REVIEW Predictors of mortality in patients with infections due to multi-drug resistant Gram negative bacteria: The study, the patient, the bug or the drug? Konstantinos Z. Vardakas a,b , Petros I. Rafailidis a,c , Athanasios A. Konstantelias a,d , Matthew E. Falagas a,b,e, * a Alfa Institute of Biomedical Sciences, Athens, Greece b Department of Medicine-Infectious Diseases, Mitera General Hospital, Hygeia Group, Athens, Greece c Department of Medicine, Henry Dunant Hospital, Athens, Greece d Department of Surgery, Aghia Sophia Children’s Hospital, Athens, Greece e Tufts University School of Medicine, Boston, MA, USA Accepted 28 October 2012 Available online 6 November 2012 KEYWORDS Risk factor; Enterobacteriacae; Escherichia coli; Klebsiella; Enterobacter; Proteus; Pseudomonas; Acinetobacter; Stenotrophomonas Summary Objective: To study the predictors of mortality among patients with multi-drug re- sistant Gram negative (MDRGN) infections and the role of MDRGN bacteria in the outcome of such patients. Methods: PubMed and Scopus databases were searched (until June 30, 2012). Data were ex- tracted and analyzed using the technique of meta-analysis. Results: 30 studies (25 retrospective) were included in the analysis; 9 provided data on predic- tors of mortality for MDRGN infections only, while 21 provided data for MDRGN vs non-MDRGN infections. Acinetobacter spp were the most commonly studied bacteria followed by Pseudo- monas aeruginosa and Enterobacteriaceae. Significant diversity was observed among studies regarding the evaluated predictors of mortality. Infection severity and underlying diseases were the most commonly reported independent predictors of mortality followed by multidrug resistance, inappropriate treatment and increasing age. In studies that included only patients with MDRGN infections, cancer (RR 1.65, 95% CI 1.13e2.39) and prior or current ICU stay (1.27, 1.02e1.56) were associated with mortality. In studies that included patients with MDRGN and non-MDRGN infections, septic shock (3.36, 2.47e4.57), ICU stay (2.15, 1.45e3.20), pneumonia (1.65, 1.09e2.52), isolation of MDRGN bacteria (1.49, 1.21e1.83), inappropriate definitive (2.05, 1.12e3.76) and empirical treatment (1.37, 1.25e1.51), and male gender (1.13, 1.05e1.21) were most commonly observed in patients who died than patients who survived. * Corresponding author. Alfa Institute of Biomedical Sciences (AIBS), 9 Neapoleos Street, 151 23 Marousi, Athens, Greece. Tel.: þ30 694 611 0000; fax: þ30 210 683 9605. E-mail address: m.falagas@aibs.gr (M.E. Falagas). 0163-4453/$36 ª 2012 Published by Elsevier Ltd on behalf of The British Infection Association. http://dx.doi.org/10.1016/j.jinf.2012.10.028 www.elsevierhealth.com/journals/jinf Journal of Infection (2013) 66, 401e414