Metagenomic Next-Generation Sequencing of Mycoplasma hominis Infection in an Immunocompromised Patient: A Case Report

Mycoplasma hominis is an underrecognized opportunistic pathogen that can cause extra-genitourinary infections, particularly in immunocompromised hosts. This case report describes a persistent soft tissue infection following a wooden splinter injury in a 52-year-old immunocompromised man, in whom M. hominis was identified by blood mNGS after conventional microbiological investigations were inconclusive. The patient developed recurrent fever, wound pain, swelling, and exudation. Empirical treatment with ertapenem and subsequent surgical intervention did not provide sustained clinical improvement, while conventional microbiological investigations remained inconclusive. Peripheral blood was therefore analyzed by mNGS, which detected M. hominis, human betaherpesvirus 5, and GB virus C. For M. hominis, nine species-specific reads were identified, with a relative abundance of 21.5% for the genus Mycoplasma and 99% confidence for species-level identification. The mNGS finding was interpreted together with the refractory clinical course and the absence of a convincing alternative bacterial pathogen. Following further surgical management and multidisciplinary evaluation, targeted antimicrobial therapy with intravenous moxifloxacin plus omadacycline was administered, followed by oral omadacycline after discharge. The patient subsequently became afebrile, pain improved, and inflammatory markers progressively declined. This case demonstrates the potential utility of blood mNGS for identifying an atypical pathogen in an immunocompromised patient with culture-negative, treatment-refractory infection. The findings also emphasize that low-read mNGS results should be interpreted in conjunction with clinical findings, conventional microbiological investigations, and treatment response.