Outcomes Associated With De-escalating Therapy for Methicillin-Resistant Staphylococcus aureus in Culture-Negative Nosocomial Pneumonia

BACKGROUND: In culture-positive nosocomial pneumonia, de-escalation (DE) from broad-spectrum empirical antimicrobials to narrower-spectrum agents has shown to decrease broad-spectrum antibiotic use without compromising patient outcomes. However, uncertainty exists regarding the safety of anti-methicillin-resistant Staphylococcus aureus (MRSA) agent DE in culture-negative nosocomial pneumonia. This study aimed to determine if anti-MRSA agent DE in culture-negative nosocomial pneumonia affects 28-day and hospital mortality, ICU and hospital length of stay (LOS), treatment failure, and safety. METHODS: This single-center retrospective cohort study included adult patients admitted from 2012 to 2017 with nosocomial pneumonia and a negative respiratory culture. DE was defined as anti-MRSA agent discontinuation within 4 days of initiation. Secondary outcomes included hospital mortality, hospital and ICU LOS, treatment failure, and occurrence of acute kidney injury (AKI). RESULTS: Of 279 patients included, 92 were in the DE group and 187 were in the no DE (NDE) group. Patients who were not de-escalated received 5 more days of MRSA coverage than patients who were de-escalated; however, there was no difference in 28-day mortality (NDE group, 28% vs DE group, 23%; difference, -5.5%; 95% CI, -16.1 to 6.5). Patients who were de-escalated had shorter hospital (DE group, 15 days vs NDE group, 20 days; difference, 3.2 days; 95% CI, 0.1-6.4) and ICU (DE group, 10 days vs NDE group, 13 days; difference, 2.2 days; 95% CI, -0.3 to 4.9) LOSs after the index date. The incidence of AKI was significantly higher in patients who were not de-escalated (DE group, 36% vs NDE group, 50%; difference, -13.8%; 95% CI, -26.9 to -0.4). CONCLUSIONS: Although anti-MRSA agent DE in culture-negative nosocomial pneumonia did not affect 28-day mortality, it was associated with a shorter hospital LOS and lower incidence of AKI.