Respiratory Tract Infection Flashcards
Types of microorganism pathogenicity
Primary
Facultative
Opportunistic
What is primary pathogenicity?
If the microorganisms infect everybody
What is facultative pathogenicity?
Need a bit of help - predisposing conditions
What determines the capacity to resist infection?
Stage of host defence mechanisms
Age of patient
Is the upper respiratory tract sterile?
No
Is the lower respiratory tract sterile?
Yes
What does resistance to organisms decrease with?
Age
Examples of URTIs
Coryza Sore throat syndrome Acute laryngotracheobronchitis Laryngitis Sinusitis Acute epiglottitis
What is coryza?
Common cold
Another name for acute layrngotracheobornchitis
Croup
Who gets acute epiglottitis?
Young children
Causative organism of acute epiglottitis
Group A beta haemolytic streptococci
Haemophilus influenzae type b (Hib)
Examples of LRTIs
Bronchitis
Bronchiolitis
Pneumonia
Respiratory tract defence mechanisms
Macrophage mucociliary escalator system - alveolar macrophages - mucociliary escalator - cough reflex - particle clearance from lungs General immune system (humoral and cellular) Respiratory tract secretions Upper resp tract acts as filter - nose hair - warms and humidifies air
Other exit routes for macrophages
Alveolar wall into lymphatic system
When can the mucosal ciliary escalator fail? What may this result in?
During viral infections
Viruses / foreign bodies retained in the lungs
What is a common reason to get bacterial lung infections?
Virus infections damage the epithelium and cause damage to the mucosal ciliary escalator
Aetiological classification of pneumonia
Community acquired Hospital acquired (nosocomial) Pneumonia in the immunocompromised Atypical Aspiration Recurrent
What is atypical pneumonia?
Pneumonia caused by unusual infectious agents
Patterns of pneumonia
Bronchopneumonia Segmental Lobar Hypostatic Aspiration Obstruction
What is bronchopneumonia?
Acute inflammation of the walls of the bronchi with adjacent bits of lung infected
What is segmental pneumonia?
Segment of the lung
What is lobar pneumonia?
Affects a lobe of the lung
What is hypostatic pneumonia?
Patient lots of accumulation of secreted fluid - usually due to bronchitis producing mucus or cardiac failure
What does bronchopneumonia look like on CXR?
Bilateral basal patchy opacification - relating to the focal nature of consolidation
Complications of pneumonia
Pleurisy Pleural effusion Empyema Mass lesion COP Constrictive bronchiolitis Lung abscess Bronchiectasis
What is pleural effusion?
Fluid in pleural space
What is COP?
Cryptogenic organising pneumonia (BOOP)
What is bronchiectasis?
Pathological dilatation of the bronchi
Causes of bronchiectasis
Severe infective episode
Recurrent infections
Proximal bronchial obstruction
Lung parenchymal destruction
What % of bronchiectasis starts in childhood?
75%
Presentation of bronchiectasis
Cough
Abundant purulent foul sputum
Haemoptysis
Signs of chronic infection
Signs of bronchiectasis
Coarse crackles
Clubbing
Ix of bronchiectasis
CT
Treatment of bronchiectasis
Postural drainage
Antibiotics
Surgery
Causes of aspiration pneumonia
Vomiting Oesophageal lesion Obstetric anaesthesia Neuromuscular disorders Sedation
Possible causes of recurrent lung infection
Local bronchial obstruction (tumour/foreign body)
Local pulmonary damage (e.g. bronchiectasis)
Generalised lung disease (CF or COPD)
Non resp disease (immunocompromised / aspiration etc)
Types of organisms causing opportunistic infections
Low grade bacterial pathogens
CMV
Pneumocystitis jirovecci
Fungi and yeasts
Air flow in airways
Bulk flow
- laminar (parallel)
- turbulent (irregular)
What happens beyond the terminal bronchiole?
Diffusion
Normal PaO2
10.5 - 13.4 kPa
Normal PaCO2
4.8 - 6.0 kPa
Types of respiratory failure
Type 1
Type 2
Type I resp failure
PaO2 < 8kPa
Pa CO2 normal or low
Type II resp failure
PaCO2 > 6.5kPa
Pa02 usually low
What are the 4 abnormal states associated with hypoxaemia?
Ventilation / perfusion imbalance (V/Q)
Diffusion impairment
Alveolar hypoventilation
Shunt
Pulmonary vascular changes in hypoxia
Physiological pulmonary arteriolar vasoconstriction
Pathology of pneumonia causing hypoxaemia
Ventilation/perfusion abnormality (mismatch)
- some ventilation of abnormal alveoli, but not enough
Shunt
- severe bronchopneumonia
- no ventilation of abnormal alveoli
- blood passing from R to L shunt of heart without contacting ventilated alveoli
When do pathological shunts occur?
AV malformations
Congenital heart disease
Pulmonary disease
Pathology of COPD causing hypoxaemia
Ventilation perfusion abnormality - airway obstruction
Alveolar hypoventilation
- reduced resp drive
- entire lung volume not being ventilated well
- increased PaCO2
Diffusion impairment - loss of alveolar surface area
Shunt
- only during acute exacerbation
- area of lung tissue that is completely airless which has no ventilation to it because the lung is either obstructed or consolidated
The concentration of CO2 and H in where makes us breath in and out?
CSF
COPD patients effect on their respiratory drive
Patients who live in a chronic hypoxic situation despite the best efforts of the kidney means the respiratory centre loses the drive from the CO2 and the H ions
Patients with COPD rely on hypoxia to give them more of a resp drive (therefore have to manage how much oxygen you give them)
What is cor pulmonale?
Right sided heart failure due to pulmonary HTN
Pathology of cor pulmonale
Pulmonary vasoconstriction Pulmonary arteriole muscle hypertrophy intimal fibrosis Loss of capillary bed Secondary polycythaemia Bronchopulmonary arterial anastomoses Chronic - hypertrophy of R ventricle
Examples of URTIs in children
Rhinitis Tonsillitis Otitis media Pharyngitis Tacheitis / LTB Laryngitis Epiglottitis
Viral infective agents causing URTIs in children
Adenovirus Influenza A and B Para flu I, III RSV Rhinovirus
What does RSV stand for?
Respiratory syncytial virus
Bacterial causes of URTIs in children
H influenzae M catarrhalis Mycoplasma S aureus Streptococci - B haemolytic - S pygoenes - non haemolytic S pneumoniae
What is rhinitis?
Inflammation of mucous membrane inside nose
When does rhinitis occur?
Winter months
Is rhinitis self limiting?
Yes
What can rhinitis be a prodrome for?
Pneumonia
Bronchiolitis
Meningitis
Septicaemia
What is otitis media?
Ear infection
Presentation of otitis media
Bulging drum
Pain
Is otitis media self limiting?
Yes
Causes of otitis media
Primary viral infection
Secondary infection
- pneumococcus
- H flu
What can otitis media lead to?
Spontaneous rupture of drum
When should otitis media be treated?
Severe uni and bilateral > 6 months
Severe pain > 48 hours
Treatment of otitis media
ANALGESIA
Investigations of tonsillitis/pharyngitis
Throat swab
Treatment of tonsillitis/pharyngitis
Nothing
10 days penicillin
What must NOT be given in tonsillitis?
Amoxicillin
Causative organism of Croup/LTB
Para influenza I
Presentation of croup
Coryza Stridor Hoarse voice Barking cough Very well
Treatment of croup
Oral dexamethasone
Causative organism of epiglottis
H influenzae type B
How common is epiglottitis?
Rare
Presentation of epiglottitis
Stridor
Drooling
Treatment of epiglottitis
Intubation
Antibiotics
What % of URTIs in children are self limiting?
> 99%
What are the lower resp tract infections in children?
Pneumonia Tracheitis Bronchitis Empyema Bronchiolitis
Common infective agents of LRTI in children
Strep pneumoniae H influenzae Moraxella catarrhalis Mycoplasma pneumoniae Chlamydia pneumonia RSV Para influenzae III influenzae A and B Adenovirus
Presentation of tracheitis
"Croup which doesn't get better" Fever Sick child Off food Lethargic
Causative organisms of tracheitis
Staph
Strep
Treatment of tracheitis
Augmentin
How common is bronchitis?
Very very common
Mostly self limiting
Presentation of bronchitis
Loose rattly cough with URTI
Post tussive vomit (glut = mucous stuff)
Chest free of wheeze / creps
Child very well
Causative organisms of bronchitis
Haemophilus
Pneumococcus
What is bronchitis an infection of?
Endobronchium
Pathology of bacterial bronchitis
Disturbed mucociliary clearance 1. minor airway malacia 2. RSV/adenovirus Lack of social inhibition Infection secondary (so no Ax)
How long does bronchitis last for?
4 weeks
What does bronchitis follow?
URTI
Criteria for persistent bacterial bronchitis
Wet cough
More than one month
Remission with Ax
What kind of diagnosis is bronchiolitis?
Clinical
What is bronchiolitis?
LRTI of infants
What % of infants get bronchiolitis?
30 - 40%
Causative organisms of bronchiolitis
RSV
Others
- paraflu III
- HMPV
What does RSV stand for?
Respiratory sinsitium virus
Presentation of bronchiolitis
Nasal stuffiness
Tachypnoea
Poor feeding
Crackles +/- wheeze
Does bronchiolitis have a predictive history?
YES
Who gets bronchiolitis?
< 12 months old
Is bronchiolitis recurrent?
NO
What day after the start of cough does bronchiolitis start to stabilise?
Day 5 - 7
How long does the whole illness of bronchiolitis last?
2 weeks
Management of bronchiolitis
Maximal observation
Minimal intervention
Investigations of bronchiolitis
NPA (cohorting)
Oxygen sats
Treatment for bronchiolitis
NONE
Oxygen
What does NPA stand for?
Naso pharyngeal aspirate
What does O2 sats in bronchiolitis indicate?
Severity
Presentation of a LRTI
48 hours > 38.5 degrees temp SOB Cough Grunting Reduced or bronchial breathing sounds
Wheeze indicates what is UNLIKELY?
A bacterial cause
Does bronchiolitis cause fever?
NO
Call the LRTI pneumonia if…..
- Signs are focal
- Creps (fine crackles)
- High fever
How to confirm diagnosis of LRTI/Pneumonia
CXR
Management of community acquired pneumonia in children
Nothing if symptoms are mild
Oral amoxycillin first line
Oral macrolide second line
IV if comiting
Do you treat bronchiolitis with Ax?
NO
Do you treat croup with Ax?
NO
Do you treat acute LRTI with Ax?
Often not indicated
Amoxicillin first line if are treated
Do you treat otitis media with Ax?
Not usually indicated
Consider amoxicillin if
- < 2 y/o
- bilateral infection
Do you treat pharyngitis/tonsillitis with Ax?
Not indicated usually
Can consider penicillin
What is the other name for pertussis?
Whooping cough
What reduces the risk and severity of pertussis?
Vaccination
Presentation of pertussis
Coughing fits
Vomiting
Colour change
What is empyema a complication of?
Pneumonia
What is empyema?
Extension of the infection into the pleural space
Presentation of empyema
Chest pain
Very unwell
Treatment of empyema
IV Antibiotics
Drainage
Do children with empyema have a good prognosis?
Yes
What organism commonly creates a cavitating pneumonia in the upper lobes, particularly in DM and alcoholics and may also be caused by aspiration?
Klebsiella pneumoniae
Features of pneumoniae caused by legionella
Dry cough
Atypical chest signs
Hyponatraemia
Lymphopenia
Causative organism of pneumonia following influenza
Staph aureus
Who is pneumonia caused by pneumocystitis jiroveci seen in?
HIV patients
Which organism accounts for 80% of pneumonia cases?
Strep pneumonia
Features of strep pneumoniae
High fever
Rapid onset
Herpes labialis
Is there a vaccine against step pneumoniae?
Yes - pneumococcus
What type of pneumonia particularly occurs in patients with COPD?
Haemophilus influenzae
Give an example of an atypical pneumonia
Mycoplasma pneumoniae
Presentation of mycoplasma pneumoniae
Dry cough
Atypical chest signs / Xray findings
Autoimmune haemolytic anaemia
Erythema multiforme
Presentation of PJP
Dry cough
Exercise induced desaturations
Absence of chest signs
What is idiopathic interstitial pneumonia? Give an example
A group of non infective causes of pneumonia
Examples include cryptogenic organising pneumoniae
What is cryptogenic organising pneumoniae?
A form of bronchiolitis which may develop as a complication of RA or amiodarone therapy
Presentation of pneumonia
Cough Sputum SOB Chest pain; may be pleuritic Fever Signs of SIRS Reduced O2 sats Reduced breath sounds / bronchial breathing
What is the classical Xray finding of pneumonia?
Consolidation
What is the risk stratification score called used for patients with community acquired pneumonia?
CURB-65
What are the parts of CURB-65?
C = confusion U = urea > 7 R = Resp rate > 30 B = BP < 90/<60 65 = Age > 65
Management of patient with a CURB 65 score of 0
Should be managed in the community
Management of a patient with a CURB 65 score of 1
Can be managed in community if sats > 92% and a CXR done
Hospital admission advised if on CXR - bilateral/multilobular shadowing
Management of a patient with a CURB 65 score of 2
Management in hospital as this indicates a severe community acquired pneumonia
What is ARDS caused by?
Increased permeability of alveolar capillaries leading to fluid accumulation in the alveoli i.e. non cardiogenic pulmonary oedema
Mortality of ARDS
40%
Causes of ARDS
Infection; sepsis, pneumonia Massive blood transfusion Trauma Smoke inhalation Acute pancreatitis Cardio pulmonary bypass
Presentation of ARDS
Acute onset and severe SOB Elevated RR Bilateral lung crackles Low O2 sats
Key investigations for ARDS
CXR
Blood gas
Management of ARDS
Oxygen
General organ support e.g. vasopressors as needed
Treat underlying cause
What is the centor criteria involved with?
Sore throat
If 3 or more of the criteria is present, 40 - 60% chance the sore throat is caused by Group A beta haemolytic streptococcus
Parts of the centor criteria
Presence of tonsillar exudate
Tender anterior cervical lymphadenopathy or lymphadenitis
History of fever
Absence of cough
NICE guidelines on timeline of treatment and recovery of Community acquired pneumonia
Week 1 - fever should resolve
Week 4 - chest pain and sputum should have significantly reduced
Week 6 - cough and SOB should have significantly reduced
Month 3 - most symptoms should have resolved, except from tiredness
Month 6 - should be returned to normal
Only indication for surgery in bronchiectasis
Localised disease on CT
When should you consider granulomatosis with polyangiitis (wegeners)?
When a patient presents with ENT, resp and renal involvement