Abstract
Hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) remain
two of the most commonly diagnosed nosocomial infections. Both are responsible for
significant morbidity and mortality in hospitalized patients. The development of HAP
and VAP is related to bacterial colonization of the oropharynx (and endotracheal tube
in VAP) with subsequent microaspiration and development of clinical infection. Diagnosis
is made based on the clinical presentation and can be confirmed by obtaining either
noninvasive or invasive microbiology culture specimens. Decisions addressing initiation
of antimicrobial therapy can be divided into clinical and bacteriological strategies.
These strategies differ in the criteria used to determine the timing of empiric therapy,
with the clinical strategy basing the decision on radiographic evidence of infection
plus clinical signs and symptoms and the bacteriological strategy requiring growth
of pathogens above a certain threshold from invasively obtained culture specimens.
Despite the delineated pathways, these decisions remain multifactorial and should
also include consideration of patient-related factors, such as immunocompetence, the
risk of multidrug-resistant infection, and overall clinical condition. Patients with
risk factors or signs of clinical decompensation should have empiric therapy initiated
at a lower threshold. However, when possible, therapy should be directed at a confirmed
infection following a positive culture result. Decisions regarding specific empiric
regimens should be based on the local prevalence of infectious microorganisms along
with their associated antimicrobial susceptibilities. Patients deemed at risk of infection
with multidrug-resistant pathogens merit broader spectrum therapy, and immunosuppressed
patients should have consideration of antifungal coverage.
Keywords
hospital-acquired pneumonia - ventilator-associated pneumonia - quantitative culture
- empiric antimicrobial therapy - multidrug resistance
