Mycobacterium szulgai: A Rare Cause of Non-Tuberculous Mycobacteria Disseminated Infection

Abstract

Mycobacterium szulgai (MS) is a rare and slow-growing type of non-tuberculous mycobacteria (NTM), with a human isolation prevalence of less than 0.2% of all NTM cases. MS may cause pulmonary infection, extra-pulmonary localized disease involving the skin, lymph nodes, bone, synovial tissue or kidneys and disseminated infection, when two or more organs are affected. When disseminated infection is present, the patients usually have an underlying immunosuppressive condition. The authors report the case of a 25-year-old patient with systemic lupus erythematosus, presenting with recurrent fever, non-productive coughing, weight loss and asthenia, as well as two violaceous plaques with superficial ulceration in the gluteal region. MS was isolated from the bronchial lavage and skin biopsy cultures, confirming the rare disseminated form of MS infection. After 10 months of follow-up on isoniazid, rifampin, ethambutol and pyrazinamide, no signs of relapse were evident. To date, only 16 other cases of MS disseminated disease have been reported.

Keywords: Cutaneous infection; Disseminated infection; Mycobacterium szulgai; Non-tuberculous mycobacteria.

Figure 1

Cutaneous manifestations. (a) Erythematous nodules on the left lower limb. (b) Violaceous plaque in the left gluteal region.

Figure 2

Enlarged mediastinal lymph node with a heterogeneous internal texture (arrow) on the computed tomography (CT) chest scan.

Figure 3

Two noncaseating epithelioid granulomas with tightly packed epithelioid cells and overlapped lymphocytes. Respiratory epithelium with normal morphology. (hematoxylin and eosin staining, × 100 magnification).

Figure 4

Skin biopsy showing neutrophilic infiltrate and focal granulomas (a) composed of histiocytes, lymphocytes and plasmacytes (b).