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Table 1.  

Term Definition
Invasive group A Streptococcus (iGAS) infection Isolation of GAS from a normally sterile site, either by PCR or culture. For this study, iGAS also includes GAS infections in which GAS was isolated from a normally nonsterile site in combination with a severe clinical presentation, such as streptococcal toxic shock syndrome or necrotizing fasciitis
Group A Streptococcus (GAS) infection Isolation of GAS from a non-sterile site in combination with clinical symptoms attributable to bacterial infection including fever (temperature ≥38°C), sore throat, wound infection, or cellulitis
Group A Streptococcus carriage Isolation of GAS from a nonsterile site but no symptoms attributable to infection with this microorganism
Home healthcare (HHC) Community health services, including district nursing teams, general practitioners, podiatry (chiropody), community midwifery, hospital outreach, and palliative care, which provide medical or nursing care within a patient’s home
Residential care Live-in accommodation that provides 24-hour care and support to its residents

Table 1. Definitions used in a study of invasive group A Streptococcus infection associated with home healthcare, England, 2018–2019

Table 2.  

Outbreak no. No. iGAS cases No. GAS cases† No. deaths No. days from first to last case No. cases without identified HHC input emm type WGS
1 14 2 2 136 1 87 N
2 7 1 2 148 0 94 N
3 6 0 3 222 0 94 Y
4 7 0 2 388 0 89 Y
5 5 5 2 179 2 89 N
6 3 0 0 75 0 1 Y
7 4 0 0 219 0 1 Y
8 2 0 1 3 0 89 Y
9 9 1 1 507 0 89 Y
10 39 95 15 487 1 44 Y
Total 96 104 28 NA 4 NA NA

Table 2. Summary of home healthcare–associated invasive group A Streptococcus infection outbreaks, England, 2018–2019*

*GAS, group A Streptococcus; HHC, home healthcare; iGAS, invasive group A Streptococcus; NA, not applicable; WGS, whole-genome sequencing. †Noninvasive GAS was not systematically investigated or recorded in all outbreaks. Available data did not enable distinction between carriage and noninvasive infection.

Table 3.  

Characteristics No. (%) IQR (range)
All outbreaks, n = 10
Total cases 96 (100) NA
Total deaths 28 (29) NA
Median cases 7 4–9 (2–39)
Median outbreak duration, d 199 139–347 (3–507)
Outbreaks with case data, n = 9
Case-patient characteristics, n = 57
Median age, y 83 77–90 (42–100)
F 39 (68) NA
M 18 (32) NA
Median days between cases 21 6–46 (1–225)
Type of residence, n = 48
Residential care 17 (35) NA
Own home 31 (65) NA
HHCW exposure, n = 96
Patient receiving care 92 (96) NA
Household contact of recipient 2 (4) NA
None identified† 2 (4) NA

Table 3. Characteristics of home healthcare–associated invasive group A Streptococcus infection outbreaks, England, 2018–2019*

*HHCW, home healthcare worker; NA, not applicable.
†Cases linked to outbreaks through whole-genome sequencing but without any identified connection to home healthcare services.


Invasive Group A Streptococcus Outbreaks Associated With Home Healthcare, England, 2018–2019

  • Authors: Laura E. Nabarro, FRCPath; Colin S. Brown, MD, FRCPath; Sooria Balasegaram, MBChB; Valérie Decraene, PhD; James Elston, FFPH; Smita Kapadia, MBBS; Pauline Harrington, MSc; Peter Hoffman, BSc; Rachel Mearkle, MBBS; Bharat Patel, MD, FRCPath; Derren Ready, PhD; Esther Robinson, MD, FRCPath; Theresa Lamagni, PhD
  • CME / ABIM MOC Released: 4/18/2022
  • Valid for credit through: 4/18/2023, 11:59 PM EST
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Target Audience and Goal Statement

This activity is intended for primary care physicians, infectious disease specialists, and other physicians who treat and manage frail patients at risk for invasive group A Streptococcus.

The goal of this activity is to evaluate the source, outcomes, and infection control measures in outbreaks of invasive group A Streptococcus.

Upon completion of this activity, participants will:

  • Analyze characteristics of invasive group A Streptococcus
  • Evaluate demographics and outcomes of the current study of invasive group A Streptococcus outbreaks
  • Assess the source of invasive group A Streptococcus outbreaks based on investigations
  • Distinguish infection control measures employed during invasive group A Streptococcus outbreaks


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  • Laura E. Nabarro, FRCPath

    Public Health England, London, United Kingdom

  • Colin S. Brown, MD, FRCPath

    Public Health England, London, United Kingdom

  • Sooria Balasegaram, MBChB

    Public Health England, London, United Kingdom

  • Valérie Decraene, PhD

    Public Health England, London, United Kingdom

  • James Elston, FFPH

    Public Health England, London, United Kingdom

  • Smita Kapadia, MBBS

    Public Health England, London, United Kingdom

  • Pauline Harrington, MSc

    Public Health England, London, United Kingdom

  • Peter Hoffman, BSc

    Public Health England, London, United Kingdom

  • Rachel Mearkle, MBBS

    Public Health England, London, United Kingdom

  • Bharat Patel, MD, FRCPath

    Public Health England, London, United Kingdom

  • Derren Ready, PhD

    Public Health England, London, United Kingdom

  • Esther Robinson, MD, FRCPath

    Public Health England, London, United Kingdom

  • Theresa Lamagni, PhD

    Public Health England, London, United Kingdom

CME Author

  • Charles P. Vega, MD

    Health Sciences Clinical Professor of Family Medicine
    University of California, Irvine School of Medicine
    Irvine, California


    Disclosure: Charles P. Vega, MD, has disclosed the following relevant financial relationships:
    Served as an advisor or consultant for: GlaxoSmithKline; Johnson & Johnson


  • Amy J. Guinn, BA, MA

    Emerging Infectious Diseases


    Disclosure: Amy J. Guinn, BA, MA, has disclosed no relevant financial relationships.

Compliance Reviewer

  • Amanda Jett, PharmD, BCACP

    Associate Director, Accreditation and Compliance
    Medscape, LLC


    Disclosure: Amanda Jett, PharmD, BCACP, has disclosed no relevant financial relationships.

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Invasive Group A Streptococcus Outbreaks Associated With Home Healthcare, England, 2018–2019: Methods



Case Definition and Data Sources

In this study, we included HHC-associated iGAS outbreaks identified in England during January 1, 2018–August 31, 2019. We identified outbreaks cross-referenced from PHE’s case and outbreak logging software, HPZone, and the RVPBRU streptococcal outbreak dataset. In addition, we contacted the healthcare-associated infection leads of each PHE center to identify any outbreaks not reported in the 2 datasets. We chose this short timeframe to ensure we could examine each outbreak in detail and maximize accurate data collection.

We included outbreaks with ≥2 cases of iGAS infection of the same emm type and linked to the same defined HHC service. We excluded outbreaks in which other exposures offered a more plausible transmission route, such as within residential care or another healthcare setting.

The inclusion criteria for individual cases within an outbreak varied between outbreaks and were set by the investigating outbreak control team (OCT). The broadest inclusion criterion for cases was defined as iGAS of the same emm type linked to the same defined HHC service. In outbreaks for which WGS was deployed, the inclusion criteria were honed to include only cases linked by sequencing, defined as ≤5 SNPs between strains. Noninvasive GAS infections and colonization were not systematically investigated or recorded in all outbreaks.

To investigate temporal trends in outbreaks, we also searched HPZone for outbreaks during January 1, 2013–December 31, 2017. We did not search other sources for outbreaks during this period and did not collect further data because the outbreaks were too distant in time for data to be accurate. We provide operational definitions used in this study (Table 1).

Data Collection and Analysis

We conducted a 1-hour qualitative semistructured telephone interview with the chair of each OCT or other nominated staff member. We asked participants standardized open-ended questions grouped into themes surrounding outbreak identification, microbiology, investigation, and infection control. We encouraged participants to elaborate on answers by asking probing follow-up questions and incorporated themes that emerged in early interviews into subsequent interviews. We explored barriers to investigation and management in a similar way and encouraged participants to identify learning points and recommendations for future outbreaks. We collected data by using a standardized interview protocol and captured audio recordings of interviews to enable further review by the interviewer. We used thematic analysis to analyze qualitative data.

When available, we collected quantitative data regarding the number of HHCWs and patients screened and treated. We collected standardized pseudonymized data on case-patients, including age, iGAS onset date, hospitalization, and outcome. When sequencing was performed, we identified cases linked by sequence data (these data are not reported here). We recorded and analyzed data in Excel (Microsoft, and Stata version 15 (StataCorp LLC, and managed data in line with PHE’s information governance policy.

Ethics Approval

This study was performed by PHE as part of its legal obligation to collect and process information about communicable disease surveillance and control under section 251 of the National Health Service Act 2006 ( No further ethics approval was required.