Brucella - Pathogenesis, Causes, Symptoms, Treatment

Brucella is small , nonmotile, non-encapsulated, gram-negative coccobacilli. And it is strictly aerobic, meaning that it needs oxygen to survive, and also, it’s facultative intracellular which means it can survive both inside and outside the cell. Finally, it’s urease and catalase positive bacteria which means it produces both these enzymes.
Brucella has 4 species most commonly associated with human disease: Brucella abortus, Brucella melitensis, Brucella suit, and Brucella Canis.
Now, Brucella can enter the body one of two ways.
First, there may be direct contact with infected animals - and the host is different for each Brucella species.
So, Brucella abortus is transmitted by cattle, Brucella melitensis is transmitted by small ruminants such as goats and sheep, Brucella canis is transmitted by dogs and Brucella suis is transmitted by swine and rodents. In this case the bacteria enters through skin lesions, mucous membranes and inhalation.The second way is ingestion of contaminated animal products such as unpasteurized milk, cheese and undercooked meat.
After the initial exposure, the organisms are phagocytosed by macrophages and monocytes, Normally, phagocytes destroy invading bacteria by wrapping them up in vesicles called phagosomes, which will merge with lysosomes to form a phagolysosome. Lysosomes are round vesicles that contain hydrolytic enzymes, which are released inside the phagolysosome to destroy the invading bacteria. However, Brucella has a few virulence factors that it uses to avoid destruction.
First, it has the ability to escape the immune recognition by using type 4 secretion system which is a collection of proteins that can dampen the immune response. However, some of them are not able to escape and are caught by macrophages and ingested. Inside the macrophage, Brucella uses another virulence factor on its outer membrane, called non endotoxic lipopolysaccharide, or LPS for short.
LPS inhibits the fusion between the phagosome and the lysosome, and allows Brucella to avoid intracellular death.So once Brucella is safe from intracellular destruction, T4SS starts secreting effector molecules.
There’s a whole bunch of these molecules, and their exact role is not yet well understood, but what we do know is that they help the bacteria travel to the endoplasmic reticulum, where it can replicate in large numbers.Now, the ability to survive and replicate inside macrophages also makes it able to travel through the bloodstream to multiple organs such as lymph nodes, liver and spleen.Additionally, when the macrophage becomes too small for the growing number of Brucellae, it bursts, releasing the bacteria into the bloodstream.
And from there, they can spread to organs such as bone marrow, central nervous system, bones, heart, and lungs.
Acute disease develops in approximately half of the patients infected with Brucella, with symptoms first appearing typically 1 to 3 weeks after exposure. Initial symptoms are nonspecific and consist of malaise, chills, sweats, fatigue, weakness, myalgias, weight loss, arthralgias, and nonproductive cough. Almost all patients have fever, and this can be intermittent in untreated patients. Patients with advanced disease can have gastrointestinal tract symptoms, osteolytic lesions or joint effusions, respiratory tract symptoms, and less commonly, cutaneous, neurologic, or cardiovascular manifestations.
Finally, the disease is treated with a combination of doxycycline and rifampin for a minimum of 6 weeks to prevent relapses.

[@noonessam4281]

Great video and nicely summarised.

[@gusemantonggopep5890]

It is Brucella suis, not Brucella suit

[@rebeccaguarnieri7085]

There is a mistake, it’s Brucella suis not suit😊

[@Mariam-jr7oq]

Amazing ..thank you soooo much

[@fatimamohammed7812]

جزاكم الله خيرًا

[@nirvana2878]

Thank you

[@skinchoots2916]

Great info! a pig I knocked over a couple of months back was under weight and something not right with it. I've just gone through some pics, and was exactly the same. I'm glad I chose not to eat it.

[@Medicwordoftheday]

Nice tutorial

[@sandrasukmamaharani7807]

I GOT IT NOW THANKUUU

[@nizamkhan2398]

Impressive

[@user-id6pe5oq8d]

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