Micro: URT infection Flashcards
Most common PCP visit for children and OMM techniques to treat it.
Acute Otitis Media (AOM)
- Auricular Drainage
- Sphenopalatine Release
Two most common causes of AOM.
- Strep pneumo
2. Haemophilus influenzae
Major virulence factor for Strep pneumo.
Capsule
-causes B cell response
What are the 3 vaccines used for S. pneumo and which groups receive which vaccines?
Polysaccharide Vaccine: PPSV23
-given to adults
Conjugate Vaccines: PCV7 and PCV13
-given to children
What is a conjugate vaccine?
Attaching a poor polysaccharide organism antigen to a carrier protein .(can be from the same microorganism), Simulating a closer environment to a real infection. It is often given to children (immature immune system) and IC patients because it stimulates a strong immune response for protection with a very low risk of causing actual disease or symptoms.
Why does the Hib vaccine against H. flu not prevent otitis media?
The vaccine works against the capsule of H. flu, its main virulence factor. The strain of H flu that causes AOM does not have a capsule.
What is different about AOM caused by S. pneumo vs. H. flu?
H. flu is often bilateral and has associated conjunctivitis
How do patients present with epiglottitis caused by H. flu?
“catcher’s position”, drooling, not wanting to swallow because it’s painful.
-inspiratory stridor
-expiratory rhonchi
(H flu type B is major cause)
3 virulence factors used by H flu in the pathogenesis of epiglottitis.
- Capsule (major)
- IgA protease
- Endotoxin (LPS)
Major cause of Croup and how it’s different from Epiglottits.
Parainfluenza virus
- Epiglottitis is abrupt onset, croup is not
- no barking cough in epiglottitis
- drooling and dysphagia in epiglottits
What are the 4 Hib vaccines?
All are conjugate vaccines
- PRP-HbOC: nontoxic diphtheria toxin
- PRP-OMP: outer Neisseria m. membrane protein
- PRP-T: tetanus toxoid
- PRP-D: diphtheria toxoid (not in infants)
What is a toxoid vs. toxin?
A toxoid is a bacterial toxin whose toxicity has been inactivated or suppressed either by chemical or heat treatment, while other properties, typically immunogenicity, are maintained.
Condition caused by Haemophilus aegypticus.
Pink Eye
Source of AOM caused by Moraxella c. and one reason why it can be difficult to treat.
Part of normal flora.
Almost all produce beta lactamase
Major bug that causes Otitis Externa, swimmers ear (acute diffuse Otitis externa), and invasive (malignant) otitis externa.
Pseudomonas
What is malignant or invasive Otitis Externa and who is at risk?
It is a severe necrotizing infection that invades cartilage and blood vessels of the pinna.
IC patients are most at risk: elderly, diabetics, AIDS
Mechanisms of antibiotic resistance in Pseudomonas.
- Mutations of porin proteins
2. Beta Lactamase production
Main cause of pharyngitis.
Viral
Main bacterial cause of pharyngitis.
Strep pyogenes
How can PE differentiate viral from bacterial pharyngitis?
Viral: more mild, usually restrictive to nose, mouth, throat
Bacterial: pus, more enlarged lymph nodes, rash, systemic symptoms: abdominal pain, vomiting
Virulence Factors of Strep pyogenes.
M-protein
SPE
Streptolysin O
What is the JONES criteria for diagnosis of Rheumatic Fever?
Joint pain Carditis Nodules Erythema marginatum Sydenham chorea
Symptoms of Nephritic syndrome caused by Strep pyogenes
Hematuria, periorbital edema
Virulence Factors associated with Nephritic syndrome caused by Strep pyogenes.
Immune complex formation and deposition in glomerulus
- NAPIr protein (nephritis associated plasmin receptor)
- SPE B
What does the ASO titer lab test diagnose?
Strep pyogenes infection
-it detects anti-streptolysin O antibodies in blood
Virulence factor of C. diphtheriae
Toxin
How is the diphtheria toxin regulated?
Iron levels
-low iron means high toxicity
What is the MOA of the diphtheria toxin?
Alpha Subunit
-ADP ribosylates (inactivates) Elongation Factor (EF) 2 preventing protein synthesis
Beta Subunit
-allows entry into the cells (especially cardiac and neural tissue which is why you see CN IX and CN X deficits)
Distinct URT clinical signs of diphtheria infection.
Gray pseudomembrane in oropharynx
Bull Neck
Media used to culture C. diphtheriae.
Loeffler or Tellurite Agar
ELEK test can be used to identify the diphtheria toxin
Treatment for diphtheria.
Penicillin Antitoxin (will only work on circulating toxin in the blood so it must be administered quickly before it gets into cells)
Name and describe the 5 virulence factors for Bordatella pertussis.
- Filamentous Hemagglutinin: binds cilia
- Pertactin: binds cilia
- Pertussis Toxin: ADP ribosylation of Gi protein increasing cAMP levels
- Adenylate Toxin: activates adenylyl cyclase increasing cAMP levels
- Tracheal Cytotoxin: destroys cilia causing cough and IL-1 release
Name the 3 phases of a pertussis infection and which is most contagious.
- Catarrhal Stage: 1-2 weeks (most contagious)
- Paroxysmal Stage: 1-6 weeks
- Convalescent Stage: 2-3 weeks
Difference between the DTP and the DTaP vaccines
DTaP does not contain pertussis cells, only virulence factors. The DTP, which contained whole cells had a lot of neurological side effects.
What is the difference between DTaP and Tdap vaccines?
Any vaccine which upper case letters means that pathogen is a stronger dose vaccine and more likely to cause actual disease. Lower case is weaker and given to immunocompromised patients (pregnant, cancer, transplant)
Agar used to diagnose pertussis.
Regan Lowe Charcoal Agar
Best lab test to diagnose pertussis.
PCR
