High-Dose Benzylpenicillin Treatment-Induced Febrile Neutropenia in HIV-Infected Male with Neurosyphilis: Case Report

<b>Background</b>: Prevention of an irreversible sequalae in neurosyphilis patients requires immediate high-dose intravenous benzylpenicillin administered for a prolonged period of time. However, life-threatening neutropenia has been reported as one of the complications following extended usage of benzylpenicillin. <b>Case presentation</b>: We report a 54-year-old male patient with HIV who developed high-dose benzylpenicillin-induced febrile neutropenia during neurosyphilis treatment. The patient developed a fever of up to 39.8 °C, severe leukopenia (<1 × 10⁹/L), and neutropenia (0.2 × 10⁹/L). He also presented with slightly elevated C-reactive protein and procalcitonin levels but had no clear symptoms of other infections. The diagnosis was confirmed by excluding other possible causes of neutropenia: flu, measles, sepsis, and HIV-related neutropenia. Third-generation antipseudomonal cephalosporin in combination with vancomycin and granulocyte colony-stimulating factor were administered, and the patient saw a rapid improvement in clinical symptoms and laboratory findings. <b>Conclusions</b>: High-dose benzylpenicillin-induced neutropenia should be considered a complication after prolonged periods of neurosyphilis treatment with high-dose benzylpenicillin when there is no evidence of other potential causes of neutropenia. Early diagnosis and proper treatment are critical in order to prevent this dangerous condition from deteriorating further.