What are the common microorganisms found in the respiratory tract?
- Viridans streptococci
- Neisseria spp
- Anaerobes
- Candida spp
What are the less common microorganisms found in the respiratory tract?
- Streptococcus pneumonia
- Streptococcus pyogenes
- Haemophillus influenza
What natural defences does the respiratory tract have to protect against infection?
- Cough and sneezing reflex
- Muco-ciliary clearance mechanisms
- Respiratory mucosal immune system
What are the muco-ciliary clearance mechanisms?
- Ciliated columnar epithelium
- Nasal hairs
What are the components of the respiratory mucosal immune system?
- Lymphoid follicles of the pharynx and tonsils
- Alveolar macrophages
- Secretory IgA and IgG
What are the main upper respiratory tract infections?
- Rhinitis (common cold)
- Pharyngitis
- Epiglottisitis
- Laryngitis
- Tracheitis
- Sinusitis
- Ottitis media
What is otitis media?
Inflammation of the middle/inner ear
What are URTs most commonly caused by?
Viruses
What viruses commonly cause URT infections?
- Rhinovirus
- Coronavirus
- Influenza/parainfluenza
- Respiratory syncytial virus (RSV)
Other than virally, what else can cause URTs?
Bacterial super-infection
What is bacterial super-infection common with?
- Sinusitis
- Otitis media
What can URTs caused by bacterial super-infection lead to?
- Mastoiditis
- Meningitis
- Brain abscess
What is pneumonia?
General term denoting inflammation of gas-exchanging region of the lung
What is pneumonia usually due to?
Infection, bacterial or viral
What is pneumonia an infection of?
The lung parenchyma
What is pneumonitis?
Inflammation of the gas-exchanging region of the lung due to causes other than infection, such as physical or chemical damage
What is lobar pneumonia?
Pneumonia localised to a particular lobe(s) of the lung
What is lobar pneumonia most often due to?
Streptococcus pneumoniae
What is bronchopneumonia?
Pneumonia that is diffuse and patchy
What path does infection take in bronchopneumonia?
It starts in the airways, and spreads to adjacent alveoli and lung tissue
What causes bronchopneumonia?
- Streptococcus pneumoniae
- Haemophilus influenza
- Staphylococcus aureus
- Anaerobes
- Coliforms
What is aspiration pneumonia?
Aspiration of food, drink, saliva, or vomit that leads to pneumonia
Who is more likely to develop aspiration pneumonia?
- Individuals with altered levels of consciousness
- Individuals with problems swallowing
Why may individuals have an altered level of consciousness?
- Anaesthesia
- Drug or alcohol abuse
Why may an individual have problems swallowing?
Nerve or oesophageal damage
What organisms are involved in aspiration pneumonia?
- Oral flora
- Anaerobes
What is interstital pnuemonia?
Inflammation of the intersticium of the lung
What becomes inflamed in interstitial pneumonia?
- Alveolar epithelium
- Pulmonary capillary endothelium
- Basement membrane
- Perivascular and perilymphatic tissues
What is chronic pneumonia?
Inflammation of the lungs that persists for an extended period of time
What common bacteria cause pneumonia?
- Streptococcus pneumoniae
- Haemophilus influenzae
- Klebsiella pneumoniae
What atypical bacteria cause pneumonia?
- Chlamydia pneumophilia
- Mycoplasma pneumoniae
- Legionella pneumophila
What hospital acquired bacteria cause pneumonia?
- Gram negative enteric bacteria
- Pseudomonas
- Staphylococcus aureus
- MRSA
What % of pneumonia is caused by Streptococcus pneumoniae?
30%
What % of pneumonia is caused by Haemophilus influenza?
13%
What % of pneumonia is caused by Chlamydia pneumophilia?
10%
What % of pneumonia is caused by gram negative enteric bacteria?
10%
What are the common respiratory tract pathogens?
- S. pneumoniae
- H. influenza
- Legionella
- Mycoplasma
- S. aureus
- Chlamydia
- Coxiella
- Klebsiella
- S. mirelli
What features are associated with respiratory tract infections caused by S. pneumoniae?
- Elderly
- Co-morbidities
- Acute onset
- High fever
- Pleuritic chest pain
What features are associated with respiratory tract infections caused by H. influenza?
COPD
What features are associated with respiratory tract infections caused by Legionella?
- Recent travel
- Younger patient
- Smoker
- Illness
- Multi-system involvement
What are the features associated with respiratory tract infections caused by Mycoplasma?
- Young
- Prior antibiotics
- Extra-pulmonary involvement
What extra-pulmonary involvement is seen in respiratory tract infections caused by Mycoplasma?
- Haemolysis
- Skin
- Joint
What features are associated with respiratory tract infections caused by S. aureus?
- Post-viral
- Intra-venous drug user
What features are associated with respiratory tract infections caused by Chlamydia?
Contact with birds
What features are associated with respiratory tract infections caused by Coxiella?
Animal contact (sheep)
What features are associated with respiratory tract infections caused by Klebsiella?
- Thrombocytopenia
- Leucopenia
What features are associated with respiratory tract infections caused by S. milleri?
- Dental infections
- Abdominal source
- Aspiration
What can make pneumonia hard to diagnose?
The presentation can be variable
What does pneumonia almost always present with?
- Malaise
- Fever
- Productive cough
What are the characteristics of the sputum in pneumonia?
May be purulent, or rusty coloured (little blood), or stained with lots of blood
What kind of pain commonly present in pneumonia?
Plureitic chest pain
How fast is the onset of pnuemonia?
May be very rapid onset
When is pneumonia likely to have a rapid onset?
When pneumococcal or staphylococcal
What is the prognosis of rapid onset pneumonia?
Can have fatal outcome in short period of time
What are the symptoms of pneumonia?
- Fever
- Chills
- Sweats
- Rigors
- Cough
- Sputum
- Dyspnoea
- Pleuritic chest pain
- Malaise
- Anorexia
- Vomiting
- Headache
- Diarrhoea
- Chest signs
What chest signs are present in pneumonia?
- Bronchial breath sounds
- Crackles
- Wheeze
- Dullness to percussion
- Reduced vocal resonance
What is classified as hospital acquired pneumonia?
Pneumonia occuring 48 hours after hospital admission
What % of hospital acquired infections does pneumonia constitute?
˜15%
Who is hospital acquired pneumonia common in?
Ventilated and post-surgical patients
How can the severity of pneumonia be assessed?
Using the CURB 65 score
How is the CURB 65 score interpreted?
- Presence of two or more of the features is an indiciation for hospital treatment
- Patients with high scoles may require ICU treatment
What does C in CURB represent?
New mental confusion
What does U in CURB represent?
Urea >7mmol/L
What does R in CURB represent?
Respiratory rate >30 per minute
What does B in CURB represent?
Blood pressure - systolic < 90 or diastolic < 60 mmHg
What samples are collected to investigate pneumonia?
- Sputum
- Nose and throat swabs
- Endotracheal aspirates
- Broncho Alveolar Lavage fluid (BAL)
- Open Lung Biopsy
- Blood culture
- Urine
- Serum
When should a blood culture be taken to investigate pneumonia?
Preferably before antibiotics
What is the purpose of a urine sample in the investigation of pneumonia?
Detect the antigens of legionella/pneumococcus
What is the purpose of a serum sample in the investigation of pneumonia?
Antibody detection
What are the microbiological investigations of pneumonia?
- Macroscopic
- Microscopy
- Culture
- PCR
- Antigen detection
- Antibody detection
What aspects of pneumonia can be examined macroscopically?
Sputum, if it is purulent or blood stained
What stains are used to examine pneumonia microscopically?
- Gram staining
- Acid fast
What is being looked for when a culture is grown to investigate pneumonia?
- Bacteria
- Viruses
What can PCR detect when investigating pneumonia?
Respiratory viruses
What can antigen detection detect when investigating pneumonia?
Legionella
What can pathogens infecting immunosuppressed hosts be?
- Virulent infection with common organism
- Infection with opportunistic pathogen
What kinds of opportunistic pathogens can infect immunosupressed hosts?
- Viruses
- Bacteria
- Fungi
- Protozoa
Give an example of an opportunistic virus
Cytomegalovirus (CMV)
Give an example of an opportunistic bacteria
Mycobacterium avium intracellulare
Give 3 examples of opportunistic fungi
- Aspergillus
- Candida
- Pneumocystis jiroveci
Give two examples of opportunistic protozoa
- Cryptosporidia
- Toxoplasma
How is pneumonia managed?
- Oral fluids (IV if severe)
- Anti-pyretic drugs
- Stronger analgesics
- Oxygen
- Antibiotics
What is the purpose of providing fluids in pneumonia?
Avoid dehydration
What is the purpose of anti-pyretic drugs in pneumonia?
Reduce fever and malaise
Give an example of an anti-pyretic drug given in pneumonia
Paracetamol
When is oxygen given in pneumonia?
If there is cyanosis
What antibiotics are given to treat pneumonia?
Varies with the type of pneumonia
What is the target organism when treating community acquired pneumonia?
Normally, Pneumococcus
What is Pneumococcus usually sensitive to?
Penicillin, or related antibiotics
What is the target organism in management of hospital aquired pneumonia?
More likely to be gram -ve
What antibiotic must be used in treating hospital acquired pneumonia?
Antibiotics that cover gram -ve organisms, e.g. IV Co-Amoxiclav
What are the potential outcomes of pneumonia?
- Resolution
- Complications
What happens in resolution of pneumonia?
Organisations and fibrous scarring
What are the potential complications of pneumonia?
- Lung abscess
- Bronchiectasis
- Empyema
What is empyema?
Pus in the pleural cavity
How is pneumonia prevented?
- Immunisation
- Chemoprophylaxis
How is pneumonia immunised against?
- Flu vaccine
- Pneumococcal vaccine
How often is the flu vaccine given?
Annually
Who is the flu vaccine given to?
High risk patients
What does the pneumococcal vaccine consist of?
Two vaccines
What is given in chemoprophylaxis for pneumonia?
Oral penicillin or erythromycin
When is chemoprophylaxis given?
When patients have higher risk of lower respiratory tract infections
What conditions can mean that patients have a higher risk of lower respiratory tract infections?
- Asplenia
- Dysfunctional spleen
- Immunodeficiency