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Bacteria from 800-year-old skeleton reveal first record of maternal sepsis
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Two calcified nodules found in the remains of a woman excavated from a Byzantine cemetery in the ancient city of Troy yielded enough DNA to reconstruct the genomes of Staphylococcus saprophyticus and Gardnerella vaginalis, which infected the woman and likely caused her death, according to a recent report.
“Calcification made little tiny suitcases of DNA and transported it across an 800-year timespan,” Caitlin S. Pepperell, MD, an infectious disease expert from University of Wisconsin School of Medicine and Public Health, said in the press release. “In this case, the amount and integrity of the ancient DNA was extraordinary… one typically gets less than 1 percent of the targeted organism.”
The researchers extracted and reconstructed DNA from the concentric layers of calcium found just below the ribs in the skeleton of a woman laid to rest in a Byzantine era graveyard. These ‘ghost cells’ uncovered in the well-preserved microfossils resembled bacteria from the genus Staphylococcus, a common bacterial pathogen. The findings help researchers understand the evolution of Staphylococcus saprophyticus and provide a molecular portrait of fatal infection in the early 13th century.
The DNA contained in the nodules on the woman, a 30-year-old farmer who showed obvious evidence of a hard, agrarian existence buried on the outskirts of ancient Troy in modern day Turkey, also revealed the DNA of her male fetus. Researchers attributed her death to chorioamnionitis, a bacterial infection of the placenta, noting that it was not uncommon for women to die from complications during pregnancy and childbirth. The woman’s pregnancy and the resulting infection was likely what preserved the bacterial DNA and presented researchers with the first archeological evidence of maternal sepsis.
Compared with the typical infection we see today, this ancient strain of Staphylococcus saprophyticus resembles the strains found in livestock and can be acquired from the environment. According to historical record, Byzantine peasants usually lived with their livestock, which could have increased the chance of infection from an isolate that appears “between the cow and human-associated staph.”
“The strain from Troy belongs to a lineage that is not commonly associated with human disease in the modern world,” Pepperell said in the release. “We speculate that human infections in the ancient world were acquired from a pool of bacteria that moved readily between humans, livestock and the environment.” – by Savannah Demko
Disclosure: Pepperell reports no relevant financial disclosures.
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