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Published on: November 4, 2016
Clonal Complexes and Antimicrobial Susceptibility Profiles of Staphylococcus pseudintermedius Isolates from Dogs in
Ricardo Videla1, Samar M Solyman1, Akshar Brahmbhatt1
1Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee , Knoxville, Tennessee.
Abstract:
Staphylococcus pseudintermedius is the primary cause of canine pyoderma and has been associated with diseases in other animals, including human beings. A high prevalence of methicillin and multidrug resistance has been reported in this bacterium in some geographic regions of the United States. Multilocus sequence type (MLST) 68 was implicated, initially, as the major clonal genotype based on a limited number of samples. The objectives of this study were to determine the population genetics of S. pseudintermedius isolated from a cross-section of the United States using a seven-locus multilocus sequence typing method, to identify clonal complexes (CCs), and to correlate sequence types with antimicrobial susceptibility profiles. A total of 190 S. pseudintermedius with 86 different MLSTs were detected and the constituents of three major CCs of methicillin-resistant S. pseudintermedius (MRSP), CC68, CC71, and CC84, were identified. Different patterns of resistance were associated with each CC. CC71 from the United States had notable differences with CC71 studied on other continents with chloramphenicol, tetracycline, and trimethoprim/sulfamethoxazole resistance. Some isolates with resistance to the broadest range of drugs tested, including that to chloramphenicol, had STs unrelated to the major CCs, suggesting the potential for the emergence of new clonal populations of MRSP that are resistant to most therapeutically useful antimicrobials.
Insights
Methicillin-resistant Staphylococcus pseudintermedius (MRSP) strains show diverse genetic backgrounds and antimicrobial resistance patterns in the US. New MRSP clones may emerge with resistance to multiple drugs, posing a therapeutic challenge.
Area of Science:
- Veterinary Microbiology
- Antimicrobial Resistance
- Population Genetics
Background:
- Staphylococcus pseudintermedius is a key pathogen causing canine pyoderma.
- Methicillin and multidrug resistance are increasingly prevalent in S. pseudintermedius, particularly in the US.
- Previous studies suggested MLST 68 as a dominant MRSP genotype based on limited data.
Purpose of the Study:
- To investigate the population genetics of S. pseudintermedius across the US.
- To identify major clonal complexes (CCs) and sequence types (STs).
- To correlate specific STs and CCs with antimicrobial susceptibility profiles.
Main Methods:
- Utilized a seven-locus multilocus sequence typing (MLST) method.
- Analyzed 190 S. pseudintermedius isolates from a diverse US population.
- Determined antimicrobial susceptibility profiles for all isolates.
Main Results:
- Identified 86 distinct MLSTs and three major MRSP clonal complexes: CC68, CC71, and CC84.
- Observed distinct antimicrobial resistance patterns associated with each CC.
- Noted significant differences in resistance profiles for CC71 strains from the US compared to other continents.
- Discovered STs unrelated to major CCs exhibiting broad-spectrum resistance, indicating potential for new MRSP emergence.
Conclusions:
- The genetic landscape of S. pseudintermedius in the US is complex, with distinct CCs exhibiting varied resistance.
- US-based CC71 strains show unique resistance patterns compared to global counterparts.
- The emergence of novel, highly resistant MRSP clonal populations is a significant concern for animal and potentially human health.
