Antimicrobial-resistance genes in the human gut prior the antibiotic-therapy era
Antibiotic-resistance has long been associated with the use and abuse of antibiotics. However, increasing evidence is suggesting that antibiotic-resistance is in fact a phenomenon that has been occurring in natural environments for thousands and possibly millions of years. With the expansion of the microbiome field, it is now possible to characterize antibiotic-resistance genes altogether in different samples, including the human gut. This has also enabled the characterization of ancient human gut microbiomes, which also include antibiotic-resistance genes. Mummified gut remains represent a unique opportunity to characterize the microbiome and antibiotic-resistance genes prior the antibiotic-therapy era. Surprisingly, mummies from the Inca and Italian nobility cultures showed to possess antibiotic-resistance-like genes similar to modern-day antibiotic-resistance genes conferring resistance to beta-lactams, sulfa, quinolones and vancomycin, just to mention a few examples. This is intriguing as it further supports that antibiotic-resistance began in the environment and was transferred to the human gut by means that remain to be investigated and are a matter of ongoing speculation.