GASTROENTERITIS is the most common bacterial cause of
GASTROENTERITIS
Definition:
– Inflammation of the lining of the
stomach and intestines, predominantly manifested by upper GI tract symptoms
(anorexia, nausea, vomiting), diarrhea, and abdominal discomfort.
Etiology and Epidemiology
–
Gastroenteritis may be of nonspecific, uncertain, or unknown etiology or of bacterial,
viral, parasitic, or toxic etiology
–
Campylobacter infection is the most common bacterial
cause of diarrheal illness in the USA
–
Person-to-person
transmission is especially common with gastroenteritis
caused by Shigella, Escherichia coli, Giardia, Norwalk virus, and rotavirus.
Pathophysiology
–
Certain bacterial species elaborate enterotoxins, which impair intestinal
absorption and can provoke secretion of electrolytes and water e.g. the enterotoxin
of Vibrio cholerae and E. coli enterotoxin
–
Some
Shigella, Salmonella, and E. coli species penetrate the mucosa of
the small intestine or colon and produce microscopic ulceration, bleeding,
exudation of protein-rich fluid, and secretion of electrolytes and water.
– Gastroenteritis may
follow ingestion of chemical toxins
contained in plants (e.g. mushrooms, potatoes, garden flora), seafood (fish,
clams, mussels), or contaminated food.
Symptoms and Signs
–
Onset
is often sudden and sometimes dramatic, with anorexia, nausea, vomiting,
borborygmi, abdominal cramps, and diarrhea (with or without blood and mucus).
–
Associated
malaise, muscular aches, and prostration may occur
–
If
vomiting causes excessive fluid loss, metabolic alkalosis with hypochloremia
occurs; if diarrhea is more prominent, acidosis is more likely
–
Excessive
vomiting or diarrhea may cause hypokalemia
– Severe dehydration and acid-base imbalance can produce
headache and muscular and nervous irritability.
– Persistent vomiting and diarrhea may result in severe
dehydration and shock, with vascular collapse and oliguric renal failure.
Diagnosis
–
A history of ingestion of potentially
contaminated food, untreated surface water, or a known GI irritant; recent
travel; and contact with similarly ill persons may be important.
–
Stool
examination for fecal WBCs and culture are indicated
–
Diagnosis
may also require culture of vomitus, food, and blood.
–
Eosinophilia
may indicate parasitic infection
General Principles of Treatment
–
Supportive treatment is most important.
–
Bed rest with convenient access to a toilet or
bedpan is desirable
–
When
nausea or vomiting is mild or has ended, oral glucose-electrolyte solutions,
strained broth, or salted bouillon may prevent dehydration or treat mild
dehydration.
–
Even
if vomiting, the patient should take frequent but small sips of such fluids
because the vomiting may resolve with volume replacement
–
If
vomiting is protracted or if severe dehydration is prominent, IV replacement of
appropriate electrolytes is necessary
–
If
vomiting is severe and a surgical condition has been excluded, an antiemetic
(e.g. dimenhydrinate 50 mg IM q 4 h, chlorpromazine >=
25 to 100 mg/day IM) or prochlorperazine 10 mg po tid (suppository 25 mg bid)
may be beneficial.
–
Meperidine
50 mg IM q 3 or 4 h may be given for severe abdominal cramps.
–
When
the patient can tolerate fluids without vomiting, bland food (cereal, gelatin,
bananas, and toast) may be added to the diet gradually.
–
If
after 12 to 24 h, moderate diarrhea persists without severe systemic symptoms
or blood in the stool, diphenoxylate 2.5 to 5 mg tid or qid in tablet or
liquid form, loperamide 2 mg po qid, or bismuth subsalicylate 524 mg (two
tablets or 30 mL) po six to eight times/day may be given.
–
Antibiotics
appropriate to sensitivity testing should be given when systemic infection is
evident.
–
However,
antibiotics do not help patients with simple gastroenteritis, nor do they help asymptomatic carriers to
“clear” rapidly.
