Background Infectious diseases are one of the most frequent reasons for consultation in the Emergency Department (ED), as well as one of the main causes of mortality and admission in the hospital. According to recent studies, antimicrobials are the second most common type of medication prescribed in the ED, so it is important to optimise their use.

Purpose To describe and to analyse the prescription of antimicrobials prescribed empirically in the ED of a third-level hospital and to analyse if microbiological samples are collected in order to establish a targeted treatment.

Material and methods Cross-sectional study of all antimicrobial prescriptions of patients waiting in the ED for admission to hospital from February 2018 to March 2018.The following variables were collected: age, sex, type of infection and microbiological samples (yes/no). It was analysed if the patient after admission maintained the same empirical antimicrobial treatment and if it was correct according to the microbial sensibility data from the sample studied. Data were collected from electronic health records and electronic prescription systems.

Results Ninety-three patients were included, 68 male and 25 female (mean 70 years, SD 13.5 years). The main clinical infections treated were: non-pneumonic lower respiratory tract (41%), urinary tract (18%) intrabdominal (12%), pneumonia (7.5%), chronic obstructive pulmonary disease exacerbation (7.5%) and other type of infections (14%).

After admission, 34% of the patients maintained empirical antimicrobial treatment, 51% treatments were changed to another antimicrobial agent and 15% of patients were discharged from the hospital.

Microbiological samples were collected before treatment in 48% of patients. According to the laboratory sample results, the empirical antimicrobial was correct in 63% of patients.

Conclusion Less than 50% of patient samples were collected before treatment and more than 35% of the empirically prescribed treatments were inadequate according to the laboratory sample results.

In order to prescribe suitable antimicrobial treatments, it is important to take microbiological samples in advance to establish a targeted treatment that could be optimised by developing a multidisciplinary group (program for optimising the use of antimicrobials (PROA)) in the ED.

References and/or acknowledgements No conflict of interest.