Anti-bacterial and skin-cancer activity of AuNP, rGO and AuNP-rGO composite using Hemigraphis alternata (Burm.F.) T. Anderson

Therapeutic effect of biosynthetic gold nanoparticles on multidrug-resistant Escherichia coli and Salmonella species isolated from ruminants

Background and Aim:

Multidrug-resistant (MDR) pathogenic microorganisms have become a global problem in ruminants as a result of the intensive use of antibiotics, causing the development of resistance among gut microbiota. The antibiotic-resistant microorganisms can be transferred from diseased animals to humans. This study aimed to determine the prevalence of MDR Escherichia coli and Salmonella spp. isolated from cattle, buffaloes, sheep, and goats suffering from respiratory signs, diarrhea, and mastitis and to screen the antibiotic sensitivity of selected isolated bacteria. It also detected antibiotic-resistance genes by polymerase chain reaction (PCR), produced green gold nanoparticles (AuNPs) using plant extracts (Artemisia herba-alba and Morus alba), and evaluated the antimicrobial activities of these biosynthesized nanoparticles on selected pathogens (E. coli and Salmonella spp.).

Materials and Methods:

MDR E. coli and Salmonella spp. were investigated using fecal samples (n=408), nasal swabs (n=358), and milk samples (n=227) of cattle, buffaloes, sheep, and goats with or without clinical signs, including respiratory manifestations, pneumonia, diarrhea, and mastitis, from different governorates in Egypt. E. coli and Salmonella spp. were isolated and identified on selective media, which were confirmed by biochemical reactions and PCR. Antimicrobial susceptibility testing against 10 commonly used antibiotics was performed using the Kirby-Bauer disk diffusion method. Antibiotic resistance genes bla_TEM, bla_SHV, bla_OXA, and bla_CTX−M were detected by PCR. The antibacterial effect of the biosynthesized AuNPs was evaluated by MIC and well diffusion assay. The biosynthesized AuNPs were also characterized by ultraviolet-visible spectrophotometry and transmission electron microscopy (TEM).

Results:

Among all fecal samples, the prevalence of E. coli was 18.4% (183/993) and that of Salmonella spp. was 16.7% (66/408), as determined by cultural and molecular tests. All isolates of E. coli and Salmonella spp. were 100% resistant to ampicillin (AM) and amoxicillin and highly resistant to cefoxitin and AM-sulbactam. The total rate of resistance genes in E. coli was 61.2% (112/183), while that in Salmonella was 63.6% (42/66) for pathogens isolated from ruminants with respiratory manifestations, pneumonia, diarrhea, and mastitis. Among the resistance genes, bla_TEM had the highest prevalence rate in E. coli (25.9%, 21/81) while bla_SHV had the lowest (9.8%, 8/81) in fecal swabs. AuNPs were successfully synthesized using aqueous leaf extract of A. herba-alba and M. alba as bioreducing agents. TEM analysis showed particle size of 10-42 nm for A. herba-alba and M. alba AuNPs. The biosynthesized AuNPs showed antibacterial activity against MDR E. coli and Salmonella spp.

Conclusion:

Rapid and accurate diagnostic methods are the cornerstone for effective treatment to reduce the risk of antimicrobial-resistant pathogenic microorganisms. This is particularly important for overcoming the increasing rate of MDR in ruminants with respiratory manifestations, pneumonia, diarrhea, and mastitis. This can be complemented by the development of AuNPs synthesized in an environmentally friendly manner AuNPs using natural plant extracts for the treatment of antibiotic-resistant microorganisms.

Biodegradable Polymers and Gold Nanoparticle-Decorated Skin Substitutes: Synthesis, Characterization, and In Vitro Biological Activities

Skin substitutes are a restorative material used to treat many skin injuries by replacing or masking the wound. It is also capable of producing an original skin type. In this study, gold nanoparticle-aided skin substitutes were prepared using biodegradable materials (chitosan, sodium alginate, and gelatin) under the magnetic stirring method. Gold ions were reduced using aqueous extract of Cyperus rotundus and Hemigraphis alternata. The formation of prepared gold nanoparticles was confirmed using spectroscopy techniques. The physical parameters of the skin substitutes were tested, and it was characterized using FTIR, DTG, laser profilometer, and FESEM analysis. HAaNP-aided skin substitutes have a bubble-like texture, and it facilitates higher water-absorbing ability. CRaNP aided skin substitutes reducing the hydrophilicity of the prepared skin substitutes. Antioxidant and antifungal skin substitute activities were carried out using DPPH radical scavenging activity and disk diffusion method, respectively. The antioxidant activity revealed the skin substitutes to possess significant free radical inhibition and as the number of gold nanoparticles increases, the activity also increases. The prepared samples show excellent activity against Aspergillus niger. The MTT assay reveals that the cancer cell (A-375) viability decreases by increasing skin substitutes' concentration. The normal cells (HEK-293) were cultured in a medium containing skin substitutes, facilitating the growth of cells. The cell attachment was observed in prepared cell lines after 24-h treatment. The results of this study suggest the prepared Cyperus rotundus and Hemigraphis alternata embedded with gold nanoparticle-aided skin substitutes are a promising material for medical and cosmetic application.