The antimicrobial crisis is a real problem. Infections produced by multiresistant bacteria are becoming more and more frequent, and available antimicrobial agents are usually scarce. Reducing the duration of antimicrobial treatments is one of the most efficient measures to control the antibiotic pressure and to optimise the use of these agents.

Bloodstream infections produced by Enterobacteria (EB) are very frequent, but the optimal duration of antibiotics to treat them is unknown, as long as no clinical trials have been specifically developed to answer this question.

Basing on expert opinions, the Infectious Diseases Society pf America (IDSA) recommends the bacteremia by EB secondary to vascular catheter infections to be treated for 7 to 14 days. This represents a variability of up to 100%. No recommendations have been published regarding the duration of treatment of bacteremia from other sources.

The objective of this project is to prove that the 7-day course of treatment for EB bacteremia is more efficient and equally safe than the 14-day scheme.

To achieve theses objectives, we propose this randomized, multicentric clinical trial with a superiority design on the duration of antimicrobial treatment for EB bacteremia in adult patients.

Inclusion criteria:

• Adults patients (equal or over 18 years old)
• Primary or secondary bloodstream infection produced by enterobacteriaceae
• Source of bacteremia properly controlled or expect to be properly controlled in the next 24 hours (i.e. bacteremia produced by infected vascular catheter, abscess, obstruction of the biliary or urinary tract).
• Patients able to understand the objectives of the clinical trial and informed consent signed.

Exclusion Criteria:

• Pregnancy
• Post-chemotherapy neutropenia expected to persist more than 7 days.
• Source of bacteremia uncontrolled at inclusion period or in the following 24 hours. The source will be considered as uncontrolled if the bacteremia is secondary to a suppurative infection potentially removable, if no action has been taken to eradicate it, including: bacteremia by vascular not removed catheter, cholangitis secondary to not derived obstruction of the biliary tract, deep abscess not drained, pyohydronephrosis without derivation of the urinary tract.
• Bacteremia secondary to infective endocarditis, bone and joint infections, or neurosurgical infections, which may require prolonged antimicrobial therapy
• Bacteremia due to enterobacteriaceae resistant to carbapenemics.
• Polymicrobial bacteremia including microorganisms different to enterobacteriaceae.
• Patients with no expectations of survival in the next 48 hours of inclusion.

Anonimized data for primary and secondary variables is planned to be shared with all the participants within 6 months of data completion.