PEGylation of Polyethylenimine Lowers Acute Toxicity while Retaining Anti-Biofilm and β-Lactam Potentiation Properties against Antibiotic-Resistant Pathogens

Abstract

Bacterial biofilms, often impenetrable to antibiotic medications, are a leading cause of poor wound healing. The prognosis is worse for wounds with biofilms of antimicrobial-resistant (AMR) bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), methicillin-resistant S. epidermidis (MRSE), and multi-drug resistant Pseudomonas aeruginosa (MDR-PA). Resistance hinders initial treatment of standard-of-care antibiotics. The persistence of MRSA, MRSE, and/or MDR-PA often allows acute infections to become chronic wound infections. The water-soluble hydrophilic properties of low-molecular-weight (600 Da) branched polyethylenimine (600 Da BPEI) enable easy drug delivery to directly attack AMR and biofilms in the wound environment as a topical agent for wound treatment. To mitigate toxicity issues, we have modified 600 Da BPEI with polyethylene glycol (PEG) in a straightforward one-step reaction. The PEG–BPEI molecules disable β-lactam resistance in MRSA, MRSE, and MDR-PA while also having the ability to dissolve established biofilms. PEG-BPEI accomplishes these tasks independently, resulting in a multifunction potentiation agent. We envision wound treatment with antibiotics given topically, orally, or intravenously in which external application of PEG–BPEIs disables biofilms and resistance mechanisms. In the absence of a robust pipeline of new drugs, existing drugs and regimens must be re-evaluated as combination(s) with potentiators. The PEGylation of 600 Da BPEI provides new opportunities to meet this goal with a single compound whose multifunction properties are retained while lowering acute toxicity.

Dual-Function Potentiation by PEG-BPEI Restores Activity of Carbapenems and Penicillins against Carbapenem-Resistant Enterobacteriaceae

“…Although the PEGylation of BPEI mitigates in vivo toxicity, 37 adverse events from systemic exposure remain a concern. Thus, we envision PEG-BPEIs as topical agents applied to acute and chronic wounds, because PEG-BPEI + antibiotic combinations can kill susceptible and resistant bacteria in their biofilm and planktonic environments.…”

“…Thus, we envision PEG-BPEIs as topical agents applied to acute and chronic wounds, because PEG-BPEI + antibiotic combinations can kill susceptible and resistant bacteria in their biofilm and planktonic environments. Both 600 Da BPEI and PEG-BPEI disrupt biofilms 31,34,35,37 and disable resistance mechanisms of lab-strains and clinical isolates of multidrug resistant P. aeruginosa, 33,35,37 MRSA, [29][30][31]33,34 and MRSE. 32,36 The data presented here demonstrate that the possible utility of PEG-BPEI potentiators can be expanded to life-threatening CRE infections.…”

“…In a mouse model, the maximum tolerable dose (MTD) is 75 mg/kg for PEG350-BPEI, whereas the MTD = 25 mg/kg for 600-Da BPEI. 37 One of the potentiation mechanisms of action (MOA) here likely involves the chelation of Zn 2+ ions essential for metalloβ-lactamases. Polyethylenimines have chelating properties with the ability to complex with some metal ions.…”

“…33,35 This paradigm applies equally to increasing the influx of β-lactamase inhibitors, such as tazobactam, and should also improve the uptake of effluxpump inhibitors. These complementary MOAs enhance the value of PEG-BPEI, which also disrupts biofilms, 37 an underlying pathology that contributes to delayed healing. 19,69,70 We envision PEG-BPEIs used as topical agents for acute and chronic wounds.…”

“…The synthesis and characterization of PEG350-BPEI has been described elsewhere. 37 Checkerboard Assays. Checkerboard assays followed the methods of Lam et al 20 to determine the synergistic effect between PEG350-BPEI or 600 Da BPEI and antibiotics against drug-resistant strains growing in cation-adjusted Mueller-Hinton broth (CAMHB).…”