Isolation and Identification of Nocardia in Suspected Tuberculosis Samples Using Paraffin Baiting Technique

Nocardia spp. is obligate aerobic filamentous bacilli, gram-positive, partially acid-fast, and non-motile bacteria. The genus Nocardia can cause infection in different parts of the body, especially the respiratory tract. The clinical signs of nocardiosis are similar to those of tuberculosis. The present study aimed to investigate the prevalence of Nocardia in sputum and bronchoalveolar lavage samples from the patients with suspected pulmonary tuberculosis using paraffin baiting Technique. In the current study, 250 samples of sputum and bronchoalveolar lavage from the patients with suspected tuberculosis were assessed using paraffin baiting technique. After collecting the samples, some microscopic slides were prepared for different types of staining and the rest of the samples were cultured in carbon-free broth containing paraffin rods and were then incubated at 35°C. The paraffin rods were checked regularly and the suspected colonies were tested for different specific phenotypic test, particularly growth in lysozyme broth.
No organisms were detected in the prepared smears. However, according to the results of the culture, two samples were isolated from the sputum. Moreover, staining the colonies by common and specific stains revealed gram positive, partially acid fast, and negative acid fast bacteria. In addition, Nocardia was confirmed by growth of the isolates in the lysozyme medium. Identification of Nocardia should be taken in to account while examination of the patients suspected to pulmonary tuberculosis.