephalothin (9.2%). Forty (61.5%) of the isolates were resistant to at least three or more antimicrobials and 10 were sensitive to all. Using a multiplex polymerase chain reaction assay based on species-specific regions of the thermonuclease (nuc) gene, 38/65 (58.5%) isolates were classified as Staphylococcus aureus, 23/65 (35.4%) as S. pseudintermedius, 2/65 (3.1%) as S. intermedius, and 2/65 (3.1%) as S. schleiferi. Analysis for the mecA gene revealed two positive isolates of S. pseudintermedius which were oxacillin-resistant, representing a first report of such organisms in the Caribbean.
  
  
  CONCLUSIONS
  Despite the relatively high prevalence of multidrug-resistant coagulase-positive staphylococci in Trinidad, these are largely susceptible to gentamicin consistent with use in clinical practice. The first detection of methicillin-resistant S. pseudintermedius (MRSP) in dogs is likely to have implications on the treatment options for otitis externa in dogs and potential public health significance.
authors.affiliation: Basic Veterinary Sciences, School of Veterinary Medicine, University of the West Indies, Mt. Hope, Trinidad, West Indies.|School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7AL, United Kingdom; Francis.Dziva@sta.uwi.edu; f.dziva@surrey.ac.uk.
authors.forename: Francis
authors.initials: F
authors.lastname: Dziva
authors.affiliation: Clinical Veterinary Sciences, School of Veterinary Medicine, The University of the West Indies, Mt. Hope, Trinidad, West Indies.
authors.forename: Crystal
authors.initials: C
authors.lastname: Wint
authors.affiliation: Clinical Veterinary Sciences, School of Veterinary Medicine, The University of the West Indies, Mt. Hope, Trinidad, West Indies.
authors.forename: Tennille
authors.initials: T
authors.lastname: Auguste
authors.affiliation: Basic Veterinary Sciences, School of Veterinary Medicine, University of the West Indies, Mt. Hope, Trinidad, West Indies.
authors.forename: Carolyn
authors.initials: C
authors.lastname: Heeraman
authors.affiliation: Basic Veterinary Sciences, School of Veterinary Medicine, University of the West Indies, Mt. Hope, Trinidad, West Indies.
authors.forename: Cherrelle
authors.initials: C
authors.lastname: Dacon
authors.affiliation: Clinical Veterinary Sciences, School of Veterinary Medicine, The University of the West Indies, Mt. Hope, Trinidad, West Indies.
authors.forename: Priscilla
authors.initials: P
authors.lastname: Yu
authors.affiliation: Clinical Veterinary Sciences, School of Veterinary Medicine, The University of the West Indies, Mt. Hope, Trinidad, West Indies.
authors.forename: Lee M
authors.initials: LM
authors.lastname: Koma
keywords: PCR; antimicrobials; mecA; otitis externa; staphylococci