In recent years, methicillin-resistant Staphylococcus aureus (MRSA) have become a truly global challenge. In addition to the long-known healthcare-associated clones, novel strains have also emerged outside of the hospital settings, in the community as well as in livestock. The emergence and spread of virulent clones expressing Panton-Valentine leukocidin (PVL) is an additional cause for concern. In order to provide an overview of pandemic, epidemic and sporadic strains, more than 3,000 clinical and veterinary isolates of MRSA mainly from Germany, the United Kingdom, Ireland, France, Malta, Abu Dhabi, Hong Kong, Australia, Trinidad & Tobago as well as some reference strains from the United States have been genotyped by DNA microarray analysis. This technique allowed the assignment of the MRSA isolates to 34 distinct lineages which can be clearly defined based on non-mobile genes. The results were in accordance with data from multilocus sequence typing. More than 100 different strains were distinguished based on affiliation to these lineages, SCCmec type and the presence or absence of PVL. These strains are described here mainly with regard to clinically relevant antimicrobial resistance- and virulence-associated markers, but also in relation to epidemiology and geographic distribution. The findings of the study show a high level of biodiversity among MRSA, especially among strains harbouring SCCmec IV and V elements. The data also indicate a high rate of genetic recombination in MRSA involving SCC elements, bacteriophages or other mobile genetic elements and large-scale chromosomal replacements.

Antimicrobial drug self-medication occurs most often in eastern and southern Europe and least often in northern and western Europe.

Interventions aimed at preventing self-medication should include public education, enforcing regulations regarding the sale of antibiotics, and implementing laws for dispensing exact prescribed tablet quantities in pharmacies. With the included determinants, we explained almost all the variance at the country level, but not at the individual level. Future studies to increase our understanding of determinants of self-medication with antibiotics should focus on individual-level factors such as doctor-patient relationships and patient satisfaction.

The most pronounced differences were for awareness about resistance, followed by attitudes towards situational use of antibiotics. Awareness about antibiotic resistance was the lowest in countries with higher prevalence of resistance.