Adding meropenem to colistin had no effect on clinical success in cases of severe Acinetobacter baumannii infections, based on data from 406 patients.

In a study published online in The Lancet Infectious Diseases, Mical Paul, MD, of Rambam Health Care Campus, Haifa, Israel, and colleagues randomized 198 patients to colistin alone and 208 to colistin plus meropenem (Lancet Infect Dis. 2018 Feb 15. doi: 10.1016/S1473-3099[18]30099-9 ).

The demographics were similar between the groups and approximately 77% of patients in each group were infected with A. baumannii.

The primary outcome was defined as clinical success 14 days after randomization; 79% (156) of the colistin-only patients and 73% (152) of the combination patients did not meet the criteria, the researchers said. In addition, no significant difference between the groups was noted in all-cause mortality at 14 days or 28 days, or for any other secondary outcomes including fever and time spent in the ICU.

The results highlight “the necessity of assessing combination therapy in randomized trials before adopting it into clinical use,” the researchers said.

The study was not designed to examine the effect of the two types of therapy on bacteria other than A. baumannii, the researchers noted. However, based on the findings, “we recommend against the routine use of carbapenems for the treatment of carbapenem-resistant A. baumannii infections,” they said.

The study was supported by EU AIDA grant Health-F3-2011-278348. Dr. Paul had no financial conflicts to disclose.

SOURCE: Paul M et al. Lancet Infect Dis. 2018 Feb 15. doi: 10.1016/S1473-3099(18)30099-9.