Disseminated Cutaneous Infection Caused by Mycobacterium colombiense

Abstract

We wish to report a case of an apparently immunocompetent 17-year-old boy with disseminated cutaneous infection caused by M. colombiense. The patient presented with deep asymptomatic erythematous nodules on his face and extremities for 4 months without any preceding history of trauma or surgery. Some of the nodules on his extremities developed into discharging ulcers, others featured slightly scaly erythematous infiltrated plaques (Fig. 1). Two months earlier, he was admitted to a local hospital on account of irregular bowel movements and an occasional slight pain in the right lower quadrant. He was diagnosed with intestinal tuberculosis according to clinical features and biopsy of the intestinal mucosa, which indicated infectious granuloma. The patient received anti-tuberculosis chemotherapy for 2 weeks but ceased taking the drugs because of severe drug-induced liver hepatitis. The past medical history of the patient only revealed chronic hepatitis B with normal liver function. Routine blood test showed mild anaemia with haemoglobin of 101 g/l. Blood culture, purified protein derivative and human immunodeficiency virus antibody tests were negative. Systemic examinations of chest X-ray, type-B ultrasonography and CT scan indicated no abnormal lesions. A skin biopsy of a nodule on the patient’s left leg displayed deep dermis showing nodular lesions with clear boundaries, collagen oedema, mucinous degeneration, blood vessel hyperplasia, infiltrated histiocytes and the absence of caseation necrosis, without special manifestation. Moderate growth of smooth, creamy, yolk yellow colonies was observed after 3 weeks of incubation only at 32 and 37°C on Lowenstein–Jensen (L–J) medium (Fig. 2A). Ziehl–Neelsen staining confirmed that the cultured organisms were acid-fast bacilli (AFB) (Fig. 2B). Pigment production testing showed that the isolated AFB was non-chromogenic. Fungal and other standard bacterial cultures were negative. Sequence analysis of 16S rDNA genes showed 99% similarity with M. colombiense strain CIP108962, and hsp65 genes indicated 99% homology with M. colombiense strain InDRE 9m. Gene sequences were analysed using the BLAST V2.0 software available at http://www.ncbi.nlm.nih.gov/ BLAST/. Gene sequencing results indicated that the strain was most similar to M. colombiense. As indicated by drug susceptibility analysis, we administered an oral regimen of clarithromycin (500 mg/ day), rifabutin (750 mg/day) and moxifloxacin (300 mg/day). After 3 months of therapy, the patient’s skin lesions greatly improved. However, his bowel symptoms did not completely improve and he continues to receive antibiotics. Disseminated Cutaneous Infection Caused by Mycobacterium colombiense