Antimicrobial resistance and antibiotic consumption in intensive care units, Switzerland, 2009 to 2018

Background: Intensive care units (ICU) constitute a high-risk setting for antimicrobial resistance (AMR). Aim: We aimed to describe secular AMR trends including meticillin-resistant Staphylococcus aureus (MRSA), glycopeptide-resistant enterococci (GRE), extended spectrum cephalosporin-resistant Escherichia coli (ESCR-EC) and Klebsiella pneumoniae (ESCR-KP), carbapenem-resistant Enterobacterales (CRE) and Pseudomonas aeruginosa (CRPA) from Swiss ICU. We assessed time trends of antibiotic consumption and identified factors associated with CRE and CRPA. Methods: We analysed patient isolate and antibiotic consumption data of Swiss ICU sent to the Swiss Centre for Antibiotic Resistance (2009-2018). Time trends were assessed using linear logistic regression; a mixed-effects logistic regression was used to identify factors associated with CRE and CRPA. Results: Among 52 ICU, MRSA decreased from 14% to 6% (p = 0.005; n = 6,465); GRE increased from 1% to 3% (p = 0.011; n = 4,776). ESCR-EC and ESCR-KP increased from 7% to 15% (p < 0.001, n = 10,648) and 5% to 11% (p = 0.002; n = 4,052), respectively. CRE, mostly Enterobacter spp., increased from 1% to 5% (p = 0.008; n = 17,987); CRPA remained stable at 27% (p = 0.759; n = 4,185). Antibiotic consumption in 58 ICU increased from 2009 to 2013 (82.5 to 97.4 defined daily doses (DDD)/100 bed-days) and declined until 2018 (78.3 DDD/100 bed days). Total institutional antibiotic consumption was associated with detection of CRE in multivariable analysis (odds ratio per DDD: 1.01; 95% confidence interval: 1.0-1.02; p = 0.004). Discussion: In Swiss ICU, antibiotic-resistant Enterobacterales have been steadily increasing over the last decade. The emergence of CRE, associated with institutional antibiotic consumption, is of particular concern and calls for reinforced surveillance and antibiotic stewardship in this setting.