Clonal Diversity and Antimicrobial Resistance of Methicillin-Resistant Staphylococcus pseudintermedius Isolated from...

Area of Science:

• Veterinary Microbiology
• Antimicrobial Resistance
• Molecular Epidemiology

Background:

• Methicillin-resistant Staphylococcus pseudintermedius (MRSP) is a significant pathogen in canine pyoderma.
• The emergence of multidrug-resistant MRSP and epidemic lineages presents therapeutic challenges in veterinary medicine.

Purpose of the Study:

• To characterize the antimicrobial resistance profiles and genetic lineages of MRSP isolates from canine cutaneous pyoderma.
• To identify the specific antimicrobial and virulence genes present in these MRSP strains.

Main Methods:

• Antimicrobial susceptibility testing using the Kirby-Bauer disc diffusion method against 14 agents.
• Polymerase Chain Reaction (PCR) to detect antimicrobial and virulence genes.
• Multilocus Sequence Typing (MLST) to determine clonal lineages.

Main Results:

• All 31 MRSP isolates exhibited multidrug-resistant profiles, with resistance to penicillin, macrolides, aminoglycosides, tetracycline, and trimethoprim-sulfamethoxazole.
• Key resistance genes (blaZ, ermB, msr(A/B), aac(6')-Ie-aph(2'')-Ia, aph(3')-IIIa, ant(4')-Ia, tetM, tetK, dfrG) and virulence factors (lukS-I/lukF-I) were identified.
• Isolates belonged to 14 sequence types (STs), including 9 known and 5 novel STs. ST123 (CC71), a common European clone, was predominant.

Conclusions:

• Canine pyoderma isolates of MRSP are predominantly multidrug-resistant and associated with specific epidemic genetic lineages.
• The findings highlight the urgent need for effective therapeutic strategies and surveillance to mitigate the threat of MRSP in veterinary medicine.