Eco-Friendly Solutions to Antibiotic Resistance in Wastewater: Integrating Plants, Nanoparticles, and Bacteriophages

Abstract

Abstract: Antibiotic resistance is a significant health issue that continues to rise due to the improper utilization of antibiotics across various sectors, leading to the emergence of a wide range of multidrug-resistant (MDR) bacteria. Therefore, an urgent need has been suggested to propose alternative strategies to combat the spread of antibiotic resistance. These non-traditional approaches involve innovative, safe, efficient, and environment-friendly methods. In this study, three methods were investigated against MDR bacteria isolated from wastewater: plants, nanoparticles, and bacteriophages. The MDR bacteria were isolated from wastewater at different treatment stages and from the contaminated seawater. The bacterial susceptibility was examined against a group of antibiotics by the Kirby Bauer disc diffusion method, and those that demonstrated multidrug resistance were further analysed and identified. After that, the selected MDR bacterial isolates were treated by six plants crude ethanol extracts (Hibiscus (H.) rosa-sinensis, Dodonaea (D.) viscosa, Cymbopogon (C.) citratus, Citrus (C.) aurantifolia, Olea (O.) europaea, and Manilkara (M.) zapota), and three nanoparticles (silver, titanium dioxide and zinc oxide), by broth microdilution method. Furthermore, raw sewage samples were screened for MDR bacteria-specific bacteriophages by agar over lay plaque assay. The study findings indicated that 30 bacterial isolates (73%) of the 41 tested ones showed multidrug resistance against three or more classes of tested antibiotics. Of those isolates, nine showed resistance to different antibiotic combinations, particularly to some showed effective action against most of the other isolates. These isolates involved three Escherichia (E.) coli strains: Klebsiella (K.) pneumoniae, Pseudomonas (P.) putida, two Aeromonas (A.) veronii strains, Enterococcus (E.) faecalis, and Streptococcus spp. Plants' crude extracts showed great antimicrobial activity against all tested isolates at minimum inhibition concentrations ranging from 6.125 to less than 0.78 mg/mL. C. aurantifolia completely inhibited the growth of P. putida, A. veronii, E. faecalis, and Streptococcus spp. at all tested concentrations. H. rosa-sinensis and D. viscosa also inhibited the growth of P. putida and E. faecalis at all concentrations. Silver nanoparticles showed the highest inhibition rates against all the bacterial isolates, particularly at a concentration of 1.0 mg/mL. There was a statistically significant difference in bacterial growth at different concentrations of silver nanoparticles. One bacteriophage strain was isolated and purified from raw sewage. It successfully infected one of the MDR E. coli strains, indicating that its narrow host range is strain specific. In conclusion, the screening of wastewater indicated the presence of a wide range of antibiotic-resistant bacteria. Plants crude extracts, nanoparticles and bacteriophages showed a remarkable antibacterial activity. These are locally sourced alternatives to antibiotics that hold promise in the fight against antibiotic-resistant bacteria.