BACKGROUND: Mycoplasma hominis is a part of the microflora of the urogenital tract
however, extra-urogenital infections due to M. hominis are rare. Herein, we present a case study of a patient who successfully recovered from a sternal wound infection caused by M. hominis. CASE PRESENTATION: We report a case of sternal wound infection caused by M. hominis following tricuspid valvuloplasty. The patient developed a severe infection despite postoperative antimicrobial therapy. Wound sample cultures grew pinpoint-sized colonies on blood agar plates, which were identified as M. hominis by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Based on the results of the antibiotic susceptibility test, effective infection management was achieved using a combination of moxifloxacin and doxycycline. CONCLUSIONS: The potential role of M. hominis as a causative agent of postoperative infections after thoracotomy may be underestimated. M. hominis should be highly suspected when patients have an indwelling catheter or when perioperative wound samples show numerous leukocytes with no visible bacteria, and are unresponsive to standard empirical treatment for postoperative infections.