Changing Epidemiology of Presumptive Community-associated-methicillin-resistant Staphylococcus Aureus in Slovenia in 2014-2015 Compared To 2010.

Introduction: Although the distinction between the Community-Associated-Methicillin-Resistant Staphylococcus aureus (CA-MRSA) and Hospital-Associated-Methicillin-Resistant S. aureus (HA-MRSA) has blurred in recent years, the CA-MRSA is an important group because of its potential to cause fulminant and severe infections. Its importance has further increased with the emergence of Livestock-Associated-Methicillin-Resistant S. aureus (LA-MRSA).

Methods: In the present study we analysed clonal distributions and virulence factors in presumptive CA-MRSA isolated from January 2014 to December 2015 and compared the results with our previous study from 2010. Phenotypic definition for presumptive CA-MRSA was based on resistance to cefoxitin and oxacillin and susceptibility to at least two of the following four antibiotics: ciprofloxacin, erythromycin, clindamycin and gentamicin.

Results: In 2014 and 2015 altogether 304 MRSA isolates fulfilled our screening phenotypic definition, 45 isolates were cultivated from clinical specimens and 259 from screening specimens. Sequence types ST398, LA-MRSA and mecC MRSA increased significantly in 2015 compared to 2010 (p-value <0.05) and were spread over Slovenia.

Conclusion: The clonal distribution of presumptive CA-MRSA has changed within the study period in Slovenia. In 2015 the most frequent clone among clinical and screening specimens was a pig-associated clone, ST398, but the number of confirmed ST398 infections remains low. While previously ST398 and mecC positive MRSA strains were geographically limited, they have spread throughout the country since 2010.