Australian Enterococcal Sepsis Outcome Programme annual report, 2013.

Area of Science:

• Medical Microbiology
• Infectious Diseases
• Epidemiology

Background:

• Enterococcal bacteraemia is a significant cause of hospital-acquired infections.
• Antimicrobial resistance in enterococci, particularly Enterococcus faecium, poses a therapeutic challenge.
• The Australian Enterococcal Sepsis Outcome Programme (AESOP) monitors trends in enterococcal infections.

Purpose of the Study:

• To determine the prevalence of antimicrobial resistance in enterococcal bacteraemia isolates in Australia.
• To characterize the molecular epidemiology of Enterococcus faecium isolates from bacteraemia.
• To compare Australian resistance rates with international data.

Main Methods:

• Prospective surveillance of 26 Australian institutions from January to December 2013.
• Analysis of 826 unique episodes of enterococcal bacteraemia.
• Antimicrobial susceptibility testing, van operon detection, pulsed-field gel electrophoresis (PFGE), and multilocus sequence typing (MLST).

Main Results:

• Enterococcus faecalis (56.1%) and Enterococcus faecium (38.5%) were the predominant species.
• Ampicillin resistance was over 90% in E. faecium but absent in E. faecalis.
• Vancomycin non-susceptibility was 40.9% in E. faecium (predominantly vanB) and 0.2% in E. faecalis.
• 41.6% of E. faecium harbored vanA or vanB genes.
• E. faecium isolates belonged to 14 major PFGE pulsotypes within clonal cluster 17.
• Predominant sequence types were ST203 (nationwide) and ST555 (western/central regions).

Conclusions:

• Enterococcal bacteraemia in Australia is frequently caused by polyclonal, ampicillin-resistant, high-level gentamicin-resistant vanB E. faecium.
• These resistant strains have limited treatment options.
• Australian vancomycin-resistant E. faecium rates are higher than in most European countries.