Immunocompetent patient

Diagnosis Common Pathogens Drug(s) of First Choice Alternative Drug(s) Comments Expected Duration

Immunocompetent patient 

admitted to the Medical Ward

Respiratory viruses

S.  pneumoniae

Mycoplasma pneumoniae

Chlamydia pneumoniae

H. influenzae

Legionella pneumophilia

Klebsiella pneumoniae

(alcoholics)

No Recent antibiotic therapy:*

Ceftriaxone

PLUS

Doxycycline

For severe beta-lactam allergy:

Levofloxacin 750mg PO/IV daily

OR

Moxifloxacin 400mg PO/IV daily

ID consultation is recommended if ICU admission or high level PCN-resistant pneumococci documented

*If patient has had recent antibiotic therapy, antibiotics from a different class should be selected (i.e. recent use of a fluoroquinolone should dictate selection of a non-fluoroquinolone regimen, and vice versa).

Consider influenza testing and treatment with oseltamivir

Consider coverage for MRSA and/or Pseudomonas aeruginosa in patients with respiratory isolation of these organisms or receipt of parenteral antibiotics within 90 days. If these organisms are not isolated, deescalate antibiotics
5 days

Immunocompetent patient 

ICU

Respiratory viruses

S. pneumoniae

Mycoplasma pneumoniae

Chlamydia pneumoniae

H. influenzae

Legionella pneumophilia

Klebsiella pneumoniae

(alcoholics)

S. aureus

Ceftriaxone

PLUS

Azithromycin 500mg IV daily

WITH OR WITHOUT*:

Vancomycin

For severe beta-lactam allergy:

Vancomycin

PLUS one of EITHER:

Levofloxacin 750mg IV daily

OR

Moxifloxacin 400mg IV daily

Consider coverage for MRSA and/or Pseudomonas aeruginosa in patients with respiratory isolation of these organisms or receipt of parenteral antibiotics within 90 days. Other MRSA risk factors to consider: recent influenza, presence of cavitary disease, empyema

Consider influenza testing and treatment with oseltamivir

If no microbiologic confirmation of MRSA then discontinue vancomycin. If coverage for Pseudomonas is started, obtain blood and sputum cultures and deescalate if this organism is not isolated.

5-7 days

American Journal of Respiratory and Critical Care Medicine, Volume 200, Issue 7, 1 October 2019, Pages e45-e67, https://www.atsjournals.org/doi/full/10.1164/rccm.201908-1581ST