Staphylococcus pseudintermedius can be misdiagnosed as Staphylococcus aureus in humans with dog bite wounds

  • S. Börjesson
  • E. Gómez-Sanz
  • K. Ekström
  • C. Torres
  • U. Grönlund


The purpose of this study was to investigate whether S. pseudintermedius is misdiagnosed as S. aureus by clinical laboratories when isolated from humans with dog bite wounds. In addition, we attempted to determine whether S. pseudintermedius isolates related to dog bite wounds share phenotypic and genotypic traits. S. pseudintermedius was identified by PCR targeting the nuc gene. Isolates were tested for antibiotic susceptibility using VetMIC GP-mo microdilution panels. The occurrence of genes encoding leukocidins, exfoliatins, pyrogenic toxin superantigens and enterotoxins was determined by PCR. The relatedness of S. pseudintermedius isolates was investigated using Multi Locus Sequence Typing (MLST). Out of 101 isolates defined as S. aureus by human clinical microbiology laboratories, 13 isolates were re-identified as S. pseudintermedius and one isolate was confirmed to carry the mecA gene, i.e. methicillin-resistant (MRSP). The MRSP isolate was also defined as multi-resistant. Two methicillin-susceptible S. pseudintermedius isolates were also multi-resistant and five were susceptible to all antibiotics tested. With the exception of three S. pseudintermedius isolates belonging to multi locus sequence type (MLST) 158, all the isolates belonged to unique STs. All isolates contained lukS/F-I, siet and se-int, and expA were identified in two isolates and expB and sec canine-sel in one isolate respectively. S. pseudintermedius is frequently misdiagnosed as S. aureus from humans with dog bite wounds showing that it can act as an opportunistic pathogen in humans. No common phenotypic and genotypic traits shared by the S. pseudintermedius isolates could be identified.


Minimum Inhibitory Concentration Fusidic Acid mecA Gene Multi Locus Sequence Typing Otitis Externa 
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The authors would like to thank the clinical microbiology laboratories for agreeing to include isolates in the study. A special thanks to all the laboratory technicians who helped with the submission of isolates to SVA.

The study was financed by Agria Animal Insurance Company and the Swedish Kennel Club’s joint research fund.

Conflict of interest

The authors declare that they have no conflict of interest.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • S. Börjesson
    • 1
  • E. Gómez-Sanz
    • 2
    • 3
  • K. Ekström
    • 1
  • C. Torres
    • 2
  • U. Grönlund
    • 1
    • 4
  1. 1.Department of Animal Health and Antimicrobial StrategiesNational Veterinary Institute (SVA)UppsalaSweden
  2. 2.Department of Biochemistry and Molecular BiologyUniversity of La RiojaLogroñoSpain
  3. 3.Environmental Genomics and Systems Biology Research Group, Institute of Natural Resource SciencesZurich University of Applied Sciences (ZHAW)WädenswilSwitzerland
  4. 4.Swedish University of Agriculture SciencesUppsalaSweden

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