MRSA infections in Norway: A study of the temporal evolution, 2006-2015

Abstract

BackgroundNorway has one of the lowest prevalences of methicillin-resistant Staphylococcus aureus (MRSA) infections in the world. This study exploits the extensive data on MRSA infections in the Norwegian surveillance system to investigate the important factors defining the MRSA epidemiology.MethodsWe performed a quasi-Poisson regression of the monthly notification rate (NR) of MRSA infections reported from January 2006 to December 2015, comparing the time trend among people with an immigrant vs. Norwegian background and domestic vs. imported infections, stratified by age groups.FindingsA total of 5289 MRSA infections were reported during the study period, of which 2255 (42·6%) were acquired in Norway, 1370 (25·9%) abroad, and 1664 (31·5%) with an unknown place of acquisition. Overall, the monthly NR increased significantly from 2006 to 2015 (+0·8% each month). The monthly increase in immigrants (+1·3%) was steeper than that in people with a Norwegian background (+0·6%). There was a significant growth (+0·4%) in the rate of domestically acquired infections, however, the NR of infections acquired abroad increased faster (+0·8%). For both imported and domestic infections, the increase occurred in persons aged < 70 years.InterpretationOur analysis suggests that immigration and importation, especially among persons aged < 40 years, represent important factors for the increasing notification rate of MRSA infections in Norway.

Quantifying the transmission dynamics of MRSA in the community and healthcare settings in a low-prevalence country

“…The model estimated an effective reproductive number of about 0.7, suggesting that circulation of MRSA in Norway was not self-sustained but maintained by the rising import of carriers from abroad. By identifying importations as a primary driver of MRSA epidemiology in a low-prevalence country, our study confirms the critical role of travel in spreading resistance (9, 28, 29). We estimated that the rise in importation has fueled an almost twofold increase in the prevalence of carriage in the general community from 2008 to 2015 up to a value of 0.37%.…”

“…Nonetheless, the control of MRSA in low-prevalence countries may be threatened by changes in the global epidemiology. First, its spread beyond the nosocomial environment into the community, mainly affecting young individuals without previous healthcare-related exposure (6–9); second, the continued growth of MRSA prevalence in countries with insufficient control combined with intensified international mobility, which are significantly contributing to the global spread of MRSA (9, 10). We currently have very limited knowledge of how the emerging community reservoir contributes to the local MRSA epidemiology in low-prevalence settings and to which degree it impacts the healthcare environments.…”

Attributable deaths and disability-adjusted life-years caused by infections with antibiotic-resistant bacteria in the EU and the European Economic Area in 2015: a population-level modelling analysis

“…The elderly population is more vulnerable to MRSA infections 20 and this population has grown since 2007; the improvement of neonatal services, leading to an increased survival of at-risk infants, might have also contributed to further increasing the size of the population at risk for MRSA infection. Studies in Sweden, 21 Finland, 22 and Norway, 23 have also found that incidence of MRSA did not decrease in these countries.…”

The fight to keep resistance at bay, epidemiology of carbapenemase producing organisms (CPOs), vancomycin resistant enterococci (VRE) and methicillin resistant Staphylococcus aureus (MRSA) in Norway, 2006 - 2017

“…Even though most imported MRSA strains after 2007 seem not to have led to significant domestic spread, our results show that the potential for transmission varies a lot between the strains. Although we experience that many MDROs imported to Scandinavian countries do not lead to further domestic spread, we also identify continuing transmission of single strains in the community and outbreaks in healthcare institutions [5].…”

“…Historically, surveillance data has indicated that Norway, along with other Scandinavian countries, has a low background prevalence of resistant organisms [2–4]. In recent years, however, it appears that the epidemiology has been changing [5–7]. Importantly, the incidence of these different bug-drug combinations may be changing differently; at different rates, in different populations and with differing effect.…”