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Staphylococcal Enterotoxin B [SEB]

Staphylococcal Enterotoxin B (SEB) is one of several exotoxins produced by Staphylococcus aureus, causing food poisoning when ingested. Staphylococcus aureus is a common bacterium found on the skin and in the noses of up to 25% of healthy people and animals. It makes seven different toxins and SEB is the toxin most frequently responsible for food poisoning. The bacterium is salt tolerant, and the toxins it produces are resistant to heat and cannot be destroyed by cooking. Staphylococcus aureus thrives in various foods including cheese, milk, sliced meat, and pudding.

Staphylococcal toxins could be used as a biological agent either by contamination of food/water or by aerosolization and inhalation. Breathing in low doses of staphylococcal enterotoxin B may cause fever, cough, difficulty breathing, headache, and some vomiting and nausea. High doses of the toxin have a much more serious effect. A BW attack with aerosol delivery of SEB to the respiratory tract produces a distinct syndrome causing significant morbidity and potential mortality.

The disease can begin as soon as 30 minutes after ingesting contaminated foods but typically begins 1-6 hours after exposure with the sudden onset of fever, chills, headache, myalgia, and nonproductive cough. In more severe cases, dyspnea and retrosternal chest pain may also be present. Fever, which may reach 103-106° F, has lasted 2-5 days, but cough may persist 1-4 weeks. In many patients nausea, vomiting, and diarrhea will also occur. In moderately severe laboratory exposures, lost duty time has been less than 2 weeks, but, based upon animal data, it is anticipated that severe exposures will result in fatalities.

In foodborne SEB intoxication, fever and respiratory involvement are not seen, and gastrointestinal symptoms are prominent. The nonspecific findings of fever, nonproductive cough, myalgia, and headache occurring in large numbers of patients in an epidemic setting would suggest any of several infectious respiratory pathogens, particularly influenza, adenovirus, or mycoplasma. In a BW attack with SEB, cases would likely have their onset within a single day, while naturally occurring outbreaks would present over a more prolonged interval.

Methicillin-resistant Staphylococcus Aureus (MRSA) is a type of bacteria that is resistant to certain antibiotics. These antibiotics include methicillin and other more common antibiotics such as oxacillin, penicillin and amoxicillin. Staph infections, including MRSA, occur most frequently among persons in hospitals and healthcare facilities (such as nursing homes and dialysis centers) who have weakened immune systems.

Treatment is limited to supportive care. No specific antitoxin for human use is available. Victims can be treated with a combination treatment of sulfa drugs and minocycline or rifampin, especially the methicillin-resistant strain. There currently is no prophylaxis for SEB intoxication. Experimental immunization has protected monkeys, but no vaccine is presently available for human use.