Efficacy of colistin/rifampin combination for treatment of ventilator associated pneumonia caused by carbapenem resistant Acinetobacter baumannii: brief report

Background: It is difficult to treat infections caused by Acinetobacter baumannii due to multiple drug resistance. The aim of this study was to determine the efficacy of combination therapy with two broad-spectrum antibiotics colistin and rifampin on clinical and para clinical indexes of the patients with ventilator-dependent pneumonia due to imipenem-resistant to A. baumannii in intensive care units of a tertiary hospital. Methods: In a descriptive cross-sectional study, fifty patients admitted to the intensive care units in Vali-Asr Hospital, Arak, Iran, from October 2014 to May 2015, with established ventilator-associated pneumonia were subjected to this study and were treated with standard dosage of colistin and rifampin daily. Once the minimum inhibitory concentration (MIC) of the A. baumannii isolates were susceptible to colistin (MIC˂2 µg/ml) and rifampin (MIC˂2 µg/ml) they were treated with three million international units of colistin in 100 ml of normal saline three times a day and 600 mg of rifampin daily. Side effects of combination therapy and variables of patients like fever, blood pressure, white blood cell count, differential count and, mortality were documented and statistically analyzed. Results: 31(62%) patients were improved after combined treatment with colistin and rifampin, 4(8%) patients were died due to bloodstream infection with A. baumannii and 15(30%) passed away in effect of other reasons. The mean of BUN (P=0.07) and creatinine significantly increased (P=0.02). Clinical variables such as fever, white blood cell count, white blood cell percentage and red blood cell sedimentation rate significantly decreased (P≤0.05). Conclusion: Colistin and rifampicin appear to be an effective and safe combination therapy for treatment of ventilator-dependent pneumonia due to imipenem-resistant to A. baumannii