A Case of Pelvic Abscess Caused by Mycoplasma hominis After Abdominal Total Hysterectomy

A woman in her 50s underwent abdominal total hysterectomy for uterine myoma. She was discharged from the hospital on postoperative day (POD) 6 following an uneventful postoperative course but returned to the outpatient clinic on POD 11 with chief complaints of fever and abdominal pain. Blood tests at presentation showed a C-reactive protein level of 22.95 mg/dL and a white blood cell count of 21300/μL, indicating an increased inflammatory response. Transvaginal ultrasonography and contrast-enhanced computed tomography (CT) revealed a small amount of ascites and a thickened pelvic peritoneum. Based on these findings, pelvic peritonitis was diagnosed and the patient was readmitted to the hospital. After admission, antimicrobial treatment with cefmetazole 3 g/day was started, but transvaginal ultrasonography on POD 13 (3 days after readmission) revealed an intra-pelvic abscess. The abscess was punctured under transvaginal ultrasonographic guidance and the puncture fluid was submitted for microbiological examination, followed by CT-guided drainage. At the same time, the antimicrobial regimen was changed to sulbactam/ampicillin 9 g/day and doxycycline (DOXY) 200 mg/day (100 mg/day from the following day). On POD 18 (8 days after readmission), Mycoplasma hominis was detected in the abscess culture, leading to the decision to increase the dose of DOXY to 200 mg. Subsequently, with improvement of subjective and objective symptoms and reduction of the abscess cavity, the patient was discharged from the hospital on POD 21 (11 days after readmission). Although M. hominis is a common urogenital commensal, it can be a potential pathogen in a patient with a pelvic abscess that occurs as a late postoperative complication and does not respond to beta-lactam antibiotics, so treatment decisions should be made with this organism kept in mind.