August 2007

Fig.2

Fig.3

Diagnosis: cutaneous Mycobacterium chelonae

Histopathology: pseudocarcinomatous hyperplasia and dermal abscess (Figure 2), negative for AFB.

Microbiology: gram stain and bacterial culture negative; mycobacterial culture positive for Mycobacterium cheloniae.

Discussion: Environmental mycobacteria are infrequent causes of soft tissue infections that need to be considered in cases of cutenous infections that fail to respond to typical therapies. The rapidly growing mycobacteria, including M. chelonae, M. abscessus, and M. fortuitum, may cause cutaneous non-healing ulcers or abscesses. These organisms are typically introduced into the skin through local trauma. The rapidly growing mycobacteria are essentially ubiquitous in the environment and pose special problems in the healthcare setting as they may colonize water supplies in hospitals- accounting for documented outbreaks. Immunocompetent individuals often present with isolated lesions, whereas immunosuppression predisposes to multifocal and disseminated disease.

Diagnosis: As in this case, one should suspect atypical organisms after failure of typical antimicrobial therapy. Most appropriate would be 2 punch biopsies- one sent for routine H&E processing and the second for culture (including routine bacterial, mycobacterial, and fungal). In the case of rapidly growing mycobacteria, special attention should be placed on the anti-microbial sensitivities as the organisms have relatively few sensitivities. Of note, histopathologic examination frequently fails to detect an organism.

Treatment: Typical therapy includes clarithromycin, although therapy should be tailored to reported sensitivities and extent of disease. There is no consensus on duration of treatment, however, therapy often needs to be continued for 6 months. In the cases of extensive soft tissue disease, adjuvant surgical excision should be considered. To date our patient has been treated with 3 months of clarithromyocin, resulting in near complete resolution of the in infection (Figure 3).

References:
1. Brandley, Readinger, and Morris. 2006. Cuteneous Infection with Mycobacterium abscessus in a Child. Pediatric Dermatology 23(2): 128-131.
2. Brown-Elliot and Wallace. 2002. Clinical and Taxonomic Status of Pathogenic Nonpigmented or late-pigmenting rapidly growing mycobacteria. Clinical Microbiology Reviews 15(4): 716-746
3. Freudenberger and Simafranca. 2006. Cutaneous Infection With Rapidly-Growing Mycobacterial Infection Following Heart Transplant: A Case Report and Review of the Literature. Transplantation Proceedings 38:1526-1529.
4. Uslan, Kowalski, Wengenack, Virk, and Wilson. 2006. Skin and Soft Tissue Infections Due to Rapidly Growing Mycobacteria: Comparison of Clinical Features, Treatment, and Susceptibility. Arch Dermatol 142: 1287-1292
5. Woeltje, K. 2006. Mycobacteria Chelonae. eMedicine.com

This case is presented by Drs. O. Jassim, K. Krone, and A. Z. Eisen.