A 71-year-old immunocompetent woman presented with a painful, erythematous, and fluctuating right gluteal abscess following a fall. Initial cultures were negative, and she received various antibiotics without resolution, leading to repeated surgical drainage. Molecular analysis via 16S rRNA gene sequencing of abscess fluid eventually identified Mycoplasma hominis as the causative agent. The patient responded well to moxifloxacin, highlighting the challenges in diagnosing fastidious organisms in extragenital sites. This case underscores the importance of considering Mycoplasma hominis in culture-negative abscesses, especially when conventional methods fail.
Key note: Mycoplasma hominis can cause extragenital abscesses in immunocompetent individuals and requires molecular diagnostics for identification.