Respiratory Tract Infections Flashcards
What does the term URTI cover?
Sinusitis
Tonsilitis
What does the term LRTI cover?
Bronchitis
Pneumonia
Empyema
Bronchiectasis
Lung abscess
Give 5 ways in which respiratory defences can be compromised
Poor swallow: CVA, muscle weakness
Abnormal ciliary function: Smoking, Kartagener’s
Abnormal mucous: CF
Dilated airways: Bronchiectasis
Defects in host immunity: HIV, Drugs
What is the abnormality seen here?
Double heart border “Sail sign”
Left lower lobe collapse
What is seen on CT here?
Densely consolidated + collapsed left lower lobe
18F
Left lower lobe pneumonia
Unwell
Raised WCC + CRP
What is the likely organism?
A. Pseudomonas aeruginosa
B. Mycobacterium tuberculosis
C. Legionella pneumophilia
D. Streptococcus pneumoniae
E. Staphylococcus aureus
D. Streptococcus pneumoniae
30-50% of CAP
Give 3 features of streptococcus pneumoniae under microscope
Gram +ve cocci (pairs + chains)
Alpha haemolytic
Optochin sensitive
List 4 symptoms/ signs of S. pneumoniae
Acute onset
Severe pneumonia
Fever, rigors
Lobar consolidation
What is S. pneumoniae almost always sensitive to?
Penicillin
What is pneumonia? How sick are patients generally?
Inflammation of lung alveoli
Community acquired or Hospital acquired
5-10% Mortality
20-40% admitted to hospital
Give 5 common signs/ symptoms of pneumonia
Fever
Cough +/- sputum
SOB
Pleuritic chest pain
Often localising signs + abnormal CXR
List 4 factors to consider when assessing possibility of pneumonia
Pre-existing lung disease
Immunocompromised
Travel, seasons, epidemics
Exposure to animals
List the 5 main causative organisms of CAP
Streptococcus pneumoniae
Staphylococcus aureus
Haemophilus influenzae
Moraxella catarrhalis
Klebsiella pneumoniae
How does age influence susceptibility to different causative organisms for CAP?
0-1m: E. coli, GBS, Listeria monocytogenes
1-6m: Chlamydia trachomatis, S aureus, RSV
6m-5y: M pneumoniae, Influenza
16-30: M pneumoniae, S pneumoniae
What are the typical causes of CAP? How many cases do they account for?
S pneumoniae
H influenza
85%
What 4 atypical organisms must be accounted for when treating CAP? Give a feature or exposure associated with each
Legionella: water exposure, A/C
Mycoplasma: barking cough, normal CXR
Coxiella burnetii (Q-fever): farm animals
Chlamydia psittaci: bird exposure
Give 7 signs that may be found on examination in a patient with CAP
Pyrexia
Tachycardia
Tachypnoea
Cyanosis
Dullness to percussion, tactile vocal fremitus
Bronchial breathing
Crackles
What investigations should be sent when suspecting CAP?
FBC, U+Es, CRP
BC, Sputum MC+S
ABG
CXR
Urinary antigen: legionella + s aureus
What is the CURB-65 score designed for?
Predicting mortality of CAP
Score 2: ?Admit
Score 2-5: Manage as severe
What are the elements of the CURB-65 score?
Confusion
Urea >7 mmol/l
RR >30
BP <90 sys, <60 dia
>65y
What is bronchitis? Which patients is it mostly seen in?
Inflammation of medium sized airways
Smokers
List 4 signs/ symptoms of bronchitis
Cough
Fever
Increased sputum production
Increased SOB
How does bronchitis appear on CXR?
Normal
List 4 organisms causative of bronchitis
Viruses
S pneumoniae
H influenzae
M catarrhalis
What is the treatment for bronchitis?
Bronchodilation
Physiotherapy
+/- Abx
What can be seen here?
Cavitation on LHS
56M
Left lower lobe pneumonia
Haemoptysis
Cavitation on CXR
What organism would you suspect?
A. S pneumoniae
B. H influenzae
C. S aureus
D. Klebsiella pneumoniae
B. H influenzae
Give 3 features of H influenzae under the microscope
Gram -ve Cocco-bacilli
Stain on Chocolate agar
May produce B-lactamase
Give 2 epidemiological features of H influenzae
15-35% CAP
More common with pre-existing lung disease
What is seen here?
Bilateral interstitial change
62M smoker
SOB
Confused
Bilateral interstitial change
Hyponatraemic
What is the likely organism?
A. Moraxella catarrhalis
B. Mycobacterium tuberculosis
C. Legionella pneumophilia
D. Cytomegalovirus
E. Staphylococcus aureus
C. Legionella pneumophilia
What similarity to atypical organisms share?
No cell wall
thus cell-wall active abx e.g. penicillin ineffective
Often extra pulmonary features e.g. hepatitis, low Na
How is legionella transmitted? What culture is required to grow it on?
Inhalation of infected water droplets e.g. A/C, fountain
Buffered charcoal yeast extract agar
What agents are required to treat atypical pneumonias?
Targeting protein synthesis:
Macrolides e.g. Clarithromycin, Erythromycin
Tetracyclines e.g. Doxycycline
Atypical organisms account for … CAP? How do they usually arise?
20%
Flu-like prodrome before fever + pneumonia
Give 4 symptoms/ manifestations of legionella pneumophila pneumonia
Confusion
Abdo pain
Diarrhoea
Multi-organ failure
What blood results are associated with legionella pneumophila pneumonia?
Hyponatraemia
Lymphopenia
What investigations should be sent for legionella pneumophila pneumonia?
Legionella urinary antigen
Sputum/ blood sample
In which organisms is Coxiella burnetii common? How is Coxiella burnetii transmitted?
Domestic/ farm animals
Aerosol/ milk transmission
How is Coxiella burnetii pneumonia and Chlamydia psittaci pneumonia diagnosed?
Serology
In which organisms is Chlamydia psittaci common? How is Chlamydia psittaci transmitted?
Birds
Inhalation
What can be seen here?
Homogenous shadowing/ shadowing with meniscus level on RHS
74F
SOB, fever, right sided pleuritic chest pain
Reduced percussion note + decreased air entry right base
Right lower lobe pneumonia
On standard abx
Not improving
What is the probable diagnosis?
A. TB
B. Empyema
C. Mesothelioma
D. MRSA pneumonia
E. Aspiration pneumonia
B. Empyema
What can be seen here?
Large empyema with collapsed lung underneath
Why are empyemas difficult to treat?
Wall around them + pus itself is very acidotic which inactivates abx
What 7 reasons may explain why a pneumonia is failing to improve with treatment?
Empyema/ abscess
Proximal obstruction: tumour
Resistant organism, inc. TB
Not receiving/ absorbing abx
Immunosuppression
Lung cancer
Cryptogenic organising pneumonia
Describe the radiograph. What is this characteristic of?
Patchy to speckled infiltration
Ground glass appearances
SARS-CoV-2
What can be seen here?
RHS apical shadowing
21M from Ecuador
Cough and weight loss
RUZ shadowing on CXR
What is the causative organism?
A. S aureus
B. Aspergillus fumigatus
C. Mycobacterium tuberculosis
D. H influenzae
E. Pneumocystis jiroveci
C. Mycobacterium tuberculosis
Why is TB sometimes referred to as “the White Plague”?
Sometimes there is a complete “white out” of chest on CXR
Give 5 clues that suggest TB
Ethnicity
Prolonged prodrome
Fevers +/- Night sweats
Weight loss
Haemopytsis
What is commonly found on CXR in TB?
Upper lobe cavitation
(can vary- abscess, miliary seeding pattern)
What staining is used to identify TB?
Auramine stain
Ziehl-Neelsen stain
What can be seen here?
Smear +ve ZN stain
TB = red rods
Acid fast bacilli
What is hospital acquired pneumonia? What investigation is desirable?
Pneumonia onset >48h in hospital
Often previous abx +/- ventilator
Bronchial lavage to differentiate upper respiratory from lower respiratory flora
List 3 main causes of HAP
31%: Enterobacteriaciae e.g. E. coli, K. pneumoniae
19%: S. aureus
17%: Pseudomonas spp
64M
Treated for LN TB
Increasing SOB over 1m
Non-productive cough
Bilateral ground-glass shadowing
What is the likely organism?
A. Aspergillus fumigatus
B. H1N1 Swine flu
C. Mycoplasma pneumoniae
D. Cytomegalovirus (CMV)
E. Pneumocystis jiroveci
E. Pneumocystis jiroveci
What can be seen here?
Bilateral ground glass shadowing
Give 2 facts about Pneumocystis jirovecii
Protozoan
Ubiquitous in environment
Give 5 features of Pneumocystis jirovecii presentation
Insidious onset
Dry cough
Weight loss
SOB
Malaise
What is the classic CXR finding of Pneumocystis jirovecii?
“Bat’s wing”
Bilateral ground glass shadowing
What investigation and treatment is needed for Pneumocystis jirovecii?
Ix: Immunofluorescnece on BAL
Rx: Septrin (Co-trimoxazole)
What is the walking test suggestive of Pneumocystis jirovecii?
attaching O2 sats probe + asking patient to walk will show desaturation on exertion
What prophylaxis should those on immunosuppressants take against Pneumocystis jirovecii?
Septrin
22M
Chemo for leukaemia
Prolonged neutropenia <1.0
Ongoing fevers
Abx failed
Interstitial change on CT
What is the likely organism?
A. MRSA
B. Aspergillus
C. Tuberculosis
D. CMV
E. Drug reaction
B. Aspergillus
What can be seen on this CT?
Interstitial changes
What are the 3 types of aspergillus?
Allergic bronchopulmonary aspergillosis
Aspergilloma
Invasive aspergillosis
Give 3 features of allergic bronchopulmonary aspergillosis
Chronic wheeze
Bronchiectasis
Eosinophilia
Give 2 features of Aspergilloma
Aspergilloma fungal ball in pre-existing cavity (often from TB)
May cause Haemoptysis
Which patients are susceptible to invasive aspergillosis? What treatment is required?
Immunocompromised
Rx: Amphotericin B
Which LRTIs are HIV patients particularly susceptible to?
PCP
TB
Atypical mycobacteria
Which LRTIs are neutropenic patients particularly susceptible to?
Fungi e.g. Aspergillus spp
Which LRTIs are bone marrow transplant patients particularly susceptible to?
CMV
Which LRTIs are splenectomy patients particularly susceptible to?
Encapsulated organisms:
S. pneumoniae
H. influenzae
Malaria
What samples should ideally be sent prior to antibiotics administration?
Sputum/ induced sputum
Blood cultures
For which species are urine antigen tests available?
S. pneumoniae
Legionella pneumophila
When are antibody tests useful in respiratory tract infections?
In organisms difficult to culture e.g. Chlamydia + Legionella
Only useful in paired serum samples e.g. at presentation + 14d later
Look for rise in antibody over time
What is the empirical therapy for mild-moderate CAP?
Amoxicillin
Or erythromycin/ clarithromycin
What is the empirical therapy for moderate-severe CAP?
Needing admission: Augmentin (co-amoxiclav) + Clarithromycin
Allergic: Cefuroxime + Clarithromycin
What is the empirical therapy for HAP?
1st: Ciprofloxacin +/- Vancomycin
2nd/ ITU: Piptazobactam + Vancomycin
What specific therapy is used for MRSA HAP?
Vancomycin
What specific therapy is used for pseudomonas HAP?
Piptazobactam or Ciprofloxacin
+/- Gentamicin
What can be recommended to prevent pneumonia?
Smoking cessation
Vaccination: Flu, pneumovax, COVID-19
