Clinical, microbiological, and molecular characterization of pediatric invasive infections by in Spain in a context of global outbreak.

UNLABELLED

In December 2022, an alert was published in the UK and other European countries reporting an unusual increase in the incidence of infections. Our aim was to describe the clinical, microbiological, and molecular characteristics of group A 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 causing infection (102 iGAS and 28 mild infections) were included in the microbiological study: 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 1 and 12; 12 predominated in 2022 but was surpassed by 1 in 2023. Spread of M1 sublineage (28/64 M1 isolates) was communicated for the first time in Spain, but it did not replace the still predominant sublineage M1 (36/64). Furthermore, a difference in types compared with the mild cases was observed with predominance of 1, but also important representativeness of 12 and 89 isolates. Pneumonia, the most frequent and severe iGAS diagnosed, was associated with the A gene, while the superantigen was associated with milder cases. iGAS isolates were mainly susceptible to antimicrobials. cgMLST showed five major clusters: ST28-ST1357/1, ST36-ST425/12, ST242/12.37, ST39/4, and ST101-ST1295/89 isolates.

IMPORTANCE

Group A (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 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.