Upper respiratory tract infections Flashcards
What is included in the upper respiratory tract
Nose, paranasal sinuses, middle ear, oropharynx, nasopharynx, laryngopharynx, tonsils and adenoids
Are majority of upper respiratory tract infections viral or bacterial
Viral
4 most common viruses causing upper resp. infections
Adenovirus
Parainfluenza virus
Respiratory syncytial virus
Rhinovirus
Usual onset of upper resp tract infections
1-3 days
How long do upper resp tract infections usually last
7-10 days
What usually causes acute pharyngitis
Group A strep
Symptoms of strep throat
Sore throat
May not have runny nose/ cough/ sneezing
Main features of colds
Watery to mucoid, sometimes purulent nasal discharge called coryza
What family is responsible for about 50% of common colds
Picrona virus family (rhinoviruses)
Incubation period for rhinoviruses colds
1-3 days
What follows incubation period of rhinoviruses
Headache, sore throat, fullness of nose
Profuse watery discharge from nose which gradually thickness
What type of immunity follows rhinovirus cold
Short period of immunity to all colds
Prolonged immunity to specific serotype causing recent infection
What is the proper name for croup
Acute laryngo-tracheo-bronchitis
What causes croup
Viruses (RSV, parainfluenza 1-3)
Signs and symptoms of croup
Hoarseness, seals bark cough, stridor
Treatment of croup
Monitor for obstruction
Inspire humidified air
Consider ribavirin
What is the single main pathogen in resp infections of childhood
Respiratory syncytial virus (RSV)
Describe morphology of paramyxoviruses
- Similar to influenza
- Roughly spherical
- Inner helical nucleocapsid
- Envelop studded with spikes of haemagglutinin and neuraminidase
Proper name for ear infection
Otitis media
What can group A strep infection lead to
- Severe sore throat
- Peritonsilar abscess
- Rheumatic fever
What causes epiglottisis
Haemophilus influenzae type B
Clinical features of group A strep
- Sore throat, fever
- Tender cervical nodes
- May lead to quinsy
- Occasionally leads to scarlet fever
- Incubation period 2-3 days
Lab diagnosis of strep A?
Bacterial culture- beta- haemolytic colonies on agar, gram positive cocci in chains, and lancefield group A (cell wall antigen)
How to treat strep A
Antibiotics
What causes glandular fever/ infectious mononucleosis
Epstein Barr virus
How is Epstein Barr virus diagnosed
- Peripheral white cell count
- Monospot test
- Detection of IgM antibodies against EBV
Management of Epstein Barr virus
Rest and analgaesia
Occasionally causes obstruction- hospital and steroids
What antibiotics should be avoided in treated secondary bacterial infection bollowing Epstein Barr?
Ampicillin (causes a rash)
What causes sinusitis
Bacterial overgrowth of normal flora
Clinical features of epiglottis
- Rapid onset of severe, sore throat, dysphagia
- May lead to resp obstruction
- Bacteria
What would CT scan of person with epiglottis show
Swelling of soft tissues in neck
Management of epiglottitis
Medical emergency:
- Airway (intubation/ tracheostomy)
- Antibiotics
- Prophylaxis for unimmunised household contacts
What microorganism causes whooping cough
Bordetella pertussis
What happens in week 1 of whooping cough
Catarrhal phase: cough increases
What happens in week 3-4 of whooping cough
Paroxysmal stage
Severe spells of cough
Whoop is created by vigorous inspiration through glottitis
May turn blue or vommit
Treatment of whooping cough
Erythromycin
How is whooping cough diagnosed
Pernasal swab
Grab negative rod
Slow growing- 5 days
Direct immunofluorescence
Define acellular vaccine
Contains inactive forms of pertussis toxin, filamentous haemagglutinin, agglutinogens, outer membrane protein
What toxin causes diphtheria
Corynebacterium diphtheriae
What does the diphtheria toxin do
Binds to EF-Tu to form inactive diphthamide EF-Tu and stop protein synthesis
What childhood vaccination prevent diphtheria
DTP
Management of diphtheria
Isolate Anti-toxin Penicillin Monitor for obstruction Contact trace
How are adenovirus spread
Droplet, formites and ingestion
What do adenoviruses infect
Mucous membrane of eye resp and gastro intestinal tract, occasionally urinary tract
Describe process of viral infection
Virus binds to cell surface
Viral genome released into cell for replication
Viral proteins produced allowing assembly of progeny virus particles to be formed and released
Where does influenza act on the body
Infects upper airways but may go down and cause pneumonia and bronchiolitis
What do we know about pandemic waves
More than one way likely
Waves last 6-8 days
Gaps may be weeks or months
Subsequent wave may be worst
How to prevent spread of influenza
Staff in hospitals should be vaccinated
How can influenza be treated pharmacologically
Zanamavir/ oseltamavir
