Invasive group A streptococcal disease and association with varicella in Germany, 1996-2009.

A nationwide laboratory-based surveillance study was conducted to analyse the epidemiology of varicella-associated invasive group A streptococcal (iGAS) infections in Germany. A total of 1342 iGAS samples were collected between 1 January 1996 and 22 September 2009. For 21 of these isolates, an association with varicella was observed. The median age of this subgroup was 4.2 years (mean 12.1). Most of these patients presented with sepsis (42.9%), streptococcal toxic shock syndrome (23.8%) and necrotizing fasciitis (19.0%). The most common complications among patients with underlying varicella were hypotensive shock and soft-tissue necrosis (38.1% each), disseminated intravascular coagulopathy (33.3%) and renal impairment (28.6%). The overall rate of complications was higher among the patients with underlying varicella than among those without. In the varicella-positive group, emm types 1 (38.1%), 12 (19.0%) and 4 (14.3%) were predominant, while among the varicella-negative isolates, emm types 1 (32.5%), 28 (14.0%) and 3 (8.3%) were found most often. Among the varicella-positive group, the rate of ssa-positive isolates was considerably higher than that among the varicella-negative group (28.6% vs. 12.6%), as well as the coexistence of speC and ssa (14.3% vs. 3.6%).