Mycolic acids and ancient DNA confirm an osteological diagnosis of tuberculosis.

Setting: The underlying trends in the past epidemiology of tuberculosis (TB) are obscure, requiring recourse to the archaeological record. It would therefore be of value to develop methods for reliable TB diagnosis in ancient populations.
Objective: To test the capability of two biomarkers, Mycobacterium tuberculosis complex mycolic acids and a DNA target (IS6110), for confirming an osteological diagnosis of TB in medieval individuals, based on the presence of Pott's disease and/or rib lesions.
Design: Osteological examination of three archaeological individuals (Medieval: approximately 1000 years old) revealed a Pott's disease case, one with no changes consistent with TB and one with rib lesions. Rib samples from these individuals were examined for the presence of Mycobacterium tuberculosis complex mycolic acids and mycobacterial DNA.
Results: Mycobacterium tuberculosis complex mycolic acids and the DNA target were detected in the Pott's disease case, whilst mycolic acids (insufficient for confirmation) alone were detected in the rib lesion case.
Conclusions: Biomarkers provide a sensitive tool to detect ancient TB. Mycobacterium tuberculosis DNA is not distributed homogeneously, making multiple sampling essential. Mycolic acids seem more reliable for ancient TB diagnosis than IS6110. The demonstrated stability of mycolic acids show that they may be of value in tracing the palaeoepidemiology of tuberculosis back into antiquity.