Epidemiological studies have proposed an association between group A streptococci (GAS) bearing a particular M serological type and pathologic conditions such as streptococcal toxic shock syndrome (STSS). M1 and M3 GAS are isolated from STSS cases more frequently, whereas M4 and M12 GAS are isolated from non-STSS cases more frequently. To investigate whether there is any difference contributing the M-type association among GAS, we compared various virulence traits, including the murine lethality of M4, M12, M1, and M3 GAS clinical isolates, which are not clonally related to one another. Murine lethality, the activities of superantigens, streptolysin O, and nicotinamide adenine dinucleotide glycohydrolase, and the presence of the speA and speC genes were closely associated with M type. These results indicate that M types may serve, in part, as markers for strains/clones with particular profiles of virulence traits and mouse lethality.
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.
The production of hydrogen peroxide (H 2 O 2 ) and related phenotypes were studied with Streptococcus pyogenes strains isolated from cases of pharyngitis or severe group A streptococcal infections. Of the 46 strains examined (34 from severe infections and 12 from pharyngitis cases), 25 strains accumulated H 2 O 2 in the culture medium when grown under glucose-limited, aerobic conditions, whereas the rest of the strains did not. There was no correlation between these traits and the type of disease from which each strain had been isolated. The H 2 O 2 -nonproducing strains tested in this study belonged to T type 3 or T type 12. The accumulation of H 2 O 2 started when the culture reached the late exponential phase. A rapid loss of cell viability accompanied H 2 O 2 accumulation but was completely prevented by the addition of a catalase, indicating that the lethality was actually caused by H 2 O 2 . Cells of H 2 O 2 -nonproducing strains were resistant to killing by phagocytes from patients with chronic granulomatous disease (CGD), whereas those of H 2 O 2 -producing strains were subject to killing. Subcutaneous inoculation of 10 5 c.f.u. H 2 O 2 -nonproducing S. pyogenes strains into the hind footpads of CGD mice provoked more prominent swelling of the footpad than did H 2 O 2 -producing strains. The mortality rate in the CGD mice infected with the H 2 O 2 -nonproducing strains was higher than that produced by the H 2 O 2 -producing strains. It is suggested that H 2 O 2 -nonproducing S. pyogenes strains are prevalent in humans and that they may be a potential threat to the health of CGD patients.
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