Infectious Diseases I

Likely Pathogens

Recommended Empiric Antibiotic(s)a

Patients without MDRO risk factor: Single antipseudomonal agent with 90% or greater empiric activity on

local ICU antibiogram, and local MRSA prevalence is less than 10-20%

P. aeruginosa

S. pneumoniae

Haemophilus influenzae

α- and β-hemolytic Streptococcus spp.

Methicillin-sensitive S. aureus (MSSA)

Antibiotic-sensitive enteric gram-negative bacilli

(GNB) (e.g., E. coli; Klebsiella spp.; Enterobacter spp.;

Proteus spp.; Serratia spp.)

Cefepime, imipenem, levofloxacin, meropenem,

piperacillin/tazobactam

Patient without MDRO risk factor: Single antipseudomonal agent with less than 90% empiric activity on

local ICU antibiogram and/or local MRSA prevalence greater than 10-20%b

P. aeruginosa

Methicillin-resistant S. aureus (MRSA)

S. pneumoniae

Haemophilus influenzae

α- and β-hemolytic Streptococcus spp.

Methicillin-sensitive S. aureus (MSSA)

Antibiotic-sensitive enteric gram-negative bacilli

(GNB) (e.g., E. coli; Klebsiella spp.; Enterobacter spp.;

Proteus spp.; Serratia spp.)

Double Antipseudomonal Coverage

Antipseudomonal β-lactamc

(aztreonam, cefepime, ceftazidime, imipenem,

meropenem, piperacillin/tazobactam)

+

Antipseudomonal fluoroquinolone (ciprofloxacin or

levofloxacin)

OR

aminoglycosided

(amikacin or tobramycin)

MRSA

Linezolid or vancomycin

Patients with MDRO risk factor

P. aeruginosa

Methicillin-resistant S. aureus (MRSA)

Acinetobacter spp.

Antibiotic-resistant enteric GNB (e.g., extended-

spectrum β-lactamase [ESBL]-producing organisms)

Stenotrophomonas maltophilia

Antipseudomonal β-lactamc

(aztreonam, cefepime, ceftazidime, imipenem,

meropenem, piperacillin/tazobactam)

+

Antipseudomonal fluoroquinolone (ciprofloxacin or

levofloxacin)

OR

aminoglycosided

(amikacin, gentamicin, or tobramycin)

AND

Linezolid or vancomycin

aAgents/classes are listed in alphabetic order.

bThere may be situations in which a patient has no MDRO risk factors but may meet the recommendation to receive dual antipseudomonal therapy and/or MRSA

coverage.

cDoripenem is no longer available in the United States. Before being discontinued, doripenem had a U.S. Food and Drug Administration (FDA) warning against use for

treatment of ventilator-associated bacterial pneumonia.

dGuidelines suggest avoiding empiric aminoglycoside if alternative agents with activity are available. New CLSI guidance have lowered MIC breakpoints and no longer

recommend the use of gentamicin in the treatment of P. aeruginosa infections.