Costs to Public Health This widespread use of antimicrobials may be contributing to the emergence of microbes resistant to them, and more worryingly, resistant to some therapeutic antibiotics used in the healthcare system. Antimicrobial resistance occurs when an antimicrobial agent is applied to a microbial population, but does not kill all of the organisms. The surviving organisms develop an immunity to the antimicrobial, and go on to reproduce and pass along this immunity.59 “Through mutation, some of [the exposed microbes’] progeny emerge with resistance to the antibacterial agent aimed at it, and possibly to other antimicrobial agents as well.”60 Antimicrobial resistant organisms are already being found for the additives discussed above. While not yet widely studied, antimicrobial resistance to silver-based additives has been reported in strains of Salmonella typhimurium, E. coli, and other bacteria, after exposure to antimicrobial silver in wound dressings.61 Microbes resistant to triclosan are also appearing. A recent study found the presence of triclosan in the body can actually promote Staph infections.64 In laboratory experiments with E. coli, researchers were able to isolate organisms with low, medium, and high levels of resistance to triclosan. In one experiment, 100 times the concentration of triclosan was required to kill a resistant strain of E. coli as compared to a strain not yet exposed to the antimicrobial. These resistant E. coli also showed resistance to a new antibiotic being tested at the time of the experiment.65
Antimicrobial resistance occurs when an antimicrobial agent is applied to a microbial population, but does not kill all of the organisms.
15
