In vitro activity of antimicrobial peptide CDP-B11 alone and in combination with colistin against colistin-resistant and multidrug-resistant Escherichia coli

Abstract

Multidrug-resistant bacteria are a growing global concern, and with increasingly prevalent resistance to last line antibiotics such as colistin, it is imperative that alternative treatment options are identified. Herein we investigated the mechanism of action of a novel antimicrobial peptide (CDP-B11) and its effectiveness against multidrug-resistant bacteria including Escherichia coli #0346, which harbors multiple antibiotic-resistance genes, including mobilized colistin resistance gene (mcr-1). Bacterial membrane potential and membrane integrity assays, measured by flow cytometry, were used to test membrane disruption. Bacterial growth inhibition assays and time to kill assays measured the effectiveness of CDP-B11 alone and in combination with colistin against E. coli #0346 and other bacteria. Hemolysis assays were used to quantify the hemolytic effects of CDP-B11 alone and in combination with colistin. Findings show CDP-B11 disrupts the outer membrane of E. coli #0346. CDP-B11 with colistin inhibits the growth of E. coli #0346 at ≥ 10× lower colistin concentrations compared to colistin alone in Mueller–Hinton media and M9 media. Growth is significantly inhibited in other clinically relevant strains, such as Acinetobacter baumannii, Pseudomonas aeruginosa, and Klebsiella pneumoniae. In rich media and minimal media, the drug combination kills bacteria at a lower colistin concentration (1.25 μg/mL) compared to colistin alone (2.5 μg/mL). In minimal media, the combination is bactericidal with killing accelerated by up to 2 h compared to colistin alone. Importantly, no significant red blood hemolysis is evident for CDP-B11 alone or in combination with colistin. The characteristics of CDP-B11 presented here indicate that it can be used as a potential monotherapy or as combination therapy with colistin for the treatment of multidrug-resistant infections, including colistin-resistant infections.

The Antimicrobial Peptide Esc(1-21) Synergizes with Colistin in Inhibiting the Growth and in Killing Multidrug Resistant Acinetobacter baumannii Strains

“…Jahangiri et al [ 36 ], proved that combination of the polycyclic peptide nisin with colistin gives rise to an additive effect against the resistant strains of A. baumannii used in their study, except for one strain against which a synergistic effect was observed (FIC = 0.5) [ 36 ]. Lately, Witherell and coworkers [ 37 ] showed a synergistic activity between the AMP CDP-B11 and colistin against several MDR Gram-negative bacteria, including A. baumannii . However, this strain had only an intermediate resistance to colistin (MIC = 1 mg/L) [ 37 ].…”

“…Lately, Witherell and coworkers [ 37 ] showed a synergistic activity between the AMP CDP-B11 and colistin against several MDR Gram-negative bacteria, including A. baumannii . However, this strain had only an intermediate resistance to colistin (MIC = 1 mg/L) [ 37 ]. To the best of our knowledge, our work is the first demonstration of the synergistic effect between the short linear cationic AMP (i.e., Esc(1-21) and colistin), against colistin-resistant A. baumannii (MIC of colistin > 4 mg/L).…”

Mercaptopurine-Loaded Sandwiched Tri-Layered Composed of Electrospun Polycaprolactone/Poly(Methyl Methacrylate) Nanofibrous Scaffolds as Anticancer Carrier with Antimicrobial and Antibiotic Features: Sandwich Configuration Nanofibers, Release Study and in vitro Bioevaluation Tests

“…To describe the resistance of tested human pathogens, antimicrobial susceptibility tests were investigated using different antibiotics categories such as; Kanamycin (30 mcg), Ampicillin (10 mcg), and Cephaloridine (30 µg) for Klebsiella rhinoscleromatis, Streptococci sp., Shigella sp ., and Staphylococcus epidermidis besides Itraconazole (10 μg), Fluconazole (25 mcg), and Clotrimazole (10 mcg) for Candida tropicalis , and Candida krusei via disc diffusion method. 27 , 28 Subsequently, antimicrobial activities of tested composite mats that contains different concentration of PCL as follows: (8% PCL/4% PMMA/1% 6-MP) (A), (4% PCL/4% PMMA/1% 6-MP) (B), and (2% PCL/4% PMMA/1% 6-MP) (C) were evaluated statistically and compared with (4% PMMA/1% 6-MP) (D), (4% PMMA) (E), and (1% 6-MP) (F) utilizing agar-well diffusion assay. 29…”

Effect and Mechanisms of Antibacterial Peptide Fraction from Mucus of C. aspersum against Escherichia coli NBIMCC 8785

“…The analysis was performed after applying 1.0 µL of a mixture of 2.0 µL of the sample and 2.0 µL of a matrix solution (7 mg/mL α-cyano-4-hydroxyquinamic acid, CHCA) in 50% acetonitrile (ACN) containing 0.1% trifluoroacetic acid (TFA), on a target plate with 192 stainless-steel wells. The mass spectrometer was calibrated with a standard mixture of angiotensin I, Glu-1-fibrinopeptide B, and ACTH (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17); the ACTH and MS/MS spectra were obtained in reflector mode. The amino acid sequences of the peptides were identified by a MALDI-MS/MS assay using precursor ions from the MS assays.…”

“…The discovery and testing of new therapeutic tools with a studied and clear effect on different bacterial infections is becoming increasingly topical. The requirements for using such kinds of therapeutic tools are also increasing [1][2][3][4][5][6].…”