CBRNE - Botulism Workup

Updated: Apr 21, 2015
  • Author: Peter P Taillac, MD; Chief Editor: Duane C Caneva, MD, MSc  more...
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Workup

Laboratory Studies

For laboratory confirmation, before treatment with antitoxin, obtain 10-15 mL of serum, 25-50 g of feces, and possibly 25-50 mL of fluid from gastric aspiration. Collect and refrigerate similar quantities of suspected food samples for testing. In constipated patients, a gentle saline enema may be required to obtain fecal specimens.

Label each specimen container with the patient's name, specimen type, date of collection, and medications being received, and send it to a state health department-approved reference laboratory in insulated cold packs. Contact your local health department for specific instructions.

Confirmation of the organism and/or toxin and toxin typing is obtained in almost 75% of cases. Early cases are more likely to be diagnosed by toxin assay, whereas later ones are more likely to have a positive culture. Laboratory confirmation of toxin presence is via a mouse bioassay, and identification of the toxin type is performed by a mouse toxin neutralization test.

Food-borne botulism

For food-borne botulism, toxin is found in serum samples 39% of the time and in stools 24% of the time. Organisms are found in cultures of stool samples 55% of the time. Stool cultures generally are more sensitive than toxin detection for specimens obtained later (> 3 d postingestion) in the course of illness.

An experimental test strip has been developed that enables field detection of type A and B toxins in foods. [6] A cell-based assay that uses a fluorescence reporter construct expressed in a neuronal cell model to study toxin activity in situ was able to detect as little as 100 pM botulism A activity in living cells, and is being evaluated for use in food matrices. [7]

Infant botulism

In patients whom infant botulism is suspected, stools and enema fluids (with minimal water added to limit dilution of toxin) are the specimens of choice, as serum is only rarely toxin positive. One also may wish to culture possible sources of clostridia, such as honey or house dust.

Other botulism forms and laboratory tests

Wound botulism: Wound botulism may be identified by detection of toxin in serum or by culture of wound specimens.

Adult colonization botulism: Organisms may be detected in stool and toxin in serum for up to 119 days following the onset of symptoms.

New methods of detection: In vitro methods of detection, including polymerase chain reaction (PCR) – based detection of clostridial genes and enzyme-linked immunoassay (ELISA) identification of toxin, have been developed. However, these methods are not widely available outside of research institutions.