Osteomyelitis due to Mycobacterium haemophilum in an adult renal transplant recipient

Abstract

Mycobacterium haemophilum is an increasingly recognized pathogen of the non-tuberculous mycobacteria family that largely infects immunocompromised adults and immunocompetent children. M. haemophilum is a fastidious and slow-growing organism that exhibits preferential growth at lower temperature with iron supplemented media, and therefore most clinical manifestations involve cutaneous infection or musculoskeletal infection of the distal extremities. It is believed that opportunistic infection occurs in immunocompromised hosts when the organism is acquired through environmental exposure. We describe the case of a 71-year-old renal transplant recipient who developed acute M. haemophilum osteomyelitis of the left foot, likely contracted from Epsom salt soaks with contaminated tap water. Outcomes of M. haemophilum infection are generally favorable in the literature. Our patient was treated with local debridement and partial amputation followed by a 3-drug anti-mycobacterial regimen until definitive amputation could be completed.

Keywords: Mycobacterium haemophilum; Non-tuberculous mycobacteria; Osteomyelitis; Renal transplant.

Fig. 1

Abnormal T1-weighted STIR bone marrow signal involving the first digit extending into the middle phalanx, with additional abnormal bone marrow edema within the middle second and third phalanges, and abnormal bone marrow signal in the middle fourth phalange, as indicated by red arrows. (Left foot Magnetic Resonance Imaging, axial view).

Fig. 2

Abundant acid-fast bacilli visualized with fluorescence microscopy of resected bone (auramine-rhodamine stain, original magnification x1000).

Fig. 3

Heavy burden of slim, rod-shaped bacteria within operative bone specimen, as indicated by red arrows. (Ziehl-Neelsen stain, original magnification x1000).

Fig. 4

Ziehl-Neelsen stain of cultured Mycobacterium haemophilum specimen demonstrating beaded acid-fast bacilli in a clumped pattern, as indicated by red arrow. (original magnification x1000).