Newspaper Dagens Medicin reports that based on international statistics a hospital the size of Danderyd's should have about two cases a year.
The bacteria can spread along with lesser infections, such as strep throat and impetigo, but necrotizing fasciitis can kill someone in less than 24 hours.
"The bacteria can be very aggressive," says orthopaedic doctor Ardalan Rahimi at Danderyd to the Metro newspaper.
Researchers are now looking into why the hospital has found so many cases of this rare infection. Those most at risk are older patients and people with weak immune systems.