Impact of antibiotic-resistant bacteria on the outcome of ventilator-associated pneumonia

Since antibiotic resistance has become a worldwide concern, there has been an ongoing debate as to whether infections caused by resistant bacteria are associated with higher mortality. Because resistant strains do not appear to be more virulent, differences in outcome may principally relate to patients' characteristics before or at the time of infection onset, and to high rates of inappropriate empirical antimicrobial treatment prescribed for antibiotic-resistant infections. In two large series of severe Staphylococcus aureus and Pseudomonas aeruginosa ventilator-associated pneumonia, we recently demonstrated that antibiotic resistance does not significantly affect intensive care unit mortality of patients receiving appropriate initial antibiotics. However, antibiotic resistance was consistently found to increase hospital length of stay. Early identification of patients with risk factors favoring antibiotic-resistant infections should prompt the initiation of an empirical antibiotic regimen covering these highly resistant bacteria, which can usually be deescalated 48 to 72 hours later when the results of microbiological samples culture become available.