Cutaneous Mycobacterium massiliense Infection of the Sole of the Feet
In February 2011, a 45-year-old male visited our hospital with a painful nodule on his left sole that had appeared four weeks ago. Before visiting our outpatient clinic, he had undergone acupuncture on his back and both extremities including the soles and palms to alleviate chronic back pain. The skin lesion on his left sole developed after a few weeks of receiving acupuncture. On physical examination, the patient showed an erythematous subcutaneous nodule with local tenderness and heat on the sole of his left foot (). There was no discharge or fluctuation. No systemic symptoms including fever were detected.\nHistological examination of a biopsy obtained from the lesion on his sole showed granulomatous inflammation with neutrophilic microabscesses in the dermis and subcutaneous fat tissue. No special staining was performed ().\nA Gram stain and a culture of the tissue specimens to identify the bacterial infection revealed negative results. Acid-fast bacili culture of the tissue specimen on liquid media (Mycobacterium growth indicator tube: middle block 7H9 broth agar) and 3% Ogawa solid media at 25℃ to 30℃ and 37℃ was done. Numerous colonies were observed after 1 week of culture on liquid media at 37℃ (). For identification of the mycobacterium species, polymerase chain reaction-hybridization (REBA Myco-ID®, M&D Inc., Wonju, Korea) was performed. We used a molecular diagnostic kit designed to identify 19 species of NTM by binding the amplifying rpo B gene product to a species-specific probe. Then the culture was identified as M. massiliense (). Susceptibility testing for antibiotics was done using the broth microdilution method according to the criteria of the Clinical and Laboratory Standards Institute. The isolate was susceptible to clarithromycin (minimum inhibitory concentration≤0.5µg/ml) and it showed intermediate susceptibility to amikacin and cefoxitin. However, the isolate was resistant to ciprofloxacin and doxycycline.\nBecause we at first considered his cutaneous lesion to be an abscess or inflammation due to a ruptured epidermal cyst, he received empirical antibiotic treatment with cefadroxil for 2 weeks. And then, based on the susceptibility results, we treated the patient with clarithromycin 100 mg a day for 4 months, and he showed improvement of both his subjective symptoms and his cutaneous lesion.