Impact of time to antibiotic therapy on clinical outcome in patients with bacterial infections in the emergency department: implications for antimicrobial stewardship

Background: Rapid initiation of antibiotic treatment is considered crucial in patients with severe infections such as septic shock and bacterial meningitis, but may not be as important for other infectious syndromes. A better understanding of which patients can tolerate a delay in start of therapy is important for antibiotic stewardship purposes. Objectives: To explore the existing evidence on the impact of time to antibiotics on clinical outcomes in patients presenting to the emergency department (ED) with bacterial infections of different severity of illness and source of infection. Sources: A literature search was performed in the PubMed/MEDLINE database using combined search terms for various infectious syndromes (sepsis/septic shock, bacterial meningitis, lower respiratory tract infections, urinary tract infections, intra-abdominal infections and skin and soft tissue infections), time to antibiotic treatment, and clinical outcome. Content: The literature search generated 8828 hits. After screening titles and abstracts and assessing potentially relevant full-text papers, 60 original articles (four randomized controlled trials, 43 observational studies) were included. Most articles addressed sepsis/septic shock, while few studies evaluated early initiation of therapy in mild to moderate disease. The lack of randomized trials and the risk of confounding factors and biases in observational studies warrant caution in the interpretation of results. We conclude that the literature supports prompt administration of effective antibiotics for septic shock and bacterial meningitis, but there is no clear evidence showing that a delayed start of therapy is associated with worse outcome for less severe infectious syndromes. Implications: For patients presenting with suspected bacterial infections, withholding antibiotic therapy until diagnostic results are available and a diagnosis has been established (e.g. by 4–8 h) seems acceptable in most cases unless septic shock or bacterial meningitis are suspected. This approach promotes the use of ecologically favourable antibiotics in the ED, reducing the risks of side effects and selection of resistance.