Capsule production by mucoid invasive S. pyogenes strains at different temperatures.

#Isolates were recovered through Active Bacterial Core surveillance for S. pyogenes during 2007–2010 in the United States. Refer to surveillance reports at http://www.cdc.gov/abcs/reports-findings/surv-reports.html.%New emm subtypes that have not yet been provided emm designations. All emm designations are shown at the downloadable database ftp://ftp.cdc.gov/pub/infectious_diseases/biotech/tsemm/.*Mucoidity assay was performed with colonies grown on THY (Todd Hewitt Yeast) agar plates.− : Basal level capsule production (less than 100 fg/cfu), not observable with visual inspection such as HSC5 or MGAS315 wild type.+ : Capsule production of 100–300 fg/cfu, barely detectable with visual inspection.++ : Capsule production of 300–500 fg/cfu, clearly detectable with visual inspection but less amount of capsule production than HSC5 CovRS null mutants incubated at 25°C.+++ : Capsule production of more than 500 fg/cfu, clearly detectable with visual observation, almost the same amount of capsule production as HSC5 CovRS null mutants incubated at 25°C.**These strains were preselected as being mucoid on blood agar plates by CDC.@Blank cells: Values were not determined.