Fluid and solid media for isolation of Brucella abortus

Area of Science:

• Veterinary Microbiology
• Bacteriology
• Food Safety

Background:

• Brucella abortus causes brucellosis, a significant zoonotic disease affecting livestock and humans.
• Accurate diagnosis of Brucella abortus in milk is crucial for herd management and public health.
• Milk Ring Test (MRT) is a common screening method for detecting Brucella-infected herds.

Purpose of the Study:

• To evaluate the efficacy of a fluid-enrichment technique for improving Brucella abortus recovery from milk.
• To compare direct cultural techniques using different media and inoculum sources.
• To determine the optimal combination of methods for enhanced Brucella abortus isolation from MRT-positive herd milk.

Main Methods:

• A fluid-enrichment technique was applied to milk samples from MRT-positive herds.
• Three different solid media were assessed for direct culture isolation of Brucella abortus.
• Inoculum preparation involved using either the cream layer or a mixture of centrifuged deposit and cream layer.

Main Results:

• The fluid-enrichment technique increased Brucella abortus recovery rates by 10-16%.
• A combined approach using fluid enrichment and direct culture with a mixed inoculum (centrifuged deposit and cream) achieved an 88% recovery rate.
• Using only the MRT cream layer as inoculum yielded a lower recovery rate of approximately 75%.

Conclusions:

• Fluid enrichment significantly enhances Brucella abortus recovery from milk.
• Combining fluid enrichment with direct culture using a mixed inoculum is highly effective for diagnosing Brucella in MRT-positive herds.
• All tested Brucella abortus biotypes (1-5 and 9) were successfully isolated, indicating broad applicability of the methods.