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.

Infectious Diseases Society of America/American Thoracic Society Consensus Recommendation Criteria for Severe Community Acquired Pneumonia in Adults

Major Criteria

• Invasive mechanical ventilation
• Septic shock with the need for vasopressors

Minor Criteria

• Respiratory rate >30 breaths/min
• PaO2/FiO2 ratio <250
• Multilobar infiltrates
• Confusion/disorientation
• Uremia (BUN level, >20 mg/dL)
• Leukopenia (WBC count, <4000 cells/mm3)
• Thrombocytopenia (platelet count, < 100,000 cells/mm3)
• Hypothermia (core temperature, <36 degrees C)
• Hypotension requiring aggressive fluid resuscitation

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

Shown below is an algorithm depicting the management of community acquired pneumonia according to the Infectious Diseases Society of America (IDSA) and Thoracic Society Consensus Guidelines on the Management of Community Acquired Pneumonia in Adults.

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 ❑ Calculate PaO2/FiO2 ratio

Order Labs: ❑ Order CBC ❑ Check BUN ❑ Perform Sputum gram stain ❑ Sputum culture ❑ Blood culture If suspecting atypical pneumonia, obtain: ❑ Urine legionella antigen ❑ Enyzme Immunoassay (EIA) ❑ Immunoflorescence ❑ PCR for atypical and viral including influenza ❑ Fibre optic bronchoscopy ❑ Biopsy for Histopathology

❑ Order a chest X-ray

❑ Evaluate for severity of illness using The PSI Algorithm ❑ Comorbid factors if any ❑ Start oxygenation if needed

❑ Start empiric therapy for Community acquired pneumonia based on the The PSI severity scale while awaiting culture results

Outpatients with no recent antibiotic exposure and no comorbidities

Outpatients with recent antibiotic exposure and no comorbidities

Hospitalized patient not in the ICU

Critically ill patients in the ICU

❑ Azithromycin Oral: 500 mg on day 1 followed by 250 mg once daily on days 2-5 I.V.: 500 mg as a single dose OR ❑Clarithromycin 250 mg every 12 hours for 7-14 days or 1000 mg once daily for 7 days OR Erythromycin 250-500 mg every 6-12 hours; maximum: 4 g daily OR ❑Doxycycline Oral, I.V.: 100 mg twice daily

❑Levofloxacin 500 mg every 24 hours for 7-14 days or 750 mg every 24 hours for 5 days OR ❑ Moxifloxacin Oral, I.V.: 400 mg every 24 hours for 7-14 days OR ❑ Gemifloxacin Oral: 320 mg once daily for 5 or 7 days OR ❑'Amoxicillin Oral: 875 mg every 12 hours or 500 mg every 8 hours 3 times daily OR ❑ Amoxicillin-clavulanate 2 gm 2 times daily OR ❑ Other alternatives include ❑ Ceftriaxone I.V: 1 g once daily, 2 g daily for patients at risk OR ❑ Cefpodoxime Oral: 200 mg every 12 hours for 14 days OR ❑Cefuroxime I.M., I.V.: 750 mg every 8 hours

❑ Ceftriaxone 1g IV daily OR ❑ Cefotaxime 1g IV q8h PLUS ❑ Azithromycin or Clarithromycin OR ❑ Respiratory fluoroquinolone (Moxifloxacin) PLUS Macrolide OR ❑Doxycycline Oral, I.V.: 100 mg twice daily

❑ Cefotaxime I.M., I.V.: 1 g every 12 hours OR ❑Ceftriaxone I.V: 1 g once daily, 2 g daily for patients at risk OR ❑Ampicillin-sulbactam I.V.: 1500-3000 mg every 6 hours PLUS Azithromycin Oral: 500 mg on day 1 followed by 250 mg once daily on days 2-5 OR ❑Ciprofloxacin 500-750 mg twice daily for 7-14 days OR ❑ Levofloxacin 500 mg every 24 hours for 7-14 days or 750 mg every 24 hours for 5 day OR ❑Moxifloxacin Oral, I.V.: 400 mg every 24 hours for 7-14 days OR ❑Gemifloxacin Oral: 320 mg once daily for 5 or 7 days PLUS ❑Aztreonam I.V.: 2 g every 6-8 hours; maximum: 8 g daily. For penicillin allergy

❑ 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.