Metagenomic next‑generation sequencing contributes to the diagnosis of Gardnerella vaginalis bacteremia associated with a rare extragenital infection and diagnostic challenges in a 13‑year‑old female patient: A case report

Gardnerella vaginalis (G. vaginalis) is a well‑recognized cause of bacterial vaginosis but is rarely associated with extragenital infections, particularly in individuals without a history of sexual activity. Metagenomic next‑generation sequencing (mNGS) enables unbiased detection of pathogens and has emerged as a valuable diagnostic approach for challenging infectious diseases. The current report outlines a case of G. vaginalis bacteremia in a 13‑year‑old female patient presenting with fever and acute bronchitis. Peripheral blood mNGS, combined with conventional microbiological investigations, was performed to identify the causative pathogen. Initial empirical treatment with piperacillin‑tazobactam and azithromycin failed to control the recurrent fever. Traditional cultures of blood, cerebrospinal fluid and bone marrow aspirate all returned negative results, whereas peripheral blood mNGS identified G. vaginalis as the potential pathogen. Following targeted therapy with metronidazole for 3 days, the patient's body temperature returned to normal, and follow‑up blood mNGS at discharge was negative for the pathogen. Due to its fastidious growth requirements, G. vaginalis is difficult to detect using conventional culture methods, which may lead to delayed diagnosis and false‑negative results. The present case highlights the utility of mNGS for timely and accurate pathogen identification in diagnostically challenging infections. The current case also broadens the recognized clinical spectrum of G. vaginalis infections by demonstrating its potential to cause bloodstream infection with persistent fever in an adolescent without a reported history of sexual activity.