Efficacy of colistin and colistin combined with rifampicin, trimethoprim sulfamethoxazole, teicoplanin for treatment of infection caused by acinetobacter baumannii strains

The increase in the frequency of hospital-acquired infections caused by multiresistant gram-negative pathogens has become an important problem worldwide. Acinetobacter baumanni, widespread in the hospital environment and increasingly prevalent in recent years as it causes hospital infections, is a gram negative cocobacia which has developed resistance for several drugs. In recent years, intensive antibiotic use and prolonged stay in intensive care unit have led to an increase in the number of infections caused by resistant strains. Multiple, resistant strains of A.baumanii are isolated at high rates, especially in intensive care units. Colistin is a commonly used antibiotic in the past and has been abandoned for a while due to nephrotoxicity. However, in resistant Acinetobacter infections, it has been re-used as a treatment option. Although colistin is a key drug in the treatment of A. baumannii infections, effective combination therapies are underway due to the emerging colistin resistance. In this study, the efficacy of colistin monotherapy was compared with combination treatments of colistin+rifampicin, colistin+trimetoprim sulfamethoxazole and colistin+teicoplanin in carbapenem resistant A. baumannii infection mouse model. It has been determined that both colistin monotherapy and combined therapies reduce A. baumannii burden in the liver and lung in the light of the obtained data. Combined therapies showed that colistin + rifampicin and colistin + trimetoprim sulfamethoxazole therapies completely removed the bacterial burden in both liver and lung cultures at 72 hours. Thus, it is possible that combination of colistin with rifampicin and trimetoprim sulfamethoxazole have higher efficacy than colistin monotherapy and combined therapy with colistin-teicoplanin. Keywords: A.Baumannii, Colistin, Antibiotherapy, Monotherapy, Combination therapy