E1- Otitis, Sinusitis, Diphtheria, Pertussis Flashcards
What are the two most common organisms that cause otitis externa?
Pseudomonas aeruginosa
Staphylococcus aureus
What are the three most common organisms that cause otitis media and sinusitis?
Streptococcus pneumoniae (most common)
Moraxella catarrhalis
Haemophilus influenza
What is the most common organism that causes diphtheria?
Corynebacterium diphtheriae
What is the most common organism that causes whooping cough (pertussis)?
Bordetella pertussis
How do you determine which organism is the causative agent of otitis externa?
Gram stain
Is pseudomonas aeruginosa gram positive or negative? What shape?
Gram negative bacilli
Many strains of pseudomonas aeruginosa produce ______, but nearly all produce ______. (Think pigment)
Pyocyanin (non fluorescent blue; generates ROS)
Pyoverdin (fluorescent green; sequesters iron)
Is staphylococcus aureus gram positive or negative? What shape?
Gram positive cocci
What is unique about staphylococcus aureus?
Coagulate positive
B-hemolytic
Is streptococcus pneumoniae gram positive or negative? What shape?
Gram positive, lancet-shaped diplococci
What is unique about streptococcus pneumoniae?
A-hemolytic
Sensitive to optochin
Is haemophilus influenzae gram positive or gram negative? What shape?
Gram negative coccobacilli
Is moraxella catarrhalis gram positive or negative? What shape?
Gram negative diplococci
What is unique about moraxella catarralis?
B-lactamase producer and oxidase positive
What are the two type of diphtheria diseases?
Cutaneous and respiratory
Is diphtheria gram positive or negative? What shape?
Gram positive bacilli
Palisades- “V” appearance
What type of oxygen requirements and agar plate does diphtheria need for growth?
Aerobic on blood agar
Toxigenic strains of diphtheria have a _____.
Phage encoded (tox) exotoxin = diphtheria toxin
_____ concentration stimulates production of diphtheria toxin, which is an ______.
Low iron
A-B exotoxin
The A portion of an A-B exotoxin is the
Catalytic subunit
The B portion of an A-B exotoxin is the
Receptor binding domain
The Diphtheria exotoxin binds to what type of receptor on the cell membrane to then be endocytosed?
Heparin-binding EGF receptor
When the diphtheria exotoxin acidifies the inside of the cell, it releases the __ subunit, which inactivates EF-2. This halts _____.
A
Protein synthesis
What is a network of fibrin + bacteria + WBCs + necrotic epithelial cells called? What disease is it associated with?
Pseudomembrane
Respiratory diphtheria
What disease is bull neck associated with?
Serious respiratory diphtheria
What types of cultures should you use to help diagnose diptheria?
Loeffler’s medium and Cycteine-tellurite agar
Besides a gram stain, what other type of stain can use use to help diagnose diphtheria?
Volutin: metachromatic (volutin) granules
If diphtheria is your presumptive dx, what should you test isolates for?
Toxin production
What four tests can be used to test for toxin production?
Elek test
PCR
ELISA
Immunochromatographic strip assay
Is Bordetella pertussis gram positive or negative? What shape?
Gram negative coccobacilli
What are the three virulence factors of Bordetella pertussis?
Endotoxin
Adhesions
Exotoxins
What are the four exotoxins produced by Bordetella pertussis?
- Pertussis toxin (A-B exotoxin)
- Adenylate cyclase toxin
- Dermonecrotic toxin
- Tracheal cytotoxin
After an average incubation period of 7-10 days, pertussis occurs in what three stages?
- Catarrhal stage
- Paroxysmal stage
- Convalescent stage
What disease stage of pertussis is associated with:
a. inflammation of mucous membranes
b. nonspecific upper respiratory tract syndrome
c. highly contagious
Catarrhal stage
What disease stage of pertussis is associated with:
a. attacks or spasms
b. paroxysmal coughing, followed by vomiting
Paroxysmal stage
What disease stage of pertussis is associated with:
a. paroxysms decrease
b. possibility of serious complications
Convalescent stage
What are possible complications seen with pertussis?
Pneumonia*
Encephalopathy
Seizures
Death
What type of serology test is used to help dx pertussis? What finding would indicate a recent infection?
ELISA
4-fold increase or high initial titer
What two test can be for a definitive dx of pertussis?
Culture on enriched medium
-Bordet Gengou agar
-Regan Lowe agar
PCR
What type of culture sample can you use to dx pertussis?
Bordet-Gengou agar
Regan-Lowe agar
