Deficiency of coenzyme A disulfide reductase in methicillin-resistant Staphylococcus aureus MRSA252 delays the secondary damage of oxacillin

Abstract:

[Objective] The expression of coenzyme A disulfide reductase in methicillin-resistant Staphylococcus aureus was up-regulated by 2.3 folds when the strain was cultured with oxacillin. Here, the bactericidal effect of oxacillin on coenzyme A disulfide reductase deficient Staphylococcus aureus was studied. [Methods] Homologous recombination mediated double-exchange techniques were used to delete genes in Staphylococcus aureus, whereas pOS1 plasmid was used to construct the complemented strain. Spectrophotometry was used to detect the proliferation ability of the strains in vitro. The bactericidal effect of oxacillin on the strains was studied by time-kill method, and 2',7'-dichlorodihydrofluorescein diacetate was used as a probe to detect intracellular reactive oxygen species levels. [Results] Coenzyme A disulfide reductase gene deleted strain grew more slowly than the parental strain (P<0.05). Under the action of oxacillin, the time-kill curve and intracellular reactive oxygen species level of the knockout strains were slightly different from that of the parental strains at 20 times MIC concentration, and the lethal rate and intracellular reactive oxygen species level of coenzyme A disulfide reductase gene deleted strains were lower than that of the parental strains at 5 times MIC concentrations. [Conclusion] At lower concentrations of oxacillin, the deletion of coenzyme A disulfide reductase gene reduced intracellular ROS levels, and the bactericidal rate, meanwhile the secondary damage was delayed.

Key words:Staphylococcus aureus;gene editing;coenzyme A disulfide reductase;reactive oxygen species;secondary damage