Streptococcal toxic shock syndrome (STSS) is a severe invasive infection characterized by the sudden onset of shock, multi-organ failure, and high mortality. In Japan, appropriate notification measures based on the Infectious Disease Control law are mandatory for cases of STSS caused by β-haemolytic streptococcus. STSS is mainly caused by group A streptococcus (GAS). Although an average of 60-70 cases of GAS-induced STSS are reported annually, 143 cases were recorded in 2011. To determine the reason behind this marked increase, we characterized the emm genotype of 249 GAS isolates from STSS patients in Japan from 2010 to 2012 and performed antimicrobial susceptibility testing. The predominant genotype was found to be emm1, followed by emm89, emm12, emm28, emm3, and emm90. These six genotypes constituted more than 90% of the STSS isolates. The number of emm1, emm89, emm12, and emm28 isolates increased concomitantly with the increase in the total number of STSS cases. In particular, the number of mefA-positive emm1 isolates has escalated since 2011. Thus, the increase in the incidence of STSS can be attributed to an increase in the number of cases associated with specific genotypes.

Thirteen Streptococcus dysgalactiae subsp. equisimilis isolates possessing Lancefield's group A antigen recovered from people in Japan during 2000 to 2004 were genotyped. The results indicate that a conserved clone has persisted and spread within Japan, and two different emm types were observed within members of this clone.

We assessed antimicrobial susceptibility against 211 Streptococcus pyogenes strains isolated from patients with severe invasive group A streptococcal infections. Overall, 3.8, 1.4, 1.4, and 0.5% of the isolates were resistant to erythromycin, clindamycin, telithromycin, and ciprofloxacin, respectively, and 10.4% had intermediate resistance to ciprofloxacin. All isolates were susceptible to ampicillin and cefotaxime.Streptococcus pyogenes (group A streptococcus) is one of the most common human pathogens. It causes a wide array of infections, the most frequent of which is acute pharyngitis (strep throat). From the late 1980s, streptococcal toxic shocklike syndrome caused by S. pyogenes became a serious problem in both developed and developing countries. Symptoms such as pharyngitis, fever, and pain may suddenly develop, and the disease may progress very rapidly in some patients to softtissue necrosis, acute kidney failure, adult respiratory distress syndrome, disseminated intravascular coagulopathy, and multiorgan failure, leading to shock and death. One approach to treat severe invasive S. pyogenes infections has been to utilize a combination of penicillin and clindamycin. The rationale is that penicillin provides coverage against 100% of S. pyogenes strains and clindamycin has demonstrated greater efficiency in experimental models of necrotizing fasciitis (8). In this study, we tested the antimicrobial susceptibility of 211 S. pyogenes strains isolated from patients with severe invasive group A streptococcal infections.The activity of the Working Group for Group A Streptococci in Japan is based on a network between the National Institute of Infectious Diseases (NIID) and prefectural public health institutes (PHIs); seven branch offices of the reference center are located in the PHIs of Fukushima, Kanagawa, Toyama, Osaka, Yamaguchi, Oita, and Tokyo. Information on streptococcal infections and clinical isolates is sent to the PHIs from 3,041 cooperative hospitals located all over Japan. All of them are collected by NIID. A total of 211 S. pyogenes isolates from 1992 to 2003 were cultured predominantly from sterile body sites of patients with severe invasive group A streptococcal infections (5, 6). All isolates were stored at Ϫ80°C until tests for susceptibility. We analyzed the antimicrobial susceptibility of the isolates by the Etest method for five drugs, ampicillin, cefotaxime, ciprofloxacin, clindamycin, and erythromycin, and by the broth microdilution method as recommended by the National Committee for Clinical Laboratory Standards (NCCLS) (7) for telithromycin. A 0.5 McFarland solution was used to inoculate a Mueller-Hinton agar plate containing 5% sheep blood (Becton Dickinson, Tokyo, Japan) for the Etest method or to inoculate Mueller-Hinton broth containing 5% lysed horse blood (Becton Dickinson) for the broth microdilution method, and the plates were incubated at 37°C in a CO 2 atmosphere. The ATCC 49619 strain of Streptococcus pneumoniae was used as a quality control. The breakpoints of resistance to th...

We surveyed emm genotypes of group A streptococcus (GAS) isolates from patients with severe invasive streptococcal infections during 2001-2005 and compared their prevalence with that of the preceding 5 years. Genotype emm1 remained dominant throughout 2001 to 2005, but the frequency rate of this type decreased compared with the earlier period. Various other emm types have appeared in recent years indicating alterations in the prevalent strains causing severe invasive streptococcal infections. The cover of the new 26-valent GAS vaccine fell from 93.5% for genotypes of isolates from 1996-2000 to 81.8% in 2001-2005.

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