Molecular Characterization of Streptococcus pyogenes Causing Invasive Disease in Pediatric Population in Spain A 12-year Study

OBJECTIVES: To perform a comprehensive description of the epidemiology of Streptococcus pyogenes invasive disease in the pediatric population in 2 regions of Spain (Catalonia and Gipuzkoa) through 12 years. METHODS: All S. pyogenes isolates causing invasive disease in pediatric patients between 2005 and 2016 were included. The emm-type and the presence of 13 exotoxin genes (speA, speB, speC, speF, speG, speH, speI, speJ, speK, speL, speM, smeZ, ssa and slo) were determined in all 93 available isolates and the Multi Locus Sequece Typing in 10% of isolates of each different emm-type. RESULTS: Overall, 103 cases of S. pyogenes invasive infections were detected: 77 in Catalonia and 26 in Gipuzkoa, being 50.5% females. The incidence rate per 100,000 children was 2.5 for Gipuzkoa and 2.6 for Catalonia, with no significant temporal trends. The median age was 30 months. The most frequent clinical presentations were: pneumonia (26.2%), bacteremia/sepsis (23.3%), septic arthritis/osteomyelitis (22.3%), cellulitis/mastoiditis (12.6%) and meningitis (6.8%). Eight children developed streptococcal toxic shock syndrome. Nine cases were preceded by varicella infection. The associated mortality rate was 3.9%. Three isolates were resistant to erythromycin, being one of them also resistant to clindamycin and 4 isolates were resistant to levofloxacine. Forteen different emm-types were detected being emm1/ST28 (40.9%) the most frequent clone in both regions followed by emm12/ST36-ST242, emm6/ST382, emm3/ST15, emm75/ST150 and emm4/ST38-39. speA gene was only detected in emm1 and emm3 isolates. Eight exotoxins were enough to assign an emm-type with a very high degree of accuracy (95%). The 30-valent vaccine would include 96.8% of isolates.