Diagnosis of nocardiosis

Diagnosis is based on culture of the pathogen. If nocardiosis is suspected, ask the laboratory to look for branching Gram-positive bacilli on microscopy and culture of skin swabs, pus and sputum. There are multiple species of Nocardia and species identification is increasingly based on molecular sequencing.

Within the Nocardia genus and even within individual species there is diversity in antimicrobial susceptibility, so susceptibility testing is essential to guide directed treatment. Although there is also regional variation in susceptibility, most isolates are susceptible to trimethoprim+sulfamethoxazole.