3+ Pneumonia Flashcards
What is CAP?
Infection of the lung parenchyma not acquired in a hospital setting
Is it more normal that not to find more than one pathogen is implicated in CAP?
Yes
What are the typical bacterial causes of CAP?
S.pneumoniae
Haemophilus influenzae
Moraxella catarrhalis
Klebsiella pneumoniae
Enteric/oral anaerobes
S.aureus
What are the atypical bacterial causes of CAP?
Mycoplasma pneumoniae
Chlamydophila pneumoniae
Legionella pneumophila
Coxiella burnetti
What are some viral causes of CAP?
SARS-COV2
Influenza
Parainfluenza
RSV
Metapneumovirus
What are some fungal causes of CAP?
Cryptococcus neoformans
Aspergillus spp.
Pneumocystis jirovecii
Who is most likely to get a fungal CAP?
Immunocompromised patients
What are some unusual bugs to be aware of if people have travelled?
Acinetobacter in tropics
Meliodosis in tropics
Histoplasmosis in central america and southern USA
TB
Chlamydia psittaci
Coxiella brunetti
Leptospirosis
What are some risk factors for CAP?
Chronic lung disease (COPD, asthma)
Chronic heart failure
Smoking
Diabetes
Chronic kidney or liver disease
Recent viral infection
Contact with young children
Alcoholism (aspiration)
Institutiionalisation
Age >70
What are some risk factors for gram-negatives?
Dementia
CVD
Alcoholism
What are some risk factors for MRSA?
Being an indigenous australian
Alcoholism
prison
Men who sleep with men
What is the pathogenesis of pneumonia?
Microbes access the lower respiratory tract:
- Aspiration
- Inhalation of droplets
- Haematogenous spread
Proliferate within the alveoli (not cleared by MAC and surfactant)
When microbes overwhelm the immune system –> inflammatory response –> white cell migration (pus), leaky membranes (fluid filled alveoli) –> reduced oxygenation
What is the histological appearance of alveoli in pneumonia?
- Congested capillaries in alveolar septa
- Inflammatory cells in RBC fill alveolar spaces
What is the typical history of pneumonia?
Sudden onset
- Fever
- Chills/rigors
- Dyspnoea
- Cough: productive or unproductive, can have haemoptysis
- Pleuritic chest pain
- Exercise intolerance
- Fatigue
What is the atypical history of pneumonia?
- Low grade fever
- Non-productive dry cough
- Dyspnoea
Extra-pulmonary features:
- Myalgia
- Arthralgia
- Headache
- GI: diarrhoea, vomiting (influenza)
What signs may be evident on examination of a patient with pneumonia?
Tachycardia
Hypotensive
Febrile
Low O2 sats
Resp distress: tachypnoea, dyspnoea, nasal flaring, accessory muscle use
Decreased air entry
Crackles, bronchial breath sounds
Dullness to percussion
What Ix do you do for pneumonia?
Bedside:
- ECG if chest pain
- Spirometry to rule out obstructive disease
Labs:
- FBC
- CRP
- UEC, LFTs, BSL
- ABG if CO2 retainer (COPD, smoker)
Imaging:
- CXR: show consolidation
- Only do CT if CXR inconclusive or recurrent infections
Micro:
- Blood culture + sputum MCS if sick, failed antibiotics, risk factors fo antibiotic resistant pathogens
- Serological testing if concerned for atypical pneumonia
- Sputum PCR if pneumocystis risk
- Legionella urinary antigen
What are some severity scales you can use?
CURB-65
Pneumonia Severity Index (PSI)
What is CURB-65?
Confused
Urea elevated
RR elevated
BP low
Age >65
What is the DDx for pneumonia?
CHF
COPD exacerbation
Asthma exacerbation
PE
Pneumothorax
Acute bronchitis
What is the overall management of CAP as inpatient?
- O2 if hypoxic
- Fluids if needed
- Electrolytes if disturbance
- Analgesia
- Bronchodilators if asthma
- VTE thromboprophylaxis
- Antibiotics
What antibiotics are first line for CAP?
If suspect S.pneumoniae: amoxicillin or ceftriaxone
If suspect legionella, mycoplasma or chlamydia (atypical): macrolide like azithromycin
Summary:
- Beta lactam: amoxicillin or ceftriaxone
OR
- Macrolide: azithromycin
When do you give oral ABx vs IV ABx for CAP?
Oral is fine for mild
Moderate CAP requires hospital admission and often will be an IV penicillin and oral doxy or macrolide
What are some complications of pneumonia?
Acute MI (increased risk with pneumonia)
Increased mortality
Respiratory failure
Abscess
Complicated effusion
