Australian Group on Antimicrobial Resistance (AGAR) Australian Enterococcal Sepsis Outcome Programme (AESOP) Annual Report 2015

Abstract

From 1st January to 31st December 2015, 31 Australian institutions participated in the Australian Enterococcal Sepsis Outcome Programme (AESOP). The aim of AESOP 2015 was to determine the proportion of enterococcal bacteraemia isolates in Australia that were antimicrobial resistant, and to characterise the molecular epidemiology of the Enterococcus faecium isolates. Of the 1,009 unique episodes of bacteraemia investigated, 95.4% were caused by either E. faecalis (55.7%) or E. faecium (39.6%). Ampicillin resistance was detected in 0.2% of E. faecalis and in 86.0% of E. faecium. Vancomycin non-susceptibility was reported in 0.4% and 50.1% of E. faecalis and E. faecium respectively. Overall 56.2% of E. faecium harboured vanA or vanB genes. For the vanA/B positive E. faecium isolates, 61.0% harboured vanB genes and 36.8% vanA genes. The percentage of E. faecium bacteraemia isolates resistant to vancomycin in Australia is significantly higher than that seen in most European countries. E. faecium consisted of 49 multilocus sequence types (STs) of which 85.6% of isolates were classified into 11 major STs containing five or more isolates. All major STs belong to clonal cluster 17, a major hospital-adapted polyclonal E. faecium cluster. Four of the five predominant STs (ST796, ST555, ST203, and ST80) were found across most regions of Australia. The second most predominant clone was non-typable by multilocus sequence typing and found only in NSW and the ACT. Overall 73.9% of isolates belonging to the five predominant STs harboured vanA or vanB genes. In conclusion, the AESOP 2015 has shown enterococcal bacteraemias in Australia are frequently caused by polyclonal ampicillin-resistant high-level gentamicin resistant vanA or vanB E. faecium which have limited treatment options.