Pneumonia | Notion

Community-acquired pneumonia (CAP) may be caused by the following infectious agents:

Streptococcus pneumoniae
- most common cause of community-acquired pneumonia: accounts for around 80% of cases
- often causes lobar consolidation (unilateral, dense, homogeneous)
- typically sudden onset, rust-coloured sputum, pleuritic pain, high fever
- associated with herpes labialis (cold sores)
Haemophilus influenzae
Staphylococcus aureus: commonly after influenza infection
atypical pneumonias (e.g. Due to Mycoplasma pneumoniae)
Klebsiella pneumoniae is classically in alcoholics
viruses

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Commonest cause of CAP = *Strep pneumoniae*

Pneumonia + Alcoholic/ cardiomyopathies + Cavitation/upper zone = Klebsiella

Pneumonia + Prior Flu = *Staph aureus*

Pneumonia + Chicken Pox Rash = Varicella

Pneumonia + Hemolytic Anemia + skin changes = Mycoplasma

Pneumonia + Hyponatraemia + Travel History (water borne) + GI = Legionella

Pneumonia + Fleeting opacities = Cryptogenic Pneumonia

Pneumonia + Fits/LOC/stroke = Aspiration Pneumonia

Pneumonia + HSV oral lesion (cold sores) = Strep pneumoniae

Pneumonia + parrot = Chlamydia psitatssi

Pneumonia + farm animals = Q fever (Coxillea brunetii)

Pneumonia + HIV = think PJP but if straight forward case Strep pneumonia is still most common

Pneumonia + Cystic fibrosis = consider Pseudomonas/Burkholderia

Pneumonia + COPD or exac = c1::Haemophilus Influenza

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Management

Criterion	Marker
C	Confusion (abbreviated mental test score <= 8/10)
U	urea > 7 mmol/L
R	Respiration rate >= 30/min
B	Blood pressure: systolic <= 90 mmHg and/or diastolic <= 60 mmHg
65	Aged >= 65 years

NICE recommend, in conjunction with clinical judgement:

consider home-based care for patients with a CURB65 score of 0 or 1 - low risk (less than 3% mortality risk)
consider hospital-based care for patients with a CURB65 score of 2 or more - intermediate risk (3-15% mortality risk)
consider intensive care assessment for patients with a CURB65 score of 3 or more - high risk (more than 15% mortality risk)

Investigations

chest x-ray
in intermediate or high-risk patients NICE recommend blood and sputum cultures, pneumococcal and legionella urinary antigen tests