Pseudomonas aeruginosa is a common bacterium in
nosocomial infection. The biofilm-forming ability and antimicrobial resistance make P. aeruginosa biofilm
infection refractory to patients requiring hospitalization, especially patients in the intensive care unit. Therefore, many alternative compounds have been developed. A newly synthesized
peptide, RP557, derived from human
cathelicidin LL-37, was evaluated for its antimicrobial and antibiofilm effect toward
carbapenem-resistant P. aeruginosa (CRPA). The results showed that regardless of the resistance to
carbapenems, the minimal inhibition concentrations of RP557 and LL-37 against P. aeruginosa were 32 µg/mL and 256 µg/mL, respectively. Both RP557 and LL-37 significantly reduced the P. aeruginosa biofilm mass at subMICs, while subMICs of
carbapenems induced biofilm formation. RP557 could also remove approximately 50% of the mature biofilm at a concentration of 64 µg/mL, while 256 µg/mL LL-37 was needed to remove it. A quarter MIC of RP557 and LL-37 was used together with
carbapenems (
ertapenem,
imipenem, and
meropenem). The results show that both RP-557 and LL-37 might increase the susceptibility to CRPA by 4-16 times. Significant gene expression level changes were observed in RP557- or LL-37-treated CRPA. Confocal images showed that biofilm structures and biofilm cell viability were significantly reduced in the LL-37- or RP557-treated groups. Therefore, RP557 and its structural origin, LL-37, could be potential treatments for
carbapenem-resistant P. aeruginosa
infection, especially for chronic biofilm
infection. IMPORTANCE Pseudomonas aeruginosa is one of the major pathogens of
nosocomial infection. Combined its biofilm-forming ability with
carbapenem-resistance, it is hard to handle P. aeruginosa
infection, especially for patients requiring hospitalization.
Antimicrobial peptide is a type of potential compound for
bacterial infection treatment. Among these, RP557 was found effective in inhibiting biofilm previously. By assessing its effect on both
carbapenem-resistant P. aeruginosa planktonic cells and biofilm, our results offered a potential treatment for
carbapenem-resistant P. aeruginosa
infection. It could be helpful to treat severe
nosocomial infection related to
carbapenem-resistant bacteria and increase the patients' survival rate.