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Clostridium- Botulinum Bacteria

Causing Botulism Disease

By: Christine Schramm

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Clostridium botulinum bacillus bacteria under an electron microscope


What is Botulism?
Botulism is a rare but serious disease caused by a nerve toxin produced by the Clostridium Botulinum bacteria. It is an endospore forming, rod shaped, gram positive bacteria that is typically found in soil, water sediment and fish. It grows in low oxygen enviornments.There are seven different kinds of botulism (named type A-G). But only types A, B, E and F cause illness in humans. Infant botulism is the most common and is caused by a child eating food infected with botulinum spores (most often honey.) The spores then grow in the intestines and release toxins. Food borne botulism is caused by eating food contaminated with the botulinum toxin (typically home canned foods.) Wound botulism is when a wound is infected with the boulinum bacteria. Adult intestinal toxemia botulism is extremely rare but occurs the same way as infant botulism. All forms of botulism effect the nervous system, cause paralysis and can be fatal.



General Info. & Morphology
Causative Agent: Botulinum neurotoxin.Classification: Prokaryote bacteria (no nucleus/organelles), spore forming.Family: Clostridiaceae.Shape and arrangement: Single baccillus.Obligate anaerobic: Strictly grows in absence of oxygen, oxygen is toxic to cells. Ferments: Carbohydrates and nitrogenous compounds such as amino acids.

Gram positive stain of Clostridium botulinum
Gram positive stain of Clostridium botulinum



Did you know?
Botulinum is the main paralytic bacterium used to produce Botox and is used for cosmetic as well as therapeutic use. In clinical treatments, it is used to relieve chronic headaches as well as relieving muscles contractions in patients with medical conditions such as multiple sclerosis, Parkinson's disease and cerebral palsy. (However, when botulinum is used to produce Botox it is purified and the neurotoxin is diluted.)

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Think twice about botox injections



Where this Bacterium is Found
Epidemiology:

  • C. botulinum is found worldwide, however it is most prevalent in developing countries.
  • Alaskan natives have highest rate of illness (mostly type E) due to cultural food preparations, avoiding thoroughly heating fish.
  • Rare in the United States. However most cases are found in California, Washington, Colorado, Oregon and New Mexico.

Statistics and prevalence:

  • In the United States, only about 145 cases reported each year. Of these, about 15% are foodborne, 65% are infant botulism, 20% are wound cases.
  • Adults rarely develop botulism, microorganisms are unable to complete with normal intestinal microbiota.
  • Person to person transmission of botulism does not occur.
  • Type A toxin is most lethal- death can result from merely tasting food (not swallowing), possible to absorb lethal does through cracked skin.
  • Type B is most prevalent in European outbreaks, responsible for majority of cases in Eastern U.S.
  • Type E toxin often found in marine or lake sediments.
  • Foodborne type- neurological symptoms usually occur within 18-36 hours after eating contaminated food, the shorter the cultivation period, the more dangerous the disease.
  • Wound type- can take 4-14 days to manifest.
  • Typical paralysis lasts 1-10 days but impairment could last months.
  • Once infected, may lead to paralysis of pulmonary or cardiac muscles, causing death from respiratory/cardiac failure.
  • In the past 50 years, the number of people who have died from botulism has decreased from 50% to approximately 3-5%.

Risk Factors:
  • Consuming and packaging your own home canned foods with low acid content that have not been properly prepared and/or stored such as green beans, asparagus, beets and corn.
  • Eating inadequately fermented fish.
  • Infants under 1yr. of age who are fed honey or ingest contaminated soil.
  • Injectable street drug users (typically using tar haroine).
  • Lab techs whom handle botulinum w/out proper safety measures.

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Home prepared vegetables.




Bacterium Motility
Reservoir: Spores in the soil, fresh water sediment, human and animal intestines.
Mode of Transportation: Botulism is not transmitted from one person to an other. The reproduction of endospores requires non-halophilic (non-salty) conditions and anaerobic (no oxygen) type environments.
Foodborne botulism: Person eats contaminated food. C. botulinum spores grow into bacteria due to inaccurate heating conditions and turn toxic.

Infant botulism: Infants ingest spores that then grow in their intestinal tract.

Wound botulism: Wound gets contaminated with spores that germinate, grow deep within wound, and produce toxin that is absorbed into the bloodstream.

Prevention:
  • Avoid improperly stored home-cooked or commercial foods, particularly low-acidic foods.
  • Do not consume improperly canned goods.
  • Toxin is often killed at high temperatures so if one chooses to eat home canned food, boil food for 10 minutes to ensure safety.
  • Foods that cannot be heated to temperatures high enough to kill the endospores should maintain a pH below 4.6, as to not harbor the bacteria.
  • Do not feed honey to infants less than 1 yr. of age.
  • C. botulinum cannot grow in high acidic conditions, high levels of oxygen, low levels of moisture or storage at temperatures below 38°F, nor in high ratios of dissolved sugar.

Botulinum toxin
Botulinum toxin


Verification and Treatment
Diagnosis:
  • Patient's history and physical examination is the first step. However, they are not typically enough to make a diagnosis.
  • Tests may be done including a brain scan, spinal fluid examination, nerve conduction test, as well as others.
Laboratory tests may need to be conducted to to determine if botulinal toxin is present in food-

  • Inoculate mice with liquid portion of food extracts; if mice die within 72 hours, poison is present.

To determine a specific type of botulism disease in patients-
  • Inoculate mice with patient samples of serum, stool, or vomit.
  • Immunize certain mice with type A, B, or E antitoxin.
  • Inoculated mice with test toxin.
  • If mice receiving a specific antitoxin live while others die, that type of toxin has been identified. (Example: Mice injected with type A antitoxin survives, type A toxin is affecting the patient.)

Symptoms Include:
  • Progressive but often temporary flaccid (drooping), symmetric paralysis
  • Paralysis starting in the face, descending downward then to limbs
  • Nausea, vomiting, abdominal swelling, constipation
  • Double or blurred vision, vertigo (dizziness)
  • Dry mouth, difficulty swallowing and speaking
  • General weakness, fatigue but no fever nor loss of consciousness

Treatments:
  • Recovery is a slow process, requires nerve endings to regenerate.
  • Extended respiratory assistance, use of ventilator, often required.
  • IV fluids/nutrients dispensed.
  • Treatments usually focus on targeting toxin, not organism.
  • Antitoxins, including heptavalent antitoxin, is effective against neutralizing all 7 types of botulism and must be administered as soon as possible after clinical diagnosis is made.
  • Foodborne- elimination of toxin (inducing vomiting or use of enemas.)
  • Wound- affected tissue is removed.

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Mouse injected with botulinum

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http://www.youtube.com/watch?v=Ug0L6pVdvoA&feature=player_detailpage

References

http://www.cdc.gov/nczved/divisions/dfbmd/diseases/botulism/

http://www.who.int/mediacentre/factsheets/fs270/en/