Infection Control for Invasive Group A Streptococcus Infection in Hospitals

This document was developed for the use of health care workers (HCWs) to prevent the transmission of invasive group A streptococcus (GAS) in hospitals. Invasive GAS disease is defined as disease with isolation of GAS from a normally sterile site (Section 5.1 of these Guidelines). For recommendations on non-invasive GAS please refer to the Public Health Agency of Canada (PHAC) Infection Control Guideline: Routine Practices and Additional Precautions for Preventing the Transmission of Infections in Health Care - Revision of Isolation and Precaution Techniques(1).

The recommendations in this document are based on PHAC infection control guidelines: Routine Practices and Additional Precautions for Preventing the Transmission of Infections in Health Care - Revision of Isolation and Precaution Techniques(1), Prevention and Control of Occupational Infections in Health Care(2) and Hand Washing, Cleaning, Disinfection and Sterilization in Health Care(3).

Some specific recommendations in this Annex may supersede existing PHAC infection control guidelines; they are based on new evidence, expert opinion and consensus. The recommendations in this Annex have been reviewed and endorsed by the PHAC Infection Control Guidelines Steering Committee. A glossary of terms is found at the end of the Annex.

Transmission of Invasive GAS in Health Care Settings

GAS is primarily spread by large droplet contact of the oral or nasal mucous membranes with infectious respiratory secretions or with exudates from wounds or skin lesions, or by direct or indirect contact of non-intact skin with exudates from skin or wounds or infectious respiratory secretions(1). Transmission between patients through contaminated hands and the reduction of transmission by handwashing was initially reported by Semmelweiss in 1848(4). Transmission by contaminated equipment or patient care products (e.g. bidets, multi-dose injection vials) has rarely been reported(5).

The incubation period for invasive GAS infection has not been determined. The incubation period for non-invasive GAS infection varies according to the clinical syndrome, usually 1 to 3 days. The infection is communicable until 24 hours of effective antibiotic treatment has been completed.

Nosocomial infections accounted for 12% of all invasive GAS infections identified during prospective surveillance in Ontario from 1992 to 2000(6). Although pre-existing GAS carriage by the patient may play a role in some cases of sporadic post-partum or postoperative infections, GAS may also be acquired from health care providers with symptomatic infection or asymptomatic carriage(5-8). Hospital outbreaks of invasive GAS have been reported in a variety of patient groups (e.g. post-partum women and newborns, postoperative surgical patients, burn patients, neonatal intensive care patients, patients in geriatric wards)(5,8).Some outbreaks have been associated with persistent carriage of GAS by asymptomatic health care providers (e.g. surgeons, obstetricians, anesthesiologists, nurses). The pharynx, vagina, rectum and/or specific areas of skin (e.g. scalp) have been sites of colonization(5,8,9). Outbreaks of GAS infection have also occurred in exposed HCWs(5,10).

Infection Control Measures To Prevent Transmission of Invasive GAS in Health Care Institutions

The transmission of invasive GAS in hospitals and long-term care facilities is most effectively prevented by adherence to good hand hygiene and other routine practices at all times. In addition, for patients with invasive GAS infection, contact and droplet precautions are required until 24 hours of effective antibiotic therapy has been administered. As most cases of nosocomial invasive GAS are sporadic, it is important to recognize clinical presentations compatible with invasive GAS early and institute additional precautions while awaiting laboratory confirmation. Active surveillance for early identification of outbreaks may also be effective in preventing some cases. Prevention of a hospital outbreak of GAS infection requires very rapid investigation and intervention once a single hospital-acquired case has been identified(6,8).For further information regarding infection control measures in long-term care facilities please see Section 6.3 of the Guidelines.

GAS Transmission

GAS Transmission

patient to patient   patient to HCW   HCW to patient

In order to effectively prevent the transmission of GAS from patient to patient, patient to HCW and/or HCW to patient, the following infection control practices are necessary:

  • Consistent adherence to good hand hygiene practice.
  • Use of routine practices at all times and for all patients, including wearing a surgical/procedure mask and eye protection or face shield when contamination of the mucous membranes is likely, for example when doing wound irrigation.
  • In addition to routine practices at all times, applying contact and droplet precautions when caring for patients with known or suspected invasive GAS disease (Section 5.1 of the Guidelines) until 24 hours of effective antimicrobial therapy is complete. For the purpose of infection control, GAS pneumonia with or without a positive blood culture is considered an invasive infection, although not identified as such for reporting.
  • Ensuring that HCWs promptly report illness possibly due to GAS (pharyngitis, impetigo, wound or skin infections, cellulitis) and comply with policies regarding not working when ill with a potentially communicable disease.
  • Investigating clusters and identifying and treating patients and staff members with symptomatic GAS infection.
  • Patients who share a room with a patient with invasive GAS are not considered as exposed and do not require prophylaxis. Unusual circumstances, e.g. the roommate has had direct mucous or non-intact skin contact with infectious respiratory tract secretions or skin lesions of an infected patient, should be assessed on a case-by-case basis.

Occupational Health Work Practices to Manage HCWs Exposed/Colonized/ Infected with GAS (invasive or noninvasive infection)

Management of HCWs exposed to GAS

  • An occupational exposure of a HCW is defined as secretions from the nose, mouth, wound or skin infection of the infected case coming into contact with the mucous membranes or non-intact skin of the HCW from within 7 days before the onset of GAS until 24 hours of effective antibiotic therapy.
  • If appropriate personal protective equipment was worn, there was no exposure.
  • The risk of development of GAS infection in exposed HCWs and the utility and efficacy of prophylaxis for this group are unknown. HCWs who have an occupational exposure to a patient with GAS soft tissue necrosis (including necrotizing fasciitis, myositis or gangrene), toxic shock syndrome, meningitis, pneumonia, other life threatening GAS disease or GAS disease resulting in death may be offered chemoprophylaxis (Tables 3 and 5 of the Guidelines). In this situation, screening and/or cultures for test of cure are not necessary. This recommendation differs slightly from current guidelines defined in Prevention and Control of Occupational Infections in Health Care(2), which indicates that management may include laboratory investigation and prophylaxis as recommended by provincial/territorial guidelines. HCWs with an occupational exposure should be counselled about the symptoms associated with GAS and advised to seek care immediately if symptoms of GAS disease (skin infection, pharyngitis, unexplained fever) develop in the 21 days after exposure.
  • An occupational exposure to a patient with a form of invasive GAS not listed above is not considered to pose a significant risk of serious disease in HCWs; if workers report a significant exposure to such patients, they should be counselled about the symptoms associated with GAS and advised to seek care immediately if symptoms of GAS disease (skin infection, pharyngitis, unexplained fever) develop in the 21 days after exposure.
  • There are no modifications to work practices or work restrictions for HCWs exposed to GAS.
  • No screening, treatment, modifications of work practices or work restrictions for HCWs in contact with a patient with a GAS infection are required when there has not been an occupational exposure.

Management of HCWs colonized or infected with GAS

  • There are no modifications to work practices or work restrictions for HCWs who are colonized with GAS and are asymptomatic if they are not epidemiologically linked to patient transmission.
  • Asymptomatic, colonized HCWs who are epidemiologically linked to transmission of GAS to patients resulting in invasive or non-invasive disease should be offered chemoprophylaxis (Table 6 of the Guidelines) and should be excluded from patient care duties until 24 hours after the start of treatment with effective antibiotic therapy.
  • HCWs with symptomatic GAS infection (invasive or non-invasive) should be offered therapy and should be excluded from patient care duties until 24 hours after the start of effective antibiotic therapy.
  • HCWs with symptomatic GAS infection and colonized HCWs linked epidemiologically to an outbreak should be informed of the potential for transmission of GAS within households and be advised that symptomatic family members should seek medical evaluation.
  • Local public health authorities should be notified of cases of invasive GAS disease or a suspected or confirmed outbreak of GAS as required by legislation.
  • Infection control and occupational health should be notified immediately of a HCW with suspected or confirmed GAS disease (invasive or non-invasive) if the HCW worked while the infection was communicable or if there is any possibility that the infection might have been occupationally acquired.
  • Occupationally acquired infections should be reported to provincial/territorial ministries of labour and/or workplace safety insurance boards, as required by legislation.

Management of possible or confirmed GAS outbreaks in hospitals

  • If, within 1 month of an invasive GAS case, one or more possibly linked additional invasive or non-invasive cases occur in either patients or staff, the situation should be treated as an outbreak until typing results are available.
  • Occupational Health, Infection Prevention and Control, and Public Health authorities should be notified and liaise if an outbreak is suspected or confirmed.
  • As part of the outbreak investigation, specimens for culture (throat, rectal, vaginal, skin lesions, stoma sites) should be obtained from HCWs and patients epidemiologically linked to the nosocomial GAS transmission. A thorough inspection of the skin should be done for HCWs who are epidemiologically linked to nosocomial GAS transmission and culture of lesion carried out as appropriate (there have been outbreaks associated with skin/scalp carriage)(5).
  • Patients and HCWs epidemiologically linked to transmission and identified as colonized by screening cultures should be promptly offered antibiotics to eradicate carriage (Table 6 of the Guidelines)(2,3). Isolates should be obtained and typed (serotyping or another equivalent method) to identify relatedness (see Annex 2: Laboratory Support for Outbreak Investigation of Invasive GAS Disease).
  • HCWs who are either colonized, symptomatic or infected with GAS and epidemiologically linked to transmission should be excluded from patient care duties until 24 hours after the start of effective antibiotic therapy and assessed for fitness to work. The type of patient/physical setting/work/hygiene practices and control measures that can be used should be assessed, and a follow-up schedule established(2,3).
  • Culture for a test of cure is recommended for individuals found to have the outbreak-related strain if there is epidemiologic evidence indicating that contact with the individual is linked to transmission. If the person remains colonized, investigation of the household contacts for carriage should be considered.
  • HCWs and/or patients who are identified by outbreak investigations and whose isolates are identified by typing as not being part of the outbreak do not require any follow-up or test of cure cultures.
  • For algorithms in cases of post-partum and post-surgical GAS disease, please refer to guidelines from the Centers for Disease Control and Prevention(8).

Writers: Rolande D'Amour, Lynn Johnston, Dorothy Moore, Mary Vearncombe and Christine Navarro

Glossary of Terms

Additional precautions: These precautions are required when routine practices are not sufficient to prevent transmission. They include contact, droplet and airborne precautions.

Contact precautions: Includes specific recommendations for personal protective equipment (such as gowns if clothing or forearms will have direct contact with the patient or contaminated environmental surfaces, and gloves upon entry into patient's room or bed space); proper use and disinfection of patient care equipment between patients; patient accommodation and transport.

Contact transmission: Includes direct contact, indirect contact and droplet (large droplet) transmission as described below. Although droplet transmission is a type of contact transmission, it is considered separately as it requires different precautions.

  • Direct contact occurs when the transfer of microorganisms results from direct physical contact between an infected or colonized individual and a susceptible host (body surface to body surface).
  • Indirect contact involves the passive transfer of microorganisms to a susceptible host via an intermediate object such as contaminated hands that are not washed between patients, contaminated instruments or other inanimate objects.

Droplet precautions: Includes specific recommendations for personal protective equipment (including masks within 1 metre of the patient); patient accommodation and transport.

Droplet transmission: Refers to large droplets, greater than or equal to 5 �m in diameter, generated from the respiratory tract of the source patient during coughing or sneezing, or during procedures such as suctioning or bronchoscopy. These droplets are propelled a short distance, < 1 metre, through the air and deposited on the nasal or oral mucosa of the new host.

Exposed HCW: To be considered an exposed HCW, secretions from the nose, mouth, skin lesions or wound of the infected case have to come in contact with the mucous membranes or non-intact skin of the HCW.

Hand hygiene: A general term that applies either to handwashing, an antiseptic handwash, an antiseptic hand rub, or a surgical hand antisepsis.

Mask: A barrier covering the nose and mouth to protect the mucous membranes from splashes or sprays and from microorganisms contained in large droplet particles (> 5 µm in size). Masks may also be used by the source patient to contain large droplet particles generated by coughing or sneezing. The term mask in this document refers to surgical/ procedure masks, not to special masks such as high efficiency dust/mist masks or respirators.

Nosocomial infection: An infection is considered nosocomial or hospital-acquired if the disease was neither present nor incubating at the time of hospital admission.

Routine practices: Routine practices are infection prevention and control practices for use in the routine care of all patients and are dependent on the task being performed and the health care setting. Routine practices outline the importance of hand-washing before and after caring for patients; the need to use gloves, masks and eye protection or face shield, and gowns when splashes or sprays of blood, body fluids, secretions or excretions are possible; the cleaning of patient care equipment; the patient's physical environment; accommodation requirements for specific patients; management of soiled linens; and precautions to reduce the possibility of HCW exposure to bloodborne pathogens by sharp objects.


  1. Health Canada. Routine practices and additional precautions for preventing the transmission of infections in health care - Revision of isolation and precaution techniques. CCDR 1999;25S4:1-142. URL: < ccdr-rmtc/99vol25/25s4/index.html>.
  2. Health Canada. Prevention and control of occupational infections in health care. CCDR 2002;28S1:1-264. URL: <http://www. 28s1/index.html>.
  3. Health Canada. Hand washing, cleaning, disinfection and sterilization in health care. CCDR 1998;24S8:1-55. URL: <http://www. s8e.pdf>.
  4. Historical vignette: The first report on Semmelweis' discovery of the cause and prevention of childbed fever. Infect Control 1982;3:478-9.
  5. Weber DJ, Rutala WA, Denny FW. Management of healthcare workers with pharyngitis or suspected streptococcal infections. Infect Control Hosp Epidemiol 1996;17:753-61.
  6. Daneman N, McGeer A, Low DE et al. Hospital-acquired invasive group A streptococcal infections in Ontario, Canada, 1992-2000. Clin Infect Dis 2005;41:334-42.
  7. Stefonek KR, Maerz LL, NielsonMP et al. Group A streptococcal puerperal sepsis preceded by positive surveillance cultures. Obstet Gynecol 2001;98:846-8.
  8. Prevention of Invasive Group A Streptococcal Infections Working Group. Prevention of invasive group A streptococcal disease among household contacts of case patients and among postpartum and postsurgical patients: recommendations from the Centers for Disease Control and Prevention. Clin Infect Dis 2002;35:950-9.
  9. Centers for Disease Control and Prevention. Nosocomial group A streptococcal infections associated with asymptomatic health-care workers - Maryland and California, 1997. MMWR 1999;48:163-6.
  10. Kakis A, Gibbs L, Eguia J et al. An outbreak of group A streptococcal infection among health care workers. Clin Infect Dis 2002;35:1353-9.
Report a problem or mistake on this page
Please select all that apply:

Thank you for your help!

You will not receive a reply. For enquiries, contact us.

Date modified: