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Introduction ⬇

Human botulism is caused by the spore-forming, obligate anaerobe, rod-shaped bacterium Clostridium botulinum. C. botulinum produces the botulinum toxin, which is the most poisonous biologic substance known. There are seven distinct antigenic types of the botulinum toxin designated types A through G. All forms of botulism are the result of absorption from a mucosal surface (e.g., GI tract or lung) or a wound into the circulatory system. C. botulinum can be found in the soil and in undercooked food that is not kept hot. Cases of waterborne botulism have not been documented, although aerosolization of the toxin and subsequent inhalation has been done experimentally. Foil-wrapped potatoes held at room temperature after baking can cause botulism, as can contaminated condiments, such as sautéed onions or cheese sauce. Botulism has been divided into five forms: (1) foodborne, (2) wound, (3) infant (up to 8 months of age), (4) adult intestinal (caused by digestive colonization of C. botulinum), and (5) iatrogenic (from cosmetic injections).

This test is used to confirm the presence of C. botulinum, which produces the botulinum toxin.

Procedure ⬆ ⬇

  1. Obtain specimens from blood, stool, gastric aspirates or vomitus, and, if available, suspected food.

  2. Obtain at least 30 mL of venous blood in a red-topped Vacutainer.

  3. Use an enema (with sterile water) to obtain an adequate fecal sample if the patient is constipated.

  4. Refrigerate all samples.

  5. Use the mouse lethality bioassay to determine whether there is any botulinum toxin present.

Procedural Alert

In some cases, an electromyogram is performed to differentiate cause of acute flaccid paralysis.

Clinical Implications ⬆ ⬇

  1. The identification of botulism neurotoxin is evidence of botulism poisoning.

  2. Mortality rates vary depending on the type of botulism poisoning (foodborne, 5%–10% with treatment in developed countries; wound botulism, 1%–15% depending on amount of wound contamination; infant botulism, 2%). Severe respiratory distress due to paralysis of muscles can lead to death.

Interventions ⬆ ⬇

Pretest Patient Care

  1. Explain the purpose, procedure, and risks of obtaining a specimen.

  2. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

Posttest Patient Care

  1. Do not isolate patients diagnosed with botulism because it is not contagious and cannot be transmitted from person to person.

  2. Review test results; report and record findings. Modify the nursing care plan as needed. Provide supportive care to patient and monitor appropriately.

  3. Monitor the patient for impending respiratory failure.

  4. Follow Chapter 1 guidelines for safe, effective, informed posttest care.

Clinical Alert

  1. Postexposure prophylaxis is limited owing to antitoxin scarcity and reactogenicity.

  2. By law, in most areas of the country, suspected botulism must be reported to local public health authorities.

Clinical Alert

  1. Laboratory personnel should observe standard precautions.

  2. Decontaminate surfaces with 0.1% hypochlorite bleach solution.

  3. Contaminated clothing should be washed with soap and water.

Interfering Factors ⬆ ⬇

The use of anticholinesterases (e.g., physostigmine salicylate or pralidoxime chloride) by the patient can interfere with the bioassay.

Reference Values ⬆

Normal

Absence of botulinum toxin

Absence of incremental response to repetitive nerve stimulation on an electromyogram