The Centers for Disease Control & Prevention has urged long-term care providers to investigate all cases of streptococcus following a large and long outbreak at a Pennsylvania nursing home.

The agency’s Morbidity and Mortality Weekly Report said 13 residents at an unnamed Montgomery County, PA facility had invasive group A streptococcus between October 2009 and September 2010. Two residents died, The Philadelphia Inquirer reported.

The CDC said it was one of the “largest and most prolonged” outbreaks of streptococcus in a nursing facility.

While Group A strep often causes strep throat, it also can cause Toxic Shock Syndrome or necrotizing fasciitis. Long-term care facilities “should investigate single cases of invasive strep infection and make sure good infection-control practices are in place,” the agency cautioned.