I. Outpatients—no comorbidities or risk factors for MRSA and Pseudomonas aeruginosa present*

Streptococcus pneumoniae, Mycoplasma pneumoniae, Chlamydia pneumoniae, Haemophilus influenzae, respiratory viruses, miscellaneous organisms (eg, Legionella, Mycobacterium tuberculosis, endemic fungi)

plus either

or

II. Outpatients—comorbidities present*

S. pneumoniae, including antibiotic-resistant forms; M. pneumoniae; C. pneumoniae; mixed infection (bacteria + atypical pathogen or virus); H. influenzae; enteric gram-negative organisms; respiratory viruses; miscellaneous organisms (eg, Moraxella catarrhalis, Legionella, anaerobes [aspiration], M. tuberculosis, endemic fungi)

plus either

Macrolide orally

or

III. Inpatient—not in intensive care unit (ICU), no risk factors for MRSA or P. aeruginosa

S. pneumoniae, H. influenzae, M. pneumoniae, C. pneumoniae, mixed infection (bacteria + atypical pathogen or virus), respiratory viruses, Legionella, miscellaneous organisms (eg, M. tuberculosis, endemic fungi, Pneumocystis jirovecii)

plus

or

Antipneumococcal fluoroquinolone orally or intravenously (alone)

IVA. ICU patient—no risk factors for MRSA or P. aeruginosa

S. pneumoniae, including antibiotic-resistant forms; Legionella; H. influenzae; enteric gram-negative organisms; Staphylococcus aureus; M. pneumoniae; respiratory viruses; miscellaneous organisms (eg, C. pneumoniae, M. tuberculosis, endemic fungi)

plus either

Antipneumococcal fluoroquinolone IV

or

IVB. Inpatient or ICU patient—MRSA or Pseudomonas risk factors present (if prior isolation is the only risk factor, add initial coverage for that pathogen only and obtain cultures)

Same as those for category IVA (above) plus MRSA or Pseudomonas

or/plus