In vitro synergistic activity of NCL195 in combination with colistin against Gram-negative bacterial pathogens

Nguyen, HoangKim; Venter, Henrietta; Veltman, Tania; Williams, Ruth; O’Donovan, Lisa A.; Russell, Cecilia C.; McCluskey, Adam; Page, Stephen W.; Ogunniyi, Abiodun D.; Trott, Darren J.

doi:10.1016/j.ijantimicag.2021.106323

Cited by 17 publications

(19 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…There are several major mechanisms through which bacteria develop resistance, including (1) reduced permeability for antibiotics and reduction of porin protein expression, (2) over-expression of efflux pumps and metabolizing enzymes for drug degradation, and (3) reduced affinity toward the drug target due to mutation of the target(s). , While the latter one usually leads to resistance to certain types of antibiotics, the first two mechanisms often result in resistance to a wide range of antibiotics and thus MDR . Indeed, the discovery of new antibiotics is still very important. − In parallel, a somewhat different approach is the sensitization of bacteria toward existing antibiotics by adjuvants with well-defined efficacy and safety profiles. − This is especially true in the case of MDR Gram-negative bacteria, which are often considered more difficult to overcome because of the existence of an outer membrane (OM). − Strategies that can permeabilize the OM of Gram-negative bacteria and increase the uptake of antibiotics would add extra ammunition to the current arsenal of effective antibiotics without the need to develop new antibiotics as the sole solution.…”

Section: Introductionmentioning

confidence: 99%

Restoring and Enhancing the Potency of Existing Antibiotics against Drug-Resistant Gram-Negative Bacteria through the Development of Potent Small-Molecule Adjuvants

Choudhury

Yang

et al. 2022

ACS Infect. Dis.

View full text Add to dashboard Cite

The rapid and persistent emergence of drug-resistant bacteria poses a looming public health crisis. The possible task of developing new sets of antibiotics to replenish the existing ones is daunting to say the least. Searching for adjuvants that restore or even enhance the potency of existing antibiotics against drug-resistant strains of bacteria represents a practical and cost-effective approach. Herein, we describe the discovery of potent adjuvants that extend the antimicrobial spectrum of existing antibiotics and restore their effectiveness toward drug-resistant strains including mcr-1-expressing strains. From a library of cationic compounds, MD-100, which has a diamidine core structure, was identified as a potent antibiotic adjuvant against Gram-negative bacteria. Further optimization efforts including the synthesis of ∼20 compounds through medicinal chemistry work led to the discovery of a much more potent compound MD-124. MD-124 was shown to sensitize various Gram-negative bacterial species and strains, including multidrug resistant pathogens, toward existing antibiotics with diverse mechanisms of action. We further demonstrated the efficacy of MD-124 in an ex vivo skin infection model and in an in vivo murine systemic infection model using both wild-type and drug-resistant Escherichia coli strains. MD-124 functions through selective permeabilization of the outer membrane of Gram-negative bacteria. Importantly, bacteria exhibited low-resistance frequency toward MD-124. In-depth computational investigations of MD-124 binding to the bacterial outer membrane using equilibrium and steered molecular dynamics simulations revealed key structural features for favorable interactions. The very potent nature of such adjuvants distinguishes them as very useful leads for future drug development in combating bacterial drug resistance.

show abstract

Section: Introductionmentioning

confidence: 99%

Restoring and Enhancing the Potency of Existing Antibiotics against Drug-Resistant Gram-Negative Bacteria through the Development of Potent Small-Molecule Adjuvants

Choudhury

Yang

et al. 2022

ACS Infect. Dis.

View full text Add to dashboard Cite

show abstract

“…In particular, MDR ESKAPE ( E nterococcus faecium, S taphylococcus aureus, K lebsiella pneumoniae, A cinetobacter baumannii, P seudomonas aeruginosa and E. coli / E nterobacter spp.) pathogens are associated with high mortality rates and increased health care setting costs [ 3 , 4 , 5 , 6 ]. It is estimated that antimicrobial resistance may cause 10 million deaths per year worldwide, exceeding the estimated combined deaths from cancers and diabetes and an investment of $100 trillion US dollars annually after 2050 unless adequately addressed [ 7 ].…”

Section: Introductionmentioning

confidence: 99%

“…To date, we have performed several in vitro and in vivo studies that indicate NCL195 is a promising candidate for further pharmaceutical development for the treatment of MDR Gram-positive bacterial (GPB) infections and have shown its in vitro activity against MDR GNB in the presence of sub-inhibitory concentrations of different adjuvants [ 4 , 5 , 28 , 29 ]. In particular, the NCL195 + colistin combination has shown efficacy against both colistin-susceptible and -resistant E. coli in mouse models (manuscript in preparation).…”

Section: Introductionmentioning

confidence: 99%

Impact of a Novel Anticoccidial Analogue on Systemic Staphylococcus aureus Infection in a Bioluminescent Mouse Model

et al. 2022

Self Cite

View full text Add to dashboard Cite

In this study, we investigated the potential of an analogue of robenidine (NCL179) to expand its chemical diversity for the treatment of multidrug-resistant (MDR) bacterial infections. We show that NCL179 exhibits potent bactericidal activity, returning minimum inhibitory concentration/minimum bactericidal concentrations (MICs/MBCs) of 1–2 µg/mL against methicillin-resistant Staphylococcus aureus, MICs/MBCs of 1–2 µg/mL against methicillin-resistant S. pseudintermedius and MICs/MBCs of 2–4 µg/mL against vancomycin-resistant enterococci. NCL179 showed synergistic activity against clinical isolates and reference strains of Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa in the presence of sub-inhibitory concentrations of colistin, whereas NCL179 alone had no activity. Mice given oral NCL179 at 10 mg/kg and 50 mg/kg (4 × doses, 4 h apart) showed no adverse clinical effects and no observable histological effects in any of the organs examined. In a bioluminescent S. aureus sepsis challenge model, mice that received four oral doses of NCL179 at 50 mg/kg at 4 h intervals exhibited significantly reduced bacterial loads, longer survival times and higher overall survival rates than the vehicle-only treated mice. These results support NCL179 as a valid candidate for further development to treat MDR bacterial infections as a stand-alone antibiotic or in combination with existing antibiotic classes.

show abstract

“…In the presence of sub-inhibitory concentrations of Gram-negative outer membrane permeabilizers (EDTA, PMB and PMBN), NCL195 was bactericidal against reference KAPE organisms [ 25 ]. While the exact mechanism or site of action of robenidine or its analogues has yet to be elucidated, we have used membrane potential measurements and transmission electron microscopy studies to indicate that robenidine and its analogues act by dissipating the membrane potential of Gram-positive and inner membrane potential of Gram-negative organisms [ 22 , 25 , 26 , 27 ].…”

Section: Introductionmentioning

confidence: 99%

In Vitro Activity of Robenidine Analogues NCL259 and NCL265 against Gram-Negative Pathogens

Venter

Russell

et al. 2022

Antibiotics

View full text Add to dashboard Cite

Multidrug-resistant (MDR) Gram-negative pathogens, especially Acinetobacter baumannii, Pseudomonas aeruginosa, Escherichia coli and Enterobacter spp., are recognized by the World Health Organization as the most critical priority pathogens in urgent need of drug development. In this study, the in vitro antimicrobial activity of robenidine analogues NCL259 and NCL265 was tested against key human and animal Gram-negative clinical isolates and reference strains. NCL259 and NCL265 demonstrated moderate antimicrobial activity against these Gram-negative priority pathogens with NCL265 consistently more active, achieving lower minimum inhibitory concentrations (MICs) in the range of 2–16 µg/mL. When used in combination with sub-inhibitory concentrations of polymyxin B to permeabilize the outer membrane, NCL259 and NCL265 elicited a synergistic or additive activity against the reference strains tested, reducing the MIC of NCL259 by 8- to 256- fold and the MIC of NCL265 by 4- to 256- fold. A small minority of Klebsiella spp. isolates (three) were resistant to both NCL259 and NCL265 with MICs > 256 µg/mL. This resistance was completely reversed in the presence of the efflux pump inhibitor phenylalanine-arginine-beta-naphthylamide (PAβN) to yield MIC values of 8–16 µg/mL and 2–4 µg/mL for NCL259 and NCL256, respectively. When NCL259 and NCL265 were tested against wild-type E. coli isolate BW 25113 and its isogenic multidrug efflux pump subunit AcrB deletion mutant (∆AcrB), the MIC of both compounds against the mutant ∆AcrB isolate was reduced 16-fold compared to the wild-type parent, indicating a significant role for the AcrAB-TolC efflux pump from Enterobacterales in imparting resistance to these robenidine analogues. In vitro cytotoxicity testing revealed that NCL259 and NCL265 had much higher levels of toxicity to a range of human cell lines compared to the parent robenidine, thus precluding their further development as novel antibiotics against Gram-negative pathogens.

show abstract

In vitro synergistic activity of NCL195 in combination with colistin against Gram-negative bacterial pathogens

Cited by 17 publications

References 35 publications

Restoring and Enhancing the Potency of Existing Antibiotics against Drug-Resistant Gram-Negative Bacteria through the Development of Potent Small-Molecule Adjuvants

Restoring and Enhancing the Potency of Existing Antibiotics against Drug-Resistant Gram-Negative Bacteria through the Development of Potent Small-Molecule Adjuvants

Impact of a Novel Anticoccidial Analogue on Systemic Staphylococcus aureus Infection in a Bioluminescent Mouse Model

In Vitro Activity of Robenidine Analogues NCL259 and NCL265 against Gram-Negative Pathogens

Contact Info

Product

Resources

About