Outbreak of invasive group a streptococcal disease among children attending a day-care center

Background: Most cases of invasive group A streptococcal (GAS) disease arise sporadically in the community, but outbreaks of severe invasive GAS infections have been reported in closed environments, such as military populations, family communities and hospitals. An outbreak of invasive GAS disease involving 3 cases of streptococcal toxic shock syndrome (TSS), one with a fatal course, occurred among children attending a day-care center located in Cantabria, Northern Spain. Objective: To determine the characteristics of GAS isolates obtained from the outbreak environment. Methods: GAS isolates obtained from children attending the same day-care facility, staff members, and family contacts were assayed for emm typing, pulse-field gel electrophoresis (PFGE), and toxingene content. One isolate obtained from the fatal case was also characterized by multilocus sequence typing. Antimicrobial susceptibility testing was done. Strains from patients unrelated to the outbreak were included for comparison. Results: All GAS isolates from children attending the day-care center, including those from streptococcal TSS cases, shared the same emm type 4, genomic pattern by PFGE (A) and toxin-gene profile. Neither the emm type nor the PFGE pattern or toxin gene profile of the outbreak-associated strains were encountered among GAS isolated from household or staff contacts. Conclusions: A clone of GAS belonging to emm type 4 and characterized by a specific PFGE pattern and toxin-gene profile was responsible for a community outbreak of streptococcal TSS disease in a child day-care center in Spain. This is the first day-care outbreak reported in our country.