Trial for the Treatment of Extensively Drug-Resistant Gram-negative Bacilli (OVERCOME)

Approximately 444 subjects who are greater than or equal to 18 to 95 years of age, are non-pregnant, and are in the inpatient setting of one of the study sites will be evaluated to treatment efficacy. Analysis will include subjects with bloodstream infection (BSI) or pneumonia due to at least one of the following gram-negative bacilli organisms: Acinetobacter baumannii, Klebsiella spp, Escherichia coli, Enterobacter spp. and/or Pseudomonas aeruginosa that demonstrates in vitro non-susceptibility defined as extensively drug-resistant Gram-negative bacilli (XDR-GNB) which includes XDR-AB, XDR-PA and CRE. If a subject has both BSI and pneumonia at the time of study enrollment, they will be included as a subject with pneumonia. Objectives: Primary: •Determine whether the treatment regimen of Colistimethate sodium (colistin) combined with a carbapenem (imipenem or meropenem) is associated with a decreased risk for mortality compared to colistin alone for subjects with bloodstream infection (BSI) and/or pneumonia due to XDR-GNB. Secondary: •Determine what treatment regimen (colistin monotherapy or colistin combined with a carbapenem (imipenem or meropenem) is more likely to reduce the emergence of colistin resistance among XDR-GNB isolates during therapy.