Washington:
Researchers have discovered genes linked to antibiotic resistance in an 11th-century mummy found in the Andes Mountains.
The finding suggests that gene mutations responsible for antibiotic resistance occurred naturally in 1,000-year-old bacteria and are not necessarily linked to the overuse of antibiotics.
An international team of scientists analysed the microbiome of the remains that were mummified naturally in the cold climate of the Andes Mountains.
Found in Cuzco, the ancient capital of the Inca empire, the mummy is currently stored in the Museum of Anthropology and Ethnology of the University of Florence, Italy.
Gino Fornaciari, professor of history of medicine and paleopathology at the University of Pisa, and colleagues carried out an autopsy on the mummy, 'Discovery News' reported.
The mummy was arranged in a fetal position and wrapped in a basket. The researchers estimated the body belonged to a woman who had died between 18 and 23 years of age.
The mummified heart, esophagus and colon (containing an enormous amount of feces) were abnormally enlarged, suggesting a symptom of a chronic case of Chagas' disease - a potentially life-threatening condition caused by the protozoan parasite Trypanosoma cruzi.
A team of international researchers from California, Puerto Rico and Italy directed by Raul Cano, a professor at the California Polytechnic State University, was able to fully sequence the bacteria DNA in the mummy's colon and feces.
The researchers found abundant DNA belonging to Trypanosoma cruzi, confirming the Chagas disease's diagnosis already made by Fornaciari in 1992 by other methods.
The woman survived for some time, despite having advanced heart disease, megacolon and megaesophagus, suggesting that she was probably treated with drugs, possibly coca leaves.
Analysis of the mummy's microbiome also showed the presence of other disease caused by bacteria, such as Clostridium difficile, from which C difficile infection that causes diarrhea and colitis originates, and some types of human papilloma virus (HPV), a sexually transmitted virus which causes cervical cancer.
While the recovered T cruzi appeared more primitive than modern forms of the modern parasite, it was 98 to 99 per cent similar to today's virus.
The researchers identified many antibiotic-resistant genes that would have made treatment with modern broad-spectrum antibiotics - such as fosfomycin and vancomycin - ineffective.
"In particular, vancomycin was discovered more than 50 years ago, and vancomycin-resistant genes have been mainly implicated with the increased use of this antibiotic," the researchers said.
The gut microbiome of the mummy, however, shows that antibiotic-resistant genes predate therapeutic use of these compounds.