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Updated: Jul 1, 2025
Characterization of Inflammatory Responses During Intranasal Colonization with Streptococcus pneumoniae
Published on: January 17, 2014
Clinical, microbiological, and molecular characterization of pediatric invasive infections by Streptococcus pyogenes
Eva Ramírez de Arellano1,2, Jesús Saavedra-Lozano2,3, Pilar Villalón4
1Laboratorio de Referencia e Investigación en Resistencia a Antibióticos e Infecciones Relacionadas con la Asistencia Sanitaria, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain.
Insights
An increase in invasive Group A Streptococcus (GAS) infections in Spanish children was observed, with pneumonia being the most common severe presentation. Surveillance is crucial, as whole genome sequencing can aid in understanding and controlling GAS outbreaks.
Area of Science:
- Microbiology
- Epidemiology
- Genomics
Background:
- Group A Streptococcus (GAS) infections saw an unusual rise in Europe in late 2022.
- Spain also reported an increase in both mild and severe GAS cases.
- The reasons for this increase and the characteristics of the involved strains were unclear.
Purpose of the Study:
- To characterize the clinical, microbiological, and molecular features of invasive GAS (iGAS) infections in Spanish children.
- To compare iGAS strains with those causing mild infections.
- To investigate the potential causes of increased iGAS incidence and severity.
Main Methods:
- Prospective recruitment of pediatric patients with GAS infections in Spain (September 2022-March 2023).
- Microbiological analysis including emm typing, antimicrobial susceptibility testing, and whole genome sequencing (cgMLST, resistome, virulome).
- Clinical data collection for cases and controls.
Main Results:
- Pneumonia was the most frequent iGAS syndrome (44.1%), often requiring pediatric intensive care.
- emm1 and emm12 were the predominant emm types, with the M1_UK sublineage appearing in Spain.
- The speA gene was associated with pneumonia, while the ssa superantigen was linked to milder cases; isolates remained largely susceptible to antimicrobials.
Conclusions:
- The rise in iGAS incidence in Spain was not linked to increased antimicrobial resistance or a significant emm type shift.
- Increased severity, particularly pneumonia, may have contributed to the observed rise in iGAS cases.
- Enhanced surveillance and the use of whole genome sequencing are recommended for better understanding and control of iGAS.
Abstract:
In December 2022, an alert was published in the UK and other European countries reporting an unusual increase in the incidence of Streptococcus pyogenes infections. Our aim was to describe the clinical, microbiological, and molecular characteristics of group A Streptococcus invasive infections (iGAS) in children prospectively recruited in Spain (September 2022-March 2023), and compare invasive strains with strains causing mild infections. One hundred thirty isolates of S. pyogenes causing infection (102 iGAS and 28 mild infections) were included in the microbiological study: emm typing, antimicrobial susceptibility testing, and sequencing for core genome multilocus sequence typing (cgMLST), resistome, and virulome analysis. Clinical data were available from 93 cases and 21 controls. Pneumonia was the most frequent clinical syndrome (41/93; 44.1%), followed by deep tissue abscesses (23/93; 24.7%), and osteoarticular infections (11/93; 11.8%). Forty-six of 93 cases (49.5%) required admission to the pediatric intensive care unit. iGAS isolates mainly belonged to emm1 and emm12; emm12 predominated in 2022 but was surpassed by emm1 in 2023. Spread of M1UK sublineage (28/64 M1 isolates) was communicated for the first time in Spain, but it did not replace the still predominant sublineage M1global (36/64). Furthermore, a difference in emm types compared with the mild cases was observed with predominance of emm1, but also important representativeness of emm12 and emm89 isolates. Pneumonia, the most frequent and severe iGAS diagnosed, was associated with the speA gene, while the ssa superantigen was associated with milder cases. iGAS isolates were mainly susceptible to antimicrobials. cgMLST showed five major clusters: ST28-ST1357/emm1, ST36-ST425/emm12, ST242/emm12.37, ST39/emm4, and ST101-ST1295/emm89 isolates.
Importance:
Group A Streptococcus (GAS) is a common bacterial pathogen in the pediatric population. In the last months of 2022, an unusual increase in GAS infections was detected in various countries. Certain strains were overrepresented, although the cause of this raise is not clear. In Spain, a significant increase in mild and severe cases was also observed; this study evaluates the clinical characteristics and the strains involved in both scenarios. Our study showed that the increase in incidence did not correlate with an increase in resistance or with an emm types shift. However, there seemed to be a rise in severity, partly related to a greater rate of pneumonia cases. These findings suggest a general increase in iGAS that highlights the need for surveillance. The introduction of whole genome sequencing in the diagnosis and surveillance of iGAS may improve the understanding of antibiotic resistance, virulence, and clones, facilitating its control and personalized treatment.
