Increased antimicrobial resistance requires effective ways to overcome the global challenge of bacterial infections, including methicillin-resistant Staphylococcus aureus (MRSA). From the emergence of MRSA to its continued evolution, it is important to explore this pathogen from fresh perspectives and develop corresponding coping strategies to counter its growing threat. New coping strategies are continuously emerging, including but not limited to enhancing penetration capabilities or targeting their virulence. This review summarizes the epidemiological characteristics, drug resistance mechanisms, and therapeutic strategies of MRSA that have emerged over the past fifteen years. The focus of this paper is to explore the promising applications and current limitations of novel MRSA control strategies. This review serves as a key resource for treating MRSA infections and discussing novel strategies to overcome bacterial drug resistance.

Rutin is a widely known plant secondary metabolite that exhibits multiple physiological functions. The present study focused on screening for synergistic antibacterial combinations containing rutin, and further explored the mechanisms behind this synergy. In vitro antibacterial test results of rutin showed that the ranges of minimum inhibitory concentration (MIC) and Minimum bactericidal concentration (MBC) are 0.125–1 and 0.125–2 mg/mL, respectively. However, rutin and amikacin have a significant synergistic effect, with a fractional inhibitory concentration index (FICI) range of 0.1875–0.5. The time bactericidal curve proved that the combination of rutin and amikacin inhibited bacterial growth within 8 h. Scanning electron microscopy (SEM) revealed that a low-dose combination treatment could disrupt the cell membrane of Escherichia coli (E. coli). A comprehensive analysis using alkaline phosphatase (AKP), K⁺, and a protein leakage assay revealed that co-treatment destroyed the cell membrane of E. coli, resulting in the significant leakage of AKP, intracellular K⁺, and proteins. Moreover, confocal laser scanning microscopy (CLSM) and red–green cell ratio analysis indicated severe damage to the E. coli cell membrane following the co-treatment of rutin and amikacin. This study indicates the remarkable potential of strategically selecting antibacterial agents with maximum synergistic effect, which could significantly control antibiotic resistance.

Escherichia coli (E. coli) is a severe foodborne pathogen, and the formation of its biofilm can enhance bacterial virulence and reduce antibiotic sensitivity, posing a significant threat to human and animal health. Ferulic Acid (FA) is a natural active product that has been proven to possess various biological activities, including anti-inflammatory, antioxidant, and antitumor properties. This study evaluated the inhibitory effect of FA on the biofilm formation of E. coli through crystal violet (CV) staining and scanning electron microscopy (SEM) and investigated the synergistic effect of FA with antibiotics, using the alamar blue (AB) assay. In addition, the regulatory effect of FA on the transcription of biofilm-related genes was analyzed using qRT-PCR technology. The results showed that FA could significantly inhibit biofilm formation, reduce the production of extracellular polymeric substances (EPS), and weaken bacterial motility, without affecting bacterial growth and metabolic activity. qRT-PCR analysis revealed that FA significantly downregulated the expression of curli-related gene csgD, flagella-related genes (flhC, flhD, and motA), and type I fimbriae gene fimA, while upregulating the transcription of c-di-GMP-related genes (pdeR, pdeA, and dosP). It is noteworthy that FA exhibits significant synergistic antibacterial effects when combined with clinically commonly used antibiotics, including sodium fosfomycin, ceftriaxone, gentamicin, and tetracycline, with the most prominent synergistic effect observed in the combination of FA and sodium fosfomycin. These results confirm that FA possesses notable anti-biofilm activity and novel synergistic antibacterial properties, providing a potential therapeutic strategy for treating E. coli infections.

There is an urgent need to find new solutions for the global dilemma of increasing antibiotic resistance in humans and animals. Modifying the performance of existing antibiotics using the nanocarrier drug delivery system (DDS) is a good option considering economic costs, labor costs, and time investment compared to the development of new antibiotics. Numerous studies on nanomedicine carriers that can be used for humans are available in the literature, but relatively few studies have been reported specifically for veterinary pharmaceutical products. Polymer-based nano-DDS are becoming a research hotspot in the pharmaceutical industry owing to their advantages, such as stability and modifiability. This review presents current research progress on polymer-based nanodelivery systems for veterinary antimicrobial drugs, focusing on the role of polymeric materials in enhancing drug performance. The use of polymer-based nanoformulations improves treatment compliance in livestock and companion animals, thereby reducing the workload of managers. Although promising advances have been made, many obstacles remain to be addressed before nanoformulations can be used in a clinical setting. Some crucial issues currently facing this field, including toxicity, quality control, and mass production, are discussed in this review. With the continuous optimization of nanotechnology, polymer-based DDS has shown its potential in reducing antibiotic resistance to veterinary medicines.

Elevated detection rates of the bla_CTX-M-55 gene in animals have been reported as a result of antibiotic misuse in clinics. To investigate the horizontal transfer mechanism of bla_CTX-M-55 and its associated mobile genetic elements (MGEs), we isolated 318 nonrepetitive strains of Escherichia coli (E. coli) from bovine samples in Xinjiang and Gansu provinces, China. All E. coli strains were screened for the CTX-M-55 gene using PCR. The complete genomic data were sequenced using the PacBio triplet sequencing platform and corrected using the Illumina data platform. The genetic environment of the plasmids carrying the resistance bla_CTX-M-55 gene was mapped using the software Easyfig2.2.3 for comparison. The results showed that all bla_CTX-M-55-positive strains were resistant to multiple antibiotics. Five strains of Escherichia coli carry the bla_CTX-M-55 gene, which is adjacent to other resistance genes and is located on the IncHI2-type plasmid. Four of the five bla_CTX-M-55-harbor strains carried translocatable units (TUs). All the donor bacteria carrying the bla_CTX-M-55 genes could transfer horizontally to the recipient (E. coli J53 Azr). This study demonstrates that the transmission of bla_CTX-M-55 is localized on IS26-flanked composite transposons. The cotransmission and prevalence of bla_CTX-M-55 with other MDR resistance genes on epidemic plasmids require enhanced monitoring and control.