Nocardiosis-an uncommon infection in patients with myasthenia gravis: report of three cases and review of literature

Abstract

Nocardiosis is a rare infection in patients with myasthenia gravis (MG). We identified three cases of MG admitted with nocardiosis in our unit. We performed systematic literature search of previous publications and identified 18 patients. This paper presents three patients and reviews the clinical characteristics of 21 patients. The first case was a 69-year-old woman with thymomatous MG who presented with pustules and left lower limb pain. Evaluation showed osteomyelitis of the pubic ramus and ileopsoas abscess. The second case was a 54-year-old man who presented in myasthenic crisis due to pulmonary nocardiosis. The third case was a 48-year-old man with thymomatous MG who presented with lung abscess. All of them recovered completely after treatment with co-trimoxazole. Analysis of the 21 patients identified four risk factors for nocardiosis in MG: elderly men; thymoma; immunosuppressant medication, mainly steroid therapy; and pre-existing lung disease. Lungs was the most common site of infection. Suppurative disease was common manifestation regardless of organ involved. Clinical course is not unfavourable.

Keywords: immunology; infection (neurology); infectious diseases; neuromuscular disease; pneumonia (infectious disease).

Figure 1

Clinical photograph showing an ulcer over the anterior aspect of the left forearm (A). MR STIR images of pelvis and upper thighs showing hyperintensities and swelling of left pectineus, obturator internus and externus, and osteomyelitis of left pubic bone and right psoas (B); modified ZN stain showing acid-fast filamentous Nocardia (C) and Gram stain showing beaded appearance of alternating Gram-positive and Gram-negative segments along a filament (D). Considerable reduction in the psoas abscess (shown by arrows) in the follow-up scan (E).

Figure 2

Chest X-ray of case 2 showing haziness over left lung (A). Culture plate of sputum of case 2 showing cotton candy appearing colonies of Nocardia spp. (B). Axial and sagittal views of CT chest of case 3 showing consolidation of right upper lobe (C–F).