An immunosuppressed patient with systemic vasculitis suffering from cerebral abscesses due to Nocardia farcinica identified by 16S rRNA gene universal PCR.

Nocardia spp. are Gram-positive, partially or variably acid-fast filamentous, branching rods of aerobic actinomycetes [1]. The most common primary site for infection in man is the respiratory tract [1,2]. Brain abscess is the most common clinical manifestation of central nervous system (CNS) infection [1]. The majority of the patients affected have underlying chronic diseases or suffer from endogenous or druginduced immunosuppression [2,3], but the pathogen can also infect persons without any risk factors [2]. However, the course of the infection tends to be more severe and prolonged in immunocompromised hosts than in patients with normal cell-mediated immunity [4]. The symptoms of brain abscesses are often nonspecific and include the classic triad of fever, headache and focal neurological deficiency [2,3]. It is important to establish the appropriate microbial diagnosis, as the list of potential microbial invaders among immunosuppressed patients, especially in transplant recipients, is large and antibiotic therapy differs [3]. The diagnostic work-up should include active diagnostic investigations for uncommon pathogens, such as radiological imaging, measurement of arabinitol in the urine, bronchoscopy in combination with bronchoalveolar lavage, biopsy and histological examinations, sputum examinations, culturing for bacteria, fungi and viral agents in body fluids, serological tests and microscopy, including acid-fast staining for opportunistic pathogens. Crypyococcus neoformans, Listeria monocytogenes, Aspergillus fumigatus, conventional bacteria, viral agents, Nocardia, Mycobacterium tuberculosis, Mucoraceae and Toxoplasma gondii have been reported to cause CNS infections in immunocompromised patients [3]. Nocardial cultures often demonstrate growth too late to be clinically useful or are discarded too early to allow growth of Nocardia [2]. It is thus important to prolong the incubation period for up to 3 weeks or more, and to use specially designed growth media to allow the growth of uncommon pathogens [1]. A new technique for fast and reliable diagnoses of CNS infections and uncommon pathogens such as Nocardia spp. has been needed for a long time [2].