Comparative evaluation of intratracheal colistimethate sodium, imipenem, and meropenem in BALB/c mice with carbapenem-resistant Acinetobacter baumannii pneumonia

SummaryObjectiveThe identification of the optimal agent for administration via the respiratory tract when treating pneumonia caused by carbapenem-resistant Acinetobacter baumannii (CRAB).MethodsA murine model of acute CRAB pneumonia was established by intratracheal (i.t.) inoculation with 2.5×107 colony-forming units (CFU) of A. baumannii strain Ab396 plus 10% porcine mucin. After 4h the infected BALB/c mice were treated intratracheally with 25μl of either 0.85% saline (control group), colistimethate sodium (CMS) (166 666 U/kg, CMS group), imipenem/cilastatin (30/30mg/kg, imipenem group), or meropenem (20mg/kg, meropenem group), every 8h. The therapeutic efficacy of these agents was examined.ResultsA. baumannii strain Ab396 was susceptible to CMS only. However, meropenem treatment did give a significantly superior survival rate (100%) compared to treatment with imipenem (50%), CMS (33%), or saline (0%) (p