An organism that shows bottle-brush growth in stab culture is most likely:

An organism that shows bottle-brush growth in stab culture is most likely:

• A. Bacillus cereus
• B. Erysipelothrix rhusiopathiae
• C. Mycobacterium tuberculosis
• D. Listeria monocytogenes

Answer: (B)

The characteristic "bottle-brush" growth observed in stab cultures is particularly associated with Erysipelothrix rhusiopathiae. This organism is a Gram-positive, rod-shaped bacterium that is known to exhibit unique growth patterns due to its ability to form filamentous structures. In stab cultures, E. rhusiopathiae displays a distinctive morphology where the growth appears as a filamentous, brush-like structure that resembles bristles or a bottle-brush. In contrast, while other organisms listed can present with different growth characteristics, they do not typically show this specific bottle-brush morphology. For example, Bacillus cereus may appear as large, flat colonies with irregular edges, and Mycobacterium tuberculosis demonstrates a more characteristic mucoid and rough growth on solid media. Listeria monocytogenes typically shows a more uniform growth pattern and may present as small, smooth colonies. Thus, the distinctive bottle-brush growth in stab culture is a key identifying feature for Erysipelothrix rhusiopathiae, making it the most likely organism associated with this morphology.

The characteristic "bottle-brush" growth observed in stab cultures is particularly associated with Erysipelothrix rhusiopathiae. This organism is a Gram-positive, rod-shaped bacterium that is known to exhibit unique growth patterns due to its ability to form filamentous structures. In stab cultures, E. rhusiopathiae displays a distinctive morphology where the growth appears as a filamentous, brush-like structure that resembles bristles or a bottle-brush.

In contrast, while other organisms listed can present with different growth characteristics, they do not typically show this specific bottle-brush morphology. For example, Bacillus cereus may appear as large, flat colonies with irregular edges, and Mycobacterium tuberculosis demonstrates a more characteristic mucoid and rough growth on solid media. Listeria monocytogenes typically shows a more uniform growth pattern and may present as small, smooth colonies.

Thus, the distinctive bottle-brush growth in stab culture is a key identifying feature for Erysipelothrix rhusiopathiae, making it the most likely organism associated with this morphology.