Approach

Oral rehydration fluids and symptom control are the mainstay of treatment in patients with uncomplicated watery diarrhea. The objective is maintenance of hydration (or rehydration in dehydrated patients) and electrolyte replacement. Occasionally, antimicrobial or other specific therapies are indicated.

Preventing further transmission through appropriate reporting, screening, and surveillance, and patient education are all essential measures in management of outbreaks.

Antiemetics are not indicated for infectious diarrhea but can be used with significant vomiting to facilitate oral rehydration.[40]

A poison center should be contacted as soon as a toxic ingestion is suspected. Management of noninfectious food poisoning is beyond the scope of this topic. Consult a specialist familiar with care of poisoned patients for guidance.

See also, Toxic ingestions in children, Marine toxins (saxitoxin, tetrodotoxin, conotoxin), Organophosphate poisoning.

Mild-to-moderate disease

Self-limiting course. Indicated by mild-to-moderate dehydration and absence of alarm signs or symptoms such as blood in stool, severe abdominal pain, fever, and extragastrointestinal manifestations.

The mainstay of management is oral rehydration solution. Oral rehydration is achieved by administering clear liquids and sodium-containing and glucose-containing solutions. A simple oral rehydration solution (ORS) may be composed of 1 teaspoon of salt and 4 teaspoons of sugar added to 1 L of water. ORS promotes co-transport of glucose, sodium, and water across the gut epithelium, a mechanism unaffected in cholera. The World Health Organization recommends a reduced osmolarity oral rehydration solution containing sodium chloride, glucose, potassium chloride, and trisodium citrate.[40][53]​​​​ If trisodium citrate is unavailable, standard oral rehydration solution may be used.

The value of antidiarrheals (e.g., loperamide, diphenoxylate/atropine) in patients with mild-to-moderate diarrhea is under discussion. They can be offered to patients whose diarrhea interferes with their ability to work or those with traveler's diarrhea.[54][55]

Adsorbents (e.g., aluminum hydroxide) help patients have more control over the timing of defecation but do not alter the course of the disease or reduce fluid loss. Antisecretory agents (e.g., bismuth) may be useful.[56]​ Adsorbents may decrease absorption of drugs such as digoxin, clindamycin, tetracyclines, and penicillamine.

In patients with mild symptoms, loperamide is safe and effective.[40]​ When invasive pathogens are suspected, antidiarrheals that target motility should be generally avoided. Decrease in intestinal motility in patients taking diphenoxylate/atropine may be detrimental to those with diarrhea resulting from Shigella or Salmonella organisms. Diphenoxylate/atropine should not be used in patients with a suspected invasive pathogen.

Antibiotics are not necessary in these patients.

Severe disease

Severe disease is indicated by the presence of signs and symptoms of severe dehydration, the presence of blood in stool, significant laboratory test abnormalities, and extra-intestinal manifestations. Patients with severe food poisoning (particularly high-risk patients, such as pregnant women and those at the extremes of age) should be admitted to the hospital for intravenous hydration and close monitoring of electrolytes and other laboratory tests as indicated.

Lactated Ringer or normal saline (sodium chloride 0.9%) solution are used for intravenous rehydration. Both fluids are essentially isotonic and have equivalent volume-restorative properties. While some differences exist between metabolic changes observed with administration of large quantities of either fluid, for practical purposes and in most situations, differences are clinically irrelevant. No demonstrable difference exists in hemodynamic effect, morbidity or mortality between resuscitation using either normal saline or lactated Ringer solution.[57]

Intravenous solutions are indicated in patients who are severely dehydrated or who have severe vomiting. Rehydration can generally be done rapidly without complication. As fecal effluent typically contains 70 mmol/L of potassium, depletion of potassium can occur and may likely need replacement.

Diphenoxylate/atropine should not be used in patients with a suspected invasive pathogen.

Empiric antibiotic therapy

All specific antimicrobial therapy should be discussed with local microbiologic/infectious disease specialists to determine local sensitivity patterns. Disease progress should be regularly monitored to ensure empiric treatment is effective.

Empiric antibiotic therapy is only given if there is evidence of bacillary dysentery by culture. It is not recommended in developed countries unless there is culture-confirmed evidence of Shigella infection, or a clear outbreak of shigellosis.[40][58]​ One Cochrane review found that antibiotics reduce the duration of diarrhea in patients with Shigella dysentery.[59]

In the absence of dysentery, antibiotics should not be administered until a microbiologic diagnosis is confirmed and Shiga toxin-producing enterohemorrhagic Escherichia coli (e.g., O157:H7) is ruled out. In patients with dysentery due to enterohemorrhagic E coli (strain O157), antibiotics may cause or worsen hemolytic uremic syndrome and should, therefore, be avoided (unless the patient is septic).[60][61]

If given, empiric antimicrobial therapy must be comprehensive and should cover all likely pathogens in the context of the clinical setting.

Patients with diarrhea (more than 4 stools/day) for more than 3 days and fever, abdominal pain, vomiting, headache, or myalgias should be treated with an agent such as a fluoroquinolone, which covers Shigella organisms. Most regimens for Shigella are single dose or at most 3 days. Immunocompromised patients may require more aggressive and specific antimicrobial agents, and for a longer duration. Fluoroquinolones, such as ciprofloxacin, have been associated with serious, disabling, and potentially irreversible adverse effects including tendonitis, tendon rupture, arthralgia, neuropathies, and other musculoskeletal or nervous system effects.[62] In addition to this, the Food and Drug Administration has issued warnings about the increased risk of aortic dissection, significant hypoglycemia, and mental health adverse effects in patients taking fluoroquinolones.[63][64]

Routine prescription of antibiotic therapy for Shigella infection is not recommended; antibiotic therapy is reserved for where it is clinically indicated or when public health officials advise treatment in an outbreak setting.[65]

In the case of Campylobacter, if antibiotics are not administered early (within 72 hours), they will have no effect. In addition, Campylobacter resistance to fluoroquinolones is common, so macrolides (e.g., azithromycin, erythromycin) are generally preferred.[40][58]​ Fluoroquinolones are only recommended for Campylobacter infection when it is considered inappropriate to use other commonly recommended antibiotics.

Enterotoxigenic E coli (ETEC) infection (traveler's diarrhea) is mainly self-limiting, but may be an indication for empiric antibiotics such as fluoroquinolones. Antibiotics should be offered to patients with severe symptoms, usually while the patient is still traveling, when it can shorten the duration of the illness.[55]​​[66]

These antibiotics have no activity against anaerobes. If the likely cause of a sick patient with diarrhea in the absence of blood is Clostridioides difficile (formerly known as Clostridium difficile)-associated diarrhea or intra-abdominal sepsis, then empirical therapy that covers anaerobes (e.g., metronidazole, amoxicillin/clavulanate) should be given.

Targeted antimicrobial therapy

Antimicrobial selection should be guided by culture sensitivity when obtained. When a specific pathogen is strongly suspected or culture-confirmed, treatment should be targeted as appropriate.

S aureus infection causing enterotoxin-induced vomiting is usually self limiting and requires supportive treatment only. If associated with bacteremia, advice should be sought from an infectious diseases/microbiology specialist.

Cystoisospora belli (formerly Isospora belli) infection is usually self-limited in immunocompetent patients; however, antibiotic therapy may be required in some patients. Expert consult is recommended for patients with immunosuppression, as these patients may need higher doses and a longer duration of treatment.[67][68]​​​

Patients who have Microsporidia and are immunocompromised are typically treated with albendazole, but specialist guidance may be required as albendazole does not treat all species.[69]​ Immunocompetent patients do not typically require treatment with antimicrobials.

Trematodiasis is generally treated with praziquantel; however, specialist guidance should be sought as dosing varies depending on the species of fluke.[5]​ Triclabendazole is recommended for Fasciola species; however, it is not available in some countries, including the US. See also, Schistosomiasis (Treatment algorithm).

Botulism

Foodborne botulism should be treated presumptively if clinically suspected. The disease is notifiable and typically antitoxin may only be available through the Centers for Disease Control and Prevention.

Swift administration of antitoxin is essential. See Botulism (Treatment algorithm).

Supportive care is the mainstay of botulism therapy.[51]​ Patients with suspected or confirmed botulism should undergo serial vital capacity assessments in the intensive care unit. In addition, patients should be assessed for the adequacy of gag and cough reflexes, control of oropharyngeal secretions, oxygen saturation, and inspiratory force. Mechanical ventilation should be considered for any patient with upper airway compromise (due to pharyngeal muscle paralysis) or a decline in vital capacity.

Gastric lavage may be attempted if the food exposure was relatively recent, but only if intubated to prevent aspiration. In the absence of an ileus, enemas may be used to eliminate unabsorbed toxin from the gastrointestinal tract.

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