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

Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated. Complications of community acquired pneumonia, such as pleural effusion, lung abscess, bacteremia and septicemia are life-threatening conditions and must be treated as such irrespective of the causes.

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.

Characterize the symptoms: ❑ Fever ❑ Cough with sputum ❑ Dyspnea ❑ Pleuritic chest pain

Examine the patient: ❑ Fever and/or ❑ Tachypnea and/or ❑ Rales and/or ❑ Increased TVF

Order Labs: ❑ Order CBC ❑ Perform Sputum gram stain ❑ Sputum culture ❑ Blood culture

❑ Order a chest X-ray ❑ Evaluate for severity of illness ❑ Comorbid factors if any ❑ Start oxygenation if needed

If suspecting atypical pneumonia then obtain ❑ Urine legionella antigen ❑ Enyzme Immunoassay (EIA) ❑ Immunoflorescence ❑ PCR for atypical and viral including influenza ❑ Fibre optic bronchoscopy ❑ Biopsy for Histopathology

❑ Start empiric therapy for Community acquired pneumonia while awaiting culture results

❑ Treat accordingly

Outpatients with no recent antibiotic exposure and no comorbidities

Outpatients with recent antibiotic exposure and no comorbidities

Hospitalized patient

Critically ill patients

❑ Azithromycin 500 mg PO single dose followed by 250 mg PO daily for 4 more days OR ❑ Doxycycline 100 mg PO for 5 days

❑ Respiratory fluoroquinolone (Moxifloxacin) OR ❑ Macrolide (Azithromycin or clarithromycin) With or Without ❑ Amoxicillin 1 g PO for atleast 5 days

❑ Ceftriaxone 1g IV daily OR ❑ Cefotaxime 1g IV q8h PLUS ❑ Azithromycin or Clarithromycin OR ❑ Respiratory fluoroquinolone (Moxifloxacin)

❑ Add Azithromycin OR ❑ Respiratory fluoroquinolone (Moxifloxacin) to ❑ B-Lactam for L.pneumophila ❑ Add Vancomycin for MRSA coverage ❑ Add IV penicillin G to cover S.Pneumoniae ❑ Add antipseudomonal B-Lactam to antipseudomonal fluoroquinolone ( Ciprofloxacin / Levofloxacin ) ❑ to cover Pseudomonas aeruginosa

❑ If culture results are available then treat accordingly ❑ If no response to treatment or then look for

❑ Pleural Effusion

❑ Empyema

Perform thoracocentesis and analyse ❑ pH ❑ Cell count ❑ Gram stain ❑ Bacterial culture ❑ Protein ❑ Lactate dehydrogenase

Drain the empyema

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.