Bacteria are notorious for developing resistance to antibiotics through rapid mutation and natural selection. Radiation is a sure way to stimulate mutations. Could the radiation that will be contaminating the environment surrounding the Fukushima Nuclear Power Plant for hundreds of years produce bacteria that are resistant to antibiotics? Researchers, Shigeyuki Nakanishi and colleagues reporting in the February 1, 2012 issue of the journal Ecotoxicology and Environmental Safety have performed experiments to find out.
The nasty ability of bacteria to develop resistance to our most powerful antibiotics is a major global problem. MRSA, a drug-resistant strain of the bacterium Staphylococcus aureus, thrives in hospitals where antibiotic use has bred a super-bug commonly known as the "flesh-eating" bacteria. Vancomycin is the only remaining antibiotic that can touch the antibiotic resistant germ, but new strains of MRSA are showing resistance even to vancomycin.
The problem is that when bacteria are exposed to environmental stresses that do not kill them all, the remaining bacteria develop mutations that allow them and their progeny to survive. So as science develops ever better ways of killing bacteria in food or in disease, the microbes counterattack by mutating. Even the wholesome process of preserving food leads to more deadly bacteria. Microgiologist Ann McMahon and colleagues reported studies in 2007 showing that Staphylococcus aureus and several other bacteria that can cause food poisoning become four times more resistant to antibiotics after exposure to acid and salt used to preserve food.
The massive 9.0 magnitude earthquake that struck in the Pacific Ocean off the North East coast of Japan generated a series of devastating tsunami waves that reached as high as 38.9 meters. The damaged Fukushima Dai-ichi Nuclear Power Station lost its cooling system, resulting in breaches of core integrity and release of radioactive material that severely contaminated the local environment and spread throughout the globe in trace amounts in the atmosphere and food chain. Although the highly contaminated vicinity surrounding the plant has been evacuated, nothing can stop wildlife, such as birds, from entering the restricted area, and the potential harmful effects from irradiating unseen bacteria in the contamination zone have escaped notice until now.
Shigeyuki Nakanishi and colleagues examined the potential effect of gamma radiation equivalent to levels in the environment surrounding the Fukushima plant to determine if doses equivalent to exposure for 1, 10, and 100 years could alter antibiotic resistance of several types of bacteria. The results showed that none of these doses of gamma radiation increased resistance to 14 different antibiotics. In fact, two bacteria, E. coli and Pseudomonas aeruginosa, became slightly more susceptible to antibiotics after gamma ray exposure.
The researchers conclude that there is no evidence to support concern that the Fukushima disaster may have bred antibiotic resistant bacteria. But, the scientists point out in their article; they were forced to treat the bacteria with a one-time exposure of radiation. How bacteria might respond to the actual situation of sub-lethal exposure to radiation surrounding the power plant for years on end is not known. Time will tell.