Methicillin-Resistant Staphylococcus aureus (MRSA) Is Increasing in Norway: A Time Series Analysis of Reported MRSA and Methicillin-Sensitive S. aureus Cases, 1997–2010

Abstract

BackgroundAccurate estimates of the incidence and prevalence of methicillin-resistant Staphylococcus aureus (MRSA) infections are needed to inform public health policies. In Norway, where both MRSA infection and carriage are notifiable conditions, the reported incidence of MRSA is slowly increasing. However, the proportion of MRSA in relation to all S. aureus isolates is unknown, making it difficult to determine if the rising incidence is real or an artifact of an increasing number of tests performed.AimTo characterize recent trends in MRSA infections and obtain a more complete understanding of the MRSA level in Norway.MethodsAll reported cases of MRSA and methicillin-sensitive S. aureus (MSSA) from Oslo County (1997–2010) and Health Region East (2008–2008), representing approximately 11% and 36% of the Norwegian population, respectively, were analyzed using a stochastic time series analysis to characterize trends.ResultsIn Oslo County, the proportion of methicillin-resistant cases increased from 0.73% to 3.78% during the study period and was well modeled by an exponential growth with a doubling constant of 5.7 years (95% CI 4.5–7.4 years). In Health Region East, the proportion of MRSA cases increased from 0.4% to 2.1% from 2002 to 2008, with a best-fitting linear increase of 0.26% (95% CI 0.21–0.30%) per year. In both cases, the choice of a linear or exponential model for the time trend produced only marginally different model fits. We found no significant changes due to revised national MRSA guidelines published in June 2009. Significant variations in the increasing time trend were observed in the five hospitals within the region. The yearly reported incidence of MSSA was relatively stable in both study areas although we found seasonal patterns with peaks in August.ConclusionThe level of MRSA is increasing in Norway, and the proportion of methicillin resistance in all S. aureus isolates are higher than the reported proportion of MRSA in invasive infections.

Recurrent furunculosis – challenges and management: a review

“…However, community acquired MRSA (CA-MRSA) has become endemic in the US and is now the most common cause of soft tissue infection in the emergency room in many countries 12–15. The prevalence of CA-MRSA is higher in the US when compared to Europe but the prevalence in Europe is rising 16–21…”

Changing epidemiology of methicillin-resistant Staphylococcus aureus in a low endemicity area—new challenges for MRSA control

“…The increase in clinical MRSA infections supports the latter. In a Norwegian study, a time series analysis revealed an actual increase in MRSA incidence irrespective of the screening policies or the amount of S. aureus findings [21].…”

<b><i>Staphylococcus aureus</i></b> and Host Immunity in Recurrent Furunculosis

“…Their resistance is determined by receptors encoded by mecA gene located on the bacterial chromosome which is an element of staphylococcal cassette chromosome mec. Acquiring resistance by S. aureus strains is associated with spreading of staphylococcal cassette chromosome mec included in the so-called genomic islands [27]. …”