Researchers found viruses containing antibiotic-resistant genes that existed long before antibiotics were invented.
The viruses were found in fossilized human feces from the 14th century, an American Society for Microbiology news release reported.
The viruses looked at in the study are phages, which are viruses that infect bacteria as opposed to infecting eukaryotic organisms such as plants, animals, and humans. Most of the viral sequences were related to those that still infect both good and bad bacteria of the digestive track.
The 14th century phage community was taxonomically different from what is usually found in modern human feces, but their functions were similar.
Bacteria in the gut plays a crucial role in human health, especially when it comes to the metabolic system; bacteriophage infecting the gut are believed to help maintain these bacteria.
The phages included antibiotic-resistant genes and "and genes for resistance to toxic compounds," the news release reported.
Toxins and antibiotics can both be found in the naturally-occurring world; the resistance genes could have been developed to protect delicate gut bacteria from these harmful substances.
"Our evidence demonstrates that bacteriophages represent an ancient reservoir of resistance genes and that this dates at least as far back as the Middle Ages," Christelle Desnues of Aix Marseille Université, said in the news release. "We were interested in viruses because these are 100 times more abundant than human cells in our bodies, but their diversity is still largely unexplored," says Desnues. "In the present study, we thus focused on the viral fraction of the coprolite by using, for the first time, a combination of electron microscopy, high-throughput sequencing and suicide PCR approaches."
The researchers plant to take a closer look at the fungi and parasites in the fossilized feces to see if they can gain more insight into microorganisms in that time and place.
