Emergence of type I restriction modification system‐negative emm1 type Streptococcus pyogenes clinical isolates in Japan

Abstract

Streptococcus pyogenes emm1 type is the dominant cause of streptococcal toxic shock syndrome (STSS) in Japan and many other developed countries. Recently, the number of STSS patients in Japan was reported to be increasing. Hence, we analyzed the S. pyogenes clinical isolates detected in Japan after 2005. We found that the regions encoding the Spy1908–1910 two-component regulatory system and the adjacent type I restriction modification system were deleted in some emm1 type isolates. The isolates with the deletion were detected only in the emm1 strains that were isolated between 2010 and 2013, but not before 2010. Twenty-six of 46 (56.5%) emm1 type isolates were isolated in 2010–2013, and among these isolates, five of seven (71.4%) emm1 type STSS isolates were shown to have that deletion. PFGE and PCR analysis for the presence of several pyrogenic exotoxin-related genes suggested that the emm1 isolates with and without the deletion shared the same genetic background. The emm1 isolates with the deletion could incorporate exogenous plasmids by experimental electroporation transformation far more efficiently. These results suggested that the novel emm1 isolates have occupied a fairly large part of total emm1 isolates.

Relevance of spontaneous fabT mutations to a streptococcal toxic shock syndrome to non‐streptococcal toxic shock syndrome transition in the novel‐type Streptococcus pyogenes isolates that lost a salRK

“…Recently, we reported that the regions encoding the SalR–SalK, a two‐component regulatory system, and the adjacent type I restriction modification system were deleted in some emm 1‐type isolates. The isolates with the deletion were detected only in the emm 1 strains that were isolated after 2010 . In this study, we call emm 1 strains with and without the deletion as ‘novel’ and ‘conventional’ emm 1 strains, respectively, unless otherwise stated.…”

Complete Bypass of Restriction Systems for Major Staphylococcus aureus Lineages

“…The method described here is based on engineering E. coli to express active type I hsdMS genes from S. aureus , but this approach can equally be applied to other bacterial species where type I RM is a barrier to genetic manipulation, such as Streptococcus spp., Staphylococcus spp., and E. coli ( 3 , 22 – 24 ). Our approach to integrate the hsdMS genes onto the chromosome stabilized the DNA, in contrast to the instability/toxicity observed for hsdMS genes.…”

Prevalence of emm1 Streptococcus pyogenes having a novel type of genomic composition

“…We previously reported that the region encoding the SalR‐SalK, a two‐component regulatory system, and the adjacent type I restriction modification system was deleted in some emm 1‐type isolates . These isolates possessed mef (A) and msr (D) genes in the conjugative prophage Ф1207.3, which are involved in macrolide resistance .…”

“…These isolates possessed mef (A) and msr (D) genes in the conjugative prophage Ф1207.3, which are involved in macrolide resistance . A S. pyogenes strain 10–85, which was isolated from a STSS patient, is one of the isolates with the above genetic features consisting of the deletion, the mef (A) possession, and the msr (D) possession . We recently announced the complete genome sequence of strain 10–85 …”