Iodine Resistance in Bacteria — Is It a Concern?

Bacterial Resistance to Iodine

Iodine resistance in bacteria is a growing concern, particularly in regions where iodine tablets are commonly used for water purification. Research has shown that certain bacteria, such as Escherichia coli (E. coli) and Pseudomonas aeruginosa, can develop resistance to iodine at concentrations as low as 0.05-0.1 mg/L. This resistance is often caused by mutations in the bacterial genome, specifically in the genes involved in DNA repair and oxidative stress response.

Factors Contributing to Iodine Resistance

Several factors contribute to the development of iodine resistance in bacteria, including the concentration and contact time of iodine, as well as the presence of organic matter and other contaminants in the water. For example, a study found that the resistance of E. coli to iodine increased significantly when the bacteria were exposed to a concentration of 0.1 mg/L for 10 minutes, compared to 1 minute. This suggests that longer contact times and lower iodine concentrations may be more conducive to the development of resistance.

Strategies to Prevent Iodine Resistance

Several strategies can be employed to prevent or mitigate iodine resistance in bacteria, including using higher concentrations of iodine, increasing the contact time, and combining iodine with other disinfectants. For example, a study found that a combination of iodine and chlorine at concentrations of 0.5 mg/L each was more effective in killing E. coli than either disinfectant alone. Additionally, using iodine tablets with a high chlorine content or incorporating other disinfectants, such as hydrogen peroxide, may also help to prevent the development of iodine resistance.