The Streptomyces genus contains over 600 species. Most are known for the ability to synthesize antibiotics.
S. somaliensis is the most common species isolated from clinical specimens. Clinically, Streptomyces are most often associated with mycetoma (similar to Actinomadura infections).
| Characteristics | Comments |
| Appearance on Gram stain | Gram-positive, filamentous, extensive branching with chains and spores; does not fragment easily; hyphae are 0.5-2.0 microns in diameter44 |
| Appearance on modified acid-fast stain (MAS) | Not partially acid-fast |
| Most often associated with clinical disease | Streptomyces sudanensus, Streptomyces somaliensis (most common) |
| Colonial growth | Discrete waxy, heaped colonies; variable growth to include leathery, granular, powdery, velvety44 |
| Phenotypic characterization44 | Casein, tyrosine hydrolysis Lysozyme resistance negative Gelatin hydrolysis positive Urea hydrolysis variable Nitrates are reduced to nitrites Degrades esculin Degrades starch |
| Temperature of optimal growth | Growth at 25-35°C |
45. CDC/Berd. Image #2983. This is a slide culture of a
Streptomyces sp. bacteria, which had been cultivated on tap water agar. Note the branching filamentous hyphae, abundant aerial mycelia, and long chains of small spores are visible, which is characteristic of all
Streptomyces spp. PHIL public domain. Created 1972. Accessed November 12, 2022.
https://phil.cdc.gov/Details.aspx?pid=298346. CDC/Ajello. Image #21826. This image depicted a frontal view of a Petri dish culture plate that had contained an unidentified growth medium, which had been inoculated with a bacterial culture labeled, 45-657-67, of Streptomyces somaliensis organisms, and which subsequently produced these irregularly-shaped, rough bacterial colonies. PHIL public domain. Created 1967. Accessed October 27, 2022. https://phil.cdc.gov/Details.aspx?pid=21826
