Localized Cutaneous Infections in Immunocompetent Individuals Due to Rapidly Growing Mycobacteria

Abstract

Rapidly growing mycobacteria (RGM) cause skin infections that are refractory to standard antibiotic regimens. Although typically associated with disseminated cutaneous or other systemic infections in immunocompromised patients, RGM sometimes cause localized cutaneous infections in immunocompetent hosts. These infections are almost always associated with precedent skin trauma and inoculation, and therefore have been implicated in outbreaks involving contaminated tattoo ink and inadequately sterilized acupuncture needles. Histologic features often include suppurative granulomatous inflammation, and microorganisms are rarely visualized with stains for acid-fast bacilli. The differential diagnosis includes granulomatous fungal and non-RGM bacterial infections as well as noninfectious suppurative or sarcoidlike conditions. Because no pathognomonic histologic features exist for cutaneous RGM infections, clinical suspicion and appropriate workup are essential to reach an accurate and timely diagnosis. Most localized cutaneous RGM infections in immunocompetent individuals respond well to either clarithromycin or amikacin, in combination with surgical debridement.

Mycobacterium fortuituminfection of the scalp after a skin graft

“…In typical cases of skin and soft tissue MF infections, the lesions develop after an inoculation period of 4–6 weeks and can present as painful nodules, abscesses, ulcers, draining sinus tracts or cellulitis 16. Histologically, older lesions have a poorly specific infiltrate, whereas acute lesions display suppurative granulomas without caseation, local tissue destruction and a mixed infiltrate 17…”

Prominent contribution of Th1, Th17, and Tregs to the host response during M. neoaurum infection

“…NTM result mainly in skin and lymphoid tissue infection, as well as lung disease (Griffith et al, 2007). Many of these microorganisms are opportunistic pathogens, especially in cancer (Umehara et al, 2015), HIV (Ristola et al, 2015), and immunodeficient patients (Fowler and Mahlen, 2014;Henkle and Winthrop, 2015). In humans, NTM cause an important infectious disease, and the main risk factor is thought to be environmental exposure.…”

Mycobacterium immunogenum folliculitis on the lower extremities of a healthy young adult

“…Other cutaneous M. immunogenum infections present as slow‐growing erythematous macules, papules or nodules, sometimes associated with pain and purulence. Lesions are most commonly on the lower extremities, although involvement of the trunk has been reported . Some reports describe a history of trauma along with exposure to contaminated water or soil .…”

“…immnogenum has responded to prolonged monotherapy and multidrug antibiotic regimens. Clarithromycin is the most successful treatment for cutaneous M. immunogenum infection . Loots et al .…”

“…Lesions are most commonly on the lower extremities, although involvement of the trunk has been reported. [2][3][4][5] Some reports describe a history of trauma along with exposure to contaminated water or soil. 3 Mitchell et al reported a case of M. immunogenum following tattoo placement.…”