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) /, methicillin-resistant (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 increased from 5% (16/299) in 2007 to 22% (191/884) in 2017 ( < 0.01), whereas MRSA decreased from 34% (35/102) to 26% (21/81) ( < 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 was 10% (105/1096) and showed an increasing trend over time; CR among (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%) ( = 0.02).