Infections of the respiratory tract

Question 1

What is rhinitis

Answer 1

Infection of nose

Question 2

What is coryza ? What are the common pathogens responsible for this

Answer 2

Rhinoviruses 
Parainfluenza viruses 
Coronaviruses 
Adenoviruses 
Enteroviruses 
May predispose patient to secondary bacterial infection

Question 3

Pharyngitis and tonsillitis is commonly caused by …

Answer 3

Adenoviruses and bacteria

Question 4

Describe infectious mononucleosis (aka glandular fever)

Answer 4

spread through spit ; symptoms extreme tiredness, swollen glands in your neck and a high temperature. Atypical mononuclear cells in peripheral blood

Question 5

Epiglottitis and croup

Answer 5

Croup - Young children ; Inspiratory stridor(noisy breathing) due to narrowed airways. caused by viruses – paraflu, RSV
Epiglottitis - Bacterial. Potentially life-threatening
Haemophilus influenzae type b (now rare)

Question 6

What are the common lower respiratory tract infectious agents

Answer 6

Influenza
Respiratory syncytial virus
SARS-CoV-2

Question 7

Describe the genome of influenza viruses

Answer 7

Segmented negative ssRNA genome
8 segments that together encode 11 proteins
Segment 4 = haemagglutinin (causes RBC to clump)
Segment 6 = neuraminidase (cleave Salic acid allow entry into host cell)
Three types : A/B/C based on internal proteins
A has subtypes based on surface proteins (HA or NA)

Question 8

Describe the pathogenesis of influenza

Answer 8

Pneumotropic - infects cells respiratory epithelium (down to alveoli ) and lysis occurs

This removes 2 innate defence mechanisms (mucus secreting cells and cilia)

Interferon production (they trigger the immune system)
Virus remains in lungs

Question 9

Complications of influenza

Answer 9

2 types of pneumonia

Primary viral pneumonia: mononuclear cell infiltrate
Secondary bacterial pneumonia: PMNL infiltrate

Cardiovascular complications - myocarditis

CNS complications - encephalitis

Question 10

Describe antigenic drift in influenza viruses

Answer 10

Occurs in both A and B flu viruses

Random spontaneous mutation in viral RNA genes encoding HA and NA

Question 11

Antigenic shift in influenza viruses

Answer 11

Occurs in influenza A only
Genetic reassortment between human and non-human viruses leading to new subtypes
Often leads to emergence of new pandemic strains a

Question 12

Describe Tuberculosis

Answer 12

A positive tuberculin skin test will develop in 2-8 months post infection

Grows well in tissue with high O2 content

Slow growing - takes 12-18 hours to duplicate

Less permeable to usual bacterial stains such as Gram stain