6.06 Food Poisoning - Staphylococcal

agk’s Library of Common Simple Emergencies

Presentation

The patient is brought to the ED 1 to 6 hours after eating, with severe nausea, vomiting, and abdominal cramps progressing into diarrhea. He appears very ill: pale, diaphoretic, tachycardic, orthostatic, perhaps complaining of paresthesias or feeling as if he is “going to die.” Others may have similar symptoms from eating the same food. The physical examination, however, is reassuring. There is minimal abdominal tenderness, localized, if at all, to the epigastrium or to the rectus abdominus muscle (which is strained by the vomiting)

What to do:

• Completely examine the patient, and perform any tests needed to rule out myocardial infarction, perforated ulcer, dissecting aneurysm, or any of the catastrophes which can present in similar fashion.
• In the meantime, infuse 0.9% NaCl or Ringer’s lactate solution intravenously and observe the patient, doing repeated vital sign checks and physical examination. In younger patients, who have the renal and cardiovascular reserve to handle rapid hydration, 1-2 liters infused over an hour often provides dramatic improvement in all symptoms.
• If the patient is improving, and beginning to tolerate oral fluids, discharge him with instructions to advance his diet over the next hours, starting with an oral rehydration solution such as
  • 3/4 teaspoon of table salt
  • one teaspoon of baking soda
  • one cup of orange juice
  • four tablespoons of sugar and
  • four cups of water.
  He should expect to be eating and feeling well in another 1 or 2 days.
• If symptoms resolve more slowly, you may want to discharge the patient with a single dose of an antiemetic or antispasmotic such as a prochlorperazine (Compazine) 25mg suppository or a dicyclomine (Bentyl) 20mg tablet.
• If hypotension or other significant symptoms persist; if the patient cannot tolerate parenteral rehydration, or cannot resume oral intake; he may have to be admitted.

What not to do:

• Do not immediately resort to medications (e.g., Compazine, Tigan) for nausea and vomiting. They may interfere with elimination of toxins, and do not help correct the fluid and electrolyte imbalances responsible for many of the symptoms.
• Do not immediately resort to medications (e.g., Lomotil, Imodium) for cramping and diarrhea, for the same reasons.
• Do not skimp on intravenous fluids.
• Do not pursue expensive laboratory investigations on straightforward cases.
• Do not presume food poisoning without a good history for it.

Discussion

Many of the symptoms accompanying any gastroenteritis seem to be related to electrolyte disturbances and dehydration, which can be substantial even in the absence of copious vomiting and diarrhea, and resistant to oral rehydration, because the gut is unable to absorb, and allows liter after liter to pool in its lumen. Lactated Ringer’s solution is the choice for intravenous rehydration, because it approximates normal serum electrolytes, and can be infused rapidly. Lactated Ringer’s approximately replaces the electrolytes lost in diarrhea, but normal saline has more of the chloride lost by vomiting.

The most common food poisoning seen in most EDs is caused by the heat-stable toxin of Staphylococcus, which is introduced into food from infections on handlers, and grows when the food sits warm. Chemical toxins have a similar presentation, but the onset of symptoms may be more immediate. Other bacterial food poisonings usually present with onset of symptoms later than 1-6 hours after eating, less nausea and vomiting, more cramping and diarrhea, and longer courses. A clearly implicated food source may give a clue to the etiology: shellfish suggesting Vibrio parahemolyticus, rice suggesting Bacillus cereus, meat or eggs suggesting Staphylococcus, Campylobacter, Clostridium, Salmonella, Shigella, enteropathic E. Coli, or Yersinia..

Whenever someone suffers any gastrointestinal upset, it is natural, if not instinctive, to implicate the last food eaten. Caution patients (especially if they are planning to sue the food supplier) that the diagnosis of food poisoning cannot be established without a group outbreak or a sample of tainted food for analysis.

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