Mortality in patients admitted with sepsis is high and the increasing incidence of infections with multiresistant bacteria is a worldwide problem. Many hospitals have local antimicrobial guidelines to assure effective treatment and limit the use of broad-spectrum antibiotics, thereby reducing the selection of resistant bacteria. We evaluated adherence to the antimicrobial treatment guidelines of our hospital in patients presenting to the emergency department (ED) with sepsis and assessed the in vitro susceptibility of isolated pathogens to the guideline-recommended treatment and the prescribed treatment. We included all adult patients with a known or suspected infection and two or more extended systemic inflammatory response syndrome (SIRS) criteria. Patients who did not receive antimicrobial treatment, presented with infections not included in the guidelines, or had more than one possible focus of infection were excluded. A total of 276 ED visits (262 patients) were included. Guideline-concordant treatment was prescribed in 168 visits (61%). In the case of guideline-disconcordant treatment, 87% was more broad-spectrum than guideline-recommended treatment. A microbiological diagnosis was established in 96 visits (35%). The susceptibility of the pathogens isolated from patients treated with guideline-concordant treatment (n=68) and guideline-disconcordant treatment (n=28) to guideline-recommended treatment (91% versus 89%) and to prescribed treatment (91% versus 93%) was similar (p=0.77 and p=0.79, respectively). In conclusion, non-adherence to the guidelines occurred frequently and resulted in more broad-spectrum empirical therapy. This did not result in a higher rate of susceptibility of the isolated pathogens to the prescribed empirical therapy.