Fulminant invasive group A streptococcal infection in children

Group A streptococcal infections dominate among invasive streptococcal infections, with the major causative agent, Streptococcus pyogenes, being quite stable in the environment and bearing a large number of chromosome encoded pathogenicity factors or transmitted by horizontal transfer through bacteriophages. Different genetic variants of S. pyogenes can have a different set of pathogenicity factors able to change during pathogen evolution and determine virulence level for specific isolate. With a short incubation period, the disease can proceed with developing invasive infection and toxic shock syndrome with unfavorable outcome within 7 days from disease onset. The purpose of this article is to increase the doctors’ alertness to early recognition and diagnosis, which directly affects adequate treatment in a timely manner and disease outcome. The data on streptococcal morbidity in Russia and worldwide, review of laboratory diagnostic methods and pathogen genetic typing are presented. The maximum number of cases of streptococcal septicemia in Russia was registered in 2022, which accounted for 69% of all cases during the 2014–2022 observation period. The article also describes two clinical cases of fulminant invasive group A streptococcal infection in children with symptoms of acute respiratory viral infections at the onset of the disease. The results of various laboratory diagnostics methods verifying the diagnosis are presented. The genetic characterization of microbial isolates was performed by deep DNA sequencing. In the biological material from patients (including autopsy in one case), S. pyogenes sequence type ST-28, serotypes emm-1.25 and emm-1.0 were identified. The increasing importance of invasive streptococcal infection for health care in Russia and other countries may be associated with a possible change in dominating S. pyogenes genetic variants. In this regard, the study on circulating S. pyogenes genotypes on an ongoing basis as part of surveillance of streptococcal infection and development of vaccine for specific prevention are required.