Disinfection and mechanism of super-resistant Acinetobacter sp. and the plasmid-encoded antibiotic resistance gene blaNDM-1 by UV/peroxymonosulfate

Abstract

• UV/PMS could efficiently inactivate ARB and control the risk of photoreactivation. • bla NDM-1 was greater resistance to UV/PMS than bla OXA-58 in the same plasmid. • ARGs base pairs number and length were responsible for ARGs removal. • 1 O 2 plays an important role on the plasmid-encoded ARGs removal in UV/PMS. The super-resistant bacteria that produce the New Delhi metallo-β-lactamase 1 (NDM-1) enzyme are becoming a conceivably major worldwide clinical issue with serious consequences. Studying the disinfection and mechanism of super-resistant bacteria and their antibiotic resistance genes (ARGs) is crucial for controlling their spread in the water environment. In this study, the disinfection of the super-resistant bacterium Acinetobacter sp. CS-2 and its transferable ARGs (plasmid-encoded bla NDM-1 and bla OXA-58 ) by ultraviolet radiation (UV), peroxymonosulfate (PMS), and ultraviolet/peroxymonosulfate (UV/PMS) exposure were investigated. UV/PMS could completely inactivate CS-2 and control the photoreactivation risk, while bacteria that underwent UV and PMS treatment had survival ratios of 0.22% and 0.28%, respectively. The removal efficiencies of bla NDM-1 and bla OXA-58 ranged from 3.64 to 4.05 log, and the advantage of UV/PMS treatment on ARGs damage was further identified by gel electrophoresis analysis. The removal efficiency of bla NDM-1 was lower than that of bla OXA-58 , which was attributed to the low number of adjacent 5′-TT-3′ harbored by bla NDM-1 . The removal rate constants of the ARGs by UV treatment were significantly correlated with the number of adjacent base pairs (e.g., 5′-TT-3′, 5′-CT-3′, 5′-TC-3′ and 5′-CC-3′) and length, with R -values ranging from 0.9044 to 0.9512. Singlet oxygen ( 1 O 2 ) played a vital role in the reduction of bla NDM-1 and bla OXA-58 in the UV/PMS treatment. UV/PMS showed high removal efficiency under natural pH conditions and in the presence of various aqueous ions (e.g., Cl − , SO 4 2− and HCO 3 − ). Overall, this study provides new understandings and theoretical support for the risk control of super-resistant bacteria and plasmid-encoded ARGs.