22 Questions
What type of antibodies may interfere with agglutination by IgG and IgM and cause a serologic test result to be negative in low serum dilutions?
IgA antibodies
What is the main limitation of the Rose Bengal Plate Test (RBPT) in endemic areas?
Lack of specificity
What is the main advantage of the Brucellacapt (Vircell, Granada, Spain) method?
It is easy to perform and has high sensitivity and specificity
What is the cut-off value for IgG agglutinin titers in diagnosing active Brucella infection?
>1:80
What method is used to detect 'blocking' antibodies that may interfere with agglutination tests?
Coombs antiglobulin method
What type of proteins are used as antigens in ELISA assays for Brucella diagnosis?
Cytoplasmic proteins
What is the primary mode of transmission of Legionella?
Inhalation of aerosolized organisms from contaminated water or soil
What is the primary site of infection for Legionella?
Respiratory tract
What is the characteristic of Legionella that makes it difficult to diagnose?
It is a fastidious organism that requires specific growth conditions
What is the definitive method of diagnosis for Legionella?
Culture of respiratory secretions using buffered charcoal yeast extract
What is the characteristic of the urinary antigen test for Legionella?
It is a rapid test that provides results within hours
What is the primary reason for the difficulty in treating Legionella infections?
The organism is an intracellular parasite that evades the host's immune system
What is the primary route of transmission of Brucella to humans through consuming dairy products?
Through unpasteurized dairy products
What is the global status of animal brucellosis?
It is a problem worldwide
What is a common symptom of brucellosis infection in humans?
Weight loss and sweating
What is the diagnostic gold standard for brucellosis?
Blood culture
What is a characteristic of Brucella species growth on agar media?
Small colonies with nonhemolytic activity
What is the purpose of Christensen's urea slant in brucellosis diagnosis?
To detect urease activity
What is the limitation of serologic assays for brucellosis?
They show variable levels of cross-reactivity with other gram-negative bacteria
What is the treatment for brucellosis infection?
Streptomycin or erythromycin
What is the significance of holding blood cultures for ≥10 days?
To allow for bacterial growth and detection
What is the purpose of using a biologic safety cabinet in brucellosis diagnosis?
To handle infected specimens safely
Learn about the diagnosis of Brucella infections, including the importance of serology, agglutination tests, and culturing. Understand the limitations of serologic assays and the need for standardized antigens.
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