Sono-photocatalytic disinfection of high strength multi-drug resistant Klebsiella pneumonia in presence of blue LED-active CdS nanorods

Abstract

The prevalence of antibiotic resistant pathogenic microbes in wastewater necessitates effective disinfection treatment to protect human health and the environment. Klebsiella pneumoniae is considered as an opportunistic and emerging human pathogen which can develop resistance towards a broad range of antibiotics. In the present study, a hybrid approach merging photocatalysis by CdS nanorods (NRs) with physico-chemical method of acoustic cavitation was investigated to disinfect MDR Klebsiella pneumonia under blue LED irradiation. Various reaction parameters like light intensity, sonication power, catalyst loading, and bacterial load were studied. Effective and complete disinfection was observed with a catalyst loading of 250 mg/L eradicating a bacterial concentration of 106 CFU/mL within 20 mins. Being a hybrid strategy, the catalyst concentration below the optimum (<1xMIC) was also able to provide significant disinfection majorly due to the synergistic effect. Primary mechanism of disinfection was inferred from the escape of intracellular nucleic acids suggesting disruption of cell membrane followed by ROS scavenging experiments which suggested the importance of various ROS species in the decontamination experiments. The stability of photocatalytic efficiency of the CdS nanorods even after multiple cycles of disinfection revealed possibilities of nanomaterial recycling for wastewater disinfection. The results suggest that the hybrid sono-photocatalytic approach can proficiently eliminate harmful multi-drug resistant bacteria and drastically reduce operational time. However, upscaling of the approach to disinfect actual wastewater remains to be investigated for environmental applications.