Blood culture is the gold standard (golden) test for typhoid fever from the 2nd day of fever onwards (especially in the first week).
Why blood culture?
- Typhoid (caused by *Salmonella Typhi*) causes bacteremia early in the illness.
- Blood culture has the *highest yield in the first week* of fever (sensitivity often 60–90% with adequate blood volume, if done before antibiotics).
- It is considered the confirmatory/gold-standard test because it directly grows the bacteria and also allows antibiotic sensitivity testing.
- Sensitivity drops significantly after the first week and if antibiotics have already been started.
Important practical points
- Collect an adequate volume of blood (ideally 10–20 mL in adults, less in children) and inoculate into culture bottles as soon as possible.
- Results usually take 2–5 days (sometimes longer).
- Prior antibiotic use reduces the chance of a positive result.
| Test | Best time | Reliability in early fever (Day 2 onwards) | Notes |
|---|---|---|---|
| Blood culture | First week (Day 2–7) | Gold standard | Confirmatory |
| Bone marrow culture | Any time | Highest sensitivity | Invasive, rarely done routinely |
| Widal test | After 7–10 days | Poor in early fever | Many false positives/negatives; not recommended as primary test |
| Typhidot / rapid IgM tests | From ~5–7 days onwards | Moderate | Useful for quick screening but not confirmatory |
| Stool culture | 2nd–3rd week | Low early | More useful later |
Summary: For fever starting from the 2nd day, request a *blood culture* (preferably before starting antibiotics). Rapid antibody tests or Widal are less reliable this early.
This is general medical information based on standard guidelines. Always consult a doctor for proper evaluation, clinical correlation, and treatment decisions. Self-diagnosis or self-medication is not advised.
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