Australian Staphylococcus aureus Sepsis Outcome Programme annual report, 2013

Area of Science:

• Medical Microbiology
• Infectious Diseases
• Epidemiology

Background:

• The Australian Staphylococcal Sepsis Outcome Programme (ASSOP) monitors Staphylococcus aureus bacteraemia (SAB).
• Methicillin resistance in SAB is a growing concern globally and in Australia.

Purpose of the Study:

• To determine the prevalence of antimicrobial resistance in Australian Staphylococcus aureus bacteraemia (SAB) isolates in 2013.
• To characterize the molecular epidemiology of SAB isolates, focusing on methicillin resistance.

Main Methods:

• Analysis of 2,010 SAB episodes from 26 Australian institutions participating in ASSOP 2013.
• Antimicrobial susceptibility testing and molecular typing of Staphylococcus aureus isolates.

Main Results:

• 19.1% of SAB episodes were methicillin-resistant (MRSA), significantly higher than in many European countries.
• MRSA-associated mortality was high (20.1%) compared to methicillin-sensitive SAB (13%).
• Dominant MRSA clones were healthcare-associated ST22-IV [2B] (EMRSA-15) and community-associated ST93-IV [2B] (Queensland CA-MRSA) and ST1-IV [2B] (WA1).

Conclusions:

• Methicillin resistance significantly increases mortality in SAB patients in Australia.
• Specific MRSA clones, both healthcare and community-associated, are driving resistance patterns.
• Continuous monitoring of antimicrobial resistance in SAB is essential for guiding clinical treatment decisions.