Chimeric Peptides Have Synergistic Effects And Antibiofilm Activity Against Multidrug-Resistant Acinetobacter Baumannii
The increasing prevalence of drug-resistant pathogens highlights the need to identify novel antibiotics. Here we investigated the efﬁcacies of four new antimicrobial peptides (AMPs) for potential drug development. The antibacterial activities, synergistic effects, and antibioﬁlm properties of the four chimeric AMPs were tested against Acinetobacter baumannii, an emerging Gram negative, nosocomial, drug-resistant pathogen. Nineteen A. baumannii strains resistant to ampicillin, cefotaxime, ciproﬂoxacin, tobramycin, and erythromycin were isolated at a hospital from patients with cholelithiasis. All four peptides exhibited signiﬁcant antibacterial effects (MIC＝3.12 to 12.5 μM) against all 19 strains, whereas ﬁve commercial antibiotics showed little or no activity against the same pathogens. An exception was polymyxin, which was effective against all of the strains tested. Each of the peptides showed synergy against one or more strains when administered in combination with cefotaxime, ciproﬂoxacin, or erythromycin. The peptides also exhibited an ability to prevent bioﬁlm formation, which was not seen with cefotaxime, ciproﬂoxacin, or erythromycin, though polymyxin also inhibited bioﬁlm formation. Indeed, when administered in combination with ciproﬂoxacin, the AMP HPMA exerted a potent synergistic effect against A. baumannii bioﬁlm formation. Collectively, our ﬁndings indicate that the AMPs tested have no cytotoxicity but possess potent antibacterial and antibioﬁlm activities and may act synergistically with commercial antibiotics.
Keywords - Acinetobacter baumannii, Drug-resistant pathogens, Chimeric peptides, Synergistic effects, Anti-biofilm properties