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Questions and Answers
Why is a detailed patient history, including occupation and dietary habits, particularly crucial in diagnosing brucellosis?
Why is a detailed patient history, including occupation and dietary habits, particularly crucial in diagnosing brucellosis?
- Brucellosis diagnosis requires confirmation that the patient has recently traveled internationally.
- Brucellosis symptoms are specific, but patient recall improves diagnostic accuracy.
- Brucellosis symptoms are nonspecific and overlap with other diseases, necessitating assessment of risk factors. (correct)
- Brucellosis diagnosis relies solely on patient-reported symptoms due to unreliable lab tests.
What is the primary reason for needing prolonged antibiotic treatment, such as with tetracycline or doxycycline combined with rifampin, in cases of brucellosis?
What is the primary reason for needing prolonged antibiotic treatment, such as with tetracycline or doxycycline combined with rifampin, in cases of brucellosis?
- To directly target the lipopolysaccharide (LPS) virulence factor.
- To prevent antibiotic resistance from developing due to the unique cell wall structure of Brucella.
- To counteract the carbohydrate fermentation that Brucella performs, which weakens the body.
- To eradicate intracellular Brucella bacteria and minimize the risk of relapse and complications. (correct)
How does Brucella typically gain entry into the human body, leading to systemic infection?
How does Brucella typically gain entry into the human body, leading to systemic infection?
- Through inhalation of airborne particles in urban environments.
- Through direct inoculation via contaminated medical equipment.
- Through consumption of contaminated food or direct contact with infected animal tissues. (correct)
- Through vector transmission by mosquitoes or ticks in rural settings.
How does the intracellular nature of Brucella contribute to its pathogenesis and clinical manifestations?
How does the intracellular nature of Brucella contribute to its pathogenesis and clinical manifestations?
What is the significance of lipopolysaccharide (LPS) in the pathogenesis of Brucella infections?
What is the significance of lipopolysaccharide (LPS) in the pathogenesis of Brucella infections?
Why are multiple blood specimens and prolonged incubation necessary for the laboratory diagnosis of brucellosis?
Why are multiple blood specimens and prolonged incubation necessary for the laboratory diagnosis of brucellosis?
What distinguishes Brucella melitensis infections from other Brucella species infections in humans?
What distinguishes Brucella melitensis infections from other Brucella species infections in humans?
How does the absence of a capsule in Brucella contribute to its pathogenesis, particularly in comparison to encapsulated bacteria?
How does the absence of a capsule in Brucella contribute to its pathogenesis, particularly in comparison to encapsulated bacteria?
What is the underlying mechanism behind the undulating fever pattern observed in brucellosis?
What is the underlying mechanism behind the undulating fever pattern observed in brucellosis?
In addition to blood cultures, what other diagnostic tests are crucial for confirming brucellosis, especially when blood cultures are negative or unavailable?
In addition to blood cultures, what other diagnostic tests are crucial for confirming brucellosis, especially when blood cultures are negative or unavailable?
Flashcards
What is Brucellosis?
What is Brucellosis?
Brucellosis is a zoonotic disease caused by Brucella species, also known as undulant fever, Mediterranean fever, or Malta fever.
Brucella Morphology
Brucella Morphology
Brucella are small, Gram-negative coccobacilli that are aerobic and facultative intracellular parasites, often arranged singly or in pairs.
Brucella Transmission
Brucella Transmission
Transmission to humans typically occurs through direct contact with infected animal tissues or ingestion of unpasteurized milk or milk products.
Brucella Virulence Factor
Brucella Virulence Factor
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Brucella Pathogenesis
Brucella Pathogenesis
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Brucellosis Symptoms
Brucellosis Symptoms
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Brucellosis Diagnosis
Brucellosis Diagnosis
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Brucella Biochemical Characteristics
Brucella Biochemical Characteristics
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Brucellosis Treatment
Brucellosis Treatment
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Study Notes
- Brucella causes brucellosis, also known as undulant fever, Mediterranean Fever, or Malta fever.
- Brucellosis is a zoonotic disease.
Brucella Species
- Brucella abortus is found in cattle.
- Brucella melitensis is found in goats and sheep.
- Brucella suis is found in pigs.
Morphology
- Brucella are small, gram-negative coccobacilli, arranged singly or in pairs.
- Brucella do not have capsules.
- Brucella are aerobic and facultative intracellular parasites.
- Brucella can survive and multiply inside host phagocytes.
Biochemical Characteristics
- Brucella does not ferment carbohydrates.
- Brucella requires complex media and a prolonged incubation period for in vitro growth.
Epidemiology
- Brucellosis is a chronic, lifelong infection in animals.
- Bacteria are located in reproductive organs.
- Bacteria are shed in large numbers in milk, urine, placenta, and other tissues during delivery or spontaneous abortion.
- Transmission to humans occurs through:
- Direct contact with infected animal tissues.
- Ingestion of unpasteurized milk or milk products.
- Inhalation of bacteria during butchery.
- Eating raw meat or blood.
- Imported cheese made from unpasteurized goat's milk.
Virulence Factors and Pathogenesis
- Lipopolysaccharide (endotoxin) is the major virulence factor and cell wall antigen.
- Brucella enters the body through cuts and abrasions in the skin or the gastrointestinal tract.
- Bacteria are transported via the lymphatic system to regional lymph nodes, where they multiply.
- Organisms are carried by the blood to organs involved in the reticuloendothelial system (liver, spleen, kidneys, bone marrow, and lymph nodes).
Clinical Features
- Incubation period is one to three weeks.
- Nonspecific symptoms include fever, chills, fatigue, malaise, anorexia, and weight loss.
- Undulant fever is named for the rising and falling pattern of the fever.
- Enlarged lymph nodes, liver, and spleen are frequently found.
- Pancytopenia can occur.
- Brucella melitensis infections are more severe and prolonged.
- Osteomyelitis is a possible complication.
Laboratory Diagnosis
- A detailed history is crucial, including patient's occupation, exposure to animals, travel history, and ingestion of contaminated foods.
- Organisms can be cultured from blood, other body fluids, or tissue specimens.
- Multiple blood specimens should be cultured.
- Bacteria grow slowly in culture, requiring enriched blood agar and extended incubation.
- Blood cultures should be incubated for two weeks before being considered negative.
- Preliminary identification is based on microscopic appearance, colony morphology, positive oxidase and urease reactions, and reactivity with specific antibodies.
- A presumptive diagnosis can be made with a four-fold increase in serum antibody titer, or a single titer of 1:160 or greater.
- Slide agglutination tests can be used.
Treatment
- Tetracycline or doxycycline combined + rifampin is used.
- Prolonged treatment is necessary to reduce relapse and complications.
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