Outbreak of Invasive Group A Streptococcus in Children-Colorado, October 2022-April 2023

Invasive Group A Streptococcal Infection in Children, 1992-2023

Importance

The resurgence of invasive group A streptococcal (iGAS) infections and progress in GAS vaccine development emphasize the importance of understanding current trends in the epidemiology of iGAS.

Objective

To describe the epidemiology of pediatric iGAS over a 32-year period.

Design, Setting, and Participants

This case series uses population-based surveillance data for iGAS in Toronto and Peel Region, Canada, including emm typing from Canada's National Microbiology Laboratory and population data from Statistics Canada. All children (age <18 years) with iGAS from January 1, 1992, to December 31, 2023, were included. Data were analyzed from July 15, 2023, to September 1, 2024.

Main Outcomes and Measures

Outcomes of interest were disease incidence over time and by age; variation in clinical presentation, disease severity, outcomes and infecting emm types; and antimicrobial resistance.

Results

Overall, 498 iGAS cases (300 [60.2%] male; median [IQR] age, 5.1 [2.7-8.6] years) occurred, including 151 (30.7%) in children with comorbidities. The most common presentations were soft tissue infection (140 cases [28.1%]) and bacteremia without focus (131 cases [26.3%]). iGAS incidence increased from 1.8 events per 100 000 population per year in 1992 to 2011 to 2.4 events per 100 000 population per year in 2012 to 2019 (incidence rate ratio, 1.3 [95% CI, 1.1-1.6]), with the increase occurring in GAS infections of the respiratory tract. Incidence declined to 1.2 events per 100 000 population per year in 2020 and 0.5 events per 100 000 population per year in 2021 before increasing to 6.0 events per 100 000 population per year in 2023. In 2022 to 2023, 18 of 56 children with iGAS (32.0%) had a viral respiratory coinfection. Varicella-associated iGAS cases declined from 23 of 137 children (16.8%) in 1992 to 2001 to 2 of 223 children (0.9%) in 2012 to 2023 (P < .001), after routine varicella vaccination implementation in 2004. Streptococcal toxic shock syndrome occurred in 29 children (5.8%), necrotizing fasciitis in 12 children (2.4%); 10 children (2.0%) died. The most common emm types were emm1 (182 of 471 isolates [38.6%]), emm12 (75 isolates [15.9%]), and emm4 (31 isolates [6.6%]). The M1UK subtype was first identified in 2019 and comprised 32 of 46 emm1 isolates (70.0%) from 2019 to 2023. Compared with other emm types, emm1 was more likely to be associated with pneumonia (odds ratio [OR], 1.99 [95% CI, 1.16-3.40]), bone and joint infections (OR, 1.70 [95% CI, 1.08-2.68]), and intensive care unit admission (OR, 1.67 [95% CI, 1.03-2.68]); emm4 was more likely to be associated with bacteremia without focus (OR, 6.10 [95% CI, 2.83-13.16]). Overall, 437 isolates (92.8%) were of emm types included in the 30-valent GAS vaccine.

Conclusions and Relevance

This case series found that pediatric iGAS incidence increased in south-central Ontario prior to and after the COVID-19 pandemic in association with increased iGAS infections of the respiratory tract. Respiratory viral coinfections were common. Different emm types were associated with differing presentations and severity.

Increased Incidence and Severity of Group A Streptococcal Infections in Children in Southeast Texas From June 2022 to May 2023

BACKGROUND

Group A Streptococcus (GAS) infections can cause a range of disease manifestations and severity, including invasive infections that can lead to death. In 2022-2023, there was an increased number of cases of invasive GAS in the United States following a decline in 2020-2022.

METHODS

We investigated this surge at a 3-hospital system of children's hospitals in Southeast Texas. Cases of invasive GAS (n = 252) were retrospectively reviewed from peak periods of infection, beginning June 2019-May 2020 and continuing each successive year until May 2023. Cases were analyzed based on patient demographics, disease manifestations, coinfections, and hospital course. Isolates grown in culture were sequenced, and the emm types and genes associated with virulence were analyzed.

RESULTS

Compared with previous years, June 2022-May 2023 had the largest number of invasive GAS cases (n = 154, 2022-2023; 34, 2021-2022; 12, 2020-2021; 52, 2019-2020). Compared with the previous 3 years, patients from 2022 to 2023 were more likely to present with complicated pneumonia (23.4% vs. 7.1%; P = 0.0009), require respiratory support (34.4% vs. 14.3%; P < 0.001), be admitted to the intensive care unit (29.2% vs. 16.3; P = 0.0235), and be infected with emm type 12 isolates (40.6% vs. 10.3%; P = 0.0030).

CONCLUSIONS

In June 2022-May 2023, there was a 5-fold surge of invasive GAS infection cases in children at Texas Children's Hospital compared with the previous 3 years. These cases required greater intensive care unit hospitalization and respiratory support requirements due to higher rates of complicated pneumonia.

Has COVID-19 Affected the Course of Chickenpox in Children?

OBJECTIVES OF THE STUDY

The aim of this study was to assess the impact of the COVID-19 pandemic on the epidemiology and clinical course of chickenpox in children based on 6 years of self-reported observations.

MATERIAL AND METHODS

The medical records of 350 patients under 18 years of age hospitalised in the Department of Paediatrics, Infectious Diseases, and Hepatology between 1 January 2018 to 31 December 2023 were analysed retrospectively.

RESULTS

During the analysed period, 350 children were hospitalised due to chickenpox, the fewest in the pandemic period, the greatest number in 2023. Complications of chickenpox were diagnosed in 297 children (84.86%). The most commonly diagnosed complications were bacterial dermatitis (168, 48%) and lower respiratory tract infections (13.42%). After the pandemic period, a generalised inflammatory reaction was observed significantly more often (p ≤ 0.01069). Among children hospitalised in 2023, 5.90% of patients with bacterial dermatitis required surgical intervention due to skin abscess or fasciitis. In 2023, 41.46% of cultures from swabs taken from skin lesions grew Streptococcus pyogenes. After the pandemic, children with chickenpox and gastrointestinal symptoms were hospitalised significantly less frequently (p ≤ 0.00001).

CONCLUSIONS

In the post-pandemic period, there were more hospitalisations of patients with chickenpox complicated by bacterial skin infection progressing to a generalised inflammatory reaction or septicaemia, related to the increase in invasive group A streptococcal infections observed in Europe. On the other hand, thanks to the widespread adaption of hygiene practices and infection prevention measures, the number of patients with gastrointestinal symptoms significantly decreased.

Impact of the SARS-CoV-2 Pandemic on the Epidemiology of Streptococcus pyogenes: A Five-Year Retrospective Study

The SARS-CoV-2 pandemic significantly affected the epidemiology of Streptococcus pyogenes, a pathogen associated with various clinical presentations such as pharyngitis, scarlet fever, and invasive diseases. This study analyzed the incidence and characteristics of S. pyogenes infections between 2018 and 2023, examining 915 cases categorized as either respiratory or non-respiratory. Respiratory infections predominantly affected children, accounting for 76% of cases, with a median age of 5 [3, 8] years, while non-respiratory infections were more common in adults, with a median age of 46.5 [34, 64] years. Invasive respiratory infections, such as pneumonia and empyema, were more frequent in children (54.8%), whereas invasive non-respiratory infections, such as primarily cellulitis, were predominantly seen in adults (90.5%). A sharp decline in S. pyogenes infections was observed during the pandemic, with respiratory cases decreasing tenfold in 2020 compared to the previous year, and non-respiratory cases experiencing a twofold reduction. However, infection rates returned to pre-pandemic levels by 2022 and 2023, with a notable resurgence of invasive respiratory infections in children following a public health alert in the United Kingdom in late 2022. These findings highlight distinct infection patterns between pediatric and adult populations and emphasize the significant impact of the pandemic on respiratory infections, particularly in children.

Group A Streptococcus Infections in Children: Epidemiological Insights Before and After the COVID-19 Pandemic

Group A streptococcus (GAS) is the cause of both mild and invasive infections in humans with a high morbidity and mortality rate. The transmission of disease usually occurs via droplets, so the implementation of infection mitigation strategies (IMS) during the COVID-19 pandemic altered the incidence of GAS infection. This review aims to provide an overview of the influence of the COVID-19 pandemic on the incidence of GAS infection in children (invasive or non-invasive). A surge in the incidence of invasive GAS infection was noted in December 2022 after the reversal of IMS. A global uprise in GAS infection (invasive and non-invasive) was noted, especially concerning the pediatric population. Children younger than 5 years old were mostly affected, with complicated pneumonia being the leading clinical manifestation, causing many deaths worldwide. Emm1, specifically M1UK, was recognized as the dominant lineage in Europe and correlated with invasive disease. Healthcare professionals need to be alert about the severity of GAS-related infections, leading to early identification and treatment.

Complicated pneumonia caused by group A Streptococcus in children - 2022/2023 infectious season outbreak and update on clinical characteristics

BACKGROUND

An increased incidence of group A Streptococcus (GAS) infections has been observed in pediatric population post-COVID-19 pandemic. While the majority of reports refer to scarlet fever or invasive GAS disease, detailed data on pulmonary manifestations such as complicated community-acquired pneumonia (CAP) are scarce. The aim of this study was to assess the contribution of GAS to complicated CAP in children during the 2022/2023 infectious season.

METHODS

We retrospectively analyzed the etiology and clinical presentation of complicated CAP patients hospitalized in our tertiary care center in Warsaw, Poland, between August 2022 and May 2023.

RESULTS

Among 91 patients with complicated CAP, GAS was the dominant cause constituting 24.2% (22/91; 95% CI 15.8-34.3%) of the study group. 68.2% of GAS pneumonia patients presented symptoms of scarlet fever, and 27.3% had preceding or concurrent viral infection. GAS complicated CAP was associated with longer hospitalization, higher incidence of chest tube insertion, but shorter duration of chest tube drainage than complicated CAP of other etiology. Children with GAS complicated CAP had higher procalcitonin concentration (28.1 vs. 1.5 ng/dL; p<0.0001) and a lower platelets level (254.5 vs. 422 × 103/μL; p = 0.0031) than those with non-GAS infection.

CONCLUSIONS

GAS is currently the predominant pathogen of complicated CAP in children. Clinicians should be aware of the current epidemiological situation and a more severe course of GAS pneumonia in this age group, and should monitor patients presenting with symptoms of scarlet fever and preceding viral infection closely.

Are Invasive Group A Streptococcal Infections Preventable by Antibiotic Therapy?: A Collaborative Retrospective Study

BACKGROUND

In winter 2022/2023, a resurgence of invasive group A streptococcal (iGAS) infections in children was observed in Europe, including Germany and Switzerland. While a simultaneous increase in consultations for scarlet fever and pharyngitis was reported in England, leading to the recommendation to treat any suspected GAS disease with antibiotics, guidelines in Germany and Switzerland remained unchanged. We aimed to investigate whether this policy was appropriate.

METHODS

We conducted a retrospective multicenter study of children hospitalized for invasive GAS disease between September 2022 and March 2023 in pediatric departments in Dresden and Berlin (Germany) and Basel (Switzerland). We reviewed medical records and conducted structured telephone interviews to analyze whether suspected GAS infections with or without antibiotic treatment were reported prehospitalization.

RESULTS

In total, 63 patients met the inclusion criteria (median age 4.2 years, 57% males); however, clinical information was not complete for all analyzed characteristics; 32/54 (59%) had ≥1 physician visit ≤4 weeks prehospitalization. In 4/32 (13%) patients, GAS disease, that is, tonsillitis or scarlet fever, was suspected; 2/4 of them received antibiotics, and a positive rapid antigen test for GAS was documented in 1 of them.

CONCLUSIONS

A small minority of patients had suspected GAS infection within 4 weeks before iGAS disease. These data suggest that there is little opportunity to prevent iGAS disease by antibiotic therapy, because in most patients-even if seen by a physician-there was either no evidence of GAS disease or when GAS disease was suspected and treated with antibiotics, consecutive invasive GAS disease was not prevented.

Impact of the COVID-19 Pandemic on Group A Streptococcal Necrotizing Soft Tissue Infections: A Retrospective Cohort Study

Background

Necrotizing soft tissue infections (NSTIs) are often caused by group A Streptococcus (GAS). As the number of invasive GAS infections decreased during the coronavirus disease 2019 (COVID-19) pandemic restrictions, this study aimed to compare the occurrence of GAS-NSTIs before, during, and after the COVID-19 pandemic restrictions.

Methods

This retrospective cohort study included adult patients with NSTIs admitted to the intensive care unit (ICU) of the University Hospital Zurich, Switzerland, from July 2008 to December 2023. NSTI cases were categorized as pre-, during, and postrestrictions. The primary outcome was the proportion of GAS in NSTI, and the exploratory secondary outcome was in-hospital death. A data analysis was conducted using Firth logistic regression adjusted for age, sex, diabetes, and initially affected body region.

Results

Overall, 74 NSTI cases were identified, with 49 occurring before, 8 during, and 17 after the pandemic restrictions. GAS was isolated in 27 (36%) cases, with 17 (35%) pre- and 10 (59%) postrestrictions, but none during the restrictions. NSTIs caused by other bacteria persisted during the restrictions. The odds of GAS were significantly lower during the restrictions (adjusted odds ratio, 0.02; 95% CI, 0.001-0.81) compared with after, while no significant differences were found between the pre- and postrestriction periods.

Conclusions

The significant decrease of GAS-NSTIs during the COVID-19 pandemic restrictions suggests that isolation measures may have prevented the transmission of GAS, resulting in a decline of GAS-NSTIs while NSTIs caused by bacteria transmitted by alternative routes persisted.

Recent Scientific Advancements towards a Vaccine against Group A Streptococcus

Group A Streptococcus (GAS), or Streptococcus pyogenes, is a gram-positive bacterium that extensively colonises within the human host. GAS is responsible for causing a range of human infections, such as pharyngitis, impetigo, scarlet fever, septicemia, and necrotising fasciitis. GAS pathogens have the potential to elicit fatal autoimmune sequelae diseases (including rheumatic fever and rheumatic heart diseases) due to recurrent GAS infections, leading to high morbidity and mortality of young children and the elderly worldwide. Antibiotic drugs are the primary method of controlling and treating the early stages of GAS infection; however, the recent identification of clinical GAS isolates with reduced sensitivity to penicillin-adjunctive antibiotics and increasing macrolide resistance is an increasing threat. Vaccination is credited as the most successful medical intervention against infectious diseases since it was discovered by Edward Jenner in 1796. Immunisation with an inactive/live-attenuated whole pathogen or selective pathogen-derived antigens induces a potent adaptive immunity and protection against infectious diseases. Although no GAS vaccines have been approved for the market following more than 100 years of GAS vaccine development, the understanding of GAS pathogenesis and transmission has significantly increased, providing detailed insight into the primary pathogenic proteins, and enhancing GAS vaccine design. This review highlights recent advances in GAS vaccine development, providing detailed data from preclinical and clinical studies across the globe for potential GAS vaccine candidates. Furthermore, the challenges and future perspectives on the development of GAS vaccines are also described.