The impact of Melittin monotherapy versus combination therapy with Imipenem or ceftazidime against Carbapenem-sensitive and Carbapenem-resistant Acinetobacter baumannii strains

Background and Aim : Acinetobacter baumannii is one of the predominant pathogens involved in hospital-acquired infections worldwide. There are limited treatment options for carbapenem-resistant Gram-negative infections such as Acinetobacter baumannii. Several ways including loading dose, higher maintenance dose, adjunct local administration and combination therapy are proposed to enhance conventional drugs efficiency. The aim of this study was to evaluate the effectiveness of a new emerged antibacterial peptide melittin alone or in combination with imipenem and ceftazidime conventional antibiotics against clinically isolated carbapenem-sensitive (CSAB) and carbapenem-resistant (CRAB) acinetobacter baumannii strains.Methods : Clinically isolated CSAB and CRAB strains were used to test minimum inhibitory concentration (MIC) by microbroth dilution method. Combination therapy was evaluated by checkerboard titration methods. The drugs dilution range used for peptide and the mentioned antibiotics were ۰.۵-۳۲ and ۰.۱۲۵-۱۲۸ μg/ml, respectively.Results : MIC of Melittin, ceftazidime and Imipenem against CSAB were ۱۶, ۰.۵, ۰.۲۵ μg/ml, respectively, and the MIC of Melittin, ceftazidime and Imipenem against CRAB were ۱۶, ۱۲۸ ? and ۱۶ μg/ml, respectively. The fractional inhibitory concentration (FIC) index for combinations of Melittin and ceftazidime against CSAB and CRAB were ۱.۳ and ۲.۰ μg/ml respectively. Moreover, the FIC index for the combination of melitin and imipenem against the CSAB and CRAB were ۱.۰۵ and ۲.۰۳ μg/ml, respectively.Conclusion : The data exhibited that the combination therapy of Melittin with ceftazidime or imipenem had no synergistic effect against CSAB and CRAB strains.

کلیدواژه ها:

Melittin ، monotherapy ، combination therapy ، carbapenem-resistant bacteria