Variability of SCCmec in the Zurich area

Area of Science:

• Microbiology
• Epidemiology
• Infectious Diseases

Background:

• Methicillin-resistant Staphylococcus aureus (MRSA) poses a significant public health threat.
• Understanding MRSA epidemiology and genetic diversity is crucial for effective control strategies.
• Previous studies indicated the emergence and spread of a specific MRSA clone among intravenous drug users in Zurich.

Purpose of the Study:

• To assess the prevalence and genetic characteristics of MRSA in Zurich during 2004 and 2006.
• To investigate changes in MRSA clonal diversity and virulence factors.
• To evaluate the impact of interventions on the spread of a specific MRSA clone.

Main Methods:

• Periodic surveys of MRSA prevalence in Zurich.
• SCCmec and ccr typing to determine MRSA genetic profiles.
• Analysis of mobile virulence determinants.
• Epidemiological data analysis.

Main Results:

• Consistently low MRSA prevalence was observed in 2004 and 2006.
• Fluctuations in SCCmec types and carriage of mobile virulence determinants indicated high clonal diversity and SCCmec recombination.
• A local MRSA clone, prevalent among intravenous drug users, significantly decreased in prevalence.
• Changes in the management of the Zurich drug scene appeared to restrict the spread of this clone.

Conclusions:

• Zurich maintained a low MRSA prevalence despite observed genetic diversity.
• High clonal diversity and recombination suggest ongoing evolution of MRSA strains.
• Interventions targeting the drug scene effectively reduced the spread of a specific MRSA clone.
• Continued surveillance is essential to monitor MRSA epidemiology and adapt control measures.