**1. Introduction**

The discovery and widespread use of antibiotics was one of the most important advances in medicine. These drugs were heralded for their effectiveness, and, as a result, began to be prescribed across the world. However, widespread use of antibiotics has resulted in the generation of mutational resistance in bacteria as well as identification of adaptational resistance mechanisms. These have led to the rise of hyper-resistant bacteria, often called superbugs [1,2]. Today, the phenomenon of antibiotic resistance has become a global public health concern, with 700,000 deaths across the globe each year attributed to antimicrobial resistance. This count is expected to reach 10 million by 2050 as the decreasing effectiveness of available market drugs continues to compound this problem [3]. Of particular concern is the widespread use of antimicrobial agents in food animals, which may be a major source of antimicrobial resistance that can spread drug-resistant pathogens to humans directly or through the environmental pollution of farm effluents [4].

Endogenous antimicrobial peptides (AMPs) are a key component of the body's innate immune system, which is critical in fighting bacteria, fungi, and lipid-enveloped viruses. AMPs are typically cationic and amphiphilic in nature, which facilitates targeted association with negatively-charged pathogenic membranes, causing membrane disruption and cell death [5,6]. Interestingly, evidence has shown that bacteria are unable to achieve high levels of resistance to AMPs, making this an important area of antimicrobial research. However, AMPs can be expensive to manufacture synthetically and can be degraded in the presence of bacterial and host proteases [7,8]. In order to circumvent these challenges, ceragenins were developed from a common bile acid as non-peptide mimics of AMPs. Structure of ceragenins are shown in Figure 1. Ceragenins are cationic and amphiphilic, giving them analogous antimicrobial properties to AMPs. They are relatively inexpensive to produce and have shown potent activity against a broad spectrum of organisms. Of particular note is that ceragenins are active against methicillin-resistant *Staphylococcus aureus* [9], colistin-resistant *Klebsiella pneumoniae* [10], and fluconazole-resistant *Candida albicans* [11] and *Candida auris* [12]. To date, no bacteria have been shown to achieve high levels of resistance to ceragenins [13,14]. Ceragenins appear to be well tolerated in tissues and exhibit both the antimicrobial and secondary properties that are characteristic of many AMPs. Because of their promising therapeutic properties, ease of production, and possible synergistic effects, ceragenins represent an important target of study for further clinical development [15–17]. In this study, the antimicrobial resistance patterns of ten Nigerian bacterial strains isolated from the environment were determined by selected ceragenins and compared to commonly used antibiotics. The effects of ceragenins on the cell membranes of these isolates were observed by scanning electron microscopy (SEM). Additionally, we assessed the potential of selected ceragenins to eradicate biofilms formed by multidrug-resistant environmental isolates.

**Figure 1.** Structures of ceragenins CSA-44, CSA-144, CSA-13 and CSA-131.
