Brucella: Reservoirs and Niches in Animals and Humans

Abstract

Brucella is an intracellular bacterium that causes abortion, reproduction failure in livestock and leads to a debilitating flu-like illness with serious chronic complications if untreated in humans. As a successful intracellular pathogen, Brucella has developed strategies to avoid recognition by the immune system of the host and promote its survival and replication. In vivo, Brucellae reside mostly within phagocytes and other cells including trophoblasts, where they establish a preferred replicative niche inside the endoplasmic reticulum. This process is central as it gives Brucella the ability to maintain replicating-surviving cycles for long periods of time, even at low bacterial numbers, in its cellular niches. In this review, we propose that Brucella takes advantage of the environment provided by the cellular niches in which it resides to generate reservoirs and disseminate to other organs. We will discuss how the favored cellular niches for Brucella infection in the host give rise to anatomical reservoirs that may lead to chronic infections or persistence in asymptomatic subjects, and which may be considered as a threat for further contamination. A special emphasis will be put on bone marrow, lymph nodes, reproductive and for the first time adipose tissues, as well as wildlife reservoirs.

Pathogenicity and Its Implications in Taxonomy: The Brucella and Ochrobactrum Case

“…Bacteria that originated from this event rapidly split from the Ochrobactrum/Brucella common ancestor following an allopatric type of speciation in an isolated environment that precluded significant horizontal gene flow and led to a close pangenome. The natural niche of all well-studied Brucella organisms is the intracellular milieu of animal cells and, although they can be temporarily isolated from contaminated materials, have never been found to multiply in open environments, even in organic substrates, and are seldom in contact with other bacteria when they are metabolically active [ 48 , 50 , 52 , 80 ]. Consequently, the selective forces exerted over Brucella organisms are determined by the relatively stable host environments, including inimical natural host defenses, adaptive immunity effectors, and availability of nutrients within cells [ 35 , 48 , 52 , 81 , 82 ].…”

Sero-Prevalence of Brucellosis in Occupationally High-Risk Groups in Three Different Districts of Khyber Pakhtunkhwa, Pakistan

“…4 Only four species are responsible for human Brucellosis including B. abortus, B. melitensis, B. suis and B. canis, and their common reservoirs include cattle, sheep and goats, pigs, and dogs respectively. 5,6 In natural hosts, the transmission mostly occurs through milk or genital secretions during mating. 7 This infection transfers from animals to humans by using raw milk and other dairy products made from milk like cheese, butter, and ice cream, etc.…”

Isolation of Brucella abortus biovar 1 from human lumbar disc bulging: a case report of brucellar discitis

“…Brucellosis is a zoonosis with a world-wide distribution, most commonly encountered in the Middle East, Latin America and Mediterranean countries. The disease is a common bacterial zoonotic infection between humans and animals, affecting various organs of the body and leading to a wide range of clinical manifestations [ 1 , 2 ]. The most common clinical manifestations of human brucellosis are fever, chills, sweating, fatigue, headache, as well as musculoskeletal and joint pain.…”