Community acquired pneumonia resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Chetan Lokhande, M.B.B.S [2]

Definition

A lower respiratory tract infection in a previously normal individual acquired through normal social contact rather than contracting it in a hospital.

Causes

Life Threatening Causes

No life threatening causes have been noted. However, complications of pneumonia could lead to life threatening situations like pleural effusion, lung abscess, bacteremia, septicemia or a secondary infection involving other organ systems.

Common Causes

• Typical Bacteria

1. Streptococcus pneumoniae
2. Haemophilus influenzae
3. Escherichia coli
4. Klebsiella pneumoniae
5. Pseudomonas aeruginosa

• Atypical Bacteria

1. Mycoplasma pneumoniae
2. Chlamydophila pneumoniae
3. Legionella pneumophila

• Viruses

1. Influenza
2. Parainfluenza
3. Respiratory syncytial virus (RSV)
4. Metapneumovirus
5. Adenovirus

Common Etiologies of Community-Acquired Pneumonia

Location	Etiologies of Community-Acquired Pneumonia
▸ Outpatient	▸ Streptococcus pneumoniae
	▸ Mycoplasma pneumoniae
	▸ Haemophilus influenzae
	▸ Chlamydophila pneumoniae
	▸ Influenza A and B, adenovirus, respiratory syncytial virus, parainfluenza
▸ Inpatient (non-ICU)	▸ Streptococcus pneumoniae
	▸ Mycoplasma pneumoniae
	▸ Chlamydophila pneumoniae
	▸ Haemophilus influenzae
	▸ Legionella
	▸ Aspiration
	▸ Influenza A and B, adenovirus, respiratory syncytial virus, parainfluenza
	▸ Yersinia enterocolitica
▸ Inpatient (ICU)	▸ Streptococcus pneumoniae
	▸ Staphylococcus aureus
	▸ Legionella
	▸ Gram-negative bacilli
	▸ Haemophilus influenzae
	▸ Acinetobacter baumannii

Management

Please find below an algorithm that summarizes the approach to community acquired pneumonia.

Do's

• Obtain a sputum gram stain, sputum culture and blood cultures before initiating antibiotic therapy.
• Provide coverage for Streptococcus pneumoniae and atypical bacteria like (Mycoplasma, Chlamydophila, Legionella ).
• Consider acute and convalescent serologic testing to identify atypical pathogens like C.pneumoniae, Q fever and Hantavirus.
• Perform aggressive fluid resuscitation, prompt antibiotic initiation, measure arterial blood gas in patients who have borderline hypoxemia or lactate.
• Treat co-existing illness like asthma and COPD with bronchodilators.
• Start empirical therapy with coverage for Pseudomonas aeruginosa and MRSA if patient is hospitalized for more than 2 days.
• Give high priority to patients with elevated blood urea nitrogen (BUN), confusion and high respiratory rate.:
• First antibiotic dose should be administered within 6 hours of admission into the emergency room.
• Shock is an exception where antibiotic should be started within an hour of hypotension. A decrease in 8% of survival rate for each hour of delay is noted.
• Treat with antibiotics for atleast 5-7 days.
• Narrow down antibiotic therapy as soon as a specific microbiological etiology is identified.
• Chest X-ray should be performed and checked for signs of consolidation, cavitation or interstitial infiltrates.
• Use fibre-optic bronchoscopy in immunocompromised individuals to detect less common organisms, do a tissue biopsy and identify anatomic lesions if any.

Dont's

• Inadvertently use of antibiotic for patients without community-acquired pneumonia who require treatment before 4 hours may increase the risk of Clostridium difficile colitis.Hence, use antibiotics judiciously.
• Don't discontinue antibiotics till the patient is afebrile for 48 to 72 hours and has signs of clinical improvement.