The project: Major MedVet-Staph results

Before starting its second funding period in 2014, the MedVet-Staph consortium has obtained the following ten main research results in its first research period (2010-2013):

  1. LA-MRSA colonization of humans with direct contact to livestock is frequent and affects 77% of all pig farmers. This colonization of pig farmers seems rather persistent even after longer periods (>1 week) of absence from animal contact.
  2. LA-MRSA belonging to CC398 account for about 2% of all MRSA isolated from human infections in Germany. However, when analysing data from regions with a high density of livestock-production separately, the burden of LA-MRSA infections is higher with LA-MRSA representing up to 14% of human MRSA deep-respiratory infections, 11% of deep-seated wound infections and 8% of bloodstream infections among hospital inpatients. This burden has significantly increased between 2004 and 2011.
  3. LA-MRSA is spreading from human-to-human in households. Preliminary data of the MedVet-Staph consortium showed that household members of veterinarians with LA-MRSA carriage are at increased risk to acquire LA-MRSA via intrafamilial transmission compared with a control group (12.8% were colonized with LA-MRSA belonging to the same clonal lineage as the isolate from the veterinarian).
  4. MRSA was detected in 9.4% of all wound swabs from equine origin, 5.7% of all samples from cats and in 3.6% of all specimens derived from dogs. The rate of the MRSA CC398 (as the predominant MRSA in livestock) was 13.2% for MRSA-positive samples from dogs, 7.9% from cats and a remarkable 87.8% from horses which poses new questions about the transmission of LA-MRSA.
  5. The occurrence of a novel homologue of the methicillin-resistance gene mec (named mecC) among human and veterinary MRSA isolates has been confirmed by the MedVet-Staph consortium.
  6. Novel transferable resistance genes located on mobile genetic elements (such as the genes vga(C), apmA, erm(T) and dfrK) were detected in LA-MRSA. Moreover, novel mutations associated with fluoroquinolone-resistance in S. aureus and a novel ABC transporter gene conferring pleuromutilin-lincosamide-streptogramin A resistance were identified for the first time in LA-MRSA isolates.
  7. Preliminary results of the MedVet-Staph consortium shown that comparing MRSA CC398 with classical human MRSA types, MRSA CC398 exerted high cytotoxic properties against human epithelial cells and expressed specific virulence factors such as α- and β-toxins on a high level. These findings are important since they show that significant factors enabling MRSA CC398 to cause human infections are present in this major LA-MRSA clonal lineage.
  8. LA-MRSA strains possessed reduced adhesion capacities to human and bovine fibronectin. and adhered less efficiently to endothelial and epithelial cell cultures if compared to human MRSA clones. This suggests that the adhesive potentials of zoonotic LA-MRSA are not likely to be a major factor for the success of zoonotic MRSA to cross the species barrier.
  9. A model enabling the prediction of the spatio-temporal MRSA dispersal through trade of livestock between German pig farms was developed.
  10. A model identifying critical points along the food chain that enable MRSA food contamination was developed. Applying this model can directly be used to establish critical control points along the slaughtering process suitable for interventions.