Micro Exam 3- Part 3
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Which types of infection are associated with infections of the URT?
Rhinitis, sinusitis, oral cavity infections, pharyngitis, laryngeotrachobronchitis, epiglottitis
Which two pathogens are associated with infections of the URT?
- Streptococcus pyogenes
- Corynebacterium diphtheriae
Which infections are associated with infections of the LRT?
Bronchitis, bronchiolitis, pneumonia
Which pathogen is associated with infections of the LRT?
Which bacteria are common normal flora of the URT?
- Corynebacterium (diphtheroids)
Which pathogen is also known as group A strep?
What are the 3 mechanisms of disease caused by S. pyogenes?
- Pyogenic inflammation
- Exotoxins/hemolysin production
Which adhesins are associated with S. pyogenes?
- M protein
- F (fibrinonectin) protein
- Collagen binding protein
What are the antiphagocytic factors associated with S. pyogenes?
- Capsule (contains hyaluronic acid)
- M protein
- C5a peptidase
Which enzymes does S. pyogenes contain that contributes to its virulence?
- Streptolysin O and S (lyse red blood cells)
- Streptokinase (activates plasminogen to plasmin to dissolve clots)
What is the number one bacterial agent of pharyngitis?
What are three secondary complications associated with S. pyogenes?
Scarlet fever, rheumatic fever, acuteglomerulonephritis
How is S. pyogenes diagnosed in the lab?
Beta hemolytic colonies, catalase negative, Baitracin susceptible, Latex agglutination (group A positive)
Are Streptococcus Catalase positive or negative?
Are Staphylococcus Catalase positive or negative?
Corynebacterium diphtheriae- gram and shape?
Gram positive rods, pleomorphic
What is the main virulence mechanism of C. diphtheriae?
- Exotoxin production
- (AB toxin; B binds to heparin-binding epidermal growth factor, A inactivates EF-2 to inhibit protein synthesis)
What are the clinical manifestations of diphtheria?
Sore throat, painful swallowing, pseudomembrane formation (breathing problems), regional lymphoadenopathy (bull neck appearance)
Which tests are used to detect the diptheria toxin?
Bordetella pertussis- gram and shape?
Gram negative coccobacilli
What are the virulence mechanisms of B. pertussis?
- -Adheres to ciliated epithelial cells in trachea
- -Toxin production
- -Tissue destruction
What are the three stages of symptoms associated with Pertussis?
- 1. Common cold symptoms (most contagious stage)
- 2. Paroxysmal cough (inspiratory whoop)
- 3. Convalescent stage
Mycobacterium tuberculosis- gram and shape?
- Does not gram stain
- Acid fast bacillus
What are the two types of acid fast stains?
What are the steps in acid fast staining?
- Primary stain= carbofuchsin
- Decolorizer= acid alcohol
- Counter stain= methylene blue
What are the unique features of the Mycobacterial cell wall?
Lipoarabinomannan and mycolic acid
What are the main virulence mechanisms of Mycobacterium tuberculosis?
- Mycolic acid
- Facultative intracellular pathogen (in macrophages)
- Induces hypersensitivity (DTH)
- Cord factor
What is the role of the cord factor found in M. tuberculosis?
- Causes cording of cells microscopically
- May inhibits PMNs
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