Photocatalytic disinfection of multidrug resistant staphylococcus haemolyticus and Escherichia coli using visible-LED: A photochemical approach to curb nosocomial infection

Undeniably, emergence of multidrug resistance (MDR) in water borne bacteria is the cataclysmic threat to global public health and may plunge the human civilization back to pre-antibiotic era. With limited technologies proven effective against MDR bacteria, there is an irrefutable need to demonstrate alternative and cost effective water disinfection strategies. In the present study, we have scrutinized the effectivity of Zinc Oxide–Kaolinite nanocomposites (ZnO–K),coated on sodium alginate beads (ZnO/K@alginate) for photocatalytic disinfection (PCD) of multi drug resistant Staphylococcus haemolyticus and Escherichia coli under visible-light emitting diode (LED). Under the same operational conditions, ZnO–K​ NC is found to have better efficiency than other photocatalysts [ZnO nanoparticles (NP)’s, Kaolinite, TiO2-Degussa P25] and traditional disinfection techniques (chlorination, hydrogen peroxide treatment, iodination, UV-C treatment). Impairment of bacterial cell membrane is supported by observation of lipid peroxidation and leakage of intracellular components to the reaction system. Additionally, fluoresces and electron microscopy established the detrimental effects on membrane integrity. Experimental evidences suggested that the hydrogen peroxide could be the principal reactive oxygen species involved in the PCD of the targeted bacteria. X-ray diffraction and atomic absorption spectroscopy indicated that ZnO/K@alginate beads could be reused for three consecutive cycles which suggests that the process may be explored for real world application to restrict the spread of nosocomial infection. [Display omitted]