An unusually large and persistent outbreak of Group A Streptococcus (GAS) in a nursing home was spread in part by infected and colonized healthcare workers, underscoring the importance of reporting symptoms, seeking treatment, practicing rigorous infection control, and not working sick, an officer in the CDC Epidemic Intelligence Service recently reported at the annual EIS meeting in Atlanta.

GAS outbreaks can be difficult to control because those merely colonized and asymptomatic can still infect their contacts, says Srinivas A. Nanduri, MD, an EIS Officer at the CDC. A strep outbreak could hit a hospital if lapses of infection control occur, but the long-term care environment has characteristics that may enhance spread, he says.

“Clusters of Group A strep infections can also occur in hospitals,” he tells HEH. “However, it is extremely unlikely that an outbreak of this magnitude would occur at an acute care hospital. In nursing homes, the population at risk, length of stay, staffing patterns, policies, and many other underlying factors are different from those found in acute care hospitals. Also, this particular outbreak is unique even among nursing home outbreaks in having affected a very large number of residents and staff.”

In February 2015, the Illinois Department of Public Health (IDPH) identified a cluster of GAS infections at a nursing home. After multiple interventions, mass antibiotic prophylaxis was implemented from April 28–May 2, 2015. Infections re-emerged in late June. In November, the IDPH requested assistance to assess risk factors for infection and recommend control measures.1

Nanduri and EIS colleagues defined cases as GAS infection among residents or employees confirmed by culture or antigen detection. They surveyed employees and observed infection control practices. To identify disease risk factors, they conducted a case-control study comparing resident cases occurring from May 3 to November 10 to controls for the same time period. To identify asymptomatic colonization, they collected throat and wound cultures from residents receiving wound care and throat cultures from employees linked to cases.

A total of 57 cases and four deaths occurred in 2015. The total included 17 cases (10 residents and seven employees) that occurred after the mass antibiotic prophylaxis.

“All symptomatic employees in the outbreak had pharyngitis,” he says. “Ill residents had a wide spectrum of presentations, with some having severe bloodstream infections and others having pharyngitis or wound infections.”

All the deaths were in residents and the mortality in those four cases was attributable to GAS infection, he says.

“It is important to note that many of these residents had underlying illnesses which increase their risk of invasive GAS infection and worsen prognosis if they become ill,” Nanduri says.

An employee survey identified seven self-reported, previously unrecorded workers with GAS illnesses since May 2015. “Employees should self-report if they have symptoms suggestive of infection with GAS,” he says. Besides relying on self-reporting by employees, GAS prevention strategies include the following:

  • education of staff about the symptoms suggestive of GAS infection,
  • active surveillance for GAS symptoms suggestive of infection through reminders when employees present to work each day,
  • employee health services should establish procedures for tracking absences, and
  • develop sick leave policies that are non-punitive, flexible, and encourage sick employees to stay home.

Investigators observed multiple lapses in hand hygiene and wound care practices, which contributed to the spread of strep. All (8 of 8) case patients included in the case-control study received wound care versus 8 of 24 (33%) in the controls. One employee and four residents were colonized with GAS. The outbreak strain matched 96% of typed isolates (27 of 28).

“The healthcare workers were wearing gloves for wound care, illustrating the importance of always performing hand hygiene before and after using gloves,” he says.

As per CDC guidelines for care of wounds infected with GAS, Nanduri cited the following precautions:

  • Wounds with no dressings or with dressings that do not adequately contain drainage: contact and droplet precautions are advised.
  • Wounds with dressing covers that adequately contain drainage: standard precautions are advised.


  1. Nanduri SA, Arwady MA, Edens C, et al. Prolonged Outbreak of Invasive Group A Streptococcus Among Nursing Home Residents — Illinois, 2015. Epidemic Intelligence Service Conference, Atlanta: May 2-5, 2016.