isolates-cases-sab-124.html
DANMAP 2015 3D
125 / 144
125 danmap 2015 a complete
mrsa
surveillance was established on a voluntary basis in 1988, improved with a systematic collection of clinical information since 1999, and ultimately became notifiable in november 2006. figure 8.13 shows the number of new
mrsa
cases
registered in the period 1994-2015. until 2001, less than 100 new
cases
were registered annually. the following increase has mostly been driven by the emergence of com- munity associated (ca-)
mrsa
, which depicted a completely new era in
mrsa
evolution and epidemiology since
mrsa
had previously been restricted to
hospital
settings. the first danish ca-
mrsa
(european ca-
mrsa
cc80-iv)
cases
were reported in 1997. these were followed by emergence of other ca-
mrsa
clones, most notably the south west pacific (st30-iv) and usa300 (st8-iv), named after the geographic epicenters of their emergence. import of these clones has occurred with travelers, migrants and refugees and has sub- sequently led to secondary transmissions in the local com- munities. the ca-
mrsa
clones share molecular characteristics, which may be of of importance for the success of these clones outside
hospital
settings were: smaller scc mec elements (carrying the meca gene, responsible for the
mrsa
phenotype) type iv and v compared to the scc mec ii and iii found in the older
hospital
clones; and carriage of the panton-valentine leukocidine (pvl) genes. the smaller scc mec elements iv and v in ca-
mrsa
may be an adaptation to the environment outside
hospital
s with less need for additional resistance genes and the pvl genes may increase infectivity in the skin and thereby transmission. despite of the increasing number of ca-
mrsa
in denmark, in- fection control procedures has ensured a low level in
hospital
s. the annual number of patients acquiring
mrsa
infections in
hospital
has remained below 50
cases
since 2006. very few larger
hospital
outbreaks have been noted with the exception of the st22-iv outbreak in vejle county that went on for more than 4 years between 2002-2006. this outbreak peaked in 2005 and accounted a total of 514
cases
during the 4 years. however, as seen in figure 8.13 the decline in
mrsa
following the ?vejle outbreak? was only temporary, since the numbers of imported
cases
, ca-
mrsa
as well as spread into health care facilities has continued. a new wave in the evolution of
mrsa
appeared with the emergence of
mrsa
in livestock (la-
mrsa
). the spread of this clone among livestock was very fast with 3% of pig herds be- ing positive in 2008, 15 % in 2011 and 68% in 2014. the first human
cases
with la-
mrsa
(cc398) occurred in 2004 and the incidence has increased dramatically in the years after, peak- ing in 2014 with 1,277 new
cases
. in 2012, a revision of the
mrsa
guidelines from the danish health authorities, depicted screening of people with livestock contact at
hospital
admis- sions. consequently, cc398
cases
are more often found by active screening than from clinical samples (20%) compared to other
mrsa
types (40-50%). the
cases
most often have docu- mented contact to pigs (85-89%). the human to human trans- mission appears to be less effective for this clone compared to others, which may be due to its adaptation to livestock as host, a feature that may be linked to the absence of the human immune modulatory genes ( scn , sak and chp ). furthermore, the predominant scc mec element found in cc398 is a type iv vari- ant (5c2&5) that is comparable large to the old
hospital
type ii and iii elements probably making cc398 less fit to survive in the community. despite the steady increase in
mrsa
in the surveillance period, the frequency has remained low compared to other european countries (earssnet.org) and most importantly the number of infections in
hospital
ized patients low. this success in keep- ing a low frequency of
mrsa
in denmark, the other nordic countries (www.nordic
mrsa
.org) and in the netherlands is most likely a result of the ?search and destroy? policy in the hospi- tals in combination with a general rational antibiotic policy. for further information: anders rhod larsen (arl@ssi.dk), andreas petersen, robert skov, (rsk@ssi.dk) staphylococcus aureus surveillance, 1996-2015
cc398-livestock-mrsa-126.html
