Streptococcus dysgalactiae ssp. equisimilis (SDSE) is increasingly being identified as a pathogen responsible for invasive and non-invasive infections. We compared the clinical features of invasive SDSE infections with those of invasive infections caused by Streptococcus pyogenes (group A streptococcus (GAS)) and Streptococcus agalactiae (group B streptococcus (GBS)). Active surveillance for invasive SDSE, GAS and GBS was maintained over 1 year at 142 medical institutions throughout Japan. Clinical information was collected together with isolates, which were characterized microbiologically. Two hundred and thirty-one invasive SDSE infections were identified, 97 other patients had infections with GAS, and 151 had infections with GBS. The median age of the SDSE patients was 75 years; 51% were male and 79% had underlying diseases. Forty-two SDSE patients (19%) presented to the emergency department. Among the 150 patients (65%) for whom follow-up was completed, 19 (13%) died and eight (5%) had post-infective sequelae (poor outcome). Insufficient white blood cell responses (<5000 cells/microL) and thrombocytopenia on admission each suggested significantly higher risk of poor outcome (ORs 3.6 and 4.5, respectively). Of 229 isolates, 55 (24%) showed an stG6792 emm type, which was significantly associated with poor outcome (OR 2.4). Clinical manifestations of invasive SDSE infections were distinct from those of invasive GBS infections. Primary-care doctors should consider invasive SDSE infections when treating elderly patients.

This infection is an increasing threat to aging populations.

Streptococcus agalactiae isolates (n ‫؍‬ 189) from patients with invasive infections were analyzed for capsular type by PCR, for antimicrobial susceptibility, and for the presence of resistance genes. In contrast to the predominance of capsular type III in children, types Ib and V were most common among adults. All 45 levofloxacin-resistant strains had two amino acid substitutions, Ser 81 Leu in the gyrA gene and Ser 79 Phe in the parC gene, and showed similar pulsed-field gel electrophoresis patterns.

Invasive pneumococcal disease (IPD) is of concern in Japan, where the heptavalent pneumococcal conjugate vaccine (PCV7) is unavailable. We determined serotypes, genotypes indicating beta-lactam resistance, and antibiotic susceptibilities of 496 isolates from normally sterile sites in patients (193 children, 303 adults) from 186 institutions between August 2006 and July 2007. Disease presentations included sepsis (46.2%), pneumonia (31.5%), and meningitis (17.5%). Mortality was 1.4% in children and 22.1% in adults, many of whom had underlying diseases. In children, serotype 6B (22.5%) was followed by 19F (14.1%), and 14 (13.1%); potential coverages of PCV7 and PCV13 were 75.4% and 93.7%, respectively. In adults, serotype 12F (14.3%) was followed by 3 (11.3%), and 6B (10.3%); 23-valent polysaccharide vaccine (PPV23) coverage was 85.4%. Most serotype 12F strains were gPISP, with pbp2b gene alteration; carbapenem had an excellent MIC90. PCV7 is recommended for children and PPV23 for adults to increase prevention against IPD.

To analyse the characteristics of infections caused by Streptococcus dysgalactiae subsp. equisimilis, clinical isolates (n5145) were collected at 11 medical institutions between September 2003 and October 2005. These isolates belonged to Lancefield group A (n55), group C (n518) or group G (n5122). Among all isolates, 42 strains were isolated from sterile samples such as blood, synovial fluid and tissue specimens from patients who were mostly over 50 years with invasive infections, and included seven cases of streptococcal toxic shock syndrome and necrotizing fasciitis. In contrast, the remaining 103 were isolated mainly from patients of all age groups with non-invasive infections such as pharyngotonsillitis. These isolates were classified into 25 types based on emm genotyping. A significant difference in emm types was observed between isolates from invasive and non-invasive infections (P,0.001): stG485, stG6792 and stG2078 predominated among isolates from invasive infections. A phylogenetic tree of complete open reading frames of emm genes in this organism showed high homology with those of Streptococcus pyogenes, but not with those of other streptococci. The presence of five different clones was estimated based on DNA profiles of isolates from invasive infections obtained by PFGE. Genes for resistance to macrolides [erm(A), three isolates; erm(B), five isolates; mef(A), seven isolates] and levofloxacin (mutations in gyrA and parC, four isolates) were identified in this organism. These results suggest the need for further nationwide surveillance of invasive infections caused by S. dysgalactiae subsp. equisimilis. INTRODUCTIONMost b-haemolytic streptococcal pathogens isolated from humans are identified as Streptococcus pyogenes (group A streptococci; GAS), Streptococcus agalactiae (group B streptococci; GBS), Streptococcus dysgalactiae subsp. equisimilis and species of the anginosus group that belong to Lancefield groups A, B, C, G or F (Facklam, 2002;Ruoff et al., 2003). In contrast to GAS and GBS, which are known to cause serious and systemic invasive infections, streptococci with Lancefield group C or G antigens were long considered to be commensal organisms that only rarely caused invasive infections as opportunistic pathogens.In 1996, S. dysgalactiae subsp. equisimilis was proposed as a new streptococcal taxon (Vandamme et al., 1996). Although rare, S. dysgalactiae subsp. equisimilis strains having group A antigen rather than group C or G antigen have also been reported (Bert & Lambert-Zechovsky, 1997;Brandt et al., 1999;Katsukawa et al., 2002 Notably, S. dysgalactiae subsp. equisimilis possesses many virulence factors shared with GAS, such as M protein (Fischetti, 1989; Schnitzler et al., 1995), streptolysin O (Gerlach et al., 1993Okumura et al., 1994), streptolysin S (Humar et al., 2002 and streptokinase (Walter et al., 1989;Ikebe et al., 2004). It has been suggested that these factors were transmitted from GAS to this species (Kalia et al., 2001).In the present report, we have described S. dysgalactiae ...