Case Report: Double trouble: a rare case of successfully treated Mycoplasma hominis and Pseudomonas aeruginosa co-infection

Background: Extra-urogenital infections due to Mycoplasma hominis (M. hominis) are rare, particularly co-infection with Pseudomonas aeruginosa (P. aeruginosa). Herein, we report on a patient who was co-infected and successfully treated despite delayed treatment. Case presentation: We reported the case of a 43-year-old man with M. hominis and P. aeruginosa co-infection after a traffic accident. The patient developed a fever and severe infection despite postoperative antimicrobial therapies. The blood culture of wound tissues was positive for P. aeruginosa. Meanwhile, culturing of blood and wound samples showed pinpoint-sized colonies on blood agar plates and fried-egg-type colonies on mycoplasma medium, which were identified as M. hominis by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) and 16S rRNA sequencing. Based on antibiotic susceptibility and symptoms, ceftazidime–avibactam and moxifloxacin were administered for P. aeruginosa infection. Meanwhile, after the failure of a series of anti-infective agents, M. hominis and P. aeruginosa co-infection was successfully treated with a minocycline-based regimen and polymyxin B. Conclusion: The co-infection with M. hominis and P. aeruginosa was successfully treated with anti-infective agents despite delayed treatment, providing information for the management of double infection.