Researchers Database

sasahara teppei

    InfectionandImmunityClinicalInfectiousDiseases Associate Professor
Last Updated :2021/10/17

Researcher Information


  • Ph. D.(Jichi Medical University)
  • M. D.(Sapporo Medical University)


Research funding number

  • 30448849

J-Global ID

Research Interests

  • Sexually transmitted infections   Healthcare associated infections   Contamination of hospital environments   Spore-forming bacteria   Infection control   

Research Areas

  • Life sciences / Infectious disease / Infection control

Academic & Professional Experience

  • 2015/01 - Today  Jichi Medical UniversitySchool of MedicineAssistant Professor
  • 2010/04  Jichi Medical UniversitySchool of MedicineReseach associate
  • 2006/04 - 2010/03  Jichi Medical University HospitalCenter for Clinical Infectious DiseasesFellow
  • 2003/04 - 2006/03  International Medical Center of JapanDept. of General Internal MedicineResident


  • 2006/04 - 2010/03  Jichi Medical University  School of Medicine, postgraduate
  • 1997/04 - 2003/03  Sapporo Medical University  School of Medicine

Association Memberships


Published Papers

  • Teppei Sasahara, Shunji Hayashi, Kouichi Hosoda, Yuji Morisawa, Yoshikazu Hirai
    BIOCONTROL SCIENCE 19 (3) 129 - 134 1342-4815 2014/09 [Refereed][Not invited]
    Bacillus cereus is a spore-forming bacterium. B. cereus occasionally causes nosocomial infections, in which hand contamination with the spores plays an important role. Therefore, hand hygiene is the most important practice for controlling nosocomial B. cereus infections. This study aimed to determine the appropriate hand hygiene procedure for removing B. cereus spores. Thirty volunteers' hands were experimentally contaminated with B. cereus spores, after which they performed 6 different hand hygiene procedures. We compared the efficacy of the procedures in removing the spores from hands. The alcohol-based hand-rubbing procedures scarcely removed them. The soap washing procedures reduced the number of spores by more than 2 log(10). Extending the washing time increased the spore-removing efficacy of the washing procedures. There was no significant difference in efficacy between the use of plain soap and antiseptic soap. Handwashing with soap is appropriate for removing B. cereus spores from hands. Alcohol-based hand-rubbing is not effective.
  • 笹原 鉄平, 大西 翼, 渡辺 美智代
    日本環境感染学会誌 = Japanese journal of environmental infecions 日本環境感染学会 29 (6) 424 - 428 1882-532X 2014 [Refereed][Not invited]
  • Masanori Ogawa, Teppei Sasahara
    JOURNAL OF OCCUPATIONAL MEDICINE AND TOXICOLOGY 7 24  1745-6673 2012/12 [Refereed][Not invited]
    Background: Biological monitoring is used to assess toluene exposure in medical examinations. The American Conference of Industrial Hygienists, Japanese Society for Occupational Health and Deutsche Forschungsgemeinschaft have proposed various biological exposure determinants, such as toluene in blood and urine, and o-cresol in urine. Toluene in blood is a common biomarker among them. Toluene is a volatile organic solvent; therefore, sample preservation under appropriate conditions before measurement is necessary. However, little study has been done on the stability of toluene in workers' blood samples under conditions simulating those of a medical examination. Finding: We carried out a pilot study on the stability of toluene in blood from humans, according to different methods of sample preservation. Toluene in blood was analyzed by head space-gas chromatography/mass spectrometry. The sealing performance of the vial was examined by using toluene-added blood and the stability of toluene in blood according to the preservation period was examined by using blood from toluene-handling workers, which was collected with vacuum blood tubes. The sealing performance of the headspace vial used in this study was good for three days and toluene in blood in tubes from workers was stable at least within 8 hours up to blood packing at 4 degrees C. Conclusion: We could propose that the collected blood need only be transferred into headspace vials on the collection day and analyzed within a few days, if the samples are preserved at 4 degrees C. Our data size is limited; however, it may be considered basic information for biological monitoring in medical examinations.
  • Masataka Oda, Manabu Hashimoto, Masaya Takahashi, Yuka Ohmae, Soshi Seike, Ryoko Kato, Aoi Fujita, Hideaki Tsuge, Masahiro Nagahama, Sadayuki Ochi, Teppei Sasahara, Shunji Hayashi, Yoshikazu Hirai, Jun Sakurai
    PLOS ONE 7 (6) e38054  1932-6203 2012/06 [Refereed][Not invited]
    Bacillus cereus (B. cereus) is a pathogen in opportunistic infections. Here we show that Bacillus cereus sphingomyelinase (Bc-SMase) is a virulence factor for septicemia. Clinical isolates produced large amounts of Bc-SMase, grew in vivo, and caused death among mice, but ATCC strains isolated from soil did not. A transformant of the ATCC strain carrying a recombinant plasmid containing the Bc-SMase gene grew in vivo, but that with the gene for E53A, which has little enzymatic activity, did not. Administration of an anti-Bc-SMase antibody and immunization against Bc-SMase prevented death caused by the clinical isolates, showing that Bc-SMase plays an important role in the diseases caused by B. cereus. Treatment of mouse macrophages with Bc-SMase resulted in a reduction in the generation of H2O2 and phagocytosis of macrophages induced by peptidoglycan (PGN), but no effect on the release of TNF-alpha and little release of LDH under our experimental conditions. Confocal laser microscopy showed that the treatment of mouse macrophages with Bc-SMase resulted in the formation of ceramide-rich domains. A photobleaching analysis suggested that the cells treated with Bc-SMase exhibited a reduction in membrane fluidity. The results suggest that Bc-SMase is essential for the hydrolysis of SM in membranes, leading to a reduction in phagocytosis.
  • T. Sasahara, S. Hayashi, Y. Morisawa, T. Sakihama, A. Yoshimura, Y. Hirai
    EUROPEAN JOURNAL OF CLINICAL MICROBIOLOGY & INFECTIOUS DISEASES 30 (2) 219 - 226 0934-9723 2011/02 [Refereed][Not invited]
    We describe an outbreak of Bacillus cereus bacteremia that occurred at Jichi Medical University Hospital in 2006. This study aimed to identify the source of this outbreak and to implement appropriate control measures. We reviewed the charts of patients with blood cultures positive for B. cereus, and investigated B. cereus contamination within the hospital environment. Genetic relationships among B. cereus isolates were analyzed. Eleven patients developed B. cereus bacteremia between January and August 2006. The hospital linens and the washing machine were highly contaminated with B. cereus, which was also isolated from the intravenous fluid. All of the contaminated linens were autoclaved, the washing machine was cleaned with a detergent, and hand hygiene was promoted among the hospital staff. The number of patients per month that developed new B. cereus bacteremia rapidly decreased after implementing these measures. The source of this outbreak was B. cereus contamination of hospital linens, and B. cereus was transmitted from the linens to patients via catheter infection. Our findings demonstrated that bacterial contamination of hospital linens can cause nosocomial bacteremia. Thus, blood cultures that are positive for B. cereus should not be regarded as false positives in the clinical setting.
  • 林俊治, 笹原鉄平, 吉村章, 森澤雄司, 高岡恵美子, 平井義一
    臨床検査 53 (4) 501 - 506 0485-1420 2009/04 [Not refereed][Not invited]
  • Teppei Sasahara, Shunji Hayashi, Yuji Morisawa, Yoshikazu Hirai
    Japanese Journal of Environmental Infections 一般社団法人 日本環境感染学会 24 (5) 312 - 318 1883-2407 2009 [Refereed][Not invited]
    Hospital towels must be disinfected by hot water cleaning. However, towels are sometimes contaminated with Bacillus cereus spores resistant to heat. Such contamination can cause healthcare associated infections. Thus, B. Cereus contamination of hospital towels should be routinely evaluated to control infections. However, standard methods for the evaluation have not yet been established. In the present study, B. Cereus contamination of hospital towels was measured using four methods the agar contact method, the swab method, the simple shaking method, and the glass bead shaking method. The agar contact method could not quantify the towel contamination. The swab method could detect only a small number of bacteria from hospital towels. Both shaking methods could detect a large number of bacteria from hospital towels. Especially, the glass bead shaking method detected twice as many bacteria as the simple shaking method. These results indicate that the glass bead shaking method is the most suitable method for evaluating B. Cereus contamination of hospital towels. In addition, our results demonstrated that B. Cereus does not have uniform distribution in towels. Therefore, evaluation of B. Cereus contamination must examine several test pieces of the same towel. © 2009, Japanese Society for Infection Prevention and Control. All rights reserved.
    神経治療学 23 (2) 151 - 155 0916-8443 2006/03 [Refereed][Not invited]

Books etc

  • 感度と特異度からひもとく感染症診療のDecision Making
    笹原鉄平 (Contributor梅毒血清検査 クラミジア・トラコマチス抗原(遺伝子検査を除く))
    文光堂 2012
  • 感染症事典
    笹原鉄平 (Contributorセレウス菌)
    オーム社 2012
  • 感染症診療ガイドライン総まとめ
    笹原鉄平 (Contributor性感染症)
    総合医学社 2010
  • 市中感染症診療の考え方と進め方IDATEN感染症セミナー
    笹原鉄平 (Contributor細菌性髄膜炎のマネジメント)
    医学書院 2009
  • 抗菌薬について内心疑問に思っていることQ&A
    笹原鉄平 (Contributor抗菌薬治療の効果判定はどのようにすればよいですか? 抗菌薬治療中, その抗菌薬を無効と判断した場合, どうしたらよいですか?)
    羊土社 2009
  • 臨床に直結する感染症診療のエビデンス
    笹原鉄平 (Contributorクリプトコッカス髄膜炎 (Cryptococcal meningo- encephalitis) の治療において血清および髄液中クリプトコッカス抗原(Cryptococcal polysaccharide antigen)のtiterモニタリングは治療効果の指標となりうるか?)
    文光堂 2008

Conference Activities & Talks


Awards & Honors

  • 2012/11 East Asian Conference on Infection control and Prevention Silver award
     Bacterial Growth in Intravenous Fluid Products 
    受賞者: Teppei Sasahara
  • 2006/10 Hospital Infection Society Poster award
     Staphylococcal scalded skin syndrome outbreak due to methicillin-resistant Staphylococcus aureus in the neonatal care unit 
    受賞者: Teppei Sasahara

Research Grants & Projects

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