Australian Group on Antimicrobial Resistance Enterococcus Surveillance Programme annual report, 2010

Area of Science:

• Microbiology
• Infectious Diseases
• Antimicrobial Resistance

Background:

• Enterococcus species are significant causes of hospital-acquired infections.
• Monitoring antimicrobial resistance patterns is crucial for effective treatment strategies.
• Previous surveys have tracked resistance trends in Australian Enterococcus isolates since 1995.

Observation:

• A 2010 Australian study surveyed key resistances in 1,386 Enterococcus isolates (98.9% E. faecalis and E. faecium).
• Ampicillin resistance was high in E. faecium (85.3%) but absent in E. faecalis.
• Vancomycin non-susceptibility in E. faecium increased to 36.5% (up from 15.4% in 2007), with significant state variations.
• Vancomycin resistance was low in E. faecalis (0.5%).
• The vanB gene was detected in 62 E. faecium and 3 E. faecalis isolates.

Findings:

• Vancomycin-resistant E. faecium isolates belonged to clonal complex 17, with ST203 being the most common.
• High-level gentamicin resistance was prevalent in both species (34.1% in E. faecalis, 66.1% in E. faecium).
• High-level streptomycin resistance was observed in 8.2% of E. faecalis and 43.8% of E. faecium.
• Linezolid non-susceptibility was more common in E. faecalis (5.8%) than E. faecium (0.9%).

Implications:

• The rising vancomycin resistance in E. faecium necessitates ongoing surveillance and infection control measures.
• Understanding the molecular epidemiology, including clonal complexes and sequence types, is vital for tracking resistance.
• The prevalence of resistance to multiple antibiotics highlights the challenge of treating Enterococcus infections.