Sublethal Sodium Hypochlorite Exposure: Impact on Resistance-Nodulation-Cell Division Efflux Pump Overexpression and Cross-Resistance to Imipenem

Sodium hypochlorite (NaOCl) is widely used in public healthcare facilities; this exposure can result in the development of bacterial tolerance to disinfectants, which has known links to antibiotic cross-resistance. However, the mechanism through which cross-resistance to antibiotics and disinfectants develops remains ambiguous. Therefore, this study aimed to examine the phenotypic and transcriptomic changes caused by disinfectant exposure in Gram-negative bacteria and determine the cause of cross-resistance to antibiotics. The results demonstrated that the misuse of disinfectants plays an important role in the emergence of disinfectant resistance and in the increase in antibiotic resistance. Antibiotic resistance may occur from the exposure of Gram-negative bacteria to subminimal inhibitory concentrations (MICs) of NaOCl. Ten passages of Gram-negative bacteria in increasingly higher subMICs of the NaOCl disinfectant were sufficient to increase the MIC to >2500 µg/mL NaOCl, particularly in