Bacterial Infections of the Respiratory Tract proximal to the Alveoli Flashcards
Haemophilus influenza requires which medium in order to grown in the laboratory?
-Requires special nutrients found in blood for growth in
laboratory
-Frequently grown on ‘chocolate agar’ or boiled blood
agar
What colour does H. influenzae stain? Why?
It stains pink because it is a Gram negative bacteria
What is the shape of Haemophilus influenza?
It is shaped either as small cocco-bacilli, or as bacilli. Shape depends on site of infection and the conditions under which the organisms are growing.
How does Haemophilus influenza avoid phagocytosis?
It has a polysaccharide capsule which is important for avoiding phagocytosis and effect of the complement
How many types of antigenic capsule of H. influenzae? Which type is most virulent?
There are 6 different antigenic types of capsule. Type B is most virulent
Where do unencapsulated strains of H. influenzae commonly colonize?
Unencapsulated strains of H. influenzae commonly colonise upper respiratory tract within first few months of
life
Give examples of diseases caused by encapulated H. influenzae strains
Encapsulated strains, primarily type B, cause serious invasive disease such as meningitis, arthritis, epiglottitis
Give examples of medical conditions caused by non-encapsulated strains of H. influenzae.
Non-encapsulated strains cause local disease of the respiratory tract e.g. otitis media, sinusitis, pneumonia
Which age group is more at risk of infection by non-encapsulated strains of H. influenzae?
Generally, it affects children more than adults.
Which type of H. influenzae strains are considered to be secondary invaders?
Non-encapsulated strains
Which bacteria cause acute otitis media? (4)
S. pneumonia, H. influenzae, S. pyogenes, S. aureus
List 5 symptoms of Acute otitis media
Pain, fever, irritability, vomiting, diarrhoea
What are the clinical findings indicative of acute otitis media?
Redness of the tympanic membrane
Fluid accumulation in the middle ear causing bulging and occasionally perforation and discharge
The accumulation of fluid in the ear causes what?
It causes temporary deafness until resorbed after a few weeks.
In children, if the fluid doesn’t resolve, what would be the consequence?
Can be detrimental to language development in young children if doesn’t resolve.
Diagnosis of acute otitis media is based on what?
It is based on clinical history and examination
What it the name of the medical procedure in which fluid is aspirated form the middle ear through the tympanic membrane?
Tympanocentesis
In what case would you have to use ear swabs?
Ear swabs only useful if there is new onset of discharge, which might occur if the tympanic membrane
perforates (rare).
What is chronic suppurative otitis media?
This is a pre-existing perforation of the eardrum with chronic recurrent discharge.
How is chronic suppurative otitis media managed?
generally focuses on cleaning and drying out of ear canal ‘aural toilette’
What are the considerations for the treatment of otitis media? (3)
-Most of otitis media is viral - so paradigm shift away from always giving antibiotics
-Decision to give antibiotics is based on age and duration of infection (<2 years is more likely to be a secondary bacterial infection)
-Sometimes give delayed presciption.
What causes acute sinusitis?
It is caused by viruses, and sometimes secondary bacterial infections.
Which bacteria are responsible for causing secondary infections of the sinuses? (4)
S. pneumonia, H. influenzae, S. pyogenes, S. aureus
(same organisms as otitis media)
What are the symptoms of acute sinusitis?
Pain, fever, blockage or pressure
When are antibiotics indicated for acute sinusitis?
Only if symptoms persist > 10 days or get worse or are very severe or patient looks toxic
What does bronchitis usually affects?
It affects the laryngo-bronchial tree
What is the cause of acute bronchitis?
It is usually viral and self-limiting
What are the signs and symptoms of acute bronchitis?
Cough, sputum production, fever, but doesn’t affect breathing
What causes chronic bronchitis?
It is caused by irritations of smoking and pollution.
Describe acute exacerbations of chronic bronchitis and or chronic obstructive pulmonary disease
Symptoms get worse for period of week or so
May be due to infection, but mostly probably due to viruses
