研究者詳細 - 佐々木　崇

論文 - 佐々木　崇

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Near-complete genome sequencing of the feline coronavirus serotype I strain FIPV-Aqua from a cat with feline infectious peritonitis in Japan.

Yoshikazu Tanaka, Eri Tanabe, Takashi Sasaki

Microbiology resource announcements 14 ( 6 ) e0035725 2025年06月 [国際誌]

DOI PubMed

Emergence of community-associated methicillin-resistant Staphylococcus aureus ΨUSA300 among Japanese people with HIV, resulted from stepwise mutations in 2010s.

Koh Shinohara, Yuki Uehara, Katsuji Teruya, Takashi Sasaki, Tadashi Baba, Hidemasa Nakaminami, Pegah Kananizadeh, Yuh Morimoto, Yoshimi Kikuchi, Shinichi Oka

Scientific reports 13 ( 1 ) 8322 - 8322 2023年05月 [査読有り] [国際誌]

Although infection with the methicillin-resistant Staphylococcus aureus (MRSA) clone USA300 is extremely rare in Japan, the uniquely evolved clone ΨUSA300 has been reported in Japan. An outbreak of a distinct USA300 clone was recently reported in an HIV/AIDS referral hospital in Tokyo. The present study investigated the evolutionary origin and genetic diversity of USA300-related clones causing regional outbreaks among people living with HIV (PLWHIV) in Tokyo. MRSA isolates collected from PLWHIV in an HIV/AIDS referral center in Tokyo were subjected to whole-genome sequencing and their genetic features were compared with those of previously described USA300 MRSA genomes. Of the 28 MRSAs isolated in 2016-2019, 23 (82.1%) were identified as USA300, with 22 (95.6%) of the latter identified as ΨUSA300. Although the genomic structure of ΨUSA300 was identical to the structures of reference USA300 strains, one clade (cluster A) was found to have acquired 29 previously identified lineage-specific mutations in a stepwise manner. The estimated divergence dates of ΨUSA300 and Cluster A were 2009 and 2012, respectively. These findings suggested that the ΨUSA300 clone had spread among PLWHIVs in Tokyo in the early 2010s, with stepwise acquisition of lineage-specific nonsynonymous mutations.

DOI PubMed

Complete Genome Sequencing of a Community-Associated Methicillin-Resistant Staphylococcus aureus ψUSA300 Strain JICS127, a Uniquely Evolved USA300 Lineage in Japan.

Koh Shinohara, Tadashi Baba, Takashi Sasaki, Katsuji Teruya, Yuki Uehara

Microbiology resource announcements 11 ( 9 ) e0071722 2022年09月 [査読有り] [国際誌]

DOI PubMed

Genetic and phenotypic diversity of methicillin-resistant Staphylococcus aureus among Japanese inpatients in the early 1980s.

Hui Zuo, Yuki Uehara, Yujie Lu, Takashi Sasaki, Keiichi Hiramatsu

Scientific reports 11 ( 1 ) 5447 - 5447 2021年03月 [査読有り] [国際誌]

To trace the linkage between Japanese healthcare-associated methicillin-resistant Staphylococcus aureus (HA-MRSA) strains in the early 1980s and the 2000s onward, we performed molecular characterizations using mainly whole-genome sequencing. Among the 194 S. aureus strains isolated, 20 mecA-positive MRSA (10.3%), 8 mecA-negative MRSA (4.1%) and 3 mecA-positive methicillin-susceptible S. aureus (MSSA) (1.5%) strains were identified. The most frequent sequence type (ST) was ST30 (n = 11), followed by ST5 (n = 8), ST81 (n = 4), and ST247 (n = 3). Rates of staphylococcal cassette chromosome mec (SCCmec) types I, II, and IV composed 65.2%, 13.0%, and 17.4% of isolates, respectively. Notably, 73.3% of SCCmec type I strains were susceptible to imipenem unlike SCCmec type II strains (0%). ST30-SCCmec I (n = 7) and ST5-SCCmec I (n = 5) predominated, whereas only two strains exhibited imipenem-resistance and were tst-positive ST5-SCCmec II, which is the current Japanese HA-MRSA genotype. All ST30 strains shared the common ancestor strain 55/2053, which caused the global pandemic of Panton-Valentine leukocidin-positive MSSA in Europe and the United States in the 1950s. Conspicuously more heterogeneous, the population of HA-MRSA clones observed in the 1980s, including the ST30-SCCmec I clone, has shifted to the current homogeneous population of imipenem-resistant ST5-SCCmec II clones, probably due to the introduction of new antimicrobials.

DOI PubMed

Nicotine Oral Administration Attenuates DSS-Induced Colitis Through Upregulation of Indole in the Distal Colon and Rectum in Mice.

Akihito Nakajima, Tomoyoshi Shibuya, Takashi Sasaki, Yu Jie Lu, Dai Ishikawa, Keiichi Haga, Masahito Takahashi, Naoko Kaga, Taro Osada, Nobuhiro Sato, Akihito Nagahara

Frontiers in medicine 8 789037 - 789037 2021年 [査読有り] [国際誌]

Nicotine affects the gastrointestinal environment and modulates ulcerative colitis (UC). However, the associations among nicotine, gut metabolites, and UC are still largely unknown. We investigated whether orally administered nicotine affected gut metabolites and dextran sodium sulfate (DSS)-induced colitis. C57BL/6 male mice were orally administered nicotine solution in drinking water prior to inducing DSS-induced colitis. Short-chain fatty acids (SCFAs) and indole in gut contents and fecal samples were measured by GC-MS and hydroxylamine-based indole assays, respectively. Oral administration of nicotine increased indole concentration in feces, but, in contrast, SCFA values did not differ with nicotine administration. Indole levels were increased in the distal colon and rectum but not in the cecum and proximal colon. DSS-induced colitis was less severe clinically and histological changes were minimal in the rectum of orally nicotine-administered mice compared to mice drinking only water. 16S rRNA microbiome on the feces revealed an increasing in Clostridium and Porphyromonas in nicotine-administered mice. In conclusion, nicotine administration was associated with increased indole levels in the distal colon and rectum and attenuated DSS-induced colitis. Oral administration of nicotine may play a potential role in indole upregulation and prevention of UC.

DOI PubMed

Corynebacterium Species of the Conjunctiva and Nose: Dominant Species and Species-Related Differences of Antibiotic Susceptibility Profiles.

Saichi Hoshi, Daisuke Todokoro, Takashi Sasaki

Cornea 39 ( 11 ) 1401 - 1406 2020年11月 [査読有り] [国際誌]

PURPOSE: Nondiphtherial Corynebacterium species are normal residents of human skin and mucosa, including the conjunctiva and nose, but can cause conjunctivitis and keratitis. Recently, resistance against various classes of antibiotics has been reported in Corynebacterium. The present study investigated the type of species and antibiotic susceptibilities of the conjunctival and nasal Corynebacterium species. METHODS: This study examined 183 strains of Corynebacterium species that were isolated from patients undergoing preoperative examinations for cataract surgery. Species were identified by RNA polymerase β-subunit-encoding gene (rpoB) sequencing. Antibiotic susceptibility tests were performed by the microdilution method according to the Clinical and Laboratory Standards Institute standard method M45. RESULTS: Corynebacterium macginleyi was the most predominant species (84%; 46 of 55) in the conjunctiva. The 2 major species in the nasal cavity were Corynebacterium accolens and Corynebacterium propinquum (44% and 31%, respectively), followed by Corynebacterium pseudodiphtheriticum (8%), Corynebacterium jeikeium (7%), and C. macginleyi (3%). In contrast to other nasal Corynebacterium species, only C. macginleyi showed a high susceptibility to macrolides. However, among nonconjunctival Corynebacterium species, C. propinquum, was unique in having a high resistance rate to levofloxacin (29%), comparable with that observed in C. macginleyi (36%). Penicillin G and tobramycin showed good susceptibility in almost all strains. CONCLUSIONS: Drug resistance against fluoroquinolones and macrolides was observed in Corynebacterium species, with the antibiotic susceptibility profiles correlating with differences of the species and niche. Nasal and conjunctival Corynebacterium profiles of drug resistance suggest habitat segregation strictly at the species level.

DOI PubMed

An outbreak of USA300 MRSA among people with HIV in Japan.

Kazuhiko Ikeuchi, Eisuke Adachi, Takashi Sasaki, Masato Suzuki, Lay Ahyoung Lim, Makoto Saito, Michiko Koga, Takeya Tsutsumi, Yasutoshi Kido, Yuki Uehara, Hiroshi Yotsuyanagi

The Journal of infectious diseases 223 ( 4 ) 610 - 620 2020年10月 [査読有り] [国際誌]

BACKGROUND: USA300 produces Panton-Valentin leucocidin (PVL), and is known as a predominant community-associated methicillin-resistant Staphylococcus aureus (MRSA) strain in the United States, but it was extremely rare in Japan. We report here an outbreak of USA300 in people with HIV (PWH) in Tokyo, Japan. METHODS: We analyzed the cases of PVL-MRSA infection between 2010 and 2020 and screened for nasal colonization of PVL-MRSA in PWH who visited an HIV/AIDS referral hospital from December 2019 to March 2020. Whole-genome sequencing (WGS)-based single nucleotide polymorphism (SNP) analysis was performed for these isolates. RESULTS: During the study period, a total of 21 PVL-MRSA infections in 14 patients were identified after 2014. The carriage prevalence was 4.3% (12/277), and PVL-MRSA carriers were more likely to have sexually transmitted infections (STIs) within a year compared with patients who had neither the history of PVL-MRSA infection nor colonization (33.3% [4/12] vs 10.1% [26/258], P=0.03). SNP analysis showed that all 26 isolates were ST8-SCCmecⅣa-USA300. Twenty-four isolates were closely related (≤100 SNP differences) and had the nonsynonymous SNPs associated with carbohydrate metabolism and antimicrobial tolerance. CONCLUSIONS: An outbreak of USA300 has been occurring among PWH in Tokyo, and a history of STI was a risk of colonization.

DOI PubMed

RNA Sequencing Identifies a Common Physiology in Vancomycin- and Ciprofloxacin-Tolerant Staphylococcus aureus Induced by ileS Mutations.

Madhuri Singh, Miki Matsuo, Takashi Sasaki, Tomomi Hishinuma, Norio Yamamoto, Yuh Morimoto, Teruo Kirikae, Keiichi Hiramatsu

Antimicrobial agents and chemotherapy 64 ( 10 ) 2020年09月 [査読有り] [国際誌]

Little is known about the mechanisms by which ileS mutations induce vancomycin tolerance in Staphylococcus aureus This study showed that transcriptome profiles were similar in vancomycin-tolerant mutants and the IleRS-inhibitor-treated parent. Notably, ileS and relA, which induce a stringent response, were upregulated. The same mechanism was responsible for cross-tolerance to vancomycin and ciprofloxacin. These findings suggest that the accumulation of uncharged isoleucyl-tRNA following ileS mutations in S. aureus was responsible for drug tolerance.

DOI PubMed

Epidemiology of methicillin-resistant Staphylococcus aureus in a Japanese neonatal intensive care unit.

Atsushi Tsujiwaki, Ken Hisata, Yudai Tohyama, Nobuaki Matsunaga, Yuki Uehara, Takashi Sasaki, Keiichi Hiramatsu, Toshiaki Shimizu

Pediatrics international : official journal of the Japan Pediatric Society 62 ( 8 ) 911 - 919 2020年08月 [査読有り] [国際誌]

BACKGROUND: There have been few reports on the genetic structure of the current population of methicillin-resistant Staphylococcus aureus (MRSA) from neonatal intensive care units (NICUs) in Japan. In the present study we conducted a molecular epidemiological analysis based on whole genome sequencing against MRSA strains in a Japanese NICU. METHODS: We performed genotyping by whole genome sequencing, polymerase chain reaction-based typing of Staphylococcal cassette chromosome mec (SCCmec) and polymerase chain reaction-based open-reading frame typing against 57 MRSA strains from fecal or nasal specimens from NICU patients in Juntendo University Shizuoka Hospital in 2013-2014. RESULTS: Forty-nine MRSA strains (86.0%) exhibited a clonal complex (CC) 1, and were divided into three sequence types (STs): ST2725 (n = 25), ST2764 (n = 21), and ST1 (n = 3). All CC1 MRSA strains had SCCmec IVa, and were resistant to new quinolones, which are limited in pediatric use, suggesting that these strains were derived from adult MRSA clones. Single nucleotide polymorphism differences of both ≤10 and >100 nucleotides were observed by pairwise, single nucleotide polymorphism analysis among ST2725 and ST2764 MRSA strains, respectively. Seven ST8 MRSA strains (12.2%) were isolated, and no strain exhibiting the Japanese hospital-associated MRSA genotype (ST5/SCCmec II) was isolated in this study. CONCLUSIONS: Our molecular epidemiological analysis suggested that ST2725 and ST2764 MRSA strains had genetic diversity that could not be explained only by a recent transmission event in the NICU. These MRSA clones might be disseminated in other Japanese hospital facilities as new endemic clones. Our results are expected to contribute to the improvement of infection control measures of MRSA in NICUs.

DOI PubMed

A Soluble Fiber Diet Increases Bacteroides fragilis Group Abundance and Immunoglobulin A Production in the Gut.

Akihito Nakajima, Takashi Sasaki, Kikuji Itoh, Takashi Kitahara, Yoshinori Takema, Keiichi Hiramatsu, Dai Ishikawa, Tomoyoshi Shibuya, Osamu Kobayashi, Taro Osada, Sumio Watanabe, Akihito Nagahara

Applied and environmental microbiology 86 ( 13 ) 2020年06月 [査読有り] [国際誌]

Immunoglobulin A (IgA) is essential for defense of the intestinal mucosa against harmful pathogens. Previous studies have shown that Bacteroidetes, the major phylum of gut microbiota together with Firmicutes, impact IgA production. However, the relative abundances of species of Bacteroidetes responsible for IgA production were not well understood. In the present study, we identified some specific Bacteroidetes species that were associated with gut IgA induction by hsp60-based profiling of species distribution among Bacteroidetes The levels of IgA and the expression of the gene encoding activation-induced cytidine deaminase (AID) in the large intestine lamina propria, which is crucial for class switch recombination from IgM to IgA, were increased in soluble high-fiber diet (sHFD)-fed mice. We found that Bacteroides acidifaciens was the most abundant Bacteroidetes species in both sHFD- and normal diet-fed mice. In addition, the gut IgA levels were associated with the relative abundance of Bacteroides fragilis group species such as Bacteroides faecis, Bacteroides caccae, and Bacteroides acidifaciens Conversely, the ratio of B. acidifaciens to other Bacteroidetes species was reduced in insoluble high-fiber diet fed- and no-fiber diet-fed mice. To investigate whether B. acidifaciens increases IgA production, we generated B. acidifaciens monoassociated mice and found increased gut IgA production and AID expression. Collectively, soluble dietary fiber increases the ratio of gut Bacteroides fragilis group, such as B. acidifaciens, and IgA production. This might improve gut immune function, thereby protecting against bowel pathogens and reducing the incidence of inflammatory bowel diseases.IMPORTANCE Immunoglobulin A (IgA) is essential for defense of the intestinal mucosa against harmful pathogens. Gut microbiota impact IgA production, but the specific species responsible for IgA production remain largely elusive. Previous studies have shown that IgA and Bacteroidetes, the major phyla of gut microbiota, were increased in soluble high-fiber diet-fed mice. We show here that the levels of IgA in the gut and the expression of activation-induced cytidine deaminase (AID) in the large intestine lamina propria, which is crucial for class switch recombination from IgM to IgA, were correlated with the abundance of Bacteroides fragilis group species such as Bacteroides faecis, Bacteroides caccae, and Bacteroides acidifaciensB. acidifaciens monoassociated mice increased gut IgA production and AID expression. Soluble dietary fiber may improve gut immune function, thereby protecting against bowel pathogens and reducing inflammatory bowel diseases.

DOI PubMed

Genetic alterations of KIT during clonal expansion and subsequent acquisition of resistance to toceranib in a canine mast cell tumor cell line.

Sena Kurita, Ryo Miyamoto, Hiroyuki Tani, Masato Kobayashi, Takashi Sasaki, Kyoichi Tamura, Makoto Bonkobara

Journal of veterinary pharmacology and therapeutics 42 ( 6 ) 673 - 681 2019年11月 [査読有り] [国際誌]

One of the potential mechanisms underlying acquired resistance to toceranib in canine mast cell tumor (MCT) is the emergence of a secondary mutation in the KIT gene. Here, genetic alterations of KIT during clonal expansion and subsequent acquisition of resistance to toceranib were investigated in the toceranib-susceptible canine MCT cell line VI-MC, which carries a KIT-activating mutation resulting in a predicted p.(Asn508Ile) amino acid change in the receptor tyrosine kinase protein KIT. Two sublines were cloned from VI-MC and toceranib-resistant sublines then were established by continuous exposure to toceranib. The mutation status of KIT in parental VI-MC and its sublines was investigated using next-generation sequencing (NGS). Additionally, effects of secondary mutations on toceranib sensitivity in p.(Asn508Ile)-mutant KIT were examined. KIT secondary mutations, including those encoding p.(Asn679Lys)-, p.(Asp819Val)-, and p.(Asp819Gly)-mutant KIT, that confer toceranib insensitivity to p.(Asn508Ile)-mutant KIT emerged only in toceranib-resistant VI-MCs. These mutations were not detected by NGS in the parental VI-MC line or in the toceranib-naive cloned VI-MCs, although the parental line and sublines exhibited genetic heterogeneity in KIT that may have been caused by genetic evolution during clonal expansion. VI-MC clones with these secondary mutations in KIT appear to have arisen from subclones during treatment with toceranib rather than being pre-existing. However, further study using a higher resolution technique will be needed to confirm the developmental mechanism of KIT secondary mutation in canine MCT cells with acquired resistance to toceranib.

DOI PubMed

A genetic variant of CYP2R1 identified in a cat with type 1B vitamin D-dependent rickets: a case report.

Takahiro Teshima, Sena Kurita, Takashi Sasaki, Hirotaka Matsumoto, Ayaka Niina, Daijiro Abe, Nobuo Kanno, Hidekazu Koyama

BMC veterinary research 15 ( 1 ) 62 - 62 2019年02月 [査読有り] [国際誌]

BACKGROUND: Vitamin D-dependent rickets is rare in animals and humans. Several types of this condition are associated with genetic variants related to vitamin D metabolism. This is the first report of type 1B vitamin D-dependent rickets in a cat. CASE PRESENTATION: Here, we describe the case of a 3-month-old female domestic short-haired cat previously fed on commercial kitten food that presented at our clinic with seizures, lethargy, and generalized pain. Serum and ionized calcium concentrations and 1,25-dihydroxycholecalciferol in this cat were low, and radiographs showed skeletal demineralization and abnormally wide growth plates on the long bones. Initially, simple vitamin D deficiency was suspected; however, the cat's profile, which included fed a well-balanced commercial diet, together with the findings of additional laboratory tests and the cat's unresponsiveness to various treatments, raised the suspicion of vitamin D-dependent rickets. Examination of the DNA sequences of CYP2R1 and CYP27B1 genes, which are genes linked with vitamin D metabolism, showed a CYP2R1 frameshift mutation in exon 5 (where T is deleted at position c.1386). This mutation alters the amino acid sequence from position 462, while the stop codon introduced at position 481 prematurely truncates the 501 amino acid full-length protein. With this knowledge, a new treatment regime based on a standard dose of calcitriol was started and this markedly improved the cat's condition. CONCLUSIONS: To the best of our knowledge, the present case is the first description of type 1B vitamin D-dependent rickets linked with a genetic variant of CYP2R1 in a cat.

DOI PubMed

Comparison of USA300 with non-USA300 methicillin-resistant Staphylococcus aureus in a neonatal intensive care unit.

Takemi Murai, Kaoru Okazaki, Kazue Kinoshita, Yuki Uehara, Hui Zuo, Yujie Lu, Yuki Ono, Takashi Sasaki, Keiichi Hiramatsu, Yuho Horikoshi

International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases 79 134 - 138 2019年02月 [査読有り] [国際誌]

OBJECTIVES: Reports of USA300 methicillin-resistant Staphylococcus aureus (MRSA) strain were still scarce in neonatal intensive care units (NICUs) and the relationship of USA300 MRSA to clinical infections is still controversial. The primary outcome was the incidence of MRSA infections caused by the USA300 and non-USA300 strains at a NICU in Japan. METHODS: This retrospective cohort study was conducted between November 2011 and October 2016 at Tokyo Metropolitan Children's Medical Center in Japan. All MRSA isolated after 48h of hospitalization were included for analysis by pulsed-field gel electrophoresis (PFGE) using the standard USA300 strain. Genes were tested for Panton-Valentine leukocidin (PVL) and arginine catabolic mobile element (ACME). A whole genome sequence was performed for representative isolates of USA300. RESULTS: In total, 109 MRSA isolates were included for analysis. PFGE classified 34 and 75 isolates of USA300 and non-USA300 MRSA, respectively. Both PVL and ACME genes were detected in USA300 and non-USA300 strains at rate of 100% (34/34) and 5.3% (4/75), respectively (P<0.05). There was no statistically significant difference in the proportion of clinical diseases between USA- 300 and non-USA 300 strains. CONCLUSIONS: Infants with USA300 MRSA infection did not differ significantly from those with non-USA300 MRSA infection.

DOI PubMed

Genetic and Transcriptomic Analyses of Ciprofloxacin-Tolerant Staphylococcus aureus Isolated by the Replica Plating Tolerance Isolation System (REPTIS).

Miki Matsuo, Miyu Hiramatsu, Madhuri Singh, Takashi Sasaki, Tomomi Hishinuma, Norio Yamamoto, Yuh Morimoto, Teruo Kirikae, Keiichi Hiramatsu

Antimicrobial agents and chemotherapy 63 ( 2 ) e02019 - 18 2019年02月 [査読有り] [国際誌]

We developed a simple, efficient, and cost-effective method, named the replica plating tolerance isolation system (REPTIS), to detect the antibiotic tolerance potential of a bacterial strain. This method can also be used to quantify the antibiotic-tolerant subpopulation in a susceptible population. Using REPTIS, we isolated ciprofloxacin (CPFX)-tolerant mutants (mutants R2, R3, R5, and R6) carrying a total of 12 mutations in 12 different genes from methicillin-sensitive Staphylococcus aureus (MSSA) strain FDA209P. Each mutant carried multiple mutations, while few strains shared the same mutation. The R2 strain carried a nonsense mutation in the stress-mediating gene, relA Additionally, two strains carried the same point mutation in the leuS gene, encoding leucyl-tRNA synthetase. Furthermore, RNA sequencing of the R strains showed a common upregulation of relA Overall, transcriptome analysis showed downregulation of genes related to translation; carbohydrate, fat, and energy metabolism; nucleotide synthesis; and upregulation of amino acid biosynthesis and transportation genes in R2, R3, and R6, similar to the findings observed for the FDA209P strain treated with mupirocin (MUP0.03). However, R5 showed a unique transcription pattern that differed from that of MUP0.03. REPTIS is a unique and convenient method for quantifying the level of tolerance of a clinical isolate. Genomic and transcriptomic analyses of R strains demonstrated that CPFX tolerance in these S. aureus mutants occurs via at least two distinct mechanisms, one of which is similar to that which occurs with mupirocin treatment.

DOI PubMed

Regional outbreak of community-associated methicillin-resistant Staphylococcus aureus ST834 in Japanese children.

Yuki Uehara, Takashi Sasaki, Tadashi Baba, Yujie Lu, Eri Imajo, Yuka Sato, Shigeru Tanno, Munehiro Furuichi, Miki Kawada, Keiichi Hiramatsu

BMC infectious diseases 19 ( 1 ) 35 - 35 2019年01月 [査読有り] [国際誌]

BACKGROUND: Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infection has recently become a challenging problem worldwide and in Japan. We experienced 10 pediatric patients infected with CA-MRSA and hospitalized from 2011 to 2014 in a tertiary care hospital in Saitama, Japan, and assessed the characteristic of the strains using a whole genome sequencing (WGS)-based approach. METHODS: CA-MRSA strains isolated from infected patients who required hospitalization for treatment were evaluated in this study. Antimicrobial susceptibility tests, molecular typing by PCR and pulse-field gel electrophoresis (PFGE) were performed to characterize MRSA strains. WGS was performed for detailed genetic analysis. RESULTS: A total of 582 MRSA strains (35.2%) were identified among 1625 S. aureus strains collected during the study period. Ten MRSA strains (1.7%) were defined as CA-MRSA clinically, and all were isolated from pediatric patients. All strains mainly caused purulent lymphadenitis, were susceptible to fluoroquinolone and tetracycline, exhibited sequence type (ST) 834 or its single-locus variants and contained staphylococcal cassette chromosome mec (SCCmec) type IVc. Phylogenic analysis by PFGE and WGS revealed close relatedness of all strains, with the number of single nucleotide polymorphisms ranging from 35 to 119 by WGS. Out of the ten strains, nine possessed the genomic island SaPISaitama2 containing tst, sec and sel genes. SaPISaitama2 comprises a mosaic of genomic islands SaPIm4 and SaPIm1 harbored by a hospital-associated MRSA strain Mu50. CONCLUSIONS: This study describes a regional outbreak of ST834-related CA-MRSA in children with a unique pathogenicity island in Japan. Pediatric patient tropism of this clone could be enhanced by susceptibility to fluoroquinolones and tetracyclines, which cannot be prescribed to children.

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Fecal Freezing Preservation Period Influences Colonization Ability for Fecal Microbiota Transplantation.

Takahashi M, Ishikawa D, Sasaki T, Lu YJ, Kuwahara-Arai K, Kamei M, Shibuya T, Osada T, Hiramatsu K, Nagahara A

J Appl Microbiol. 126 ( 3 ) 973 - 984 2019年 [査読有り]

The Microbial Composition of Bacteroidetes Species in Ulcerative Colitis Is Effectively Improved by Combination Therapy With Fecal Microbiota Transplantation and Antibiotics.

Dai Ishikawa, Takashi Sasaki, Masahito Takahashi, Kyoko Kuwahara-Arai, Keiichi Haga, Shoko Ito, Koki Okahara, Akihito Nakajima, Tomoyoshi Shibuya, Taro Osada, Keiichi Hiramatsu, Sumio Watanabe, Akihito Nagahara

Inflammatory bowel diseases 24 ( 12 ) 2590 - 2598 2018年11月 [査読有り] [国際誌]

Background: We previously reported that fresh fecal microbiota transplantation (FMT) after triple-antibiotic therapy (amoxicillin, fosfomycin, and metronidazole [AFM]; A-FMT) synergistically contributed to the recovery of phylum Bacteroidetes composition associated with the endoscopic severity and treatment efficacy of ulcerative colitis (UC). Here, we performed further microbial analyses using a higher-resolution method to identify the key bacterial species in UC and determine whether viable Bacteroidetes species from donor feces were successfully colonized by A-FMT. Methods: The taxonomic composition of Bacteroidetes in 25 healthy donors and 27 UC patients at baseline was compared at the species level using a heat-shock protein (hsp) 60-based microbiome method. Microbiota alterations before and after treatment of UC patients were also analyzed in 24 cases (n = 17 A-FMT; n = 3 mono-AFM; n = 4 mono-FMT). Results: We found species-level dysbiosis within the phylum Bacteroidetes in UC samples, which was associated with reduced species diversity, resulting from hyperproliferation and hypoproliferation of particular species. Moreover, in responders treated with A-FMT, diversity was significantly recovered at 4 weeks after a fresh round of FMT, after which high degrees of similarity in Bacteroidetes species composition among recipients and donors were observed. Conclusions: A-FMT alleviated intestinal dysbiosis, which is caused by the loss of Bacteroidetes species diversity in patients with UC. Eradication of dysbiotic indigenous Bacteroidetes species by AFM pretreatment might promote the colonization of viable Bacteroidetes cells, thereby improving the intestinal microbiota dysbiosis induced by UC. Our findings serve as a basis for further investigations into the mechanisms of FMT.

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Development of a New Application for Comprehensive Viability Analysis Based on Microbiome Analysis by Next-Generation Sequencing: Insights into Staphylococcal Carriage in Human Nasal Cavities.

Yu Jie Lu, Takashi Sasaki, Kyoko Kuwahara-Arai, Yuki Uehara, Keiichi Hiramatsu

Applied and environmental microbiology 84 ( 11 ) e00517 - 18 2018年06月 [査読有り] [国際誌]

The nasal carriage rate of Staphylococcus aureus in human is 25 to 30%, and S. aureus sporadically causes severe infections. However, the mechanisms underlying staphylococcal carriage remain largely unknown. In the present study, we constructed an rpoB-based microbiome method for staphylococcal species discrimination. Based on a microbiome scheme targeting viable cell DNA using propidium monoazide (PMA) dye (PMA microbiome method), we also developed a new method to allow the comprehensive viability analysis of any bacterial taxon. To clarify the ecological distribution of staphylococci in the nasal microbiota, we applied these methods in 46 nasal specimens from healthy adults. PMA microbiome results showed that Staphylococcaceae and Corynebacteriaceae were the most predominant viable taxa (average relative abundance: 0.435262 and 0.375195, respectively), and Staphylococcus epidermidis exhibited the highest viability in the nasal microbiota. Staphylococcus aureus detection rates from nasal specimens by rpoB-based conventional and PMA microbiome methods were 84.8% (39 of 46) and 69.5% (32 of 46), respectively, which substantially exceeded the values obtained by a culture method using identical specimens (36.9%). Our results suggest that Staphylococcaceae species, especially S. epidermidis, adapted most successfully to human nasal cavity. High detection of S. aureus DNA by microbiome methods suggests that almost all healthy adults are consistently exposed to S. aureus in everyday life. Furthermore, the large difference in S. aureus detection rates between culture and microbiome methods suggests that S. aureus cells frequently exist in a viable but nonculturable state in nasal cavities. Our method and findings will contribute to a better understanding of the mechanisms underlying carriage of indigenous bacteria.IMPORTANCE Metagenomic analyses, such as 16S rRNA microbiome methods, have provided new insights in various research fields. However, conventional 16S rRNA microbiome methods do not permit taxonomic analysis of only the viable bacteria in a sample and have poor resolving power below the genus level. Our new schemes allowed for viable cell-specific analysis and species discrimination, and nasal microbiome data using these methods provided some interesting findings regarding staphylococcal nasal carriage. According to our comprehensive viability analysis, the high viability of Staphylococcus species, especially Staphylococcus epidermidis, in human nasal carriage suggests that this taxon has adapted most successfully to human nasal tissue. Also, a higher detection rate of S. aureus DNA by microbiome methods (84.8%) than by a culture method (36.9%) suggests that almost all healthy adults are consistently exposed to Staphylococcus aureus in the medium and long term. Our findings will contribute to a better understanding of the mechanisms underlying the carriage of indigenous bacteria.

DOI PubMed

Risk factors of fecal colonization with extended-spectrum β-lactamase-producing Enterobacteriaceae in special nursing homes in Japan.

Yokoyama K, Uehara Y, Sasaki T, Hiramatsu K

J Gen Fam Med. 19 ( 3 ) 90 - 96 2018年05月 [査読有り] [国内誌]

Objective: Japanese welfare facilities for the elderly are called as special nursing home (SNH), providing conventional-type with group care or unit-type with individual care. We investigated the risk factors of fecal colonization with extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) of elderly who required care at SNH in Japan. Methods: The feces discharged on diaper were obtained from the total of 100 residents with fecal incontinence in 9 SNHs located in Tokyo, Japan. The samples were cultured on ESBL selection agar, and ESBL-E were determined by the antimicrobial susceptibility test and genetic analysis. The status of the residents and the characteristics of facilities, especially about the incontinence care, were obtained by questionnaire methods. Statistical analysis was performed to determine the factors related to carriage of ESBL-E. Results: Extended-spectrum β-lactamase-producing Enterobacteriaceae was isolated from 53 of 100 SNH residents. Risk factors of colonization among the individual residents were not found. The prevalence of ESBL-E carriage was significantly higher in the 6 conventional-type facilities than in the 3 unit-type facilities (P = .015). The cart for diaper exchange was used in 5 of 6 conventional-type facilities in 9 SNHs, and their residents tended to show high of ESBL-E colonization rate. The residents living in unit-type facilities which do not use gloves for changing diaper tended to show high ESBL-E colonization rate than other 2 facilities using gloves. Conclusions: It is suggested that using the cart for changing diaper has relation to carry ESBL-E. In the facilities using cart, revision of their methods of excretion care will be needed.

DOI PubMed

Maternal High Fiber Diet during Pregnancy and Lactation Influences Regulatory T Cell Differentiation in Offspring in Mice

Akihito Nakajima, Naoko Kaga, Yumiko Nakanishi, Hiroshi Ohno, Junki Miyamoto, Ikuo Kimura, Shohei Hori, Takashi Sasaki, Keiichi Hiramatsu, Ko Okumura, Sachiko Miyake, Sonoko Habu, Sumio Watanabe

JOURNAL OF IMMUNOLOGY ( AMER ASSOC IMMUNOLOGISTS ) 199 ( 10 ) 3516 - 3524 2017年11月 [査読有り]

Short-chain fatty acids (SCFAs), the end products of dietary fiber, influence the immune system. Moreover, during pregnancy the maternal microbiome has a great impact on the development of the offspring's immune system. However, the exact mechanisms by which maternal SCFAs during pregnancy and lactation influence the immune system of offspring are not fully understood. We investigated the molecular mechanisms underlying regulatory T cell (T-reg) differentiation in offspring regulated by a maternal high fiber diet (HFD). Plasma levels of SCFAs in offspring from HFD-fed mice were higher than in those from no fiber diet-fed mice. Consequently, the offspring from HFD-fed mice had higher frequencies of thymic T-reg (tT(reg)) and peripheral T-regs. We found that the offspring of HFD-fed mice exhibited higher autoimmune regulator (Aire) expression, a transcription factor expressed in the thymic microenvironment, suggesting SCFAs promote tT(reg) differentiation through increased Aire expression. Notably, the receptor for butyrate, G protein-coupled receptor 41 (GPR41), is highly expressed in the thymic microenvironment and Aire expression is not increased by stimulation with butyrate in GPR41-deficient mice. Our studies highlight the significance of SCFAs produced by a maternal HFD for T-reg differentiation in the thymus of offspring. Given that Aire expression is associated with the induction of tT(regs), the maternal microbiome influences T-reg differentiation in the thymus of offspring through GPR41-mediated Aire expression.

DOI

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