Table 2.

 Summary of bacterial intestinal infections that cause bloody diarrhoea

Pathogen	Sources	Incubation period	Clinical presentation	Diagnosis	Treatment
Campylobacter jejuni	Mainly from farm and domestic animals and animal food products, especially undercooked chicken	1-3 days (occasionally up to 10 days)	Fever and diarrhoea; bloody diarrhoea in up to 50%; usually lasts less than 1 week, with relapses in up to 25%	Stool culture; selective growth medium needed	Antibiotics reserved for those with severe symptoms or impaired immunity4
Salmonella species	Mainly food borne—can cause large outbreaks; farm animals (especially undercooked poultry); pets (including reptiles); person to person transmission less frequent; infants (3-5 months) especially vulnerable	6-48 hours (occasionally longer)	Gastroenteritis-like illness, often with fever lasting 3-4 days; bloody mucoid diarrhoea may follow as colitis develops; colitis may persist for 1-12 weeks	Stool culture; may stay positive for weeks	Antibiotics not usually beneficial and may prolong bacterial carriage5; antibiotics reserved for young infants, those with suspected bacteraemia or with extraintestinal spread, and those with impaired immunity
Yersinia enterocolitica	Farm and domestic animals; epidemics related to contaminated milk and ice cream	3-7 days	Usually presents with fever, abdominal pain, and diarrhoea; blood present in the stool in about 30%; illness usually lasts 1-3 weeks	Stool culture; organism easily missed so the laboratory should be advised of suspicion	No evidence of benefit with antibiotics, and diagnosis is often late; antibiotics reserved for those with impaired immunity or extraintestinal spread
Shiga toxin producing Escherichia coli (such as O157 H7)	Often caused by foods contaminated with bovine faeces, such as undercooked minced (ground) beef; large outbreaks may occur	3-9 days	Often presents with watery diarrhoea, which progresses to bloody diarrhoea; typically lasts 3-8 days; haemolytic uraemic syndrome can develop after 3-16 days	Specialised diagnostic techniques needed	Antibiotics seem to have no clinical benefit and may increase the risk of haemolytic uraemic syndrome6
Shigella species	Highly contagious; usually person to person transmission; occasional outbreaks from contamination of food or water; most common between 6 months and 5 years of age; more severe in adults	1-4 days	A few patients present with gastroenteritis-like illness; most experience lower abdominal pain, bloody mucoid stools, and fever; illness may be life threatening, with septicaemia	Stool microscopy shows pus cells and red cells; the organism is fastidious and requires prompt inoculation into appropriate medium for culture	Treated with antibiotics (for example, ciprofloxacin); during outbreaks or in high prevalence areas in the developing world antibiotics are given presumptively