Diagnostic clue for cutaneous characteristics of streptococcus pyogenes infection after COVID-19 epidemic in pediatrics in Beijing

Background Recent studies have presented an increase in group A streptococcal (GAS) infections especially after COVID-19 epidermic. We aim to identify cutaneous characteristics of GAS infection after epidemic in pediatrics and investigate the molecular epidemiology. Methods Demographic data, laboratory examination, pharyngeal and cutaneous swab samples were collected. Rapid antigen detection test (RADT) and cultures was performed. Antimicrobial susceptibility test was performed according to the distribution of conventional antibiotics and Clinical and Laboratory Standards Institute (CLSI) recommendations. emm (M protein coding gene) typing was examined by polymerase chain reaction (PCR). Results A total of 60 GAS strains were collected during 2023. We identified 15 generalized GAS infection patients, median age 91.47-month. 12 patients had + RADTs. Patients had preceding illnesses, including upper respiratory tract infections, pharyngitis, sore throat and paronychia/blistering dactylitis/ hand and foot abscess. 10 patients had fever within one month before onset of GAS infection, including influenza A virus, influenza B virus, and mycoplasma pneumoniae. 10 patients have abnormal blood routine, 3 patients had urine routine and electrocardiogram. The most common emm type was emm 12.0 (11, 73.33%), followed by emm 12.67 (2, 13.33%). GAS isolates were sensitive to penicillin, ceftriaxone. Study limitations The number of patients evaluated by this study can still be considered limited; other than that, our study is a single center, which many lead to bias. Further research is needed to explore the mechanism. Conclusions GAS strains included from patient's throat, skin, urinary tract infection and female genital tract infection have been identified as the same GAS strains, with the same emm subtypes. Paronychia/blistering dactylitis/ hand and foot abscess is diagnostic clue for cutaneous characteristics GAS. There is association among GAS infection, emm type and clinical manifestations.