Acute diarrhoea

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Chapter 15 ACUTE DIARRHOEA

• Acute infectious diarrhoea is common worldwide and is responsible for significant patient hospitalisation and mortality.

• Acute diarrhoea is defined as an increase of stool frequency (greater than three stools per day or at least 200 g of stool per day) lasting less than 14 days.

• The principal recognised causes of diarrhoea include viruses, bacteria and protozoa.

• Assessment should focus on the severity of illness, need for rehydration and the identification of the aetiology of the illness on the basis of history and clinical findings.

• Management of acute diarrhoea should include fluid resuscitation, empirical antibiotics or specific antibiotic therapy if the causative organism is isolated.

DEFINITION

Diarrhoea is a leading cause of death worldwide. It is defined as an alteration in normal bowel habit characterised by an increase in volume, water content and frequency of bowel movements, and must have a weight of at least 200 g stool per day.

A more practical approach for the definition of diarrhoea is the presence of three or more loose watery stools per day or a distinct change in a person’s normal bowel routine. A working definition of diarrhoea is based upon the duration of symptoms:

• Acute—less than 14 days in duration

• Persistent—more than 14 days but less than 30 days in duration

• Chronic—more than 30 days in duration.

PATHOPHYSIOLOGY

The symptoms of acute diarrhoea vary according to the portion of the intestine that is involved in the disease process. Infectious diarrhoea is often associated with symptoms of nausea, vomiting and abdominal cramps.

The small intestine functions as a fluid and enzyme secretory organ and nutrient absorbing region. Therefore, a pathogen affecting this region will produce symptoms of watery diarrhoea, which is usually of large volume and is associated with abdominal cramping, bloating and weight loss.

The colon is involved in absorption of fluid and salt, as well as excretion of potassium. When this area is involved, the symptoms include frequent, regular small volume, often painful defecation. Fever and bloody mucoid stools are common.

AETIOLOGY

Infectious and non-infectious causes may be responsible for acute diarrhoea (Table 15.1).

TABLE 15.1 Agents that commonly cause acute diarrhoea

Bacteria

• Campylobacter

• Salmonella

• Escherichia coli O157:H7

• Clostridium difficile

Viruses

• Caliciviruses (norovirus and Norwalk-like and related viruses)

• Adenovirus types 40 and 41

Protozoa

• Cryptosporidium

• Entamoeba histolytica

Infectious causes include bacteria, viruses and protozoa.

Bacteria

• Campylobacter: most common bacterial cause usually from poultry, meat, dairy products and contaminated water.

• Salmonella: usually from poultry and livestock.

• Shigella: highly contagious spreads from person to person.

• Escherichia coli: O157:H7: usually from contaminated meat, can be associated with haemolytic uraemic syndrome.

• Clostridium difficile: major cause of nosocomial colitis occurring after antibiotic-induced alteration of bowel flora and subsequent proliferation of an endogenous strain. Can also be contagious.

Viruses

Viruses cause the vast majority of all cases of acute diarrhoea.

• Caliciviruses (norovirus/Norwalk): can be detected in vomitus and faeces as compared with bacterial causes of diarrhoea (which is usually shed in faeces alone). Contaminated food or water are the usual primary causes but person-to-person contact is a secondary cause.

• Rotavirus: usually occurs in young children (<2 years). Highly contagious.

• Adenovirus types 40/41: usually spread by person-to-person contact.

• Astrovirus: usually spread by person-to-person contact.

Protozoa

Protozoa are usually waterborne, but may spread from the faecal to oral route. Only need small inoculum for infection.

• Cryptosporidium.

• Entamoeba histolytica.

Non-infectious causes

Non-infectious causes include drugs, food allergies, primary gastrointestinal diseases (e.g. inflammatory bowel disease) and other disease states, including thyrotoxicosis and carcinoid syndrome.

ASSESSMENT

A good clinical history is important and may allow empiric therapy to be started without the need for any further diagnostic investigation. Initial evaluation should focus on the need for rehydration, severity of illness and identification of a likely causative agent.

Assessment of the severity of dehydration is critical in the management of acute diarrhoea. Features suggestive of severe dehydration and subsequent need for hospital admission and intravenous fluid replacement include tachycardia, >20 mmHg decrease in systolic blood pressure, postural hypotension, poor skin turgor, severe dry mucosa and sunken eye balls. Other indications for consideration of hospital admission include stool frequency (>8/day), fever, significant constitutional symptoms, large amount of bloody diarrhoea, immunocompromised host, infants or the elderly.

Fever suggests infection with invasive bacteria (Salmonella, Shigella or Campylobacter), enteric viruses or a cytotoxic organism such as Clostridium difficile or Entamoeba histolytica.

Clostridium difficile should be suspected after recent antibiotic use or hospitalisation.

Food history is important.

• Symptoms that begin within 6 hours of ingestion suggest a preformed toxin of Staphylococcus aureus or Bacillus cereus.

• Symptoms within 16 hours suggests Clostridium perfringens.

• Symptoms emerging after 16 hours suggest viral or bacterial infection (e.g. enterotoxigenic or enterohaemolytic Escherichia coli).

INVESTIGATIONS

Stool culture

The diagnostic yield from stool culture is poor: 1.5%–5.6% positive in a number of large epidemiological studies. Routine culture can identify Salmonella, Campylobacter and Shigella.

Specifically request cultres for Yersinia, enterohaemolytic E. coli (EHEC), viruses and Vibrio.

Ova, cysts and parasites need to be specifically requested and are particularly useful for persistent diarrhoea, as well as in patients exposed to infants in daycare centres. However, cultures are not particularly cost effective as organisms are shed only intermittently.

Clostridium difficile toxin assay is particularly useful in people who have had prior antibiotic exposure.

Endoscopy

Not routinely required. However, it may be useful in distinguishing ischaemic colitis from infectious colitides.

Useful in immunocompromised patients when cytomegalovirus is in the differential diagnosis.

Faecal leucocytes and occult blood

Presence supports the diagnosis of a bacterial aetiology.

Faecal lactoferrin latex agglutination

Faecal lactoferrin latex agglutination (LFLA) is a marker for faecal leucocytes. It is more precise and less vulnerable to variations than faecal leucocytes.

TREATMENT

Symptomatic measures are generally all that are required and include hydration with solutions that contain water, salt and sugar. The composition of the oral rehydration solution recommended by the World Health Organization (WHO) consists of:

• 3.5 g sodium chloride

• 40 g sucrose (or 20 g glucose)

• 2.9 g trisodium citrate dehydrate or 2.5 g sodium bicarbonate

• 1.5 g potassium chloride in one litre of clean drinking water.

The use of an antimotility agent, loperamide, may be considered in patients with acute diarrhoea but is contraindicated in diarrhoea caused by invasive organisms because the intestinal stasis mediated by the medication may enhance invasion by the pathogen or delay clearance of the organism from the bowel. These patients often present with fever or bloody motions.

Empiric antibiotic treatment may be considered in those patients where there can be a significant reduction in diarrhoea and other symptoms. The group of patients in whom this should be considered include those with:

• moderate to severe travellers’ diarrhoea

• more than 8 stools per day, volume depletion and symptoms lasting more than a week

• signs and symptoms of bacterial diarrhoea, such as fever and bloody diarrhoea.

The antibiotic of choice is an oral fluoroquinolone (ciprofloxacin 500 mg twice daily or norfloxacin 400 mg twice daily) for 3–5 days. Or, if fluoroquinolone resistance is suspected, erythromycin 500 mg twice daily is an acceptable alternative.

If nosocomial diarrhoea is suspected, discontinue the offending antibiotic, if possible, and start treatment with metronidazole 250 mg four times daily until C. difficile toxin assay is available.

Persistent diarrhoea from suspected Giardia infection should be treated with metronidazole 250–750 mg three times daily for 7–10 days.

Remember that if enterohaemorrhagic E. coli is suspected or proven, there is no benefit from the use of antibiotics and indeed antibiotic treatment may possibly increase the risk of the haemolytic uraemic syndrome by the increase in production or release of Shiga toxin.

When an intestinal bacterium or protozoon is isolated, specific antibiotic therapy can be prescribed (Table 15.2).

TABLE 15.2 Recommendations for therapy against specific pathogens

Organism	Recommendations for adults
Campylobacter species	Erythromycin 500 mg b.i.d. for 5 days
Salmonella (non-typhi species)	Not recommended in mild to moderate disease.
Salmonella (non-typhi species)	For severe disease, sulfamethoxazole/trimethoprim if susceptible or fluoroquinolone antibiotic for 5–7 days
Shigella species	Trimethoprim-sulfamethoxazole 160/800 mg respectively b.i.d. for 3 days (if susceptible) or fluoroquinolone antibiotic for 3 days
Escherichia coli Shiga toxin producing (O157:H7)	Supportive treatment only
Toxigenic Clostridium difficile	Offending antibiotic withdrawn if possible, treat with metronidazole 250 mg q.i.d. to 500 mg t.i.d. for 10 days
Cryptosporidium species	If severe, consider paromomycin, 500 mg t.i.d. for 7 days
Giardia	Metronidazole 250–750 mg t.i.d. for 7–10 days
Entamoeba histolytica	Metronidazole 750 mg t.i.d. for 5–10 days, plus either diiodohydroxyquin 650 mg t.i.d for 20 days or paromomycin 500 mg t.i.d. for 7 days

b.i.d. = twice daily; q.i.d. = four times daily; t.d.s. = three times daily.

SUMMARY

Infectious diarrhoea is common worldwide. The majority of infections are self-limiting. A patient’s history is crucial as it may allow the early use of empiric antibiotic therapy (Figure 15.1). Clinical evaluation should identify if there is any evidence of volume depletion and oral rehydration solution can be started early to decrease the rate of hospitalisation. Stool cultures are often not required but should be considered in patients with severe illness, bloody diarrhoea or those with underlying inflammatory bowel disease in whom the distinction between a flare-up or coexisting infection needs to be excluded. Antimotility agents may be useful in symptomatic patients without evidence of fever or bloody stools.

FIGURE 15.1 Management of acute diarrhoea.

FURTHER READING

Bouza E, Burillo A, Munoz P. Antimicrobial therapy of Clostridium difficile-associated diarrhea. Med Clin North Am. 2006;90:1141-1163.

Guerrant RL, Van Gilder T, Steiner TS. Practice guidelines for the management of infectious diarrhea. Clin Infect Dis. 2001;32:331-350.

Manatsathit S, Dupont HL, Farthing M, et al. Guideline for the management of acute diarrhea in adults. J Gastroenterol Hepatol. 2002;17:S54-S71.

Musher DM, Musher BL. Contagious acute gastrointestinal infections. N Engl J Med. 2004;351:2417-2427.

Thielman NM, Guerrant RL. Clinical practice. Acute infectious diarrhea. N Engl J Med. 2004;350:38-47.

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