Serological, cultural, and molecular analysis of Brucella from Buffalo milk in various regions of Iran

Brucellosis is a significant infection that causes abortion, decreased milk production, and sterility in livestock, which greatly affects the industry. This study aimed to determine the prevalence of Brucella in buffalo milk samples across various regions of Iran, utilizing serological, molecular, and cultural analyses. A total of 1860 buffalo milk samples were collected from industrial, semi-industrial, and traditional buffalo farms in four major buffalo breeding provinces. The milk ring test agglutination test (MRT) was initially conducted on all milk samples, followed by culture and molecular testing for positive and negative samples in MRT. The study revealed positive results for the presence of Brucella DNA in various provinces of Iran. The MRT had a relatively low sensitivity, with results ranging from 0 to 0.7% in different provinces. However, the AMOS PCR method showed a significantly higher presence of Brucella DNA, ranging from 13 to 46% in these provinces. The highest abundance of Brucella bacterial DNA was found in Ardabil province, while the lowest was in West Azerbaijan province. Brucella abortus was the most commonly detected bacteria, followed by Brucella melitensis. Interestingly, the B. abortus vaccine strain RB51 was detected in 26.3% of positive samples of B. abortus. The culture assay of milk samples further confirmed the presence of B. melitensis biovar 1 in one sample from Khuzestan province. Overall, the study emphasizes that the AMOS PCR method is the most sensitive in detecting Brucella-exposed milk, while the sensitivity of milk sample culture and MRT is relatively lower.