Synergistic effect and antibiofilm activity of the antimicrobial peptide K11 with conventional antibiotics against multidrug-resistant and extensively drug-resistant Klebsiella pneumoniae

Abstract

IntroductionInfections caused by drug-resistant Klebsiella pneumoniae are now a serious problem for public health, associated with high morbidity and mortality due to limited treatment options. Therefore, new antibacterial agents or a combination of agents as the first line of treatment are urgently needed. K11 is a novel antimicrobial peptide (AMP) that has demonstrated in vitro antimicrobial activity against several types of bacteria. Additionally, K11 has previously shown no hemolytic activity. Herein, the antibacterial activity, the synergistic action of K11 in combination with different conventional antibiotics and the antibiofilm activity of K11 against multidrug-resistant (MDR) and extensively drug-resistant (XDR) K. pneumoniae were investigated. Meanwhile, the stability and ability to induce the bacterial resistance of K11 were also tested.MethodsFifteen clinical isolates of MDR/XDR K. pneumoniae were used in this study. The minimum inhibitory concentration (MIC) of K11 against these isolates was determined by the broth microdilution method. In vitro synergy between K11 and antibiotics was evaluated using the checkerboard methodology. The antibiofilm activity of K11 against K. pneumoniae strong biofilm producers were explored by the crystal violet staining. The stability in different environments and resistance induction of K11 were evaluated by MIC determination.ResultsThe MIC values of K11 against MDR/XDR K. pneumoniae isolates were 8-512 μg/mL. Intriguingly, the synergistic effects were clearly observed for K11 in combination with chloramphenicol, meropenem, rifampicin, or ceftazidime, whereas no synergy was observed when K11 was combined with colistin. Besides, K11 effectively prevented biofilm formation against K. pneumoniae strong biofilm producers in a concentration-dependent manner starting at 0.25×MIC and exerted an enhancing effect when administered in combination with meropenem, chloramphenicol, or rifampicin. Additionally, K11 demonstrated high thermal and wide pH stability along with good stability in serum and physiological salts. Significantly, K. pneumoniae showed no induction of resistance even after prolonged exposure to a sub-inhibitory concentration of K11.ConclusionThese findings indicate that K11 is a promising candidate with potent antibacterial and antibiofilm activities without inducing resistance and acts synergistically with conventional antibiotics against drug-resistant K. pneumoniae.

The Antimicrobial, Antibiofilm and Anti-Inflammatory Activities of P13#1, a Cathelicidin-like Achiral Peptoid

“…CAMPs are widely recognized as some of the most attractive solutions to the antibiotic resistance problem, in fact, their peculiar mechanism of action makes a rapid insurgence of resistant strains more unlikely [3][4][5][6][7]. Until now, however, it has been difficult to translate CAMPs into clinical practice due to some relevant drawbacks; first of all, their sensitivity to proteases results in short in vivo half-lives and limited administration routes.…”

“…Cationic antimicrobial peptides (CAMPs), which are essential components of the innate immune system in eukaryotes, are small peptides with broad-spectrum antimicrobial activity [1,2]. They are very promising antimicrobials for two main reasons: (a) CAMP-resistant strains have rarely been isolated [3][4][5][6][7], and (b) activity has been observed on both actively dividing and resting cells (e.g., the subpopulations of bacterial biofilms) [8], differing from several conventional antibiotics.…”

Relationship between biofilm formation and antibiotic resistance of Klebsiella pneumoniae and updates on antibiofilm therapeutic strategies

“…K11 (KWKSFIKKLTKKFLHSAKKF-NH2) is a novel antimicrobial peptide derived from natural AMPs (cecropin A1, melittin, and maganin 2), was reported to have antimicrobial and antibiofilm activity against MDR and e x t e n s i v e l y d r u g -r e s i s t a n t ( X D R ) K . p n e u m o n i a e (Chatupheeraphat et al, 2023). K11 displayed a dose-dependent biofilm inhibition against four strong-biofilm-forming strains of MDR/XDR K. pneumoniae, causing approximately 32% to 80% decrease in the biofilm biomass at the concentration of 0.25 × MIC to 1 × MIC.…”

A Comprehensive Review of Recent Research into the Effects of Antimicrobial Peptides on Biofilms—January 2020 to September 2023

“…However, AMP K11 generated synergistic effects against this bacterium in combination with ceftazidime, chloramphenicol, meropenem, and rifampicin but not colistin antibiotics. K11 also exhibited good stability in physiological salts and serum, as well as high pH and high thermal stability [16]. Another AMP (Pt5-1c) showed synergistic activity in combination with traditional antibiotics against MDR bacteria including K. pneumoniae, S. aureus, and E. coli [17], while a combination of acidic sophorolipid nanoparticles and LL-37 peptides severely damaged the cell membrane of E. coli as shown by atomic force microscopy (AFM) and effectively killed E. coli, S. aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa [18].…”

“…Housefly larval AMP phormicin C-NS was modified using benzoic and sorbic acid (food preservatives) and inhibited C. albicans bud-to-hyphal transition, as well as biofilm formation [81]. Cnt [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34], the C-terminal part of the AMP Crotalicidin derived from rattlesnake venom, inhibited biofilm formation by disrupting the plasma membrane of C. albicans reference strains and flucanozole-resistant isolates [82]. The scorpion venom-derived AMP ToAP2 dose-dependently inhibited the early phase of biofilms (by 60-99.85% at 25-100 µM) [83].…”