Respiratory tract infections Flashcards
In a healthy “normal” state which part of the respiratory tract is sterile?
lower resp tract is normally sterile but upper resp tract is not - some organisms are present in healthy individuals (normal flora)
What defence mechanisms does the respiratory system have?
cilia
mucus production
cough and swallow mechanism and immunoglobulins (IgA)
What are some of the key elements of a respiratory history?
symptoms: cough, nature of sputum, haemoptysis, pleuritic pain, fever, night sweats, coryzal symptoms (nasal discharge, facial pain, muscle aches and pains, lethargy)
History of travel
employment - exposure to animals, air conditioning, student, occupational exposures
does pt keep birds
underlying/predisposing illness
unwell contacts
What are the key factors of an URTI?
common short-lived, rarely serious usually viral aetiology only require abx if: - bacterial aetiology known or suspected - systemically unwell - features or high risk of complications
What tend to be the classic URTI symptoms?
acute coryza - nasal discharge, sneezing, cough
pharyngeal involvement = sore throat
laryngeal involvement = hoarse or lost voice
can be complicated by tracheitis/bronchitis = wheeze
nasal congestion, facial pain/pressure should raise possibility of sinusitis
What are the causative agents of URTI in the nasopharynx?
rhinovirus, coronavirus, S. aureus
What are the causative agents of URTI in the oropharynx?
group A streptococcus, cornyebacterium diphtheriae, epstein-barr virus, adenovirus
What are the causative agents of URTI in the epiglottis?
H. influenzae
What are the causative agents of URTI in the larynx-trachea?
Parainfluenza, S. aureus
What are the symptoms of epiglottitis and what organisms normally cause it?
haemophilus influenzae type B - nearly completely disappeared due to vaccine
- acute onset fever, sore throat, respiratory distress
- must avoid manipulation of the throat - need help call ENT
What are the symptoms of sinusitis and what are the common organisms that cause?
inflammation of the lining of the sinuses
s.aureus, H.influenzae, and anaerobes
What are the characteristics of pharnygitis (sore throat/tonsilitis)?
inflammation, exudate, fever, tender cervical lymph nodes
difficult to differentiate between viral and bacterial pharyngitis on basis of clinical findings
What are common organisms that cause pharyngitis, and its complications?
streptococcus pyogenes - group A streptococcal most common bacterial cause = about 30%
Complications:
- scarlet fever (characteristic red rash all over body)
- rheumatic fever
- post-strep glomerulonephritis
What are the symptoms of whooping cough and how is it transmitted ?
bordetella pertussis bacteria
- mild, cold like symptoms
- develop into coughing fits (characteristic barking cough), can persist for weeks to months
person to person, coughing and sneezing
When are the vaccinations for whooping cough?
2, 3 and 4 months booster pre-school
What are the important viruses in RTI?
influenza/parainfluenza
RSV
novel coronavirus
What are the 3 main types of influenza?
A, B and C
- A and B = most of disease burden
What is meant by influenza virus is antigenically unstable?
constantly changing
- antigenic DRIFT = minor changes to the amino acid sequence of the haemagglutinin
- antigenic SHIFT = major changes in HA
Seasonal epidemics and pandemics
- H1N1
- HSN1 avian influenza
Which groups are offered influenza vaccination and how is it diagnosed?
risk groups are offered it each year
components of vaccine aim to cover circulating strains
throat swab detection by PCR
How is RSV transmitted and what are the symptoms?
transmitted by large droplets and secretions
- occurs regularly each year
generally mild but children (<6 months) develop most severe disease (bronchiolitis and pneumonia)
60% will have been infected prior to 1st birthday
disease in childhood doesn’t give lifelong protection
What can novel coronoaviruses cause?
respiratory infections of varying severity in humans and animals
Severe acute respiratory syndrome (SARS)
Middle east respiratory syndrome coronoavirus (MERS-CoV)
- camels are suspected primary source of infection
What are the common LRTI?
pneumonia - infection of lung tissues
Acute bronchitis/bronchiolitis - inflammation of the bronchi
primary difference is pneumonia has radiological changes
What are some pre-disposing conditions for LRTIs?
alcoholic - S. pneumonia, h. influenzae, K pneumonias
COPD - H influenzae, S pneumoniae
Cystic fibrosis - pseudomonas, staphylococci
Post influenza - staphylococci , H influenzae, s pneumoniae
Mechnical ventilation - klebsiella, MRSA, p.auruginosa, enterobacter
What are the signs and symptoms of community acquired pneumonia?
typical: fever, chest pain and purulent sputum
Atypical: dyspnoea and cough, minimal sputum production, more systemic upset
