How does one isolate the microorganism that causes botulism from a steak?  How is Staphylococcus Aureus isolated from tap water?

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boblawrence | (Level 1) Associate Educator

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A toxin produced by the microorganism Clostridium botulinum causes botulism.  This organism is present worldwide in soil and water.  Types of botulism are as follows:

Food borne botulism:  Caused by ingestion of uncooked, improperly canned foods, especially vegetables, cured pork, ham, smoked or raw fish, honey and corn syrup.  Spoors of the organism in the food produce a potent neurotoxin.  Symptoms occur 8-36 hours after ingestion and may include trouble talking or swallowing, double vision, dry mouth, nausea and vomiting and trouble breathing.

Wound botulism:  Occurs when organisms contaminate an open wound, especially if the wound has dead tissue.  The spoors grow and produce toxin in the wound.

Infant botulism:  Occurs when the infant ingests the organism that contaminates certain foods, most notably honey and corn syrup.  Infants under 1 year of age should never be given honey.  The organisms grow in the infant’s gastrointestinal tract where the toxin is produced.

To answer your question, the organism Clostridium botulinum is not normally cultured or grown from the suspected food such as a steak.  Instead, the laboratory detects the toxin itself.  The botulism organism can be cultured or grown from an infected wound in wound botulism, and from the stool in the case of infant botulism.

Botulism toxin is detectable in suspected food and in the serum and stool of patients affected with food borne botulism.  The toxin is also detectable (along with the organism) in the stool of patients with infant botulism.

The second part of your question refers to Staphylococcus aureus organisms in tap water.  This is not an issue, since staphylococci are not ordinarily a contaminant of tap water.  Tap water may contain coliform bacteria that are found in the intestines of man and animals, whose feces may contaminate water supplies.  Tap water may also contain viruses and yeasts, and occasionally Legionella bacteria, but not staphylococci.

Staph. Aureus becomes a health issue when food is contaminated by contact with food preparers who may have a staph. skin infection.  The organisms multiply in the food as it sits at room temperature and produce a toxin.  The toxin, when ingested, causes cramps, diarrhea, nausea and vomiting; so called staphylococcal food poisoning.