Genotypic relatedness and phenotypic characterization of Staphylococcus schleiferi subspecies in clinical samples from dogs

• DOI: 10.2460/ajvr.72.1.96
• Publication Date: 2011-01-01T08:03:24Z
• Authors: Christine L. Cain; Daniel O. Morris; Kathleen O'Shea; Shelley C. Rankin
• Keywords: Coagulase; 0301 basic medicine; Genotype; Staphylococcus; Genetic Variation; Gene Expression Regulation, Bacterial; 04 agricultural and veterinary sciences; Staphylococcal Infections; Polymerase Chain Reaction; Electrophoresis, Gel, Pulsed-Field; 3. Good health; 0403 veterinary science; 03 medical and health sciences; Dogs; Animals; Dog Diseases; Latex Fixation Tests

Abstract Objective—To assess the degree of biological similarity (on the basis of genotype determined via pulsed-field gel electrophoresis [PFGE]) between isolates of 2 Staphylococcus schleiferi subspecies (S schleiferi subsp coagulans and S schleiferi subsp schleiferi) in clinical samples obtained from dogs. Sample Population—161 S schleiferi isolates from 160 canine patients. Procedures—A commercial microbiology identification system was used to identify each isolate as S schleiferi. Isolates underwent slide and tube coagulase testing and antimicrobial susceptibility testing. A mecA PCR assay and a latex agglutination test for penicillin-binding protein 2a (PBP2a) were also performed on each isolate. Clonal clusters with a similarity cutoff value of 80% were identified via PFGE. Results—Of the 161 isolates, 61 (38%), 79 (49%), and 21 (13%) were obtained from cutaneous sites, ears, and other sites, respectively; 110 (68%) were coagulase negative, and 51 (32%) were coagulase positive. Among the coagulase-negative and coagulase-positive isolates, 65% (71/110) and 39% (20/51) were oxacillin resistant, respectively. All oxacillin-resistant isolates yielded positive results via mecA PCR assay and PBP2a latex agglutination testing. Via PFGE, 15 major clusters and 108 individual pulsed-field profiles were identified. Oxacillin-resistant and oxacillin-susceptible isolates clustered separately. Clonal clusters were heterogeneous and contained representatives of both subspecies. Conclusions and Clinical Relevance—Coagulase-positive and coagulase-negative isolates were not genotypically distinct and may represent a single S schleiferi sp with variable coagulase production, rather than 2 biologically distinct subspecies. Further studies are needed to characterize clinical or epidemiological differences associated with infections with coagulase-positive and coagulase-negative S schleiferi in dogs.