synergistic peptide-antibiotic approach to combatmultidrug-resistant acinetobacter baumannii

Background: antibacterial peptides have a broad antibacterial spectrum and are not affected by classical resistance mechanisms; therefore, they can be used in combination with classic antibiotics to treat multidrug-resistant acinetobacter baumanniiinfections, making them an alternative for the development of new therapeutic strategies. objectives: this study aimed to assess the effectiveness of combining amphiphilic peptides, specifically c12-prp and mastoparan, with antibiotics in combating a. baumanniiclinical isolates. methods: we investigated combinations that inhibited the growth of a. baumanniiclinical isolates, consisting of 24 extensively drug-resistant (xdr) and 11 pan-drug-resistant (pdr) strains collected between january 2004 and december 2014 at chosun university hospital using a multiple combination bactericidal test (mcbt). a time-kill study was used to confirm the bactericidal activity and synergism of the four combinations selected via mcbt. results: four combinations (c 12-prp-colistin, c 12-prp-rifampicin, mastoparan-colistin, and mastoparan-rifampicin) showed 100% (24/24) synergy with xdr a. baumanniistrains. however, in the case of the pdr strains, only two combinations, c 12-prp-colistin and mastoparan-colistin, showed a 9.1% (1/11) synergy. moreover, the mastoparan-colistin and mastoparan-rifampicin combinations showed 100% (24/24) bactericidal activity against the xdr a. baumanniistrains, whereas the c 12-prp-colistin and c 12-prp-rifampicin combinations showed 91.7% (22/24) bactericidal activity. none of the combinations showed bactericidal activity against pdr strains. conclusions: our study highlighted the substantial synergistic antibacterial efficacy of c 12-prp and mastoparan peptides when combined with colistin or rifampicin. furthermore, this approach could be a promising alternative for developing new treatment strategies for xdr a. baumanniiinfections.