Evolving landscape of methicillin-resistant Staphylococcus pseudintermedius: the emergence of new epidemic waves across Europe, Asia and North America.

Objective: This study aims to identify spatiotemporal variations in clonal diversity and antimicrobial resistance of methicillin-resistant Staphylococcus pseudintermedius (MRSP).

Materials and methods: A PubMed search (June 2016-December 2023), combined with data from PubMLST and a previous review (September 2007-May 2016), identified 2654 isolates. Multinomial logistic regression (MLR) and Bayesian regression models (BRMs) were used to assess associations between clonal complexes (CCs) and variables (sample type, continent and period), with MLR results feeding into the BRM.

Results: A shift in MRSP clonal structure was observed after 2013. A decline in the prevalence of historically dominant lineages, such as CC71 in Europe, CC68 in North America and CC45 in Asia, coincided with the global emergence of CC551, as well as CC556 and CC1431 in North America, and CC363 and CC1631 in Asia. Resistance to non-β-lactams increased in North America, particularly for chloramphenicol (6%-59%), remained largely stable in Europe except for tetracycline, and decreased in Asia. Striking differences among CCs were observed, with CC71 exhibiting the highest resistance rates and a greater likelihood of being isolated from clinical samples.

Discussion: The observed associations between specific CCs and resistance patterns provide valuable insights into the factors driving these epidemiological changes, including regional antimicrobial use patterns (e.g. chloramphenicol usage in North America) and potential fitness advantages of emerging lineages. These dynamics parallel those seen in methicillin-resistant Staphylococcus aureus.

Conclusion: The evolving MRSP landscape highlights the need for sustained global surveillance to monitor clonal diversity, antimicrobial use and resistance trends.