What are the recommended tests and treatment for typhoid diagnosis?

Diagnosis and Management of Typhoid Fever

Blood culture is the primary recommended diagnostic test for typhoid fever, followed by treatment with ceftriaxone 2g IV daily for 10-14 days as first-line therapy. 1

Diagnostic Methods for Typhoid Fever

Primary Diagnostic Tests (in order of recommendation):

1. Blood Culture

   • Sensitivity: 40-80%
   • Should be collected before antimicrobial administration
   • Considered the primary diagnostic method 1

2. Bone Marrow Culture

   • Gold standard with higher sensitivity
   • Particularly valuable if antimicrobials have been administered
   • In adults, 1 ml of bone marrow culture provides similar sensitivity to 15 ml of blood culture 2

3. Stool Culture

   • Sensitivity: 35-65%
   • Beneficial for detecting enteric fever pathogens
   • Using 2g rather than 1g of stool increases isolation rates by 10.5% 2

4. Culture-Independent Methods

   • Panel-based multiplex molecular diagnostics from stool and blood specimens
   • Nucleic acid amplification tests (NAATs) for rapid detection
   • PCR with blood samples shows higher sensitivity (84.5%) compared to blood culture (61.8%) 3
   • PCR with urine samples (69.3% sensitivity) can be a useful complementary test 3

Tests NOT Recommended:

• Serologic tests (including Widal test)
  • Poor performance characteristics
  • Low sensitivity (39%) 3
  • Should not be relied upon for diagnosis 1

Treatment Recommendations

First-line Treatment:

• Ceftriaxone 2g IV every 24 hours for 10-14 days
  • Especially important for patients returning from Asia due to increasing fluoroquinolone resistance
  • 14-day duration recommended to reduce risk of relapse 1

Alternative Treatments:

• Azithromycin

  • For uncomplicated cases or step-down therapy
  • When fluoroquinolone resistance is confirmed 1

• Fluoroquinolones

  • Use only if confirmed sensitive to both ciprofloxacin and nalidixic acid
  • Not recommended for empiric therapy due to increasing resistance 1

Special Considerations:

• Treatment should be started empirically in clinically unstable patients with strong suspicion of enteric fever
• Steroids should be considered in severe cases 1
• Monitor for antimicrobial resistance, particularly to fluoroquinolones in South and Southeast Asia

Common Pitfalls to Avoid

• Relying solely on the Widal test for diagnosis
• Failing to collect blood cultures before starting antibiotics
• Using fluoroquinolones empirically without considering regional resistance patterns
• Overlooking typhoid fever in patients with fever but without diarrhea
• Not considering typhoid in febrile travelers returning from endemic areas 1

Follow-up and Public Health Considerations

• Typhoid fever is a notifiable disease in most countries
• For patients working in food service, child care, or healthcare settings, follow-up stool cultures may be required
• Three negative stool cultures obtained at least 24 hours apart, at least 48 hours after cessation of antimicrobial therapy, and not earlier than 1 month after symptom onset may be required for readmission to work 4
• If any follow-up stool culture yields Salmonella Typhi, monthly stool cultures during the subsequent 12 months are recommended until at least 3 consecutive cultures are negative 4

By following this evidence-based diagnostic and treatment approach, clinicians can effectively identify and manage typhoid fever while minimizing complications and preventing further transmission.