Australian Group on Antimicrobial Resistance (AGAR) Australian Gram-negative Surveillance Outcome Program (GnSOP).

The Australian Group on Antimicrobial Resistance (AGAR) performs regular period-prevalence studies to monitor changes in antimicrobial resistance in selected enteric gram-negative pathogens. The 2021 survey was the ninth year to focus on bloodstream infections caused by Enterobacterales, and the seventh year where Pseudomonas aeruginosa and Acinetobacter species were included. The 2021 survey tested 8,947 isolates, comprising Enterobacterales (8,104; 90.6%), P. aeruginosa (745; 8.3%) and Acinetobacter species (98; 1.1%), using commercial automated methods. The results were analysed using Clinical and Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints (January 2022). Of the key resistances, resistance to the third-generation cephalosporin ceftriaxone was found in 12.5%/12.5% (CLSI/EUCAST criteria) of Escherichia coli and in 6.1%/6.1% of Klebsiella pneumoniae. Resistance rates to ciprofloxacin were 12.3%/12.3% for E. coli; 7.2%/7.2% for K. pneumoniae; 5.4%/5.4% for Enterobacter cloacae complex; and 3.7%/8.0% for P. aeruginosa. Resistance rates to piperacillin-tazobactam were 2.8%/6.5%; 2.9%/9.9%; 18.4%/28.1%; and 6.9%/12.8% for the same four species, respectively. Seventeen Enterobacterales isolates from 17 patients were shown to harbour a carbapenemase gene: 12 blaIMP-4; two blaNDM-7; one blaNDM-1; one blaOXA-181; and one blaKPC-2. No transmissible carbapenemase genes were detected among P. aeruginosa or Acinetobacter isolates in the 2021 survey.