Current Status of Nocardia Taxonomy and Recommended Identification Methods

The genus Nocardia has had a long and complex history with an equally complex taxonomy. Recent advances in molecular identification methods have vastly expanded the number of recognized Nocardia species, further complicating the taxonomy of the genus. Because of the increasing number of clinically relevant species, biochemical identification methods are no longer adequate to allow discrimination among species. Molecular methodologies, specifically gene sequencing, has now become the gold standard for nocardial identification. We present a summary of the history of the genus Nocardia and provide information on methods for the detection and identification of suspected Nocardia isolates that may be present in patient specimens.