Group A Streptococcus virulence and host factors in two toddlers with rheumatic fever following toxic shock syndrome

BackgroundRheumatic fever (RF) classically occurs after group A Streptococcus (GAS) pharyngitis in children aged over 5 years in developing countries. The present report describes the bacterial and host determinants in non-related toddlers who developed RF diagnostic criteria after toxic shock syndrome (TSS).Methods and resultsA 13-month-old boy and a 14-month-old girl presented GAS TSS. After several weeks, multiple subcutaneous nodules as well as migratory polyarthritis or monoarthritis developed in both children, fulfilling Jones criteria of RF. The relevance of the Jones criteria for very young children is, however, debatable and their use might lead to the unnecessary prescribing of secondary prophylaxis. A molecular analysis of both bacterial and host factors was carried out in an attempt to decipher the combination that could have led to such uncommon, but very similar presentations. The two GAS isolates belonged to the usual, although distinct, invasive emm-types 1 and 3. Both isolates carried a wide set of prophage-encoded virulence factors, with only the speG and speA superantigen-encoding genes in common. Both patients shared the HLA DQB1*0301 allele, which has been associated with susceptibility to GAS necrotizing fasciitis.ConclusionsOur study exemplifies the particularity of RF in young children and the complex role of superantigens and streptodornases in GAS-related pathologies.