Rapid increase of multi-drug resistant Pseudomonas aeruginosa in Greece - WHONET-Greece (2020-2023)

Abstract Background Multidrug-resistant (MDR) Pseudomonas aeruginosa has been documented as a significant threat associated with adverse patient outcomes. We aimed to describe the rapid increase in the prevalence of an MDR P.aeruginosa phenotype at the national level, as detected through the Greek Electronic System for the Surveillance of Antimicrobial Resistance (WHONET-Greece). Methods Routine susceptibility data of 22,236 P.aeruginosa isolates of hospitalized patients in forty-five hospitals, isolated over the past four years (2020-2023) were analyzed using ‘Resistance profiles’ analysis of WHONET software(ver.2023), considering five antimicrobial groups/agents. Results We confirmed the rapid increase in the prevalence of a carbapenem-resistant P.aeruginosa (CRPA) phenotype resistant to all five antimicrobial groups/agents tested (carbapenems, piperacillin-tazobactam, cephalosporins, fluoroquinolones and aminoglycosides). The prevalence increased by 63.8% in 2023 (from 15.2% to 24.9%, 1.64-fold increase), whereas in the last 24 months of the study period a 2.13-fold increase was observed (from 11.7% to 24.9%). In parallel, the prevalence of all other CRPA profiles decreased in 2023 from 22.5% to 17%. We also examined the prevalence of this MDR phenotype in the different NUTS-1 regions of the country, which revealed that the rapid increase is mainly observed in Attika (EL3, 19/45 hospitals) and Central Greece (EL6, 8/45 hospitals) where prevalence reached 25.4% and 26.2% in the second half of 2023 respectively. Northern Greece (EL5, 15/45 hospitals) showed a steady increase over the four years (12% to 19.3%), while in the Aegean Islands/Crete region (EL4, 3/45 hospitals) the prevalence levels were stable. Conclusions There is an emerging multi-drug CRPA phenotype in Greece. Only with systematic, nationwide surveillance could we identify and verify such threats. The findings of this study should be used for targeted interventions and further analysis through molecular techniques. Key messages • The early detection of such emerging multi-drug CRPA phenotype in Greece allows for for targeted interventions and further analysis through molecular techniques. • Systematic surveillance of antimicrobial resistance based on routine susceptibility data is a great way to identify and verify emerging public health threats.