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Australian Group on Antimicrobial Resistance (AGAR) Australian Staphylococcus aureus Sepsis Outcome Programme (ASSOP) Annual Report 2020

Coombs, G.W.ORCID: 0000-0003-1635-6506, Daley, D.A., Yee, N.W.T., Shoby, P. and Mowlaboccus, S. (2022) Australian Group on Antimicrobial Resistance (AGAR) Australian Staphylococcus aureus Sepsis Outcome Programme (ASSOP) Annual Report 2020. Communicable Diseases Intelligence, 46 .

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From 1 January to 31 December 2020, forty-nine institutions around Australia participated in the
Australian Staphylococcus aureus Sepsis Outcome Programme (ASSOP). The aims of ASSOP 2020
were to determine the proportion of Staphylococcus aureus bacteraemia (SAB) isolates in Australia
that were antimicrobial resistant, with particular emphasis on susceptibility to methicillin; and to
characterise the molecular epidemiology of the methicillin-resistant isolates. A total of 2,734 SAB episodes
were reported, of which 79.7% were community-onset. Of S. aureus isolates, 17.6% were methicillin
resistant. The 30-day all-cause mortality associated with methicillin-resistant SAB was 14.2%,
which was not significantly different from the 13.3% mortality associated with methicillin-susceptible
SAB (p = 0.6). With the exception of the β-lactams and erythromycin, antimicrobial resistance
in methicillin-susceptible S. aureus was rare. However, in addition to the β-lactams, approximately
35% of methicillin-resistant S. aureus (MRSA) were resistant to erythromycin, 33% to ciprofloxacin,
13% to tetracycline, 13% to gentamicin and 4% to co-trimoxazole. When applying the European
Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints, teicoplanin resistance
was detected in four S. aureus isolates. Resistance was not detected for vancomycin and linezolid.
Resistance to non-beta-lactam antimicrobials was largely attributable to two healthcare-associated
MRSA (HA-MRSA) clones: ST22-IV [2B] (EMRSA-15) and ST239-III [3A] (Aus-2/3 EMRSA). The
ST22-IV [2B] (EMRSA-15) clone is the predominant HA-MRSA clone in Australia. However, 85%
percent of methicillin-resistant SAB isolates were community-associated MRSA (CA-MRSA) clones.
Although polyclonal, approximately 77% of CA-MRSA clones were characterised as: ST93-IV [2B]
(Queensland CA-MRSA); ST5-IV [2B]; ST45-V [5C2&5]; ST1-IV [2B]; ST30-IV [2B]; ST8-IV [2B];
and ST97-IV [2B]. The CA-MRSA clones, in particular ST45-V [5C2&5], have acquired multiple antimicrobial
resistance determinants including ciprofloxacin, erythromycin, clindamycin, gentamicin
and tetracycline. The multi-resistant ST45-V [5C2&5] clone accounted for 11.0% of CA-MRSA. As
CA-MRSA is well established in the Australian community, it is important to monitor antimicrobial
resistance patterns in community- and healthcare-associated SAB as this information will guide
therapeutic practices in treating S. aureus sepsis.

Item Type: Journal Article
Murdoch Affiliation(s): Antimicrobial Resistance and Infectious Disease Laboratory
Publisher: Australian Government. Dept. of Health
Copyright: © 2022 Commonwealth of Australia as represented by the Department of Health
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