In 2007, pig MRSA of the CC398 type comprised only 2% of all notified MRSA cases in Denmark. This year, the type presently accounts for more than 35% of cases. The overwhelming majority of these cases are carriers of the bacterium and have no symptoms of staphylococcal infection, and only a very limited number of persons become seriously ill due to the infection.
In the 2007-2013 period, the SSI received a total of 8,375 MRSA isolates for characterisation, and 15% of these were of the CC398 type, which can be transmitted from pigs to humans. Both the number and the share of CC398 cases increased during the period.
Thus, only 2% of cases were CC398 in 2007, whereas this share had increased to 31% in 2013. The figures covering the period from January to April of 2014 show that this trend continues as 784 MRSA strains have been received to date in 2014, of which 36% were CC398.
The number of MRSA cases of the CC398 type, which is closely associated with pigs, increased substantially from 232 cases in 2012 to 463 cases in 2013. The number now accounts for 31% of all MRSA cases. As in previous years, the overwhelming majority, 87%, had direct contact to pigs or were members of households with persons who had contact to pigs. Only 24% had a clinical infection at the time of their diagnosis (40% in 2012).
Part of the increase is owed to the fact that more of the infected persons are now being detected. Today, all patients who are admitted to hospital are asked if they work with pigs or live at a pig-producing farm. Those who do are tested for MRSA even if they show no signs of being infected with the bacterium. This is so because in 2012 the Danish Health and Medicines Authority issued a revised guideline on MRSA in which contact with pigs was listed as a risk situation for MRSA infection.
Wednesday June 18, 2014/ SSI/ Denmark.