Nocardia Arthritis: 3 Cases and Literature Review

Abstract

Nocardia are Gram-positive filamentous bacteria responsible for infections ranging from opportunistic life-threatening disseminated diseases to chronic skin and soft-tissue infections.Even if virtually all organs can be infected, articular involvement is rare. Therefore, we report 3 recent cases and performed a literature review of cases of Nocardia arthritis in order to describe clinical features, therapeutic challenges, and outcome of these patients.Among 34 patients (31 in the literature plus our 3 cases), 21 (62%) were due to hematogenous dissemination, 9 (26%) were due to direct bacterial inoculation through the skin, and in 4 cases, the mechanism of infection was unknown. Four out of these 34 cases occurred on prosthetic joints.Whereas hematogenous infections mostly occurred in immunocompromised hosts (17 of 21, 81%), direct inoculation was mostly seen in immunocompetent patients.Eighty-two percent of patients (28 out of 34) received trimethoprim-sulfamethoxazole-containing regimens and median antibiotic treatment duration was 24 weeks (range, 12-120) for hematogenous infections and 12 weeks (range, 6-24) for direct inoculations. Outcome was favorable in 27 cases despite unsystematic surgical management (17 cases) without sequelae in 70% of the cases.Nocardia arthritis is rare but its management is complex and should rely on a combined approach with rheumatologist, infectious diseases expert, and surgeon.

FIGURE 1

Magnetic resonance imaging (MRI) and computed tomography (CT) scans of the left knee of patient 1. (A) Postcontrast sagittal T1-weighted knee MRI at the diagnosis of nocardiosis (April 2012) showing joint effusion, enhancing synovitis (white arrow) and femoral and patelar osteomyelitis (white arrowheads: bone enhancement after gadolinium injection). (B) Second knee MRI performed 5 months (August 2012) after initial surgery with persisting joint effusion, enhancing synovitis and an increase in bone enhancement after gadolinium injection. (C) Concomitant (August 2012) sagital knee CT scan showing femoral osteolytic lesion on the location of the intense bone enhancement seen on the MRI. (D) and (E) Follow-up knee CT scans in October 2012 (D) and April 2013 (E) showing persisting osteolysis (white arrowheads) and extra articular calcifications (white arrows). CT =  computed tomography; MRI = magnetic resonance imaging.

FIGURE 2

Acquisition of resistance toward levofloxacin during the antibiotic treatment of patient 1. Susceptibility was tested using an Etest^® strip applied on blood agar plates inoculated by confluent swabbing of the surface with a 1 McFarland standard organism suspension. The plates were incubated at 35°C under a 5% CO₂ atmosphere and growth was monitored every 24 h for 3 days. A. Strain obtained in March 2012, with a levofloxacin MIC of 0.75 μg/mL (susceptible). B. Strain obtained in August 2012, with a levofloxacin MIC > 4 μg/mL (resistant).MIC = minimal inhibitory concentration.