Microbiology on Brucella Cultures

What is the primary type of milk used for making the cheese mentioned?

Which of the following best describes the initial pathway for organisms after entry?

What is the role of the thoracic duct in the described process?

After entering the bloodstream, where do the organisms primarily travel next?

Which of the following statements is true regarding the progression of organisms post-entry?

What is the specific carbon dioxide concentration required for the growth of brucella abortus?

Which other Brucella species is noted for thriving in the absence of elevated carbon dioxide concentrations?

Which media type is indicated for culturing Brucella abortus?

What distinguishes the growth environment of Brucella abortus compared to other Brucella species?

What would be the likely impact on the growth of Brucella abortus if cultured in an atmospheric condition with 0% CO2?

Brucella and Its Growth Requirements

Brucella abortus requires 5–10% CO2 for optimal growth, while other related species thrive in ambient air.
Cheese made from unpasteurized goats' milk is notably a common transmission vehicle for Brucella.

Pathogenesis

Brucella organisms enter the body, spread through lymphatic channels, and regional lymph nodes before reaching the bloodstream via the thoracic duct.
Once in the bloodstream, Brucella can travel to various organs, particularly affecting parenchymatous organs.
They primarily exist intracellularly in lesions and evade immune responses due to their antiphagocytic capsule.

Immune Response and Infection Spread

T cells and B cells encounter Brucella in lymph nodes, resulting in compromised immune response as these immune cells cannot effectively target the bacteria.
The bacteremic state occurs as the bacteria penetrate white and red blood cells, leading to their presence in the bloodstream.

Affected Organs

Common sites of infection include:
- Liver
- Spleen
- Bone marrow
- Lymph nodes
- Lungs
- Other tissues
Infected organs may present lesions such as granulomas, which consist of macrophage infiltration filtering foreign bodies from blood and tissues.

Clinical Findings

The incubation period for brucellosis typically ranges from 1 to 6 weeks.
Initial symptoms are insidious and include malaise, fever, weakness, and sweats.
Patients may experience increased body temperature and specific blood test results indicating Brucella infection.

This quiz covers the requirements for the growth of Brucella species, specifically focusing on blood culture media and Trypticase-soy agar. Learn about the specific CO2 needs for Brucella abortus and its growth conditions compared to other species.