Australian Group on Antimicrobial Resistance (AGAR) Australian Gram-negative Surveillance Outcome Program (GnSOP) Bloodstream Infection Annual Report 2023.

Abstract: The Australian Group on Antimicrobial Resistance (AGAR) performs regular period-prevalence studies to monitor changes in antimicrobial resistance in selected enteric gram-negative pathogens. From 1 January 2023 to 31 December 2023, a total of 57 hospitals across Australia participated in the Australian Gram-negative Surveillance Outcome Program (GnSOP). The 2023 survey tested 10,453 isolates, comprising Enterobacterales (9,503; 90.9%), P. aeruginosa (806; 7.7%) and Acinetobacter species (144; 1.4%), using commercial automated methods. The results were analysed using European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints (January 2024). Key resistances reported are to the third-generation cephalosporin ceftriaxone in 12.9% of Escherichia coli and in 6.9% of Klebsiella pneumoniae complex isolates. Resistance rates to ciprofloxacin were 14.5% for E. coli; 7.8% for the K. pneumoniae complex; 3.2% for the Enterobacter cloacae complex; and 7.6% for P. aeruginosa. Resistance rates to piperacillin-tazobactam were 6.0%; 9.4%; 23.3%; and 13.7% for the same four species/complexes, respectively. Thirty Enterobacterales isolates from 30 patients were shown to harbour a carbapenemase gene: ten with a bla_NDM gene (bla_NDM-1 [4], bla_NDM-5 [4], bla_NDM-7 [2]); nine with a bla_OXA-48-like gene (bla_OXA-244 [4], bla_OXA-48 [2], bla_OXA-181 [1], bla_OXA-232 [1], bla_OXA-484 [1]); eight with bla_IMP-4; two with bla_NDM-5 + a bla_OXA-181-like gene; and one with bla_KPC-2 + bla_NDM-5 + bla_OXA-181. Transmissible carbapenemase genes were also detected in two Acinetobacter baumannii complex isolates (bla_OXA-23; bla_OXA-23 + bla_OXA-58 + bla_IMP-4) and one P. aeruginosa (bla_IMP-4).