<i>Candida haemulonii</i>Complex Species, Brazil, January 2010–March 2015

Two cases of M. arupense infection have been reported in immunosuppressed persons, both in HIV/AIDS patients (manifesting as pulmonary infection in 1 patient and disseminated disease in the other) (6). In our study, the immunocompromised patient with M. arupense tenosynovitis received canakinumab, a relatively new biologic agent with a prolonged selective IL-1 -blockade. Even though the contribution of canakinumab in this case is confounded by concomitant immune deficiencies (natural killer cell deficiency, high-dose corticosteroids), the temporal association between initiation of canakinumab and the onset of symptoms raises concern of a possible association. Animal studies have shown that IL-1 plays a key role in host resistance to mycobacterial infections by regulating Th1/Th2 immune responses and inducing granuloma formation (9). Clinical trials and systematic reviews assessing the safety of IL-1 inhibitors, including anakinra, rilonacept, and canakinumab, have not shown that these drugs lead to an increased risk of tuberculosis or other mycobacterial infections (10). Nonetheless, our report provides increased evidence that M. arupense is an emerging cause of tenosynovitis and that it is potentially associated with immunosuppression.