PCR-Negative Leptospirosis: A Case Report

Pathogenic spirochetes of the genus Leptospira produce Leptospirosis, an emerging zoonotic infection that is frequently observed in tropical areas and frequently manifests as an undifferentiated fever. Because of its preliminary level of laboratory tests and generalized clinical signs, early diagnosis is still difficult. 
We describe a 63-year-old male farmer patient who developed a high-grade fever, myalgia, thrombocytopenia, altered liver function, and hemodynamic abnormalities. Initial Leptospira IgM ELISA and Polymerase Chain Reaction (PCR) results were negative despite a high level of clinical suspicion, and repeated serological testing revealed seroconversion with positive IgM, validating the diagnosis. The patient required critical care management with mechanical ventilation, inotropes support, and broad-spectrum antibiotics along with doxycycline. 
This case highlights the diagnostic dilemma of early Leptospirosis, especially in patients who have already been exposed to antibiotics or tests performed during the leptospiremic phase before antibody development. Careful clinical evaluation and repeated serological testing are necessary to confirm the diagnosis. In endemic areas, timely empirical treatment with doxycycline will save the patient.