Week 5 - bacterial and fungal respiratory tract infections

Question 1

List some physical host defence mechanisms

Answer 1

Hairs in the anterior nares
Saliva
Sloughing of epithelial cells
Cough/epiglottic reflex
Structural anatomy
Mucociliary escalator

Question 2

List some immunological host defence mechanisms

Answer 2

Adenoids and tonsils
Alveolar lining fluid
Cytokines and immunoglobulins from cell mediated immunity
Leukocytes/monocytes

Question 3

How are Respiratory tract infections (RTIs) transmitted?

Answer 3

Via airborne transmission through droplets via sneezing, talking, coughing etc

Question 4

List the different Upper respiratory tract infections

Answer 4

Pharyngitis/tonsilitis
Sinusitis
Laryngitis
Otitis media

Question 5

What is pharyngitis/tonsillitis?

Answer 5

Inflammation of the pharynx/tonsils
Symptoms including: Inflamed pharyngeal membrane
Pharyngeal pain
Exudate (fluid that leaks out of the blood vessels to nearby tissues, made of cells, proteins etc) that covers the pharynx and region of the tonsils
Oedema (swelling) of the uvula

Can cause: headache, pyrexia (fever), chills, abdominal pain

Question 6

What are the causes of pharyngitis?

Answer 6

Leading cause is S. pyogenes aka group A strep
Can be Group C or G strep

Question 7

How is pharyngitis treated?

Answer 7

10 days of the antibiotic penicillin V.

Question 8

What are some complications of S. pyogenes pharyngitis?

Answer 8

Day after infection: scarlet fever, peritonsillar abscess

Weeks after infection: rheumatic fever/heart disease, acute glomerulonephritis

Question 9

What are the culture condition of S pyogenes aka Group A strep

Answer 9

Blood agar
37 degrees celsius
Anaerobic conditions to enhance haemolysis, or CO2 enriched air

Question 10

What are the stages of pertussis (whooping cough) also an upper respiratory tract infection

Answer 10

1. Incubation - 2 week duration
2. Mild cough/sneezing - 10 day duration
3. Cough and whoop on inhalation, individual is exhausted, suffers cyanosis, vomiting, convulsions - 2-4 week duration
4. convalescent period (recovery) - 1-2 week duration

Question 11

What is the bacteria that causes pertussis (whooping cough?)

Answer 11

Bordetella pertussis (B pertussis and B parapertussis)

It is a thin gram negative coccobacillus, encapsulated, an aerobe.

is highly contagious

Question 12

What are the different lab diagnosis of whooping cough?

Answer 12

Bacterial culture
PCR of perusal swabs
Serology

Question 13

How does one usually get infected with lower respiratory tract infections?

Answer 13

Via bacterial access:
-through airborne transmission
-aspiration from nasopharynx
-aspiration of foreign objects: food, vomit
-haematogenous spread (carried by blood)

Via predisposing factors:
-an underlying chronic respiratory disease
-smoking
-viral infection
-an already immunocompromised individual

Question 14

List the different infections of the lungs

Answer 14

Tuberculosis
Empyema
Bronchitis
Bronchiolitis
Pneumonia
Aspiration pneumonia ans lung abscess

Question 15

What are the features of pneumonia?

Answer 15

Alveoli fill with pus/fluid making breathing painful and limiting oxygen intake

Symptoms such as: cough, purulent sputum, pyrexia, consolidation of lung, fatigue, anorexia, sweats, nausea

Question 16

What re the different types of pneumonia?

Answer 16

Community acquired typical pneumonia
Community acquired Atypical pneumonia
hospital acquired pneumonia

Question 17

What are the differences between community acquired typical and community acquired Atypical pneumonia ?

Answer 17

Typical:
-acute onset
-sputum is produced
-can be caused by strep pneumoniae, staph aureus

Atypical:
-chronic onset, very little sputum produces
-can be caused by mycoplasma pneumoniae, legionella pneumophiolia etc

Question 18

What is hospital acquired pneumonia?

Answer 18

Where one is in intensive care
Can be caused by antibiotic resistance like MRSA, Resistant gram negative bacilli

Question 19

What are the diagnostic/therapeutic challenges of pneumonia?

Answer 19

Diagnosis can be difficult’
Many microorganisms can cause the disease and some are commensals and some can’t even be cultured
Antibiotic resistant pathogens

Question 20

What are the different types of lab investigations to diagnose pneumonia?

Answer 20

Sputum culture: but it’s hard too collect good specimens, also there may be previous antibiotic therapy still present
Blood culture:
Serology

Question 21

What are the steps of sputum collection?

Answer 21

the patient has to rinse their mouth out in order to reduce URT commensal contamination

Collect it early morning to increase chance of being purulent

Avoid collecting saliva, only collect sputum.

Question 22

Why should sputum samples be transported to the lab quickly?

Answer 22

To m maintain delicate organism
To prevent overgrowth of robust organisms

Question 23

What type of lab are sputum samples handed in?

Answer 23

Containment level 3 lab

Question 24

What is haemoptysis?

Answer 24

When you cough up blood

Question 25

How can you find out what bacteria is in the sputum sample?

Answer 25

1. Gram stain

Question 26

How is sputum cultured?

Answer 26

The sample is homogenised to reduce viscosity and to distribute the organisms evenly in the sample.

Then dilute at 1:1000 to help dilute out commensals

Question 27

What media would you use to isolate the pathogens found in the sputum?

Answer 27

Blood agar - Co2 enriched air
Chocolate agr - Co2 enriched air
Maconkey, CLED agar - air
Sabouraud agar - air

Question 28

learn about cystic fibrosis slides

Question 29

List some organisms that colonise the lung causing infection

Answer 29

Staph aureus
Pseudomonas aeruginosa
etc

Question 30

Describe pseudomonas aeruginosa

Answer 30

Gram negative motile bacillus, oxidase positive

Question 31

Learn the rest of the slides