Respiratory Tract Infections Flashcards
What are the URTIs?
o Sinusitis
o Tonsillitis
What are the LRTIs?
Bronchitis
Pneumonia
Empyema
Bronchiectasis
Lung abscess
What effects on the body does respiratory defence compromise have?
· 18yo female; fever, cough and malaise
· Diagnosed with flu by GP (no ABx given)
· Attended A&E with…
o T 38C 87% sats on room air
o Chest clear, RR 24 Bloods (WCC 40.8, Neut 36.3, CRP 63)
What investigations wold you do?
o CXR double heart border (‘Sail’ sign)
o CT densely consolidated and collapsed lower lobe
o CXR double heart border (‘Sail’ sign)
o CT densely consolidated and collapsed lower lobe
Diagnosis?
LL pneumonia
What is streptococcus pneumonia?
o Alpha-haemolytic and optochin-sensitive
o Gram-positive cocci (chains and pairs)
o 30-50% of CAP
o Acute onset
§ Severe pneumonia Fever and rigors Lobar consolidation
o Almost always penicillin-sensitive
o Penicillin-resistance strains may be imported from Southern Europe
What is pneumonia?
inflammation of the lung alveoli
What is the presentation of pneumonia?
Fever
Cough
Abnormal CXR
Pleuritic chest pain
SoB
What are the types of pneumonia?
§ Community-acquired
§ Hospital-acquired/nosocomial (i.e. ventilator-associated)
What underlying factors contribute to pneumonia?
§ Pre-existing lung disease
Immunocompromise
§ Geography, seasons, epidemics
Travel, exposure to animals
What causes CAP?
· Streptococcus pneumoniae
· Haemophilus influenzae
· Moraxella catarrhalis
· Staphylococcus aureus
· Klebsiella pneumoniae
Which pathogens affect which agre group?
What are the cauess of CAP?
· TYPICAL (85%)
o Streptococcus pneumoniae
o Haemophilus influenzae
· ATYPICAL (15%)
o Legionella
o Mycoplasma
o Coxiella burnetii (Q fever) from exposure to farm animals
§ Hepatitis
o Chlamydia psittaci (Psittacosis) from exposure to birds
§ Splenomegaly, rash, haemolytic anaemia
What are the clinical features of CAP?
§ Symptoms:
· SoB Cough ± sputum Fever
· Rigors Pleuritic chest pain Malaise, N&V
§ Examination:
· Pyrexia Tachycardia Tachypnoea
· Cyanosis Bronchial breathing Crackles
· Dullness to percussion/tactile vocal fremitu
What Ix should you do for CAP?
· FBC, U&E, CRP BCs, Sputum MC&S
· ABGs CXR
What is the CURB 65?
· Confusion
· Urea > 7 mmol/L
· RR > 30
· BP < 90 systolic, < 60 diastolic
· 65+ years
2 = consider admitting
2-5 = manage as severe / consider ITU
What is bronchitis?
inflammation of medium-sized airways
What is the presentation of bronchitis?
§ Cough
§ Fever
§ Increased sputum production
§ Increased shortness of breath
CXR is usually NORMAL
What organisms cause bronchitis?
§ Viruses
§ Streptococcus pneumoniae
§ Haemophilus influenzae
§ Moraxella catarrhalis
What is the treatment of bronchitis?
§ Bronchodilation
§ Physiotherapy
§ Antibiotics
· 56yo man; flu-like illness
· Presented with cough, fever, haemoptysis, pyrexia (but not severely unwell)
CXR shows cavitation
Differentials?
o Staphylococcus aureus
o Klebsiella pneumoniae
o Haemophilus influenzae
o TB
What is H influenzae?
o Gram-negative cocco-bacilli (stain on chocolate agar)
o 15-35% of CAP
o More common with pre-existing lung disease
o May produce beta-lactamase
· 62yo man; SOB
· Confusion, smoker, 91% saturation on room air, chest exam normal, hyponatraemia
· CXR showed bilateral interstitial change
Ddx?
§ Mycoplasma
Legionella
§ Chlamydia
Coxiella
What is Legionella?
o Spread via inhalation of infected water droplets
o It is grown on a buffered charcoal yeast extract
o Can cause multi-organ failure
Which antibioitcs are used for atypicals?
Protein synthesis inhibitors:
§ Macrolides (clarithromycin/erythromycin)
§ Tetracyclines (doxycycline)
o Extra-pulmonary features (e.g. hepatitis, hyponatraemia) – characteristic of atypical pneumonias
o Account for 20% of CAP
o Often have a flu-like prodrome before fever and pneumonia
o Extra-pulmonary features (e.g. hepatitis, hyponatraemia) – characteristic of atypical pneumonias
o Account for 20% of CAP
o Often have a flu-like prodrome before fever and pneumonia
What is legionella?
o Aerosol spread and associated with environmental outbreaks
o Associated with:
§ Confusion Abdominal pain Diarrhoea
§ Lymphopaenia Hyponatraemia
o Investigation: urinary antigens
o Sensitive to macrolides
What is coxiella?
o Common in domesticated farm animals
o Transmitted by aerosol or milk
o Investigation: serology
o Sensitive to macrolides
What is Chlamydia?
o Spread from birds by inhalation
o Investigation: serology
o Sensitive to macrolides
Why might empyema not improve?
Failure to improve on treatment:
o Empyema/abscess Proximal obstruction (tumour)
o Resistant organisms (travel hx) Not receiving/absorbing antibiotics
o Immunosuppression Other diagnosis (lung cancer, cryptogenic organising pneumonia
How is TB diagnosed?
o Clues -> Ethnicity, Prolonged prodrome, Fevers, Weight loss, Haemoptysis
o CXR -> classically upper lobe cavitation (but can vary)
o Staining:
§ An auramine stain and a Ziehl-Neelsen stain will be done
§ Red rods are the acid-fast bacilli
What is HAP?
o A pneumonia onset >48 hours in hospital
o Patients have often had previous antibiotics and maybe even ventilation
o Bronchial lavage is desirable (differentiate upper respiratory from lower respiratory flora)
o Aetiology of HAP
§ Enterobacteriaciae (e.g. E. coli, K. pneumoniae) – 31% Staphylococcus aureus – 19%
§ Pseudomonas spp – 17% Haemophilus influenzae – 5%
§ Acinetobacter baumanii – 4% Fungi (Candida spp) – 7%
What would pneumocystis pneumonia cause on CXR?
bilateral ground-glass shadowing (“bat’s wing”)
What is Pneumocystic Jirovecii?
o Protozoan
o Ubiquitous in the environment
o Insidious onset
§ Dry cough Weight loss
§ SOB Malaise
How do you manage Pneumocystis pneumonia?
· Investigations: bronchoalveolar lavage
· Treatment: co-trimoxazole (septrin)
· Prophylaxis: co-trimoxazol
What can aspergillus cause?
o Allergic bronchopulmonary aspergillosis
§ Chronic wheeze
§ Eosinophilia
§ Bronchiectasis
o Aspergilloma
§ Fungal ball, often in pre-existing cavity
§ May cause haemoptysis
o Invasive aspergillosis
§ Immunocompromised
§ Treatment: amphotericin B
What LRTIs can different immnosuppressed groups get?
How do you diagnose LRTIs?
o Sputum/induced sputum Blood cultures BAL
o Pleural fluid Antigen tests Antibody tests
o Immunofluorescence PCR
o Antigen Tests
§ Limited urine antigen tests available for: Legionella pneumophila Streptococcus pneumoniae
§ Send in severe CAP
What are antibody tests?
§ Only useful on paired serum samples (one acutely unwell and another when getting better)
· Usually collected on presentation and 10-14 days later
§ Looks for a rise in antibody level over time
§ Most useful organisms to send antibody tests for because they are difficult to culture:
· Chlamydia Legionella
What is immunofluorescence?
§ Antibody is labelled with fluorescent dye
§ Often used in virology
§ PCP immunofluorescence is the most commonly used one in microbiology labs
§ PCP may also be detected by Silver stain in cytology labs
How do you treat CAPs?
§ Mild-Moderate: Amoxicillin [OR erythromycin/clarithromycin]
§ Moderate-Severe
· Needing hospital admission: Co-amoxiclav (augmentin) AND clarithromycin
· Allergic: Cefuroxime AND clarithromycin
How do you treat HAPs?
§ 1st Line -> Ciprofloxacin ± vancomycin
§ 2nd Line/ITU -> Piptazobactam AND vancomycin
§ Specific Therapy:
· MRSA: Vancomycin
· Pseudomonas: Piptazobactam OR ciprofloxacin ± gentamicin
What is the treatment of general pneumonia?
o Cefuroxime and clarithromycin (hypotensive -> query allergic)
o Fluid resuscitation
o Supplemental O2
o Senior support requested
How can you prevent pneumonia?
o Smoking cessation
o Vaccination:
§ Childhood immunisation schedule
§ Adults -> influenza annually, pnemovax every 5 years
