This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Highlights In vitro synergy was seen in only a portion of MDR A. baumannii strains tested. Majority of observational studies did not show added benefits of combination therapy. No strong RCT data to support combination therapy. Some novel agents are promising options for the treatment of MDR A. baumannii.