Typhoid Fever: Key Investigations and Management
KEY INVESTIGATIONS
Essential Initial Tests
- Blood cultures (2 sets): Take prior to any antibiotic therapy; sensitivity 40-80% (highest in first week), up to 80% overall 1, 2
- Bone marrow culture: Higher sensitivity than blood culture (35-65% vs blood culture) 1
- Full blood count (FBC): Look for lymphopenia and thrombocytopenia, both common in typhoid 1
- Urea & electrolytes (U&E) and liver function tests (LFTs): Essential baseline 1
- Malaria film and rapid diagnostic test (RDT): Mandatory in all febrile travelers from tropical areas to exclude malaria 1
Tests to AVOID
- Widal test: Lacks sensitivity and specificity; NOT recommended 1
- Rapid serological tests (Typhidot, Typhidot-M, Tubex): Mixed results; not reliable for definitive diagnosis 1, 3
Antibiotic Sensitivity Testing - Critical Caveat
- Ciprofloxacin disc testing is unreliable for Salmonella typhi/paratyphi 1, 2
- Only consider fluoroquinolone-sensitive if ALSO sensitive to nalidixic acid on disc testing 1
MEDICAL MANAGEMENT
First-Line Treatment (Empirical)
For patients from Asia or with unstable clinical condition, start treatment empirically:
- Intravenous ceftriaxone: First-line agent, especially for patients from Asia where >70% of isolates are fluoroquinolone-resistant 1, 2
- Treatment duration: 14 days to reduce relapse risk 1, 2
- Steroids: Consider adding in severe cases 1, 2
Oral Alternatives for Uncomplicated Disease
- Azithromycin: Suitable oral alternative if fluoroquinolone resistance confirmed; relapse rate <3% 1, 2
- Fluoroquinolones: Only use if nalidixic acid sensitivity confirmed; average fever clearance <4 days, cure rates >96%, relapse rates <8% 1, 2
- Cefixime: Oral alternative but treatment failure rates 4-37.6%; less reliable 1
Geographic Resistance Patterns
- >70% of S. typhi and S. paratyphi imported to UK are fluoroquinolone-resistant 1
- All isolates reported in 2006 were ceftriaxone-sensitive 1
- Pakistan: Ciprofloxacin-resistant and ceftriaxone-resistant typhoid now common 4
NON-MEDICAL MANAGEMENT
Supportive Care
- Hydration and electrolyte management: Essential for all patients 4
- Monitor for complications: Gastrointestinal bleeding, intestinal perforation, typhoid encephalopathy occur in 10-15% of patients, typically in second week of untreated illness 2, 4
- Isolation precautions: Implement appropriate infection control for fecal-oral transmission 4
Prevention Strategies
Vaccination (Pre-exposure):
- Typhoid vaccines: Two types available (oral Ty21a and injectable Vi-polysaccharide); offer 50-80% protection 1
- Oral Ty21a vaccine: For immunocompetent persons ≥6 years; booster every 5 years 1
- Vi-polysaccharide vaccine: For persons ≥2 years; booster every 2 years 1
- Indications: Travelers to moderate-high risk areas, household contacts of chronic carriers, laboratory personnel 1
- Limitation: Does NOT protect against Salmonella Paratyphi A, B, or C 1
Water, Sanitation, and Hygiene (WASH):
- Avoid high-risk foods and beverages in endemic areas 1
- Hand hygiene: Critical adjunct to vaccination 1
- Safe water and sanitation infrastructure: Cornerstone of prevention 4
Public Health Notification
- Mandatory reporting: Typhoid is a notifiable disease; report to appropriate health department with isolate submission 1
CLINICAL PEARLS
- Fever pattern: Gradual onset over 3-7 days with malaise, headache, myalgia 4
- Symptoms may be altered by previous antimicrobial use 4
- Most tropical infections become symptomatic within 21 days of exposure 1
- Early treatment results in better outcomes than delayed treatment 2
- Average hospital stay: 10.8 days 5