Staphylococcus aureus and methicillin resistance in Switzerland: regional differences and trends from 2004 to 2014.

F Olearo,Wc Albrich,A Kronenberg,Centre Swiss,N Vernaz,S Harbarth

doi:10.4414/smw.2016.14339

Abstract

The global epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) is heterogeneous. The objective of this study was to evaluate MRSA epidemiology in Switzerland over an 11-year period. We conducted a retrospective study with time series analysis on S. aureus including MRSA and non-multidrug resistant MRSA (NmMRSA). We used NmMRSA as a marker for community-acquired MRSA. NmMRSA was defined as MRSA susceptible to at least three of the following agents: ciprofloxacin, clindamycin, tetracycline and trimethoprim-sulfamethoxazole. A total of 14 648 MRSA and 115 917 methicillin-susceptible S. aureus (MSSA) isolates were included. Despite an overall decrease of the proportion of MRSA among S. aureus clinical isolates (from 14% in 2004 to 8% in 2014), an increasing trend in NmMRSA was observed. Variations in geographical distribution were noted, with a decrease in the proportion of MRSA in the Italian- and French-speaking regions (from 20-26% in 2004 to 12% in 2014) and low prevalence (3-5%) in the German-speaking region. We noticed an increase in the proportion of MRSA in outpatients (+0.03% per quarter per year) and in the younger population (+0.05% per quarter per year) compared with a decreasing trend in inpatients and the elderly. The proportion of MRSA among S. aureus isolates in Switzerland decreased overall from 2004 to 2014. Worrisome increases of NmMRSA were found in younger persons and outpatients.

Highlights

Methicillin-resistant Staphylococcus aureus (MRSA) combines virulence and resistance with remarkable adaptive qualities to the human host and is associated with either carriage or a broad spectrum of infectious conditions causing significant clinical and health-economic adverse outcomes [1]
We conducted a retrospective study with time series analysis on S. aureus including methicillinresistant Staphylococcus aureus (MRSA) and non-multidrug resistant MRSA (NmMRSA)
NmMRSA was defined as MRSA susceptible to at least three of the following agents: ciprofloxacin, clindamycin, tetracycline and trimethoprim-sulfamethoxazole

Summary

Introduction

Methicillin-resistant Staphylococcus aureus (MRSA) combines virulence and resistance with remarkable adaptive qualities to the human host and is associated with either carriage or a broad spectrum of infectious conditions causing significant clinical and health-economic adverse outcomes [1]. Regarding Europe, recent data from the European antimicrobial resistance interactive database (EARS-Net), which covers a wide network of national surveillance systems in Europe, show that, after a general rise in prevalence, MRSA proportions among S. aureus isolates seem to be decreasing in Europe since the beginning of this decade, as observed in North America [3]. It is, a heterogeneous picture as Sweden, Estonia, Austria and Romania still show rising trends in MRSA prevalence (European Centre for Disease Prevention and Control, ECDC 2013). There is a paucity of comparable epidemiological data from Switzerland, which offers a unique per-

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