Increase in Invasive Group A Strep Infections, 2022–2023

CDC is looking into an increase in invasive group A strep (iGAS) infections among children in the United States. iGAS infections include necrotizing fasciitis and streptococcal toxic shock syndrome.

Investigate All Outbreaks of Group A Streptococcus Infections in Long-Term Care Facilities

What you need to know
  • An effective investigation of invasive group A Streptococcus (GAS) infections can help prevent additional cases and subsequent outbreaks in long-term care facilities (LTCFs).
  • The investigation tools below provide detailed approaches to investigating and controlling GAS outbreaks in LTCFs.
  • This page also includes recommended antibiotic regimens for GAS carriage eradication that have been used in previous outbreaks.

Investigate even a single case

Given the potential to prevent additional cases and subsequent outbreaks in this population at high risk of severe outcomes, an investigation is warranted for even a single case of invasive GAS infection in a resident of a LTCF.

Investigation Tools
Decision tool for investigating group A Streptococcus infections in long-term care facilities

The purpose of the investigation is to:

  1. Identify any additional symptomatic cases among residents and staff
  2. Identify and treat asymptomatic carriers
  3. Assess and improve current infection control practices in the facility
  4. Identify potential transmission routes (when two or more cases are identified in a 3–4-month period)

Tools to investigate outbreaks

The tools to investigate clusters of invasive and non-invasive GAS infection depend on the number and type of cases that have been identified. Each increase in cases necessitates a bigger response to control the outbreak.

Below are links to detailed investigation tools for three potential scenarios. You can also download the Investigation Toolkit to print and share the information for all three scenarios.

These investigation tools can also be used to respond to clusters of non-invasive GAS infections, such as clusters of wound infections or pharyngitis.

Investigation Strategies
  • 1 Case
    1 case of invasive GAS infection
  • 2 Cases
    2 cases (at least 1 invasive) of GAS infection in a 3–4-month period
  • 3 or More Cases
    3 or more cases (at least 1 invasive) of GAS infection in a 3–4-month period

Antibiotic regimens for GAS carriage eradication during outbreaks

Multiple antibiotic regimens have been recommended for GAS carriage eradication either in the 2002 U.S. guidelines for postpartum and post-surgical outbreaks1 or in Canada’s guidelines for prevention and control of invasive GAS disease2. Several have been used in previous outbreaks for GAS carriage eradication.

Choose regimen on a case-by-case basis

Which antibiotic regimen to use for GAS carriage eradication during an outbreak depends on multiple considerations, and LTCFs and public health should carefully consider the pros and cons of each regimen on a case-by-case basis with the LTCF medical director and LTCF infection prevention and control personnel.

Multiple regimens are likely needed

It’s likely necessary to choose multiple regimens, including a first-line regimen and alternative regimens for those who have allergies to antibiotics or who are at risk for drug-drug interactions with antibiotic regimens.

First-line regimens that do not need susceptibility test results

GAS is universally susceptible to beta-lactam antibiotics, including penicillin and cephalosporins. LTCFs and public health do not need to consider antibiotic susceptibility when selecting one of these treatment regimens.

Table 1: Universally susceptible antibiotic regimens, with dosages
Antibiotic regimen Dosage(s)
Benzathine penicillin G (BPG) plus rifampin1,3,5 BPG: 600,000 units for patients <27 kilograms (kg) or 1,200,000 units for patients ≥27 kg intramuscular (IM) in a single dose
Rifampin: 20 mg/kg/day (maximum daily dose 600 mg/day) oral in 2 divided doses for 4 days
First-generation cephalosporins, such as cephalexin2,3,5 Cephalexin: 25-50 mg/kg/day (maximum daily dose 1000 mg/day) in 2-4 divided doses for 10 days

Alternative regimens that need susceptibility test results prior to use

LTCFs and public health should only consider clindamycin or macrolides if the outbreak strain is documented as susceptible to these antibiotics.

Clindamycin and macrolide (e.g., azithromycin) resistance have been commonly reported. Among invasive disease isolates in 2021, 35% of GAS isolates were macrolide resistant and 34% of isolates were clindamycin resistant6.

Table 2: Antibiotic regimens, with dosages, needing susceptibility testing
Antibiotic regimen Dosage(s)
Azithromycin1,4 12 mg/kg/day (maximum daily dose 500 mg/day) in a single dose daily for 5 days
Clindamycin1,3 20 mg/kg/day (maximum daily dose 900 mg/day) in 3 divided doses for 10 days
  1. CDC. Prevention of Invasive Group A Streptococcal Infections Workshop Participants. 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(8):950–9. Erratum in: Clin Infect Dis. 2003;36(2):243.
  2. Public Health Agency of Canada. Supplement—Guidelines for the prevention and control of invasive group A streptococcal disease. Can Commun Dis Rep. 2006;32S2(October 2006).
  3. Dooling KL, Crist MB, Nguyen DB, et al. Investigation of a prolonged group A streptococcal outbreak among residents of a skilled nursing facility, Georgia, 2009–2012. Clin Infect Dis. 2013;57(11):1562–7.
  4. Morita JY, Kahn E, Thompson T, et al. Impact of azithromycin on oropharyngeal carriage of group A Streptococcus and nasopharyngeal carriage of macrolide-resistant Streptococcus pneumoniae. Ped Infect Dis J. 2000;19(1):41–6.
  5. Nanduri SA, Metcalf BJ, Arwady MA, et al. Prolonged and large outbreak of invasive group A Streptococcus disease within a nursing home: Repeated intrafacility transmission of a single strain. Clin Microbiol Infect. 2019;25(2):248.e241–7.
  6. Centers for Disease Control and Prevention. Active Bacterial Core Surveillance, Bact Facts Interactive data dashboard, Emerging Infections Program Network, group A Streptococcus. Available at ABCs Bact Facts Interactive Data Dashboard.