What are the differences in diagnosis and treatment between typhoid fever (Salmonella Typhi/Paratyphi) and non‑typhoidal Salmonella infections?

Typhoid vs Non-Typhoidal Salmonella: Key Diagnostic and Treatment Differences

Typhoid fever (caused by S. Typhi/Paratyphi) requires immediate empiric antibiotic therapy with ceftriaxone or azithromycin, while non-typhoidal Salmonella (NTS) gastroenteritis should NOT be treated with antibiotics in most cases due to risks outweighing benefits.

Clinical Presentation Differences

Typhoid Fever (Enteric Fever)

• Systemic febrile illness with fever almost invariable 1
• Prolonged fever duration (typically >1 week)
• Non-specific symptoms: headache, constipation OR diarrhea, dry cough 1
• Classic signs (when present): toxic appearance, bronchitic chest, splenomegaly, tympanitis 2
• Travel history to endemic areas is crucial - particularly Indian subcontinent 1, 3
• Complications in 10-15% if untreated >2 weeks: GI bleeding, intestinal perforation, encephalopathy 1

Non-Typhoidal Salmonella

• Self-limited gastroenteritis with acute diarrhea (often bloody) 4
• Fever, abdominal pain, vomiting common but illness resolves in days 4
• Symptoms typically last <10-14 days 4
• Usually no travel history required 5

Critical Pitfall: Paratyphoid A can present with fewer "classic" signs - significantly less anorexia (57%), toxic appearance (54%), and coated tongue (64%) compared to typhoid, potentially mimicking viral infections 2.

Diagnostic Approach

For Suspected Typhoid Fever

Blood cultures are the cornerstone - highest yield within first week of symptoms 1

• Collect blood, stool, AND urine cultures before starting antibiotics 4
• Multiple blood cultures essential: 21% of paratyphoid cases only positive on second sample 2
• Stool/urine cultures become positive after first week 1
• Bone marrow culture has higher sensitivity than blood if available 1

Laboratory findings:

• Widal test is NOT recommended - lacks sensitivity/specificity 1
• Only 57% of paratyphoid cases show significant Widal titers 2
• Leucopenia in only 25% of cases 2
• Eosinopenia is constant and diagnostically useful 2, 5

For Suspected NTS Gastroenteritis

• Stool culture is primary diagnostic method 4
• Blood cultures rarely positive (1/16 cases vs 7/9 in typhoid) 5
• Culture-independent diagnostic tests (CIDTs) available but not validated for proof of cure 4

Treatment Algorithms

Typhoid Fever Treatment

Empiric therapy MUST be started immediately if clinical suspicion is high and patient unstable 4, 1

First-line empiric therapy (before susceptibility results):

• Ceftriaxone IV - preferred due to widespread fluoroquinolone resistance 1, 6

  • 70% of S. Typhi/Paratyphi imported to UK are fluoroquinolone-resistant 1

  • All isolates remain sensitive to ceftriaxone 1

Alternative oral therapy (for uncomplicated disease):

• Azithromycin - lower risk of clinical failure (OR 0.48) and relapse (OR 0.09) compared to fluoroquinolones and ceftriaxone respectively 6
• Azithromycin resistance currently rare 1

Avoid:

• Fluoroquinolones as first-line (especially from Asia) unless proven sensitive 1, 7
• Cefixime has 4-37.6% treatment failure rates 1

Critical Evidence: Early treatment dramatically improves outcomes - intestinal perforation and death were significantly more common in pre-antibiotic era 4. Patients treated early have better outcomes than those treated later 4.

Non-Typhoidal Salmonella Treatment

DO NOT treat with antibiotics in most cases 4

Rationale:

• Vast majority are self-limited 4
• Antibiotics provide only ~1 day symptom reduction 4
• Antibiotics INCREASE prolonged Salmonella shedding 4
• Risks outweigh modest benefits 4

Exceptions requiring treatment:

• Severe illness with signs of sepsis 4
• Immunocompromised patients 4
• Infants <3 months 4
• Patients with neurologic involvement 4

If treatment indicated:

• Azithromycin or third-generation cephalosporin (depending on local resistance patterns) 4
• Fluoroquinolones only if local susceptibility confirmed 4

Carrier State Management

Typhoid Carriers

• Asymptomatic S. Typhi carriers SHOULD be treated to reduce transmission 4
• Chronic carriage occurs in 3-5% after acute infection 8
• Fluoroquinolones show high decolonization efficacy rates 4
• Particularly important for food handlers, healthcare workers, childcare providers 4

NTS Carriers

• Asymptomatic NTS carriers in low-risk settings do NOT need treatment 4
• Adults commonly shed sporadically for weeks 4
• Outbreaks from carriers are rare with proper hand hygiene 4
• High-risk workers (food service, healthcare, childcare) follow local public health guidance 4
• Repeat cultures required by some jurisdictions before return to work 4

Important: Culture-independent tests cannot confirm clearance - traditional culture methods required for proof of cure 4.

Key Distinguishing Features Summary

Feature	Typhoid Fever	Non-Typhoidal Salmonella
Travel history	Almost always present [5]	Usually absent [5]
Primary culture site	Blood (7/9 cases) [5]	Stool [5]
Fever duration	Prolonged (>1 week) [1]	Short (<1 week) [4]
Eosinopenia	100% [5]	77.8% [5]
Antibiotic indication	Always [4,1]	Rarely [4]
Carrier treatment	Yes [4]	Usually no [4]