Week 12 - Topic 1: Upper Respiratory Tract Infections Flashcards
How do URTIs happent?
Viruses attach to receptors in the cells of mucous membranes (eyes, nose, pharynx, throat, lungs)
Name some URTI
Chronic/acute sinusitis Acute rhinitis (allergic or viral) Laryngitis Pharyngitis Tonsilitis Acute tracheobronchitis
Why do URTI often cause ear infections?
Because the auditory channel (eustachian tube) is connected to the pharynx, so viruses will travel from the URT to the middle ear to cause otitis media
What defense mechanism against microorganisms does the lacrimal apparatus have?
Tears: washing action + lysozymes + secretatory IgA
Why can URTI cause eye infections?
Viruses can travel from the URT to the eyes through the nasolacrimal duct. They can also block the lacrimal gland ducts from producing tears (defense mechanism)
What URT virus causes what kind of eye infection?
Adenovirus and pinkeye (conjuctivitis)
Why do people with respiratory illnesses, such as COPD, have a higher chance of infection?
They have difficulty getting rid of secretions = “clogged” lungs = microorganisms remain stuck in lungs = higher risk of pneumonia and infections
What delimitates the lower respiratory tract?
From the trachea to the lungs (alveoli)
What are 4 natural first line defences against respiratory infections?
1) Ciliated cells in bronchi to push viruses out
2) Coughing reflex
3) Exhaling contaminants out (air movement)
4) Macrophages in alveoli
What can interfere with out natural host defences against URTI?
- Smoking
- Alcohol
- Being immunocompromised (loss of function in macrophages)
What are the 3 portal of entries for microorganisms in the respiratory tract?
1) Inoculation of conjunctiva or nasal passages
2) Aspiration of mouth flora or food (through choking)
3) Inhalation of small aerosolized droplets <3 um diameter
What is so dangerous about small aerosolized droplets?
They are small enough to bypass cilia and enter the lungs
How do you prevent inoculation of conjuctiva and nasal passages?
Do not touch your face
What is an endemic?
Disease that perpetually exists in a particular region/population
Ex: TB in certain areas
What is an outbreak?
The occurrence of cases of disease in excess of what would normally be expected in a defined community
Excess = more than 3 cases
What is an epidemic?
When it spreads to several communities at about the same time
What is a pandemic?
When it spreads throughout the world, over several countries/continents –> usually occurs URTI
What are 3 normal flora that cause infections in the nares?
1) Haemophilus influenzae
2) Moraxella catarrhalis
3) Staph aureus
What are the 3 normal flora that cause infections in the pharynx?
1) Staph spp.
2) Strep pneumoniae
3) Strep pyognes (Group A) –> only some people are carriers
**all gram + cocci
What are the 7 normal flora that cause infections in the eye?
Gram + cocci:
1) Staph aureus
2) Staph epidermidis
3) Strep spp
Gram + bacilli:
4) Corynebacterium spp
5) Propionibacterium acnes
Gram - cocci:
6) Moraxella
7) Neisseria spp
True or False: Most infections are spread through contact + droplet.
True
How does conjunctivitis usually happen?
Self inoculation by touching the mucous membranes of the eyes
How do you prevent conjunctivitis (3)?
1) Hand hygiene
2) Environmental cleaning of high touch surfaces
3) High level disinfection of instruments that touch eyes (ex: eye pressure inducer at optometry clinics)
What mode of transmission is conjunctivitis?
Contract droplet
