Usefulness of Nested Polymerase Chain Reaction with Clinical Specimens for Diagnosis of Leptospirosis: a Case Series and a Review of Literature

A culture of the Leptospira species and the microscopic agglutination test (MAT) are considered as the reference standard for the diagnosis of leptospirosis, but both tests are imperfect for early diagnosis. We describe 4 patients diagnosed with leptospirosis using nested polymerase chain reaction (N-PCR) that targeted the 16S rRNA gene and the passive hemagglutination assay (PHA). In our 4 cases, Leptospira DNA in the urine, plasma, or cerebrospinal fluid (CSF), was detected by N-PCR in the early phase of leptospirosis, except in the sample from the buffy coat. Especially, case 3 showed that N-PCR with the urine and CSF was positive 8 days after symptom onset, but not for the plasma or buffy coat. We report 4 cases of leptospirosis that were diagnosed by N-PCR that targeted the 16S rRNA gene with urine, plasma, or CSF, but not the buffy coat. Three were cured by doxycycline but the case 4 was fatal. Detection of Leptospira DNA by PCR from the urine and CSF, in addition to plasma, may be helpful to confirm the diagnosis.