Available online 2 September 2022

Abstract

Mycoplasma hominis is a commensal pathogen normally found in urogenital tract of humans and has been associated with a wide variety of extra-genitourinary infections, such as mediastinitis, bacteremia, and septic arthritis, particularly in immunocompromised patients. Here, we present a case of a 48-year-old male, who had been treated with fingolimod for relapsing multiple sclerosis and presented with fever and right-sided hip pain following total hip arthroplasty. CT scan revealed localized fluid collection in the right quadriceps femoris muscle adjacent to the joint cavity of right hip. The percutaneously aspirated fluid grew M. hominis, which was also isolated from blood culture. With diagnosis of periprosthetic joint infection, the patient underwent surgical debridement with retained prosthesis and was treated with antimicrobial agents. Infected granulation tissues excised from the hip was observed under an electron microscope, which revealed electron-dense rounded structures contained in neutrophils, consistent with Mycoplasma particles. Fingolimod, an immunomodulatory drug that acts on the sphingosine-1-phosphate receptor and prevents the egress of lymphocytes from lymph nodes, might increase host susceptibility to a systemic M. hominis infection.

Section snippetsBackground

Mycoplasma hominis is a commensal bacterium which resides in the genitourinary tracts of adults and has been associated with various genitourinary infections, such as pelvic inflammatory diseases or chorioamnionitis [1,2]. M. hominis can also cause a wide range of extra-genitourinary infections; mediastinitis [3,4], bacteremia [5,6], intraabdominal abscesses [7,8], septic arthritis [9], meningitis [10], brain abscess [11], and endocarditis [12] have been reported particularly in

Case presentation

A 48-year-old Japanese man with multiple sclerosis (MS) was admitted to the hospital because of fever and worsening pain in the right hip. The patient had been treated with fingolimod for the last 7 years for relapsing MS, following intermittent use of prednisolone which was last used 5 years prior. Eleven days prior to the present admission, he underwent total hip arthroplasty of the right hip for the management of steroid-induced osteonecrosis of the femoral head. His post-operative course

Discussion

PJI caused by M. hominis is a rare but serious complication after arthroplasty, which could occur in both immunocompetent and immunocompromised patients [18]. According to a recently published report in which 6 cases of M. hominis PJI were reviewed, PJI tended to develop in the early postoperative period, usually within 10 days after the surgery, and in most cases, the diagnosis was established based on positive culture from the synovial fluid or fluid accumulated near the joint, as experienced

Authors’ contributions

EM and AS drafted and prepared the manuscript. YK, YR, TS, YT, RI, RJ, TI and YD supervised and edited the manuscript. All authors read and approved the final manuscript. All authors meet the ICMJE authorship criteria.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Consent for publication

Informed consent was obtained from the patient for the publication of case report, which may be made available upon request.

Declaration of competing interest

None.

Acknowledgement

Not applicable.

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© 2022 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.