Postoperative Disseminated Mycoplasma hominis Infection with False-Negative Blood Cultures: A Case Report

Mycoplasma hominis commonly colonizes the genitourinary tract and primarily affects immunocompromised individuals. It is mostly confined to localized infections, with bloodstream dissemination being rare. Because of its fastidious nutritional requirements, the organism is seldom recovered by routine blood culture, and the absence of a cell wall renders it intrinsically resistant to many first-line antimicrobials. Consequently, the diagnosis and treatment of M. hominis bloodstream infections remain challenging.

A 72-year-old man developed persistent fever and marked systemic inflammation after lumbar spine surgery. Despite empirical broad-spectrum antibiotics, he progressed to severe incisional infection, pulmonary infection, and effusions in multiple serous cavities-including the left interlobar fissure, pleural space, and pericardium. Routine blood and urine cultures remained negative until two weeks after surgery, when M. hominis was first isolated from incisional exudate and definitively identified by MALDI-TOF MS. The patient ultimately recovered after surgical debridement and combination therapy with doxycycline plus moxifloxacin. During this period, we used Mycoplasma-specific liquid media combined with Columbia blood agar and subsequently recovered M. hominis from the patient's sputum, urethral swabs, and initially culture-negative blood samples. MALDI-TOF MS cluster analysis confirmed that all isolates belonged to a single clonal group responsible for disseminated infection.

Immunocompromised patients with postoperative indwelling catheters constitute a high-risk population for hematogenous dissemination of M. hominis. In patients with persistent fever and negative routine cultures, M. hominis infection should be actively suspected. Timely targeted mycoplasma culture and MALDI-TOF MS confirmation are essential.