La nocardiose, une maladie en expansion

Bacteremia and adrenal gland abscess due to Nocardia cyriacigeorgica: a case report and review

BACKGROUND

Nocardia cyriacigeorgica is one of the most common Nocardia species found in human infections, recently reclassified. Even though Nocardia may affect all organs by hematogenous dissemination, bacteremia are uncommon. Among all possible dissemination sites, the involvement of the adrenal glands is particularly rare.

CASE PRESENTATION

We report here a rare case of Nocardia disseminated infection with notably bacteremia and adrenal gland abscess, in a 77-years-old immunocompetent man. Adrenal gland abscess diagnosis was made by imaging (computerized tomography, magnetic resonance and positron emission tomography scan). A complete regression of all lesions including the left adrenal gland was obtained after 6 months of antibiotics. A review of literature was also performed.

CONCLUSION

Nocardia bacteremia is a rare event but blood cultures may help to improve detection of Nocardia spp. in a non-invasive way. Adrenal abscess due to Nocardia spp. is very rare with only fourteen cases reported in the literature, but it is a true cause of adrenal masses. Our report suggests that clinician should be aware of this rare location and prioritize a non-invasive diagnosis strategy.

Recurrent Empyema Thoracic Secondary to Pulmonary Nocardiosis in Immunocompetent Patients

Pulmonary nocardiosis is a rare disorder that mainly affects immune-compromised patients. We report a 37-year-old male who presented with persistent fever associated with productive cough. During this course of therapy, he had recurrent admissions for empyema thoracic. Clinically, his vital signs were normal. Blood investigations show leukocytosis with a significantly raised erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). Sputum acid-fast bacilli (AFB) was scanty 1+ and sputum mycobacterium culture was negative. Chest X-ray (CXR) showed consolidative changes with mild to moderate pleural effusion on the right side. Skin biopsy was taken and showed Paecilomyces species. A computed tomography scan (CT thorax) was performed and revealed a multiloculated collection within the right hemithorax with a split pleura sign. Decortications were performed and tissue culture and sensitivity (C+S) growth of Nocardia species. And it is sensitive to sulfamethoxazole-trimethoprim and completed treatment for 4 months. This case highlights that pulmonary nocardiosis should be kept in mind in also immune-competent patients, especially in suspected cases of tuberculosis not responding to antitubercular therapy.

Rare case of osteomyelitis of tibial shaft caused by Nocardia cyriacigeorgica

Nocardiosis is a rare infection caused by the aerobic actinomycete of the Nocardia genus. In most cases, nocardiosis manifests as a lung infection or a bone lesion. Due to the nonspecific and mild clinical manifestations of nocardiosis, the establishment of definite diagnosis can be difficult. When antibiotic therapy is incorrectly targeted, only the symptoms of the disease are suppressed. The mainstay in the treatment of Nocardia osteomyelitis has so far been the combined surgical debridement with long-term, initially intravenous, antibiotic administration. We present the successful conservative treatment of a nocardiosis osteomyelitis of the tibia caused by the Nocardia cyriacigeorgica species in an 81-year-old female patient that manifested itself as a secondary affection on top of a primary nocardiosis infection of the lung. From microbiological examination, N. cyriacigeorgica was discovered; the identification was made using matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) with an identification score of 1.9. The sensitivity was evaluated using E test. Sensitivity to trimethoprim/sulfamethoxazole, amikacin, imipenem, and linezolid was demonstrated. The bacteria were shown to be resistant to ciprofloxacin. For treatment, trimethoprim/sulfamethoxazole was used due to the value of minimum inhibitory concentration, which was 0.25 mg/L. The initial dose of 960 mg of trimethoprim/sulfamethoxazole every 8 h was reduced to 960 mg every 12 h after 3 months. The total duration of treatment was 7.5 months. Under the established treatment, the bone and lung lesions healed. Nocardiosis of the long bone is considered a rare disease and its precise diagnosis has not yet been standardized. We used the MALDI-TOF MS method for the identification of the causal organism which is a fast and reliable method according to current world literature even when compared with the rRNA genetic sequencing reference method. Our case study presents a rare case of osteomyelitis of tibial shaft caused by N. cyriacigeorgica and its successful conservative treatment.

[Nocardiosis: A retrospective case series of 19 patients]

INTRODUCTION

Nocardiosis are uncommon. The diagnosis may be difficult, with significant morbidity and mortality, often occurring on frail patients. Few data are available in France.

METHODS

A retrospective single center study was conducted from 2002 to 2014 and included all patients with at least one positive microbiological sample for Nocardia with a follow-up in our hospital.

RESULTS

Nineteen patients, including 15 men, were included with a mean age of 58 years (25-85). Seventeen had a risk factor (lung diseases [13], corticosteroids [12], solid neoplasia [2], HIV infection [2], diabetes mellitus [3], kidney transplant [2], lymphopenia [1]). Infections' locations were: pulmonary (12), brain (3), skin (2), lymph node (1) and corneal (1). The slow growth leads to a median of 35 days for a positive result (3-95). Nine species were identified. Fifteen patients (79%) received one or more lines of antibiotics including: cotrimoxazole (9), amoxicillin (7) cefotaxime/ceftriaxone (7) imipenem (3), or amikacin (3). The average duration of antibiotic therapy was 207 days. Four patients did not receive antibiotics due to a late result or a bacterial co-infection masking nocardiosis. Five patients died (26%) including 2 with cerebral nocardiosis. Six patients were cured, 4 suffered a relapse, 4 had an unknown evolution, and 1 was still treated.

CONCLUSION

Our study shows that nocardiosis is a disease difficult to treat. A better understanding of this type of infection is necessary.

The Nocardia cyriacigeorgica GUH-2 genome shows ongoing adaptation of an environmental Actinobacteria to a pathogen's lifestyle

Background

Nocardia cyriacigeorgica is recognized as one of the most prevalent etiological agents of human nocardiosis. Human exposure to these Actinobacteria stems from direct contact with contaminated environmental matrices. The full genome sequence of N. cyriacigeorgica strain GUH-2 was studied to infer major trends in its evolution, including the acquisition of novel genetic elements that could explain its ability to thrive in multiple habitats.

Results

N. cyriacigeorgica strain GUH-2 genome size is 6.19 Mb-long, 82.7% of its CDS have homologs in at least another actinobacterial genome, and 74.5% of these are found in N. farcinica. Among N. cyriacigeorgica specific CDS, some are likely implicated in niche specialization such as those involved in denitrification and RuBisCO production, and are found in regions of genomic plasticity (RGP). Overall, 22 RGP were identified in this genome, representing 11.4% of its content. Some of these RGP encode a recombinase and IS elements which are indicative of genomic instability. CDS playing part in virulence were identified in this genome such as those involved in mammalian cell entry or encoding a superoxide dismutase. CDS encoding non ribosomal peptide synthetases (NRPS) and polyketide synthases (PKS) were identified, with some being likely involved in the synthesis of siderophores and toxins. COG analyses showed this genome to have an organization similar to environmental Actinobacteria.

Conclusion

N. cyriacigeorgica GUH-2 genome shows features suggesting a diversification from an ancestral saprophytic state. GUH-2 ability at acquiring foreign DNA was found significant and to have led to functional changes likely beneficial for its environmental cycle and opportunistic colonization of a human host.