Salmonella Infection
Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management
Definition
Salmonella infection (salmonellosis) is a bacterial gastroenteritis caused by Salmonella species, typically presenting with diarrhoea, fever, and abdominal cramps.
Aetiology
- Caused by Salmonella enterica, including serotypes Typhimurium and Enteritidis.
- Transmission via ingestion of contaminated food (poultry, eggs, dairy, meat) or water.
- Person-to-person spread occurs via the faecal-oral route.
Pathophysiology
- Bacteria invade the intestinal mucosa, triggering an inflammatory response.
- Increased intestinal secretion leads to watery diarrhoea.
- Some serotypes (e.g., S. Typhi) can invade the bloodstream, causing systemic disease (typhoid fever).
Risk Factors
- Consumption of undercooked or contaminated food.
- Poor hand hygiene after handling raw meat.
- Travel to endemic regions (higher risk of typhoid fever).
- Immunocompromised individuals (HIV, chemotherapy patients).
- Exposure to reptiles (as they can carry Salmonella).
Signs and Symptoms
- Non-typhoidal salmonellosis:
- Watery or bloody diarrhoea.
- Fever and chills.
- Abdominal cramps and nausea.
- Vomiting (less common).
- Typhoid fever (S. Typhi):
- Prolonged fever and relative bradycardia.
- Rose spots (erythematous macules on the trunk).
- Hepatosplenomegaly.
- Constipation (early) followed by diarrhoea.
- Complications: bacteraemia, reactive arthritis, intestinal perforation (typhoid fever).
Investigations
- Stool culture: gold standard for diagnosis.
- Blood cultures: positive in typhoid fever.
- Full blood count (FBC): may show leukocytosis or leukopenia.
- Renal and liver function tests: assess dehydration and organ involvement.
- Widal test: for serological detection of typhoid fever (not routinely used due to low specificity).
Management
1. Supportive Care:
- Oral rehydration therapy (ORT) for mild cases.
- IV fluids in severe dehydration.
- Avoid antimotility agents (e.g., loperamide) to prevent prolonged infection.
2. Antibiotic Therapy:
- Uncomplicated non-typhoidal salmonellosis: usually self-limiting; antibiotics not required.
- Severe disease or immunocompromised patients: ciprofloxacin or azithromycin.
- Typhoid fever: azithromycin (mild cases) or ceftriaxone (severe cases).
3. Prevention:
- Proper food handling and cooking.
- Handwashing after handling raw poultry and before eating.
- Typhoid vaccination for travellers to endemic regions.
4. Referral:
- Infectious diseases: for severe or recurrent cases.
- Gastroenterology: for persistent symptoms requiring further investigation.
- Public health: for outbreak investigation and reporting.