Pilot randomised controlled trial of meropenem versus piperacillin-tazobactam for definitive treatment of bloodstream infections.

Infections of the blood are extremely serious and require intravenous antibiotic treatment. When the infection results from antibiotic resistant bacteria, the choice of antibiotic is an extremely important decision. Some types of bacteria produce enzymes that may inactivate essential antibiotics, related to penicillin, called 'beta-lactams'. Furthermore high level production of these enzymes can occur during therapy and lead to clinical failure, even when an antibiotic appears effective by laboratory testing. However, this risk of this occurring in clinical practice has only been well described in a limited range of antibiotic classes in a type of bacteria called Enterobacter. There is currently uncertainty as to whether a commonly used, and highly effective antibiotic, called piperacillin-tazobactam is subject to the same risk of resistance developing while on treatment. Infections caused by Enterobacter (and other bacteria with similar resistance mechanisms) are often treated with an alternative drug called meropenem (a carbapenem antibiotic), which is effective but has an extremely broad-spectrum of activity. Excessive use of carbapenems is driving further resistance to this antibiotic class - which represent our 'last-line' of antibiotic defence. As such, we need studies to help us see whether alternatives to meropenem are an effective and safe choice. No study has ever directly tested whether these two antibiotics have the same effectiveness for this type of infection. The purpose of this study is to randomly assign patients with blood infection caused by Enterobacter or related bacteria to either meropenem or piperacillin/tazobactam in order to test whether these antibiotics have similar effectiveness.