265. Blood culture results pre- and post- antimicrobial administration in the Medicine Intensive Care Unit: a retrospective study in South Bronx

Abstract

BackgroundIt is intuitive that obtaining blood cultures prior to administering antibiotics can increase the likelihood of a positive blood culture result. Surviving Sepsis Campaign Hour-1 bundle stipulates that obtaining a blood culture and administering antibiotics within 1 hour is a critical determinant of survival. However, the diagnostic sensitivity shortly after antibiotic administration remains unknown. In clinical practice, some health care providers delay antibiotic administration in order to first obtain a blood culture.MethodsAdult patients (> 18 years of age) admitted to the Medicine Intensive Care Unit in Lincoln Medical Center, located in South Bronx, New York City, from 09/2019 to 12/2019. Patients needed to have at least one blood culture obtained within 12 hours of admission and have received intravenous antibiotics during the admission to the Medicine Intensive Care Unit.ResultsOf 327 patients screened, 196 met enrolment criteria and 253 sets of blood cultures underwent analysis. Blood cultures grew bacteria in 21.8% of pre-antimicrobial group whereas 26.9% in post-antimicrobial group (p=0.37). 25.9% of patients received antibiotics within 1 hour before blood culture sampling, while 34.0% of patients received antibiotics >1 hour prior to obtaining blood culture. Blood culture results positive for coagulase-negative staphylococci were more prevalent in the pre-antimicrobial group.Table 1. Patient Characteristics Table 2. Number of blood cultures obtained and blood culture result Table 3. Initial antimicrobial agent and 30-day mortality ConclusionIn the sequence of blood culture and antibiotic administration, there is no 30-day survival difference in pre-antimicrobial group and post-antimicrobial group (p=0.15), as long as both received antibiotics within 12 hours of coming to the hospital. Coagulase-negative staphylococci were higher in the pre-antimicrobial group which may indicate that the health care provider hastily obtained the blood culture in a non-sterile manner. Antibiotic administration should not be delayed because of pending blood culture collection. In addition, given that more than 70% of patients were ultimately found to have negative blood cultures, it would be useful to develop practical tools to identify low-risk patients that can be treated without obtaining blood culture, as the blood culture would not be likely to provide diagnostic information.Figure 1: Hours Before and After IV Antibiotic Started Figure 2: Distribution of Blood Culture Before and After IV Antibiotics Disclosures All Authors: No reported disclosures