| ウェルシュ菌 |
|
ウェルシュ菌のグラム染色像
|
| 分類 |
ドメ
イン |
: |
細菌 Bacteria |
| 門 |
: |
フィルミクテス門
Firmicutes |
| 綱 |
: |
クロストリジウム綱
Clostridia |
| 目 |
: |
クロストリジウム目
Clostridiales |
| 科 |
: |
クロストリジウム科
Clostridiaceae |
| 属 |
: |
クロストリジウム属
Clostridium |
| 種 |
: |
C. ペルフリンゲンス
Clostridium perfringens |
|
| 学名 |
Clostridium perfringens
(Veillon & Zuber 1898)
Hauduroy et al. 1937 |
ウェルシュ菌（ウェルシュきん、学名：Clostridium perfringens）とはクロストリジウム属に属する嫌気性桿菌である。河川、下水、海、土壌中など自然界に広く分布している[1]。ヒトを含む動物の腸内細菌叢における主要な構成菌であることが多い。少なくとも12種類の毒素を作り、α, β, ε, ιの4種の主要毒素の産生性によりA, B, C, D, E型の5つの型に分類される。Clostridium perfringens B型菌の毒素はヒツジの赤痢の原因となる。
かつてClostridium welchiiという学名で呼ばれていたことがある。ウィリアム・H・ウェルチ（英語版）が分離培養し1892年にBacillus aerogenes capsulatusと命名したが、後年ウェルチにちなんでBacterium welchii Migula 1900という学名が与えられ、ついでBacillus welchiiやClostridium welchiiと呼ばれるようになった。しかし命名規約上はBacterium welchiiよりも早く命名されたBacillus perfringens Veillon and Zuber 1898に優先権があるため、これが1937年にクロストリジウム属に移されて現在の学名として登録されている。
一般に、ビフィズス菌などと対比され、悪玉菌の代表とされている。臭い放屁の原因、悪玉の常在菌である。
目次
- 1 性状
- 2 病原性
- 3 脚注
- 4 参考文献
- 5 関連項目
- 6 外部リンク
性状
グラム陽性非運動性偏性嫌気性であり、生体内または血清添加培地で増殖した場合、莢膜を形成する。一般に芽胞は形成されにくい。至適増殖温度は43-47℃。分裂時間は45℃で約10分間と短い。37℃で最も多くの毒素を産生する[1]。
毒素
A型菌はα毒素、B型菌はα, β, ε毒素、C型菌はα, β毒素、D型菌はα, ε毒素、E型菌はα, ι毒素を産生する。
- (α) アルファー毒素は、ガス壊疽の際の毒素で組織破壊作用があり、肺から吸引した場合、致命的な肺の障害を起こす恐れがあり他の生物兵器同様、テロリストによる使用が懸念されている。
- (β) ベータ毒素は、壊死性腸炎の際の毒素で組織破壊作用がある。
- (ε) イプシロン毒素は、動物実験で神経毒性が見つかっている。
- (ι) イオタ毒素は細胞毒性を示す[2]。
病原性
ウェルシュ菌はその発症機序、病型により、ガス壊疽、出血性腸炎、エンテロトキセミア、食中毒の4種に区別される。
- ガス壊疽
- 主にA型菌により全身中毒症状を示す。但し、全てのA型菌がエンテロトキシン生産性を示すわけではない。
- 出血性腸炎またはピグベル (pigbel)
- C型菌により腸炎を発症、腸管に壊死性病変、出血性病変を形成する。パプアニューギニアの高地で多い。
- エンテロトキセミア
- 毒血症を示す。詳細はエンテロトキセミアを参照。
- 食中毒
- 給食病または給食菌 (food service germ) やカフェテリア菌 (cafeteria germ) の別名で呼ばれることもある。A型菌の産生するエンテロトキシンによる生体内毒素型の食中毒である。芽胞が一旦高温処理される事で芽胞形成能が活性化され、同時に溶存酸素が減少すると共に競合する他の菌が減少し増殖の好条件が成立し、緩徐に冷却される間（至適増殖温度）に食品中で増殖する。毒素の摂取ではなく原因菌の1千万-1億個以上の摂取により、腸管内で菌の増殖と共に芽胞が形成され同時に毒素が産生され毒素により発症する[3]。8〜20時間の潜伏期の後、水様性の下痢を引き起こす。腹痛と下痢は必発であるが嘔吐、発熱は見られない、1〜2日で回復し、予後は良好である[4]。
- 芽胞のみ100℃・1気圧・1時間の加熱で不活性化されず、残存する可能性がある[3]。タンパク性食品が原因食となる場合が多い。
脚注
- ^ a b 『スタンダード栄養・食物シリーズ8 食品衛生学（第3版）』 一色賢司編、2010年、東京化学同人、p.69-70、ISBN 978-4-8079-1603-0
- ^ ウエルシュ菌主要毒素の構造と機能及び活性発現機構に関する研究 日本細菌学雑誌 第61巻 第4号 367-379, 2006
- ^ a b ウエルシュ菌による食中毒について 横浜市衛生研究所感染症・疫学情報課
- ^ ウェルシュ菌 財団法人 日本中毒情報センター
参考文献
- 鹿江雅光、新城敏晴、高橋英司、田淵清、原澤亮編 『最新家畜微生物学』 朝倉書店 1998年 ISBN 4254460198
- 獣医学大辞典編集委員会編集 『明解獣医学辞典』 チクサン出版 1991年 ISBN 4885006104
関連項目
- 気腫疽
- 悪性水腫
- 牛壊死性腸炎
- 鶏壊死性腸炎
- レシチナーゼ反応
外部リンク
- 津下英明「アクチン特異的ADPリボシル化毒素の構造と機能」、『生物物理』第43巻第4号、日本生物物理学会、2003年7月25日、 168-173頁、 doi:10.2142/biophys.43.168、 NAID 110001157629。
- Clostridium perfringensA型菌による新生豚の死亡例 北海道渡島家畜保健衛生所
- ウエルシュ菌 Clostridium perfringens 岡山県立大学
- 国立感染症研究所 感染症情報センター
- 感染症の話 2001年第7週 ウェルシュ菌感染症
- ウェルシュ菌食中毒 (Vol. 29 p. 216-217: 2008年8月号)
|
この項目は、真正細菌（バクテリア）に関連した書きかけの項目です。この項目を加筆・訂正などしてくださる協力者を求めています（Portal:生き物と自然／ウィキプロジェクト 生物）。 |
| Clostridium perfringens |
|
| Photomicrograph of gram-positive Clostridium perfringens bacilli. |
| Scientific classification |
| Kingdom: |
Bacteria |
| Phylum: |
Firmicutes |
| Class: |
Clostridia |
| Order: |
Clostridiales |
| Family: |
Clostridiaceae |
| Genus: |
Clostridium |
| Species: |
C. perfringens |
| Binomial name |
Clostridium perfringens
Veillon & Zuber 1898
Hauduroy et al. 1937 |
Clostridium perfringens (formerly known as C. welchii, or Bacillus welchii) is a Gram-positive, rod-shaped, anaerobic, spore-forming pathogenic bacterium of the genus Clostridium.[1] C. perfringens is everpresent in nature and can be found as a normal component of decaying vegetation, marine sediment, the intestinal tract of humans and other vertebrates, insects, and soil. It has the shortest reported generation time of any organism at 6.3 minutes in thioglycollate medium.[2]
C. perfringens is the third most common cause of food poisoning in the United Kingdom and the United States though it can sometimes be ingested and cause no harm.
Infections due to C. perfringens show evidence of tissue necrosis, bacteremia, emphysematous cholecystitis, and gas gangrene, which is also known as clostridial myonecrosis. The toxin involved in gas gangrene is known as α-toxin, which inserts into the plasma membrane of cells, producing gaps in the membrane that disrupt normal cellular function. C. perfringens can participate in polymicrobial anaerobic infections. Clostridium perfringens is commonly encountered in infections as a component of the normal flora. In this case, its role in disease is minor.
The action of C. perfringens on dead bodies is known to mortuary workers as tissue gas and can be halted only by embalming.
Contents
- 1 Motility
- 2 Food poisoning
- 3 Infection
- 4 Diagnosis
- 5 Treatment
- 6 Food poisoning incidents
- 7 References
- 8 External links
Motility
Although they lack flagella, C. perfringens bacteria are able to glide across surfaces because their bodies are lined with filaments from end-to-end. The hypermotile variants such as SM101, are often found arising on the edges of colonies on agar plates. Video microscopy of their gliding movement suggest that they form long, thin filaments that allow them to move rapidly like bacteria with flagella. Genome sequencing was used to identify the cause(s) of the hypermotile phenotype and their direct derivatives. In comparing them, strains SM124 and SM127, hypermotile derivatives of strains SM101 and SM102, respectively, contained 10 and 6 nucleotide polymorphisms (SNPs) relative to their parent strains. A mutation in cell division genes is the common feature of the hypermotile strains.[3]
Food poisoning
In the United Kingdom and United States, C. perfringens bacteria are the third most common cause of foodborne illness, with poorly prepared meat and poultry, or food properly prepared but left to stand too long, the main culprits in harboring the bacterium.[4] The clostridium perfringens enterotoxin (CPE) mediating the disease is heat-labile (inactivated at 74 °C (165 °F)). It can be detected in contaminated food (if not heated properly), and feces.[5] Incubation time is between six and 24 (commonly 10-12) hours after ingestion of contaminated food.
Since C. perfringens forms spores that can withstand cooking temperatures, if cooked food is let stand for long enough, germination can ensue and infective bacterial colonies develop. Symptoms typically include abdominal cramping, diarrhea; vomiting and fever. The whole course usually resolves within 24 hours. Very rare, fatal cases of clostridial necrotizing enteritis (also known as pigbel) have been known to involve "Type C" strains of the organism, which produce a potently ulcerative β-toxin. This strain is most frequently encountered in Papua New Guinea.
Many cases of C. perfringens food poisoning likely remain subclinical, as antibodies to the toxin are common among the population. This has led to the conclusion that most of the population has experienced food poisoning due to C. perfringens.
Despite its potential dangers, C. perfringens is used as the leavening agent in salt rising bread. The baking process is thought to reduce the bacterial contamination, precluding negative effects.[6]
Infection
Clostridium perfringens is the most common bacterial agent for gas gangrene, which is necrosis, putrefaction of tissues, and gas production. It is caused primarily by Clostridium perfringens alpha toxin. The gases form bubbles in muscle (crepitus) and the characteristic smell in decomposing tissue. After rapid and destructive local spread (which can take only hours), systemic spread of bacteria and bacterial toxins may cause death. This is a problem in major trauma and in military contexts. C. perfringens grows readily on blood agar plate in anaerobic conditions, and often produces a double zone of beta hemolysis.
Research published in 2014 suggested that a strain of C. perfringens might be implicated in multiple sclerosis (MS). Tests in mice found that a toxin made by a rare strain of C. perfringens caused MS-like damage in the brain, and earlier work had identified this strain of C. perfringens in a human with MS.[7] MS patients were found to be ten times more immune-reactive to the epsilon toxin than healthy people.[8]
Diagnosis
C. perfringens can be diagnosed by Nagler's reaction where the suspect organism is cultured on an egg yolk media plate. One side of the plate contains anti-alpha-toxin, while the other side does not. A streak of suspect organism is placed through both sides. An area of turbidity will form around the side that does not have the anti-alpha-toxin, indicating uninhibited lecithinase activity. Other tests/reactions: Catalase: Negative, Spot indole: Positive, Lecithinase: Positive, Lipase: Negative, Litmus Milk: Stormy Fermentation, Reverse CAMP plate: Positive, Gas Liquid Chromatography products: (Acetic, Butyric and Lactic Acids).
Treatment
If suspected on clinical grounds, treatment should begin without waiting for lab results. Traumatic wounds should be cleaned. Wounds that cannot be cleaned should not be stitched shut. Penicillin prophylaxis kills many clostridia and is thus useful for dirty wounds and lower leg amputations. A high infectious dose is required; the carrier state persists for several days.
Food poisoning incidents
On May 7, 2010, 42 residents and 12 staff members at a Louisiana state psychiatric hospital experienced vomiting, abdominal cramps, and diarrhea. Within 24 hours, three patients had died. The outbreak was linked to chicken which was cooked a day prior to being served and was not cooled down according to hospital guidelines. The outbreak affected 31% of the residents of the hospital and 69% of the staff who ate the chicken. It is unknown how many of the affected residents ate the chicken.[9]
In May 2011, a man died after allegedly eating food contaminated with the bacteria on a transatlantic American Airlines flight. The man's wife and daughter are suing American and LSG Sky Chefs, the German company that prepared the inflight food.[10]
In December 2012, a 46-year-old woman died two days after eating a Christmas Day meal at a pub in Hornchurch, Essex, England. She was among about 30 people to fall ill after eating the meal. Samples taken from the victims contained C.perfringens. The hotel manager and the cook were jailed for offences arising from the incident.[11]
In December 2014, 87-year-old Bessie Scott died three days after eating a church potluck supper in Nackawic, New Brunswick, Canada. Over 30 other people reported signs of gastrointestinal illness, diarrhea and abdominal pain. The province's acting chief medical officer says Clostridium perfringens is the bacteria that most likely caused the woman’s death.[12]
References
- ^ Ryan KJ; Ray CG, eds. (2004). Sherris Medical Microbiology (4th ed.). McGraw Hill. ISBN 0-8385-8529-9. [page needed]
- ^ "BioNumber Details Page". BioNumbers.
- ^ Liu, Hualan; McCord, Kristin D.; Howarth, Jonathon; David, Popham L.; Jensen, Roderick V.; Melville, Stephen B. (July 2014). "Hypermotility in Clostridium perfringens Strain SM101 Is Due to Spontaneous Mutations in Genes Linked to Cell Division". Journal of Bacteriology 196 (13): 2405–2412. doi:10.1128/JB.01614-14.
- ^ Warrell; et al. (2003). Oxford Textbook of Medicine (4th ed.). Oxford University Press. ISBN 0-19-262922-0. [page needed]
- ^ Murray; et al. (2009). Medical Microbiology (6th ed.). Mosby Elsevier. ISBN 978-0-323-05470-6. [page needed]
- ^ Juckett, Gregory; et al. (November 2008). "The Microbiology of Salt Rising Bread" (PDF). West Virginia Medical Journal (22). Retrieved 22 July 2015.
- ^ "Multiple sclerosis 'linked to food bug'". BBC. 29 January 2014. Retrieved 29 January 2014.
- ^ http://www.foxnews.com/health/2014/01/29/bacterial-toxin-may-trigger-multiple-sclerosis-research-finds/?intcmp=trending
- ^ "Fatal Foodborne Clostridium perfringens Illness at a State Psychiatric Hospital — Louisiana, 2010". Centers for Disease Control and Prevention. Retrieved 16 November 2013.
- ^ Mohn, Tanya (1 December 2011). "Passenger dies in-flight, family says airline to blame". Overhead Bin. MSNBC. Retrieved 2012-02-13.
- ^ "Pub chef and manager jailed over Christmas dinner that left a diner dead". The Guardian. 23 January 2015. Retrieved 3 August 2015.
- ^ "Woman's death likely caused by bacteria from Christmas supper". CBC. 12 December 2014.
External links
- Clostridium perfringens genomes and related information at PATRIC, a Bioinformatics Resource Center funded by NIAID
- Pathema-Clostridium Resource
- Firmicutes (low-G+C) Infectious diseases
- Bacterial diseases: G+
- primarily A00–A79, 001–041, 080–109
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|
| Bacilli |
Lactobacillales
(Cat-) |
| Streptococcus |
| α |
| optochin susceptible: |
|
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| optochin resistant: |
- S. viridans: S. mitis
- S. mutans
- S. oralis
- S. sanguinis
- S. sobrinus
- milleri group
|
|
|
| β |
| A: |
- bacitracin susceptible: S. pyogenes
- Group A streptococcal infection
- Streptococcal pharyngitis
- Scarlet fever
- Erysipelas
- Rheumatic fever
|
|
| B: |
- bacitracin resistant, CAMP test+: S. agalactiae
- Group B streptococcal infection
|
|
| ungrouped: |
- Streptococcus iniae
- Cutaneous Streptococcus iniae infection
|
|
|
| γ |
- D
- BEA+: Streptococcus bovis
|
|
|
| Enterococcus |
- BEA+: Enterococcus faecalis
- Enterococcus faecium
|
|
|
Bacillales
(Cat+) |
| Staphylococcus |
| Cg+: |
- S. aureus
- Staphylococcal scalded skin syndrome
- Toxic shock syndrome
- MRSA
|
|
| Cg-: |
- novobiocin susceptible
- novobiocin resistant
|
|
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| Bacillus |
- Bacillus anthracis
- Bacillus cereus
|
|
| Listeria |
|
|
|
|
| Clostridia |
| Clostridium (spore-forming) |
| motile: |
- Clostridium difficile
- Clostridium botulinum
- Clostridium tetani
|
|
| nonmotile: |
- Clostridium perfringens
- Gas gangrene
- Clostridial necrotizing enteritis
|
|
|
| Peptostreptococcus (non-spore forming) |
- Peptostreptococcus magnus
|
|
|
| Mollicutes |
| Mycoplasmataceae |
- Ureaplasma urealyticum
- Mycoplasma genitalium
- Mycoplasma pneumoniae
|
|
| Anaeroplasmatales |
- Erysipelothrix rhusiopathiae
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