Cutaneous Non-Tuberculous Mycobacterial Infections in the Outpatient Setting: Presentation of a Case, Review of the Literature, and Therapeutic Considerations
December 2014 | Volume 13 | Issue 12 | Case Report | 1495 | Copyright © 2014
Tara Spicer and Kenneth Beer MD
University of Florida, Gainesville, FL
Mycobacterial infections are not common issues for many dermatologists. Recognition and treatment of these infections are
frequently delayed by incorrect diagnoses. Frequently, the diagnosis of a mycobacterial infection is hampered by coinfection with
bacteria including Staphylococcus. In some instances, patients will have infections with both mycobacteria and Staphylococcus. For
some patients, as was the case with the patient reported herein, a biopsy is required to establish an accurate diagnosis. Physicians
need to keep an open mind when presented with cutaneous infections and consider mycobacterial infections for patients that do
not improve with standard antibacterial medications.
J Drugs Dermatol. 2014;13(12):1495-1497.
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The prevalence of non tuburculous mycobacterial cutaneous infections is small, with an estimated rate of between 0.9 cases per 100,000.1 Many dermatologists will not see a case of cutaneous mycobacteria during their training and most will go their entire careers without recognizing a case of mycobacteria. However, there is data to suggest that cutaneous mycobacterial infections are more prevalent than previously recognized.1 Some of the patients with this infection may also be infected with bacterial organisms and have positive cultures for bacteria. This can delay the diagnosis and make treatment difficult. Clinicians should have a high index of suspicion for atypical mycobacterial infections.
A 74 year-old man presented to a dermatology office complaining of a rash on his arm. The rash had been present for several weeks and was spreading. He had seen his primary care physician who began him on an oral antibiotic. The rash spread and he decided to obtain a dermatologic opinion. The patient was evaluated and noted to be afebrile and in no acute distress.
Examination revealed an exudative, indurated, erythematous plaque on the skin overlying his left distal humerus and proximal ulna (Figure 1).
Review of systems was negative for pulmonary symptoms, fevers, night sweats, weight loss, or fatigue. He was taking no medications and had no allergies. The initial clinical opinion was that he had a methicillin resistant staphylococcus aureus infection that was resistant to the antibiotics previously utilized. A culture was taken for bacteria and the patient was begun on minocycline 100 mg twice a day. After approximately 7 days, he was evaluated again and found to be no better. The cultures for bacteria grew staphylococcus aureus, sensitive to minocycline, ciprofloxacin, and sulfa. Since he had shown no improvement on the minocycline, his medication was changed to sulfamethoxasole/ trimethoprim. Following two weeks on this drug, he failed to demonstrate any improvement.
Although the patient had no obvious immunosuppression, consideration for atypical mycobacterial and deep fungal infections was entertained. In order to determine what the etiology of the eruption was, a series of three-millimeter punch biopsies were performed. These biopsies were processed for histologic evaluation as well as for culture for atypical mycobacterium and fungal organisms. Following several weeks of culture, mycobacterium abscessus was identified by culture as well as by DNA probing. Susceptibility testing demonstrated that the organism was sensitive to clarithromycin, linezolid, and ciprofloxacin.
Histopathology revealed suppurative and granulomatous inflammation with focal acid fast organisms (Figure 2). Higher power (Figures 3 and 4) showed histiocytes and lymphocytes with no evidence of eosinophils or organisms. Special stains for atypical mycobacteria revealed organisms. The patient was sent for infectious disease consultation.
Treatment with clarithromycin 500 mg twice a day was initiated and the patient was evaluated on an ongoing basis. After approximately six weeks, a slight improvement of the erythema and induration was noted. The patient was seen at monthly intervals until his six-month visit at which time the eruption had resolved.
Mycobacterial infections may present in otherwise healthy individuals and may be masked by bacterial infections that pre-