What is the role of blood culture in the evaluation of leptospirosis?

Updated: Jul 08, 2021
  • Author: Sandra G Gompf, MD, FACP, FIDSA; Chief Editor: Michael Stuart Bronze, MD  more...
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Answer

Isolating the organism by culture allows definitive diagnosis. Leptospires remain viable in anticoagulated blood for as long as 11 days; hence, specimens can be mailed to a reference laboratory for culture. The infecting serovar can be isolated only by culture.​ [41]

Blood cultures may be negative if drawn too early or too late. Leptospires may not be detected in the blood until 4 days after the onset of symptoms (7-14 d after exposure). Once the immune system is activated, blood cultures may again become negative. Leptospires may be isolated from the cerebrospinal fluid (CSF) within the first 10 days.

Leptospires may be isolated from the urine for several weeks after the initial infection. In some patients, urine cultures may remain positive for months or years after the onset of illness. Positive urine cultures may take as long as 8 weeks to grow.


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