A Case of Mycolicibacterium mucogenicum Infection in the Right Back.

Background: In November 2023, our hospital confirmed a case of Mycolicibacterium mucogenicum infection in the right back. The patient sought medical attention at our hospital due to "a right back lump for 2 months, ruptured for 1 month." Two months ago, the patient's back collided with a fire hose and developed a local walnut sized lump. The lump was soft, painless when pressed, and there was no obvious redness or swelling around it. The patient went to a private hospital for incision and drainage treatment on their own. One month later, the condition did not improve and there was yellow pus exuding from the incision site. For additional diagnosis and treatment, the patient went to our hospital for treatment.

Methods: Back MRI (Magnetic Resonance Imaging) and abdominal ultrasound. Right back abscess incision and drainage surgery, pus pathogen examination: pus bacterial smear, bacterial culture, and identification. Auxiliary examinations: urine routine, blood routine, liver function, kidney function, blood lipids, and blood sugar.

Results: Back MR: Abnormal signal shadow of subcutaneous soft tissue in the lower back, suggesting inflammatory lesions with abscess formation. Acid fast staining of pus: positive. Culture and identification of pus bacteria (Matrix-assisted laser desorption ionization time-of-flight mass spectrometry, MALDI-TOF MS): Mycolicibacterium mucogenicum. Clinical treatment plan: Clarithromycin 500 mg bid po+ minocycline 100 mg bid po, abscess in-cision and drainage, 5-aminolevulinic acid photodynamic therapy (ALA-PDT) qd. After 14 days of treatment, the patient's incision base tissue showed excellent activity, no obvious bleeding or exudation, slight redness and swelling around the wound, and normal skin temperature. The patient improved and was discharged.

Conclusions: This article reports a case of Mycolicibacterium mucogenicum infection in the right back. The Mycolicibacterium mucogenicum was quickly and accurately identified by MALDI-TOF MS, and clinical treatment with antibiotics combined with 5-aminolevulinic acid photodynamic therapy (ALA-PDT) was used. The patient improved and was discharged. I hope that in the future, this study can provide assistance for the clinical diagnosis and treatment of Mycolicibacterium mucogenicum.