Synopsis
Distinguish four major bacterial diarrhoeal syndromes, recognise invasive and toxin-mediated complications, select public-health testing and use antimicrobials only where benefit outweighs organism-specific harm.
- Campylobacter commonly causes fever, cramping and sometimes bloody diarrhoea after poultry, unpasteurised milk, animal or water exposure; most cases need fluids only.
- Non-typhoidal Salmonella usually produces self-limiting gastroenteritis after food or animal exposure, but bacteraemia can seed arteries, bone and prostheses.
- Shigella has a very low infectious dose and causes fever, cramps, tenesmus and small-volume bloody or mucoid stool with important person-to-person spread.
- STEC produces severe cramping and bloody diarrhoea, often with little fever; antibiotics and antimotility drugs may increase toxin exposure and are avoided.
- Send stool culture or PCR in bloody, severe or outbreak-associated disease and ensure culture and susceptibility follow molecular detection when required.
- Take blood cultures for sepsis, enteric fever differential, immunosuppression or suspected invasive Salmonella disease.
- Antibiotics are not routine for Campylobacter or uncomplicated non-typhoidal Salmonella; selected severe or high-risk disease is treated from susceptibility and local guidance.
- Notify and coordinate with the health-protection team for STEC, Shigella, outbreaks and occupational or institutional transmission concerns.
Key red flags
Bloody diarrhoea with falling platelets, fragmented red cells or rising creatinine suggests STEC-associated haemolytic uraemic syndrome.
Severe abdominal tenderness, guarding, distension or absent bowel sounds indicates possible perforation, ischaemia or toxic megacolon.
Persistent non-typhoidal Salmonella bacteraemia with back, abdominal or chest pain suggests infected arterial tissue or vascular graft.
Shigellosis in a sexual network or after international travel may be extensively drug resistant and needs susceptibility-led treatment.
Campylobacter illness followed by ascending weakness, areflexia, facial weakness or breathing difficulty suggests Guillain–Barré syndrome.
Any invasive disease in pregnancy, older age, immunosuppression, haemoglobinopathy or major vascular disease needs early specialist review.
Fever, urgency, tenesmus and frequent small-volume stool containing blood or mucus suggest invasive distal colitis and easy transmission.
Severe abdominal cramps and bloody diarrhoea with limited fever after farm, animal, food or linked-case exposure raises toxin-mediated risk.
Persistent fever, positive blood cultures, focal bone pain or aortic-region pain indicates extra-intestinal infection requiring imaging and prolonged treatment.
Investigation priorities
Detect Campylobacter, Salmonella, Shigella and Shiga toxin genes and preserve isolates for susceptibility and public-health typing.
Management branches
An adult has bloody diarrhoea, severe cramping or epidemiological exposure compatible with STEC.
- Isolate, rehydrate and send urgent stool testing that includes Shiga toxin detection and culture.
- Avoid antibiotics and antimotility drugs until STEC is excluded or a specialist identifies a compelling alternative indication.
- Obtain baseline and serial full blood count, platelets, creatinine, blood film and haemolysis markers according to severity.
- Escalate falling platelets, haemolysis, reduced urine or neurological change to renal and critical-care teams immediately.