What type of bacteria is Brucella spp.?

Brucella spp. are characterized as facultative intracellular bacilli, which means they have the ability to survive and replicate within host cells while also being able to grow in culture outside of the host. This adaptability is crucial for their pathogenicity, as they can evade the host's immune response by residing within macrophages. The bacilli shape of Brucella is a defining feature, distinguishing it from cocci (which are spherical), and obligate anaerobic bacteria, which cannot survive in the presence of oxygen. Additionally, the term "spiral-shaped" accurately describes a different category of bacteria (such as spirochetes), making it distinctly different from Brucella’s bacillary form. Understanding these characteristics is crucial in recognizing the behavior and treatment of infections caused by Brucella spp.