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Not only are bacteria evolving resistance to antibiotics, but they are changing to become immune to antiseptics used to stop their spread in hospitals. One bacterium is in the process of evolving an entirely new species suited to the niche of spreading through places of medical care. As disturbing as this is to health administrators, some scientists see an opportunity to harness these powers, opening up new manufacturing techniques for polymers like nylon.
Clostridium difficile is a bacterium that infects the gut and is the world’s leading cause of diarrhea. Unpleasant for anyone, it can be lethal for those whose health is compromised by other factors. A study of C. difficile strains' genetics has found they are approaching the point they can be considered two species.
Besides being a rare opportunity to watch the thing creationists say isn’t possible before our eyes, the work reveals one strain is becoming adapted to a hospital niche. It's developing resistance to hospital-grade disinfectants and thriving in the guts of those consuming a Western-style, sugar-rich diet.
According to a study of 906 strains published in Nature Genetics, C.difficile started evolving apart 76,000 years ago, long before antiseptics. However, the pace of change has accelerated so that C. difficile clade A, which makes up around 70 percent of the C. difficile samples taken from patients in hospitals, may soon deserve a new scientific name. Like many bacteria, C. difficile forms endospores that allow it to survive in hostile environments, before returning to its vegetative form when conditions improve. It is the spores that are increasingly resistant to popular hospital cleaning products.
Acinetobacter baumannii is also a disease-causing bacteria that has evolved resistance to antiseptics, but its methods are different and potentially useful. A. baumannii produces a protein, called Acel, which pumps the antiseptic chlorhexidine out of the cell so it can't kill the bacterium.
"The gene that encodes the AceI protein appears to be very old, but chlorhexidine was only created in the twentieth century," Dr Karl Hassan from Australia's University of Newcastle said in a statement. "So the gene can't have the native function of protecting against chlorhexidine. It's a side reaction that is fortunate for the bacteria." Moreover, this transportation capacity is not limited to chlorhexidine, but can be adapted to remove a lot of the chemicals we might use to try to control disease-causing bacteria.
Damaging as the bacteria's good fortune is for us, Hassan makes the case in Proceedings of the National Academy of Sciences this cloud could have a substantial silver lining. He told IFLScience that the molecules Acel is suited to moving include the grimly named cadaverine and putrescine. These molecules got their names because of their foul smells, but they are chemically quite similar to the precursor molecules for nylon. The two molecules have been used to make a type of nylon, but at the moment the process is absurdly expensive.
Hassan hopes it will be possible to harness Acel's transportation affinity for the two molecules to do this much more cheaply. He told IFLScience the product would be no more biodegradable than existing polymers, but it would avoid the need to use petrochemicals in nylon manufacturing, thus making the production, if not disposal, of nylon products more environmentally friendly.
