Antimicrobial and Antibiofilm Activity of Human Cationic Antibacterial Peptide (LL-37) and Its Analogs Against Pan-Drug-Resistant Acinetobacter baumannii

Background Human cationic antibacterial peptide hCAP18/LL-37 is the only known cathelicidin, which is part of the innate immune system of humans. The antimicrobial activity of LL-37 against multi-drug-resistant Acinetobacter baumannii has been reported recently, however, whether LL-37 and its analogues (LL/CAP18 and FF/CAP18) have antimicrobial activity against pan-drug-resistant Acinetobacter baumannii (PDRAB) is still unknown. Objectives This study aims to clarify the antimicrobial activity of LL-37 and its analogues against PDRAB. Methods In this study, we evaluated LL-37 and its truncated analogs inhibitory effect on the growth of PDRAB by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) analysis, we also examined the effect of LL-37 and its analogs on bacterial biofilm formation by using a quantitative crystal violet assay. Results LL-37 and its truncated analogs were effective in inhibiting the growth of PDRAB and had a rapid killing ability. After exposure to the peptides, the development of the PDRAB biofilm was inhibited. Strong inhibitory and dispersion effects of FF/CAP18 on the biofilm were confirmed by fluorescence microscopy and field emission scanning electron microscopy. Conclusions This results show that FF/CAP18 is a potential antimicrobial agent for treating pan-drug–resistant bacterial infections.