Multiple Brain Abscesses Caused by Nocardia asiatica in a Patient With Systemic Lupus Erythematosus: The First Case Report and Literature Review

Dear Editor, Nocardia species are uncommon pathogens that affect immunosuppressed patients; although cerebral nocardiosis is a rare condition, it is associated with significant morbidity and mortality [1]. Because Nocardia species exhibit different antibiotic susceptibilities, accurate species identification is important for prognoses. To the best of our knowledge, this is the first case of Nocardia asiatica brain abscesses reported in a systemic lupus erythematosus (SLE) patient. A 51-yr old man visited our emergency department on May 2016 complaining of left leg weakness, dysarthria, dizziness, nausea, vomiting, and uncontrolled fever lasting three days. His past medical history consisted of SLE (diagnosed in August 2002) treated intermittently with steroid and platelet transfusion because of severe thrombocytopenia. In addition, in April 2015, he was diagnosed as having diabetes; however, no medical treatment had been undertaken. His last admission to hospital, due to severe thrombocytopenia (6×10/L), was two months prior to this presentation. He was subsequently treated with danazol (400 mg twice daily), hydroxychloroquine (200 mg twice daily), methotrexate (15 mg/week), and prednisolone (15 mg/day). At presentation, the patient’s temperature was 39.1°C, and blood tests indicated a white blood cell count of 11.03×10/L with a differential count of 76.2% neutrophils. Serum C-reactive protein (71.9 mg/L) and erythrocyte sedimentation rate (28 mm/ hr) were elevated. Brain magnetic resonance imaging (MRI) revealed multiple contrast-enhanced lesions in both cerebral and cerebellar hemispheres (Fig. 1A). A subsequent brain abscess aspiration removed 5 mL of a yellowish aspirate; Gram staining of the aspirate revealed gram-positive filamentous branched bacilli, and specimen culturing on blood agar plates for 48 hr at 37°C under aerobic conditions yielded white, rough, and dry colonies, which also presented gram-positive filamentous branched bacilli and were modified acid fast bacilli stain-positive (Fig. 1BE). 16S rRNA gene sequencing was performed for isolate identification according to the CLSI guidelines with primer pair forward 4F and reverse 801R [2]. The isolate 16S rRNA sequence (671 bp; GenBank accession number KY417120) showed 100% homology with N. asiatica (KC333452.1) and N. abscessus (GU471235.1). Alternative gene targets, such as the secA1 gene, are necessary for accurate species discrimination in the Nocardia asteroides group, because several N. asiatica, N. abscessus, N. asteroides, and N. arthritidis strains share ≥99.6% identity [2]. Thus, gene amplification and additional sequencing of secA1 were performed with primer pair forward F47 and reverse ConR. The results (497; KY417121) showed 99.4% (494/497) and