Invasive Group A Streptococcal Infections in 10 US States.

Summary

In population-based surveillance across 10 US states (21,312 cases; 1,981 deaths), invasive GAS incidence rose from 3.6 to 8.2 per 100,000 persons between 2013 and 2022, with the largest relative increase among adults aged 18–64 and the highest absolute incidence in those ≥65. High-risk groups included American Indian/Alaska Native populations, people experiencing homelessness, people who inject drugs, and long-term care residents. Nonsusceptibility to macrolides and clindamycin increased from 12.7% to 33.1%.

Key Findings

• 21,312 invasive GAS cases with 1,981 deaths were identified across 10 US states (2013–2022).
• Incidence increased from 3.6 to 8.2 per 100,000; largest relative increase in adults 18–64, highest absolute incidence in ≥65.
• Higher incidence among American Indian/Alaska Native persons, people experiencing homelessness, people who inject drugs, and long-term care residents.
• Macrolide and clindamycin nonsusceptibility rose from 12.7% to 33.1% among tested isolates.

Clinical Implications

Heightened surveillance and targeted prevention for high-risk groups are needed. Rising clindamycin nonsusceptibility may affect adjunctive antitoxin strategies in severe GAS (e.g., streptococcal toxic shock), prompting local susceptibility review when selecting adjunctive therapy.

Limitations

• Observational design limits causal inference; potential under-ascertainment or reporting variability across sites
• Surveillance limited to 10 states; generalizability to national estimates may be imperfect

Future Directions

Evaluate drivers of incidence increase, assess clinical outcomes by resistance phenotype, and accelerate GAS vaccine development and implementation research in high-risk populations.