海外専門家コメント
MRSAなどの耐性菌にも効く、新たな抗生物質の開発について：海外専門家コメント
・これは、2015年1月11日にジャーナリスト向けに発行したサイエンス・アラートです。
・記事の引用は自由ですが、末尾の注意書きもご覧下さい。
＜SMC発サイエンス・アラート＞
MRSAなどの耐性菌にも効く、新たな抗生物質の開発について：海外専門家コメント
アメリカ、ノースイースタン大学のKim Lewis教授らのグループは、自然環境中の未知の微生物群から、多様な細菌を殺し、耐性菌に対しても効果がある新たな抗生物質を発見しました。「iChipツール」という独自の手法により、これまで培養できなかった微生物由来の物質を調べたことで得られた成果です。「テイクソバクチン（ Teixobactin）」と名付けられたこの抗生物質は、バンコマイシンと同様に、細菌の細胞壁合成を阻害するとのことです。
抗生物質は細菌による感染症の治療薬として広く普及していますが、多用することで細菌の突然変異を誘発し、薬剤に耐性を示すものが増えています。バンコマイシンはメチシリン耐性黄色ブドウ球菌（MRSA）を殺菌できる強力な抗生物質で、「薬剤耐性菌の切り札」として使われてきましたが、すでにバンコマイシン耐性腸球菌（VRE）やバンコマイシン耐性ブドウ球菌（VRSA）なども出現しています。
今回、著者らは、マウスなどの実験によって、テイクソバクチンが、MRSAや、同じく院内感染で大腸炎を引き起こすクロストリジウム・ディフィシル、結核菌などの多様な細菌を殺すことを確認しました。ヒトに用いる薬剤にするには数年以上かかると思われますが、新規の抗生物質が開発できていない現状を打破するものと期待されています。論文は1月8日付けのNatureに掲載されました。
論文原著
Kim Lewis. et al., "A new antibiotic kills pathogens without detectable resistance", Nature 517, 455–459, 2015
http://dx.doi.org/10.1038/nature14098
翻訳は迅速さを優先しております。ご利用の際には必ず原文をご確認ください。
Prof Neil Woodford
Head of Public Health England’s Antimicrobial Resistance and Healthcare Associated Infections Reference Unit
年々、抗生物質に対する耐性が強力になっており深刻です。今回の成果は現状を打破する可能性をもたらしたもので、歓迎すべきといえます。ただし、一部の細菌（大腸菌などのグラム陰性菌）には効かないため、さらなる抗生物質の開発が必要です。
原文
“Public Health England welcomes the development of new therapies that can be used to treat bacterial infections successfully. The rise in antibiotic resistance is a threat to modern healthcare as we know it so this discovery could potentially help to bridge the ever increasing gap between infections and the medicines we have available to treat them.
“Although this is a step forwards, this new discovery would not be suitable for treating infections caused by E.coli, Klebsiella or other Gram-negative bacteria. These are the focus of many concerns about antibiotic resistance and finding a new potential treatment for these would be a major breakthrough.
“Taking any potential antibacterial compound from discovery to successful licensing is a long, costly and difficult process. However it is one that needs to be encouraged while we tackle other elements that contribute to the development of antibiotic resistance and seek to preserve the antibiotics we do have.”
Dr Richard Seabrook
Head of Business Development at the Wellcome Trust, (Richard Seabrook works in innovation and technology transfer at the Wellcome Trust, including managing funding for drug seeding, quite a few of which are antimicrobials
よいニュースですが、研究はまだ始まったばかりです。薬剤耐性菌の出現が深刻化しているにもかかわらず、この数十年間、新たな抗生物質の開発は進んでいませんでした。培養困難だった土壌細菌をも対象にできる今回の解析手法は、薬に結びづく新たな化合物を探索するのに有効です。ただし、今回のテイクソバクチンは実験動物段階で、ヒトにも有効かどうかは定かではありません。
原文
“Although still in the early stages of research, the discovery of a potential new class of antibiotics is good news: the development of new antibiotics has stalled in recent decades, while resistance to existing drugs becomes an ever more serious threat to human health. Screening previously unculturable soil bacteria is a new twist in the search for novel compounds that might have antibiotic potential and it is encouraging to see this approach yielding results. However, we will not know whether teixobactin will be effective in humans until this research is taken from animal testing in the lab to clinical trials.”
Prof. Mark Woolhouse
Professor of Infectious Disease Epidemiology, University of Edinburgh
今回の成果は「金脈の一部」にすぎず、まだ未知の微生物由来の抗生物質が多く眠っていると思います。耐性菌による被害を食い止めるために、より多くの種類の抗生物質を探索すべきでしょう。
原文
“Any report of a new antibiotic is auspicious, but what most excites me about the paper by Lewis et al. is the tantalising prospect that this discovery is just the tip of the iceberg. Most antibiotics are natural products derived from microbes in the soil. The ones we have discovered so far come from a tiny subset of the rich diversity of microbes that live there. Lewis et al. have found a way to look for antibiotics in other kinds of microbe, part of the so-called microbial “dark matter” that is very difficult to study. Others have done the same thing using different approaches. It may be that we will find more, perhaps many more, antibiotics using these latest techniques. We should certainly be trying – the antibiotic pipeline has been drying up for many years now; we need to open it up again, and develop alternatives to antibiotics at the same time, if we are to avert a public health disaster.”
Dr Angelika Gründling
Reader in Molecular Microbiology, Imperial College London,
抗生物質を作り出す微生物を遺伝子レベルで探索し、配列や化学構造を同定できる新たな手法を開発できた点が大きいと思います。これまで培養できなかった微生物由来の物質が探せるようになります。
原文
“Antimicrobial resistance is a widespread problem that is slowly undermining our ability to treat common bacterial infections. The study by Ling et al., which describes the discovery of a new antibiotic that kills a large range of bacteria, raises our hopes that new antibiotics can be brought to the clinics in the not too distant future. The authors used an old strategy, looking for antimicrobials naturally produced by bacteria, but now with a new and important twist – in a new group of bacteria, which in the past were considered unculturable. The authors developed a method to propagate many of these ‘unculturable’ bacteria, which allowed them to tap them as a source of new antimicrobials. The great hope is now that many more new antibiotics can be uncovered in a similar manner. This study is also a great testimony for the technological advances that have been made in recent years and the speed with which one can now progress from the discovery of a new compound, to the identification of it chemical structure, its producer down to the genes coding for the enzymes required for its production.
“But before getting too carried away, it’s important to bear in mind that the new antibiotic only works against certain types of bacteria – such as MRSA and Streptococcus, and not on other multi-drug resistant pathogens such as E. coli, Klebsiella and Pseudomonas, which are all major causes of infection in humans. And of course the new antibiotic described in the paper has yet to be tested in humans. It is possible that it might not be as effective as hoped and there could be unforeseen side-effects that might limit its use.”
Dr Bob Lauder
Associate Dean in the Faculty of Health and Medicine, Lancaster University
新しい解析手法はコストや規模がそれほど大がかりではなく、現実的です。ただし、テイクソバクチンをヒトに投与するには、安全性や投与量を調べる必要があります。
原文
“The search for new antibiotics is an enormous challenge, and this work reports a major development in this arena. The importance of this arena is seen in the fact that the Longitude Prize 2014 chose antibiotic resistance as the topic for the prize from a wide range of really major social issues such as dementia and the provision of safe drinking water and food.
“Antibiotics made many conditions which were normally fatal, survivable, and so they have had an enormous impact on all of our lives. However, the widely recognised danger of antibiotic resistance, when bacteria develop resistance to an antibiotic rendering it much less useful, could undermine the progress in healthcare in this area made over the last 70 years.
“The costs of discovering, developing and testing a new antibiotic are huge and the financial risks are large as the antibiotic may have a limited lifespan if bacterial resistance develops. In fact few new antibiotics have been identified in the last 30 years and so this thorough study, is a welcome development in a field looking for new advances.
“The antibiotic identified is a bacterial product; produced by one soil bacteria to stop the growth of others. However, rather than grow these using conventional microbiological approaches, the approach taken by this group was to explore antibiotic production in the soil. This allowed them to access the products from bacteria which cannot be cultured in a lab. In fact it is likely than the vast majority of bacteria in soil cannot easily be cultured in the lab, and so this is likely to be an approach which is more widely used in the future to access novel antibiotics.
“The authors have conducted a detailed and thorough study which has reported the structure of this new antibiotic. Although this is a complex molecule it has a structure which is very likely to be suitable for synthesis, and hence production at a cost and scale which would be appropriate for a therapeutic material.
“The report is very exciting but more work needs to be done before this new antibiotic can be used. While the initial toxicity studies reported suggest that it will likely be safe to use, that work needs to be developed. In addition more detailed studies will be needed to understand dosage, how much and how often should it be taken. The data suggest that it may be cleared from human plasma quite quickly.
“This new antibiotic appears to work in an interesting way, attacking key parts of the bacterial coat. While that may make it less likely that antibiotic resistance develops, that's not a certainty and we'll all need to use this new compound, and any others developed carefully, otherwise we risk wasting the potential this antibiotic has.”
Prof Roger Pickup
Associate Dean for Research, Lancaster University
非常にエキサイティングな手法が開発されました。今までなかったユニークな効果を発揮する抗生物質開発につながるかもしれません。ただし、医療や農業、畜産業における抗生物質の濫用をやめる、単なる風邪やインフルエンザで抗生物質を処方しないよう医学教育を徹底する、といったことは必要でしょう。
原文
“This is a very exciting development. In the microbial world the uncultured majority, which constitutes >99.9% of all bacteria, are rarely exploited for their products. Tapping into this vast resource by culture has been unfunded by government and industry, perhaps as it not considered exciting science in comparison to the characterisation of the microbial world by methods such as the next generation sequencing. Coupled with the reluctance of the pharmaceutical industry to fund the discovery of new antibiotics, the identification of this new antibiotic in this often unexplored sphere of microbiology is very exciting. This may lead to the discovery of more unique antibiotics that can come on line and replace, or work in tandem, with current therapies that fight infection, particularly those caused by bacteria currently resistant to the spectrum of antibiotics available to us at present.
“These ‘magic bullets’ have been discovered before only to have their effectiveness whittled away by the emergence of bacteria resistant to those antibiotics. Although the prediction that developing bacterial resistance to Teixobactin will be more difficult due to its mode of action, precaution is a key principle here. Bacteria are tenacious in their ability to rapidly evolve and become resistant to antibiotics; lessons have been learnt from the current antibiotic crisis and these must implemented if Teixobactin is to be an effective readily available drug for fighting infection. These lessons include educating the public and medical professionals to prevent indiscriminate use of prescriptions (this drug will not fight cold and flu [viral diseases]), controlling its use in farming and animal production and using it as a second line defence if current antibiotics fail. Hopefully the pharmaceutical industry will take note of this discovery and direct funds to explore and exploit the bacteria that, at present, remain uncultured.”
●●●参考資料●●●
薬剤耐性菌をめぐる最近のイシュー
AFP通信（2014.12.17）
リオ五輪セーリング会場で薬剤耐性菌発見、医療廃棄物由来か
http://www.jiji.com/jc/a?g=afp_all&k=20141217032152a
AFP通信(2014.8.31)
高まる薬剤耐性菌リスク、インドの抗生物質多用が世界の問題に
http://www.afpbb.com/articles/-/3024540
産経新聞（2014.3.20）
4年で患者114人感染 多剤耐性菌、死者も 国立病院機構大阪医療センター
http://www.sankei.com/west/news/140320/wst1403200004-n1.html
薬剤耐性菌について
日本感染症学会
多剤耐性菌を正しく理解するための Q&A
http://www.kansensho.or.jp/mrsa/100913publicqa.html
国立感染症研究所
薬剤耐性菌感染症
http://www.nih.go.jp/niid/ja/route/dr.html
記事のご利用にあたって
マスメディア、ウェブを問わず、科学の問題を社会で議論するために継続して
メディアを利用して活動されているジャーナリストの方、本情報をぜひご利用下さい。
「サイエンス・アラート」「ホット・トピック」のコンセプトに関してはコチラをご覧下さい。記事の更新や各種SMCからのお知らせをメール配信しています。
サイエンス・メディア・センターでは、このような情報をメールで直接お送りいたします。ご希望の方は、下記リンクからご登録ください。（登録は手動のため、反映に時間がかかります。また、上記下線条件に鑑み、広義の「ジャーナリスト」と考えられない方は、登録をお断りすることもありますが御了承下さい。ただし、今回の緊急時に際しては、このようにサイトでも全ての情報を公開していきます）【メディア関係者データベースへの登録】 http://smc-japan.org/?page_id=588
記事について
○ 私的／商業利用を問わず、記事の引用（二次利用）は自由です。ただし「ジャーナリストが社会に論を問うための情報ソース」であることを尊重してください（アフィリエイト目的の、記事丸ごとの転載などはお控え下さい）。
○ 二次利用の際にクレジットを入れて頂ける場合（任意）は、下記のいずれかの形式でお願いします：
・一般社団法人サイエンス・メディア・センター ・（社）サイエンス・メディア・センター
・（社）SMC ・SMC-Japan.org○ この情報は適宜訂正・更新を行います。ウェブで情報を掲載・利用する場合は、読者が最新情報を確認できるようにリンクをお願いします。
お問い合わせ先
○この記事についての問い合わせは「御意見・お問い合わせ」のフォーム、あるいは下記連絡先からお寄せ下さい：
一般社団法人 サイエンス・メディア・センター（日本） Tel/Fax: 03-3202-2514
