RT Journal Article SR Electronic T1 Multicentre open-label randomised controlled trial to compare colistin alone with colistin plus meropenem for the treatment of severe infections caused by carbapenem-resistant Gram-negative infections (AIDA): a study protocol JF BMJ Open JO BMJ Open FD British Medical Journal Publishing Group SP e009956 DO 10.1136/bmjopen-2015-009956 VO 6 IS 4 A1 Yaakov Dickstein A1 Leonard Leibovici A1 Dafna Yahav A1 Noa Eliakim-Raz A1 George L Daikos A1 Anna Skiada A1 Anastasia Antoniadou A1 Yehuda Carmeli A1 Amir Nutman A1 Inbar Levi A1 Amos Adler A1 Emanuele Durante-Mangoni A1 Roberto Andini A1 Giusi Cavezza A1 Johan W Mouton A1 Rixt A Wijma A1 Ursula Theuretzbacher A1 Lena E Friberg A1 Anders N Kristoffersson A1 Oren Zusman A1 Fidi Koppel A1 Yael Dishon Benattar A1 Sergey Altunin A1 Mical Paul YR 2016 UL http://bmjopen.bmj.com/content/6/4/e009956.abstract AB Introduction The emergence of antibiotic-resistant bacteria has driven renewed interest in older antibacterials, including colistin. Previous studies have shown that colistin is less effective and more toxic than modern antibiotics. In vitro synergy studies and clinical observational studies suggest a benefit of combining colistin with a carbapenem. A randomised controlled study is necessary for clarification.Methods and analysis This is a multicentre, investigator-initiated, open-label, randomised controlled superiority 1:1 study comparing colistin monotherapy with colistin–meropenem combination therapy for infections caused by carbapenem-resistant Gram-negative bacteria. The study is being conducted in 6 centres in 3 countries (Italy, Greece and Israel). We include patients with hospital-associated and ventilator-associated pneumonia, bloodstream infections and urosepsis. The primary outcome is treatment success at day 14, defined as survival, haemodynamic stability, stable or improved respiratory status for patients with pneumonia, microbiological cure for patients with bacteraemia and stability or improvement of the Sequential Organ Failure Assessment (SOFA) score. Secondary outcomes include 14-day and 28-day mortality as well as other clinical end points and safety outcomes. A sample size of 360 patients was calculated on the basis of an absolute improvement in clinical success of 15% with combination therapy. Outcomes will be assessed by intention to treat. Serum colistin samples are obtained from all patients to obtain population pharmacokinetic models. Microbiological sampling includes weekly surveillance samples with analysis of resistance mechanisms and synergy. An observational trial is evaluating patients who met eligibility requirements but were not randomised in order to assess generalisability of findings.Ethics and dissemination The study was approved by ethics committees at each centre and informed consent will be obtained for all patients. The trial is being performed under the auspices of an independent data and safety monitoring committee and is included in a broad dissemination strategy regarding revival of old antibiotics.Trial registration number NCT01732250 and 2012-004819-31; Pre-results.