Bacteria In Ancient Andean Mummies Had Genes For Antibiotic Resistance

The Llullaillaco mummy is often considered the best preserved Andean mummy discovered. Pedro Groover/Flickr CC BY 2.0
Josh Davis 22 Oct 2015, 07:53

The Andes' distinctive mix of both an incredibly dry and yet bitterly cold environment, in combination with the highly ritualized burials of the ancient peoples who lived there around a thousand years ago provides the perfect environment for natural mummification. This gives archaeologists a uniquely detailed insight into the lives of these people, from the opulent clothes they wore, to the hearty meals they ate just before death.

The mummies are also able to give researchers a fascinating glimpse of how the human microbiome has changed during this time. By taking a sample from the gut of female mummy found in Peru that dates to between 980 and 1170 C.E., the scientists were able to sequence parts of her microbiome, as well as figure out what it was that led to her death. Interestingly, they found that the bacteria contained genes associated with antibiotic resistance, showing that that this trait predates the therapeutic use of antibiotics. The results are published in PLOS ONE.           

Originally from the Inca city of Cuzco, Peru, the pre-Columbian mummy was originally discovered at some point in the second half of the 19th century and shipped to Italy. The female, thought to have been around 20 years old at death, was bound in a fetal position and then placed inside a basket with only the face and parts of her hands showing through a gap. While the head was almost entirely skeletonized, the rest of the body was remarkably intact, a result of the dry and cold environment surrounding Cuzco.

When performing the autopsy on the mummy, the team got a few hints as to what might have caused her untimely death. Her heart, esophagus and colon were incredibly swollen, with the colon containing a surprising amount of “paleofeces.” These symptoms pointed to a chronic case of Chagas’ disease. Caused by a parasite known as Trypanosoma cruzi, it is endemic to South America, and still infects around 7 million people around the world today. After conducting DNA analysis on samples, they eventually found sequences of T.cruzi in mummy, confirming their previous suspicions.

When the researchers got to the gut of the body, they took every precaution to prevent contamination. Here they found that the gut was dominated by Clostridium species, while the paleofeces mainly consised of Turicibacter. In addition to this, they also found evidence of some strains of human papillomaviruses. But what surprised the researchers the most was the discovery of putative antibiotic resistant genes, like penicillin-binding proteins and multi-drug transporters that help shuttle compounds out of the cell.

These findings suggest that the genes necessary for bacteria to resist antibiotics were already present in the microorganisms for a long time before the widespread use of these medicines, and while modern therapeutics might have increased their prevalence, they didn’t necessarily initiate the original resistance. 

Main image credit: Pedro Groover/Flickr CC BY 2.0

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