Clinical Subject Page

Salmonellosis

Salmonellosis is an infection caused by bacteria of the genus Salmonella. It is commonly acquired through contaminated food or water and usually causes acute gastroenteritis with diarrhea,abdominal cramps, fever, nausea, and vomiting

Also called

Salmonella infection

ICD-10

A02.9

Specialty

Infectious

Onset

Acute

Reviewed

August 2026

On This Page

Overview

Overview
Etiology & Risk Factors

Etiology & Risk Factors
Pathophysiology

Pathophysiology
Clinical Presentation

Clinical Presentation
History Taking

History Taking
Physical Examination

Physical Examination
Investigations

Investigations
Diagnosis

Diagnosis
Management

Management
Complications

Complications
Prognosis

Prognosis
Key Points / Clinical Pearls

Key Points / Clinical Pearls

Overview

–Salmonellosis ranges from mild self-limited gastroenteritis to severe invasive disease.

-It can be broadly divided into:

Nontyphoidal Salmonella infection: primarily causes gastroenteritis but can become invasive.

Typhoidal Salmonella infection: caused by Salmonella Typhi or Salmonella Paratyphi and causes enteric fever.

Teaching point Most nontyphoidal Salmonella gastroenteritis is self-limited and requires supportive care rather than routine antibiotics.

Etiology & Risk Factors

-Etiology

–Salmonellosis is caused by Salmonella species, which are Gram-negative, facultatively anaerobic bacilli.

Transmission usually occurs through ingestion of contaminated:

Eggs
Poultry
Meat
Unpasteurized milk
Contaminated food or water

-Animal contact can also transmit infection.

-Risk Factors for Salmonellosis

Consumption of contaminated food
Exposure to reptiles or other infected animals
Extremes of age
Immunosuppression
Reduced gastric acidity

Pathophysiology

Ingestion of Salmonella → survival through the gastrointestinal tract → invasion of intestinal mucosa → inflammatory response → intestinal secretion and mucosal dysfunction → diarrhea and abdominal cramps → possible bloodstream invasion → bacteremia and systemic infection

Clinical Presentation

-Symptoms:

Salmonellosis commonly causes:

Diarrhea
Fever
Abdominal cramps
Nausea
Vomiting
Headache
Malaise

Diarrhea may occasionally contain blood or mucus.

-Signs:

Fever
Abdominal tenderness
Increased bowel sounds
Signs of dehydration
Tachycardia in significant fluid loss

-Invasive Salmonellosis is more likely in infants, older adults, and immunocompromised patients.

Important Note Severe Salmonellosis is more likely in young children, malnourished patients, and immunocompromised individuals.

History Taking

-Ask about:

Onset and duration of diarrhea
Frequency and character of stools
Blood or mucus in stool
Fever
Abdominal pain
Vomiting
Fluid intake and urine output
Recent food consumption
Undercooked eggs, poultry, or meat
Unpasteurized food or milk
Recent travel
Animal or reptile exposure

Physical Examination

-General Examination

Temperature
Heart rate and blood pressure
Hydration status
Mental status
Signs of systemic toxicity

-System-Specific Examination:

Abdominal tenderness
Abdominal distension
Bowel sounds
Signs of peritonitis in severe disease

Investigations

-Biochemistry / Specific Tests

Electrolytes and renal function when significant dehydration is present
Stool culture when microbiological confirmation is required
Blood cultures when bacteremia or sepsis is suspected
Antimicrobial susceptibility testing when clinically indicated

-Imaging

Not routinely required for uncomplicated Salmonellosis.

Imaging may be indicated when complications or an alternative diagnosis is suspected.

-Special / Confirmatory Tests

Stool Culture

Stool culture can confirm nontyphoidal Salmonella gastroenteritis and allows antimicrobial susceptibility testing.

For suspected enteric fever, blood cultures are particularly important.

Important Investigation Note

Stool culture is most useful in severe, persistent, bloody, outbreak-associated, or high-risk cases rather than every patient with uncomplicated acute diarrhea.

Diagnosis

Salmonellosis is usually suspected from acute diarrhea, fever, abdominal cramps, and an appropriate exposure history.

Typical gastroenteritis → assess severity and dehydration → stool culture when indicated → blood cultures if invasive disease is suspected.

The organism is confirmed by microbiological culture or appropriate molecular testing.

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Management

Non-Typhoidal Salmonella · Management

Management by Scenario

Scenario	General Management	Antibiotic	Duration
Uncomplicated gastroenteritis Immunocompetent adult	Oral rehydration — mainstay. Rest, bland diet. No antidiarrhoeals (prolong carriage). Stool culture to confirm.	Antibiotics NOT indicated — prolong faecal carriage, increase relapse, select resistance	Self-limiting 4–7 days
High-risk patient Immunocompromised, SCD, asplenia, extremes of age	Oral/IV rehydration. Blood cultures before antibiotics. Admit if systemic features.	Ciprofloxacin 500 mg BD PO or 400 mg IV BD Ceftriaxone 2g IV OD — fluoroquinolone resistant	5–7 days
Bacteraemia	Blood cultures × 2. IV access. Echo if endovascular source suspected. CT aorta in elderly — exclude mycotic aneurysm.	Ciprofloxacin 400 mg IV BD → PO step-down Ceftriaxone 2g IV OD — if resistant	14 days
Osteomyelitis (SCD)	MRI/bone scan to confirm. Orthopaedic review. Surgical drainage if abscess present.	Ciprofloxacin IV → PO step-down Ceftriaxone 2g IV OD	4–6 weeks
Mycotic aneurysm	Urgent vascular surgery. CT angiography. IV antibiotics pre/post-op.	Ceftriaxone 2g IV OD — preferred Ciprofloxacin PO — long-term suppression post-surgery	6 weeks IV; lifelong PO if repair not possible
Reactive arthritis	NSAIDs for joint pain and inflammation. Physical therapy. Antibiotics do not alter course.	Treat active GI infection only if still ongoing. Antibiotics do not prevent or shorten reactive arthritis.	NSAIDs: weeks–months

Resistance note: Fluoroquinolone resistance rising — especially travel-acquired (South/Southeast Asia). Send stool + blood cultures with sensitivity. Azithromycin 500 mg OD × 5 days — alternative for fluoroquinolone-resistant NTS in high-risk patients.

Typhoid Fever (Enteric Fever) · Management

Antibiotic Management by Scenario

Scenario	1st Line	Alternative	Duration
Uncomplicated typhoid Sensitive strain — outpatient	Azithromycin 1g OD PO — now preferred 1st line (less resistance, oral, safe in pregnancy) Ciprofloxacin 500 mg BD PO — if fluoroquinolone sensitive	Cefixime 400 mg OD PO	5 days (azithromycin) 7–14 days (others)
Severe / hospitalised	Ceftriaxone 2g IV OD — drug of choice. Step-down to oral when improving.	Azithromycin IV → PO Ciprofloxacin IV — if sensitive	10–14 days
MDR typhoid Resistant to ampicillin + chloramphenicol + TMP-SMX	Ceftriaxone 2g IV OD Azithromycin 1g OD PO	Ciprofloxacin — if fluoroquinolone sensitive	10–14 days
XDR typhoid Resistant to all 1st-line + fluoroquinolones + 3rd-gen ceph	Azithromycin 1g OD PO — often still sensitive Meropenem IV — severe XDR	Tigecycline — salvage	14 days
Chronic carrier Stool positive >12 months	Ciprofloxacin 750 mg BD PO × 4 weeks Cholecystectomy if gallstones + persistent carriage	Amoxicillin high dose × 3 months	4 weeks
Intestinal perforation	Emergency laparotomy + Ceftriaxone IV + Metronidazole IV	Meropenem IV — severe sepsis / polymicrobial	Until clinically clear post-op
Typhoid encephalopathy	Ceftriaxone IV + Dexamethasone 3 mg/kg loading → 1 mg/kg q6h × 48h	Steroids shown to reduce mortality in severe encephalopathy	Steroids 48h; antibiotics 14 days

Supportive care: IV fluids. Paracetamol — avoid NSAIDs (GI bleed risk). Soft diet. Strict stool precautions + hand hygiene. Notify public health. Monitor daily for perforation signs (sudden pain + rigidity + ↑WBC = emergency). Vaccine (Vi polysaccharide or Ty21a oral) for travellers — does not cover S. paratyphi.

Complications

Typhoid Fever (Enteric Fever) · Complications

Weekly Disease Progression

Week 1 — Invasion

Stepladder fever rising to 39–40°C

Headache, malaise, dry cough

Constipation more common than diarrhoea

Relative bradycardia — pulse-temperature dissociation

Week 2 — Fastigium

Sustained plateau fever 40°C

Rose spots — salmon-pink macules, abdomen/trunk

Splenomegaly, hepatomegaly

"Pea soup" diarrhoea, delirium

Week 3–4 — Complications

Intestinal perforation — 1–3%

GI haemorrhage

Encephalopathy, myocarditis

Relapse in 10%

Complications — Detail

Complication	Details	Management
Intestinal perforation Most feared — 1–3%	Ileal perforation at Peyer's patches — sudden worsening abdominal pain, board-like rigidity, ↑WBC, free air on CXR/AXR	Emergency laparotomy — primary repair or resection. Broad-spectrum IV antibiotics.
GI haemorrhage	Peyer's patch ulceration → melaena or frank rectal bleeding. May be massive. Typically week 3.	IV fluids, blood transfusion. Endoscopy ± intervention. Continue antibiotics.
Typhoid encephalopathy	Delirium, coma, seizures. High mortality. Mechanism: endotoxin-mediated CNS toxicity.	Dexamethasone IV + antibiotics — shown to reduce mortality
Myocarditis	ECG changes, arrhythmias, cardiac failure. Rare. Week 2–3.	Cardiac monitoring, supportive. Treat arrhythmia.
Cholecystitis / chronic carrier	Gallbladder colonisation — chronic carrier if stool positive >12 months. Gallstones predispose. Public health risk.	Ciprofloxacin 4 weeks. Cholecystectomy if gallstones + persistent carriage.
Relapse	10% — milder episode 2 weeks after apparent recovery. Same strain. More common after chloramphenicol treatment.	Repeat antibiotic course — same or switch agent
Haemolytic anaemia / DIC	Rare. G6PD deficiency increases haemolysis risk. DIC in severe sepsis.	Transfusion, haematology review. Treat underlying infection aggressively.

Non-Typhoidal Salmonella · Complications

Complications of NTS

Complication	Details	Who is at risk
Bacteraemia / Septicaemia	Salmonella enters bloodstream — persistent fever, rigors, no localising symptoms. Most common invasive complication. Occurs in ~5% overall.	Immunocompromised, extremes of age, sickle cell, asplenia
Salmonella osteomyelitis	Classic SCD association — Salmonella is the most common cause of osteomyelitis in sickle cell disease (not S. aureus). Long bones affected. Bone pain + fever.	Sickle cell disease
Mycotic (infected) aneurysm	NTS tropism for abnormal vasculature — atherosclerotic aorta especially. Back/abdominal pain + bacteraemia. Surgical emergency — CT aorta urgently.	Elderly, atherosclerosis
Reactive arthritis	Post-infectious oligoarthritis 2–4 weeks after GI infection. HLA-B27 association. Knees, ankles, sacroiliac joints. May include urethritis + conjunctivitis — Reiter's triad.	HLA-B27 positive
Meningitis	Rare — predominantly neonates and infants. High mortality and neurological sequelae.	Neonates, infants
Haemolytic uraemic syndrome (HUS)	Microangiopathic haemolytic anaemia + thrombocytopenia + AKI. More commonly E. coli O157 but NTS can trigger.	Children

Prognosis

The prognosis of uncomplicated Salmonellosis is generally excellent, with most patients recovering within several days without antibiotics. Severe invasive disease has a higher risk of complications and death, particularly in infants, older adults, and immunocompromised patients.

Key Points / Clinical Pearls

Salmonellosis is caused by Salmonella species.
It is commonly transmitted through contaminated food or water.
Poultry, eggs, and meat are important sources.
Nontyphoidal Salmonella commonly causes acute gastroenteritis.
Typical symptoms include diarrhea, fever, and abdominal cramps.
Vomiting and nausea may also occur.
Dehydration is an important complication.
Most uncomplicated cases are self-limited.
Oral rehydration is the main treatment.
Stool culture is useful in severe, persistent, bloody, or outbreak-associated disease.
Blood cultures are important when bacteremia or enteric fever is suspected.
Antibiotics are not routinely required for uncomplicated nontyphoidal Salmonellosis.
Invasive Salmonellosis may cause bacteremia and sepsis.

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Centers for Disease Control and Prevention (CDC). Salmonella .
Centers for Disease Control and Prevention (CDC). Typhoid Fever .
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Hohmann EL. Nontyphoidal Salmonellosis. Clin Infect Dis. 2001;32(2):263-269. PubMed .
Shane AL, Mody RK, Crump JA, et al. 2017 Infectious Diseases Society of America Clinical Practice Guidelines for the Diagnosis and Management of Infectious Diarrhea. Clin Infect Dis. 2017;65(12):e45-e80. PubMed .
National Library of Medicine (NIH). Salmonellosis . StatPearls.