Antibiotic resistance in Swiss nursing homes: analysis of National Surveillance Data over an 11-year period between 2007 and 2017

Background We evaluated data from isolates of nursing home (NH) patients sent to the Swiss centre for antibiotic resistance (ANRESIS). We focussed on carbapenem-resistance (CR) among Gram-negative pathogens, extended-spectrum cephalosporin-resistant (ESC-R) Escherichia coli / Klebsiella pneumoniae , methicillin-resistant Staphylococcus aureus (MRSA), and glycopeptide-resistant enterococci (GRE). Methods NH patient isolates from 01/2007 to 10/2017 were extracted. Temporal trends in resistance were described and risk factors associated with ESC-R and MRSA were assessed. For every administrative subdivision in Switzerland (i.e. canton), we calculated a coverage rate, defined as number of beds of governmentally-supported nursing homes, which sent ≥1 isolate in each 2014, 2015, and 2016, divided by the total number of supported beds. Results We identified 16′804 samples from 9′940 patients. A majority of samples (12′040; 71.6%) originated from the French/Italian speaking part of Switzerland. ESC-R E. coli increased from 5% (16/299) in 2007 to 22% (191/884) in 2017 ( P < 0.01), whereas MRSA decreased from 34% (35/102) to 26% (21/81) ( P < 0.01). Provenience from the German (vs. French/Italian) speaking part of Switzerland was associated with decreased risk for ESC-R (OR 0.5, 95% CI 0.4–0.7) and for MRSA (OR 0.1, 95% CI 0.1–0.2). CR among Pseudomonas aeruginosa was 10% (105/1096) and showed an increasing trend over time; CR among Enterobacteriaceae (37/12′423, 0.3%) and GRE (5/1′273, 0.4%) were uncommon. Overall coverage rate was 9% (range 0–58% per canton). There was a significant difference between the French/Italian (median 13%, interquartile range [IQR] 4–43%) and the German speaking cantons (median 0%, IQR 0–5%) ( P = 0.02). Conclusions ESC-R among E. coli is emerging in Swiss NHs, whereas MRSA show a declining trend over time. A minority of NHs are represented in ANRESIS, with a preponderance of institutions from the French/Italian speaking regions. Efforts should be undertaken to improve resistance surveillance in this high-risk setting.