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Investigating 3+ cases (at least 1 invasive) of group A Streptococcus infection

Investigation Tools
Masked healthcare professional talking with a mature male patient sitting in a wheelchair.


Use this strategy in a long-term care facility (LTCF) when:

  • 3 or more cases of symptomatic group A Streptococcusa (GAS) infections have been identified among residents,
  • At least one invasive infection has been identified, and
  • Symptom onset of the most recent case occurs within 4 months of the prior case.

Laboratory or hospital

Actions laboratory or hospitalb should take

1. Report the case to local public health authorities
2. Notify the LTCF
3. Save the GAS isolate

LTCF or public health agency

Actions LTCF or public health agency should take

1. Identify additional symptomatic cases

  • Conduct a retrospective chart review of facility residents over previous month. Review records at LTCF, referral hospitals, and referral laboratories.
  • Survey all current residents and healthcare personnel (HCP), including consultants, for symptoms of GAS infection.
  • Culture symptomatic residents and HCP as clinically indicated.
  • Treat residents and HCP as clinically indicated.
  • Maintain active surveillance for additional invasive or noninvasive cases among LTCF residents for 4 months from onset of most recent GAS case.

2. Identify potential asymptomatic carriers

  • Screen all residentsg by culture, except those on GAS treatment within the last 14 days. Sites to culture for residents:c
    • Throat
    • Skin lesions
    • Ostomy sites
  • Screen epidemiologically-linked HCP by culture and consider screening all HCP,i except those on GAS treatment within the last 14 days. Sites to culture for HCP:j
    • Throat
    • Skin lesions
  • Treat anyone with a positive culture. See table for antibiotic regimens.
  • Re-screen, by culturing the same sites listed above, anyone with a positive culture 7 to 10 days after they complete treatment.

3. Assess infection control measures

  • Review and audit HCP adherence to infection control practices.
    • Hand hygiene, preferably using alcohol-based hand rub/sanitizer
    • Appropriate selection and proper use of personal protective equipment (PPE)d
    • Cleaning and disinfection of environmental surfaces and reusable wound care equipmente
    • Maintaining separation between clean and soiled equipment to prevent cross contamination
    • Dedicating multidose medication containers to a single patient or resident whenever possible. If multidose medication containers are used for more than one resident, restrict the medication containers to a centralized medication area and do not bring them into the immediate resident treatment area (e.g., resident room/cubicle).f
  • Review and audit infection control practices for wound care and respiratory care.
  • Educate HCP on signs and symptoms of GAS infection.
  • Educate HCP on the importance of not working while ill.
  • Review sick leave policies.
  • Consider restricting visitors for a limited time period.
  • Consider cohorting residents with GAS infection and HCP caring for these residents.
  • Consider halting new admissions in affected units or floors.

4. Conduct an epidemiologic and laboratory investigation

  • Investigate potential linkages between cases, including close contacts (roommates and close social contacts) and HCP.
  • If isolates from ≥2 cases available, emm typing and whole genome sequencing can be used to look for strain relatedness.h
  1. If GAS is isolated from a wound AND accompanied by necrotizing fasciitis or streptococcal toxic shock syndrome, then it is considered an invasive GAS infection case.
  2. Often cases of invasive GAS will first be identified either by an acute care hospital where the resident of an LTCF has been transferred for additional evaluation and medical care or by a laboratory that processes specimens collected at LTCFs. Thus, these facilities should ensure that invasive GAS infection or positive GAS cultures collected from normally sterile body sites are reported to local public health authorities and the LTCF where the patient resides. Additionally, these facilities should save the isolate for possible future assessments of strain relatedness in case additional cases are identified.
  3. Examples of ostomy sites that should be cultured when screening residents for GAS carriage include gastrostomy and nephrostomy. Collection of cultures should only be performed by personnel trained in the appropriate management of these types of devices and ostomy sites. In order to assure sterility of sterile lines or devices is not compromised, cultures should not be collected from insertion sites for sterile lines or devices in the absence of signs or symptoms of infection. Staff should monitor the insertion sites for invasive medical devices (e.g., peripherally inserted central catheters) visually when changing the dressing or by palpation through an intact dressing on a regular basis, depending on the clinical situation of the individual resident. If patients have tenderness at the insertion site, fever without obvious source, or other manifestations suggesting local or bloodstream infection, the dressing should be removed to allow thorough examination of the site.
  4. As part of Enhanced Barrier Precautions (EBP) use of a gown and gloves is recommended during high-contact care activities (e.g., wound care; central line, urinary catheter, feeding tube, tracheostomy or ventilator device care or use) for residents with a wound or invasive medical device.
    Additional PPE use, as described below, is recommended to control a GAS outbreak.
    1. Residents with suspected or confirmed GAS infection or colonization should be placed on appropriate Transmission-Based Precautions pending culture results:
      1. Wound—Residents with GAS cultured from a wound, ostomy, or device-insertion site should remain on Contact and Droplet Precautions until 24 hours after the initiation of effective antibiotic therapy and any wound drainage stops or can be contained by a dressing. HCP should then return to use of EBP.
      2. Throat—Residents with GAS cultured from their throat should remain on Droplet Precautions until 24 hours after the initiation of effective antibiotic therapy.
      3. Note: Continued use of a facemask by HCP during all wound care activities or when handling invasive medical devices is recommended until the outbreak is over.
    2. HCP with suspected or confirmed GAS infection or GAS colonization should be managed as described in Epidemiology and Control of Selected Infections.
  5. EPA-registered disinfectants or detergents/disinfectants that best meet the overall needs of the healthcare facility for routine cleaning and disinfection of environmental surfaces and resident care equipment and proper handling of indwelling medical devices should be selected.
  6. Multidose medication containers (e.g., creams, sprays, ointments) should be dedicated to a single resident whenever possible. If it is not possible to dedicate an entire tube or container of wound care medication to an individual resident, then a small amount should be allocated (e.g., into a medication cup) for single resident use prior to the wound care procedure. If multidose medication containers are used for more than one resident, the medication container should be restricted to a centralized medication area (e.g., clean medication cart) and should not be brought into the immediate resident treatment area (e.g., resident’s room/cubicle). The remainder of the multidose container should be properly stored in a dedicated clean area. Any container entering resident care areas should be dedicated for single-resident use or discarded after use.
  7. In situations in which all case-patients reside in a single unit, floor, or building within the LTCF, screening by culture of residents may be limited to residents in that unit, floor, or building. This decision should be made on a case-by-case basis in consultation with the facility infection prevention and control team and public health. Factors to consider include whether cases are clustered by location, the size and layout of the facility, and the mobility of patients with GAS infection and people who are identified as GAS carriers.
  8. Results from GAS strain characterization can provide additional evidence to support your recommendations. emm typing is used to characterize and measure the genetic diversity among GAS isolates. Finding 2 or more isolates from an outbreak of the same emm type may indicate that intrafacility transmission is occurring, although repeated introductions from the community of the same emm type can also occur. Whole genome sequencing (WGS) provides more detailed and precise data for identifying outbreaks. For example, WGS assesses emm type and antibiotic susceptibility at the same time and identifies important surface protein types/virulence traits and exotoxin profiles. WGS can be used to assess relatedness in outbreak investigations.
  9. Whether to screen only epidemiologically-linked HCP by culture for GAS in the facility or all HCP is a decision that should be made on a case-by-case basis in consultation with the facility infection prevention and control team and public health. Factors to consider in making this decision should include the size, persistence, intractability, and severity of the outbreak, as well as feasibility and logistics of screening HCP.
  10. For outbreaks that persist despite other outbreak control measures, consider screening HCP with strong epidemiologic links to case patients by self-collected vaginal and anal or rectal cultures in addition to throat and skin lesion cultures. GAS can colonize throat, skin lesions, vagina, and anus and rectum. Previous outbreaks in healthcare settings have been linked to HCP who were colonized at one or more of these sites. For example, in outbreaks with a predominance of case-patients who have wounds and are receiving wound care, the wound care team members might be considered for screening for GAS carriage by culture from throat and skin lesions and self-collected vaginal and anal or rectal swabs.