Eight-year trends in the relative isolation frequency and antimicrobial susceptibility among bloodstream isolates from Greek hospitals: data from the Greek Electronic System for the Surveillance of Antimicrobial Resistance – WHONET-Greece, 2010 to 2017

Background Antimicrobial resistance (AMR) changes over time and continuous monitoring provides insight on trends to inform both empirical treatment and public health action. Aims To survey trends in relative isolation frequency (RIF) and AMR among key bloodstream pathogens using data from the Greek Electronic System for the Surveillance of AMR (WHONET-Greece). Methods This observational study looked into routine susceptibility data of 50,488 blood culture isolates from hospitalised patients in 25 tertiary hospitals, participating in the WHONET-Greece for trends over time between January 2010 and December 2017. Only the first isolate per species from each patient was included. Hospital wards and intensive care units (ICUs) were analysed separately. Results During the study, the RIF of Acinetobacter baumannii increased in wards, as did the proportion of A. baumannii isolates, which were non-susceptible to most antibiotics in both wards and ICUs. Coincidently, Klebsiella pneumoniae RIF declined while the respective rates of non-susceptible isolates to carbapenems and gentamicin increased. Pseudomonas aeruginosa RIF remained stable but decreasing proportions of non-susceptible isolates to all studied antibiotics, except imipenem were observed. Escherichia coli RIF increased as did the proportion of isolates non-susceptible to third-generation cephalosporins, carbapenems and fluoroquinolones. Concerning Staphylococcus aureus , a decline in the percentage of meticillin resistant isolates in ICUs was found, while the percentages of Enterococcus faecium isolates with non-susceptibility to vancomycin stayed stable. Conclusions Recognising these trends over time is important, since the epidemiology of AMR is complex, involving different ‘bug and drug’ combinations. This should be taken into consideration to control AMR.