Infectious Diseases I

If an invasive strategy with quantitative cultures is used, it is suggested that antibiotics be withheld

rather than continued if quantitative culture results are below the diagnostic threshold for VAP (i.e.,

PSB less than 1000 CFU/mL; BAL less than 10,000 CFU/mL).

Antibiotic therapy for VAP is empiric or definitive.

concentrations related to pathogen minimum inhibitory concentration (MIC) dosed optimally using

evidence-based pharmacokinetic and pharmacodynamic principles.

Empiric antibiotic therapy should be initiated in patients with clinical suspicion for VAP (Table 1).

Patients with septic shock should receive antibiotics within 1 hour from onset of hypotension (see

Sepsis chapter).

Inappropriate empiric antibiotic therapy for VAP (i.e., delay in or absence of antibiotics active

against identified causative pathogen[s]) is associated with increased mortality.

To decrease the likelihood of inappropriate therapy, empiric antibiotic selections should be based on:

Presence of MDRO risk factor

ii.

Local VAP pathogen prevalence, particularly MRSA

iii.

Local antibiotic susceptibility patterns (i.e., ICU-specific antibiogram)

All patients with suspected VAP should receive an antibiotic active against MSSA, P. aeruginosa,

and other gram-negative bacilli.

Suggest prescribing two antipseudomonal antibiotics from different classes in patients with

any of the following:

being considered for monotherapy (i.e., multidrug-resistant [MDR] P. aeruginosa)

MDRO risk factor

ii.

ICU MRSA prevalence greater than 10%–20% of S. aureus. (Note: MRSA rates vary between

centers, ICUs, and populations, with general rates in U.S. hospitals greater than 20% [https://

resistancemap.onehealthtrust.org/AntibioticResistance.php].)

iii.

Prevalence of MRSA is not known

Combination antibiotic therapy using agents with similar bacterial spectra but different mechanisms

of action may be necessary to increase the likelihood of appropriate empiric antibiotic therapy for

other gram-negative pathogens.

Lower respiratory tract cultures should be obtained before initiation of antibiotic therapy to increase

the likelihood of identifying causative pathogen(s). Inappropriate delays in initiation of antibiotic

therapy should be avoided in unstable patients (e.g., patients with septic shock).

Empiric antibiotic therapy should be de-escalated to definitive therapy, depending on identified

pathogen(s) and antibiotic susceptibilities. The GRACE-VAP trial, a recently published non-

inferiority trial evaluated the use of Gram stain-guided restrictive antibiotic therapy in treatment

of VAP. The authors found that Gram stain-guided was non-inferior to guideline-directed therapy

in clinical response (76.7% vs. 71.8%), 28-day mortality (13.6% vs. 17.5%), and similar ICU-free