Nocardia is a genus of weakly staining Gram-positive, catalase-positive, rod-shaped bacteria. It forms partially acid-fast beaded branching filaments (acting as fungi, but being truly bacteria). Some species are nonpathogenic, while others are responsible for nocardiosis. Most Nocardia infections are acquired by inhalation of the bacteria or through traumatic introduction. The diagnosis of nocardiosis is established with culture of the causative organism from the infection site(s). Because nocardiae grow slower than common bacteria, the microbiology laboratory should always be notified when nocardiosis is clinically suspected. This is particularly true when sputum is the submitted specimen. Respiratory secretions, skin biopsy samples, and aspirates from abscesses are the most common specimens from which Nocardia species are identified. Direct smears or histopathologic stains of these specimens can be highly suspicious, as noted above. Nocardia species can usually be isolated in 3-5 days.