178Impact of Delaying methicillin-resistant Staphylococcus aureus (MRSA) Pneumonia Treatment Until Microbiologic Documentation

Background. Well-designed clinical studies have shown the importance of accurate empiric antibiotic coverage for critically ill patients suffering from an infection. However, these studies may lack external validity regarding the importance of early methicillin-resistant Staphylococcus aureus (MRSA) pneumonia due to the underrepresentation of this population. Two major clinical trials documenting the mortality benefit of early and accurate empiric antibiotics only reported 3.1% of patients having an MRSA infection and 15.6% of patients with documented Staphylococcus aureus infection. Methods: This is a retrospective, descriptive, single center study to evaluate the impact on patient outcomes of delaying coverage for the treatment of MRSA pneumonia in intensive care unit (ICU) patients. The primary endpoint was to evaluate the in-hospital mortality of ICU patients with positive MRSA cultures from a respiratory source empirically treated with an anti-MRSA antibiotic compared to those not treated empirically. Secondary endpoints were to evaluate the hospital and ICU length of stay among surviving patients that received empiric or delayed therapy. Results. From January 2010 to September 2013 total of 68 patients with similar baseline characteristics were included in the study analysis, 45 in the empiric and 23 in the delayed group. There was 24.4% mortality in the empiric treatment group compared to 26.1% in the delayed treatment group with an absolute risk increase of 1.7% (95%CI -20.3-23.5). Among 51 surviving patients the mean hospital length of stay was 20.7 days in the empiric and 21.5 in the delayed group. The mean ICU length of stay was 7.8 days in the empiric compared to 10.5 days in the delayed group, a 2.7 day absolute increase in the delayed group. Conclusion. There does not appear to be a difference in hospital length of stay. However, the data implies a clinically meaningful increased ICU length of stay when delaying MRSA pneumonia therapy. Future study with an appropriately powered sample still necessary for more precise estimates and evaluation of adjusted results. Disclosures. All authors: No reported disclosures.