Treatment algorithm

Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups: see disclaimer

INITIAL

mild-to-moderate disease

1st line – oral hydration

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INITIAL
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mild-to-moderate disease
1st line – 

oral hydration

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 ORS containing 2.6 g/L sodium chloride, 13.5 g/L glucose, 1.5 g/L potassium chloride, 2.9 g/L trisodium citrate (75 mmol/L sodium, 65 mmol/L chloride, 75 mmol/L anhydrous glucose, 20 mmol/L potassium, 10 mmol/L citrate).[40][50]​​​​​ If trisodium citrate is unavailable, standard WHO ORS may be used, which contains 3.5 g of sodium chloride, 2.5 g of sodium bicarbonate, 1.5 g of potassium chloride and 20 g of glucose per litre of water.

Consider – antidiarrhoeal

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INITIAL
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mild-to-moderate disease
Consider – 

antidiarrhoeal

Additional treatment recommended for SOME patients in selected patient group

The value of antidiarrhoeals (e.g., loperamide, diphenoxylate/atropine) in patients with mild-to-moderate diarrhoea is under discussion. They can be offered to patients whose diarrhoea interferes with their ability to work or those with traveller's diarrhoea.[51][52]

Adsorbents (e.g., aluminium 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.[53]

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, antidiarrhoeals that target motility should be generally avoided.

Decrease in intestinal motility in patients taking diphenoxylate/atropine may be detrimental to those with diarrhoea resulting from Shigella or Salmonella organisms.

Primary options

aluminium hydroxide: consult product literature for guidance on dose

OR

bismuth subsalicylate: consult product literature for guidance on dose

OR

diphenoxylate/atropine: 5 mg orally every 6-12 hours when required, maximum 20 mg/day

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OR

loperamide: 4 mg orally for the first dose, followed by 2 mg after each loose stool, maximum 16 mg/day

Consider – antiemetic

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INITIAL
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mild-to-moderate disease
Consider – 

antiemetic

Additional treatment recommended for SOME patients in selected patient group

Antiemetics (e.g., metoclopramide, ondansetron) are not indicated for infectious diarrhoea but can be used with significant vomiting to facilitate oral rehydration.[40]

Metoclopramide should be used for up to 5 days only in order to minimise the risk of neurological and other adverse effects.[67]

Primary options

metoclopramide: 10 mg orally/intramuscularly/intravenously every 8 hours when required for a maximum of 5 days, maximum 30 mg/day

OR

ondansetron: 8 mg orally/intravenously every 8 hours when required

severe disease

1st line – intravenous rehydration

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INITIAL
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severe disease
1st line – 

intravenous rehydration

Lactated Ringer or normal saline (sodium chloride 0.9%) solution. 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 haemodynamic effect, morbidity or mortality between resuscitation using either normal saline or lactated Ringer solution.[54]

Intravenous solutions are indicated in patients who are severely dehydrated or who have severe vomiting.

Rehydration can generally be done rapidly without complication. For example, if there is 10% dehydration in a 75 kg adult, and the fluid deficit is 5 to 7 L, the volume can be administered over 2 to 4 hours (i.e., 2-4 L/hr).

As faecal effluent typically contains 70 mmol/L of potassium, depletion of potassium can occur and may likely need replacement but not to exceed 10 mEq/hour with intravenous administration.

Consider – antiemetic

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INITIAL
|
severe disease
Consider – 

antiemetic

Additional treatment recommended for SOME patients in selected patient group

Antiemetics (e.g., metoclopramide, ondansetron) are not indicated for infectious diarrhoea but can be used with significant vomiting to facilitate oral rehydration.[40]

Metoclopramide should be used for up to 5 days only in order to minimise the risk of neurological and other adverse effects.[67]

Primary options

metoclopramide: 10 mg orally/intramuscularly/intravenously every 8 hours when required for a maximum of 5 days, maximum 30 mg/day

OR

ondansetron: 8 mg orally/intravenously every 8 hours when required

Plus – empirical antibiotic therapy

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INITIAL
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severe disease
|
diarrhoea >3 days and/or systemic symptoms
Plus – 

empirical antibiotic therapy

Treatment recommended for ALL patients in selected patient group

Empirical 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][55]

In the absence of dysentery, antibiotics should not be administered until a microbiological diagnosis is confirmed and Shiga toxin-producing enterohaemorrhagic Escherichia coli (e.g., O157:H7) is ruled out. There is no evidence that treatment with antibiotics is helpful for Shiga toxin-producing enterohaemorrhagic E coli, and taking antibiotics may increase the risk of haemolytic uraemic syndrome.[57][58]

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

Patients with diarrhoea for more than 3 days and fever, abdominal pain, vomiting, headache, or myalgias should be treated with an agent that covers Shigella organisms (e.g., fluoroquinolone). 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.[59] In addition to this, the US Food and Drug Administration has issued warnings about the increased risk of aortic dissection, significant hypoglycaemia, and mental health adverse effects in patients taking fluoroquinolones.[60][61]

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.[62]

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][55]​ Fluoroquinolones are only recommended for Campylobacter infection when it is considered inappropriate to use other commonly recommended antibiotics.

If the likely cause of a sick patient with diarrhoea in the absence of blood is Clostridioides difficile (formerly known as Clostridium difficile)-associated diarrhoea or intra-abdominal sepsis, then empirical therapy that covers anaerobes (e.g., metronidazole or amoxicillin/clavulanate) should be given.

Enterotoxigenic E coli (ETEC) infection (traveller's diarrhoea) is mainly self-limiting, but may be an indication for empirical antibiotics such as fluoroquinolones. Antibiotics should be offered to patients with severe symptoms, usually while the patient is still travelling, when it can shorten the duration of the illness.[52]​​[63]

Most antibiotics are given for 5 to 10 days (except azithromycin, which is usually given for 3 days) depending on the pathogen suspected or isolated. Immunocompromised patients may require more aggressive and specific antimicrobial agents and for longer duration.

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

Primary options

ciprofloxacin: 500 mg orally twice daily

OR

azithromycin: 500 mg orally once daily for 3 days

OR

erythromycin base: 500 mg orally twice daily

OR

metronidazole: 500 mg orally three times daily

OR

amoxicillin/clavulanate: 500 mg orally three times daily

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suspected foodborne botulism

1st line – antitoxin + supportive care

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INITIAL
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suspected foodborne botulism
1st line – 

antitoxin + supportive care

Toxin produced by Clostridium botulinum causes symptoms.

Notifiable; discuss with local authority/US Centers for Disease Control and Prevention for provision of antitoxin.

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

Supportive care is the mainstay of botulism therapy.[49]​

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.

ACUTE

known infecting organism

1st line – supportive care ± targeted antimicrobial therapy

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ACUTE
|
known infecting organism
1st line – 

supportive care ± targeted antimicrobial therapy

All patients should receive supportive care, consisting of hydration (intravenous hydration and/or oral rehydration solution depending on severity of disease) and anti-sickness medication for patients unable to keep fluids down. Advise patients to seek medical help if they are not improving or have reduced urine output.

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.

See Shigella infection (Treatment algorithm)​.

See Salmonellosis (Treatment algorithm) (non-typhoid Salmonella).

See Typhoid infection (Treatment algorithm)​.

See Foodborne E coli infection (Treatment algorithm)​.

See Campylobacter infection (Treatment algorithm)​.

See Yersinia infection (Treatment algorithm)​.

See Cholera (Treatment algorithm)​.

See Non-cholera Vibrio infections (Treatment algorithm)​.

See Giardiasis (Treatment algorithm)​.

See Cryptosporidiosis (Treatment algorithm)​.

See Amoebiasis (Treatment algorithm)​.

See Listeriosis (Treatment algorithm)​.

See Brucellosis (Treatment algorithm)​.

See Botulism (Treatment algorithm)​.

S aureus infection causing enterotoxin-induced vomiting is usually self limiting and requires supportive treatment only. If associated with bacteraemia, 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 consultation is recommended for patients with immunosuppression, as these patients may need higher doses and a longer duration of treatment.[64][65]

Patients who have Microsporidia infection and are immunocompromised are typically treated with albendazole, but specialist guidance may be required as albendazole does not treat all species.[66]​ Immunocompetent patients do not typically require treatment with antimicrobials.

Trematodiasis is generally treated with praziquantel; however, consultant 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. See also, Schistosomiasis (Treatment algorithm).

All specific antimicrobial therapy should be discussed with local microbiological/infectious disease specialists to determine local sensitivity patterns.

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Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups. See disclaimer

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