MRSA in a one health perspective

Norway has, as the only country in the world, implemented a control strategy for LA-MRSA in the swine population which includes a surveillance program covering the entire swine population and a “search and destroy” policy at pig farm level for elimination of LA-MRSA from affected farms. The rationale behind this strategy is to avoid the swine population to become a permanent reservoir of MRSA with a potential spill-over to the human population. Our research focuses on experiences and opportunities provided by this control strategy, with a primary focus on epidemiological investigations combined with the use of whole-genome sequencing data. Evaluation of the effect of MRSA eradication at farm level is also a prioritized area, in addition to optimization of detection methods for LA-MRSA and development of transmission models.

Figure 1. Phylogenetic analysis for understanding diversity and spread of methicillin-resistant Staphylococcus aureus (MRSA) CC398 isolates in Norway. Human-adapted (HuA) and livestock-associated (LA) clades are highlighted. Identified outbreaks in relation to Norwegian livestock are highlighted, including outbreaks 1 (red), 2 (blue), and 3 (yellow). Inner circle represents Norwegian isolates (filled squares), Danish pig production isolates (open squares), and other isolates (blank [no squares]). Middle circle represents sample environment with livestock, meat, and environmental samples (filled squares) and human isolates (open squares). Outer circle depicts occurrence of specific fluoroquinolone-associated resistance mutations in gyrA (Ser84Leu) and parC (Ser80Tyr).

Reference figure 1: Methicillin-Resistant Staphylococcus aureus CC398 in Humans and Pigs in Norway: A “One Health” Perspective on Introduction and Transmission. Clin Infect Dis. 2016 Dec 1;63(11):1431-1438