Disseminated nocardiosis in an immunocompetent host with occupational exposure

Abstract

Nocardia is a genus of Gram-positive, partially acid-fast bacteria consisting of over 120 species, of which 50 are recognized as human pathogens. Nocardia spp. are common colonizers in the environment, particularly in soil and water. Nocardia spp. typically cause opportunistic infections in the immunocompetent host, although cases of nocardiosis have been described in those with a normal immune system. Nocardiosis can be localized, most often in the skin or lung, or be disseminated, with involvement of the brain, bone, and visceral organs. Treatment of nocardiosis is complex, as multiple culture-directed antibacterials with appropriate tissue penetration may need to be used for a prolonged duration. To our knowledge, we describe the first successfully treated case of disseminated Nocardia beijingensis infection in an immunocompetent host with doxycycline and trimethoprim-sulfamethoxazole and hypothesize that his occupational exposure to ubiquitous saprophytes may have led to his infection.

Keywords: Disseminated; Doxycycline; Immunocompetent; Nocardia; Nocardiosis; Occupational health.

Fig. 1

Chest computed tomography demonstrating consolidation within the lateral right middle lobe, inferior right upper lobe and superior right lower lobe, associated with locules of gas and a confluent area of central cavitation.

Fig. 2

Bronchoalveolar lavage of the right middle lobe, demonstrating branching, filamentous Gram-positive bacilli, partially acid-fast staining on: A) Gram stain, B) modified Kinyoun stain, and C) Kinyoun stain, all at 1000 × magnification.

Fig. 3

Head computed tomography demonstrating intra-axial rim-enhancing masses in the bilateral parietal lobes and right temporal lobe, associated with significant adjacent vasogenic edema without distant mass effect.

Fig. 4

Chest computed tomography demonstrating resolution of opacification in the right middle lobe.

Fig. 5

Head computed tomography demonstrating resolution of previously identified enhancing foci.