Mycolic acids as diagnostic markers for tuberculosis case detection in humans and drug efficacy in mice.
Bottom Line: Quantification of specific precursor → fragment transitions of approximately 2000 individual mycolic acids (MAs) resulted in high analytical sensitivity and specificity.Furthermore, we quantified MA species in lung tissue of TB-infected mice and demonstrated effective clearance of MA levels following curative rifampicin treatment.Thus, our results demonstrate for the first time the feasibility and clinical relevance of direct detection of mycobacterial lipids as biomarkers of TB infection.
Affiliation: Yong Loo Lin School of Medicine, Department of Biochemistry, National University of Singapore, Singapore. email@example.comShow MeSH
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Mentions: To evaluate our method for monitoring drug efficacy, we measured MAs in lung tissue of mice infected with MTB. These animals are routinely used in pre-clinical studies for development of novel treatments against TB. One commonly used marker for drug efficacy is body weight, which is only indirectly related to TB infection. The signatures of major MAs in mouse lung (Fig 3A) were very comparable to those observed in human sputum samples (Fig 2B). The bacillary burden of these mice as assessed by CFU in their lungs was 15.2 × 106 on average (as assessed in 5 out of the 10 animals tested for MA levels). We also measured MA levels in TB-infected mice that had been treated with the bactericidal antibiotic rifampicin (30 mg/kg body weight for 4 weeks), after which the mice were cured of TB (no detectable CFU in the lungs) (Jayaram et al, 2003). Impressively, the MAs in lung tissue of treated mice were significantly reduced compared to untreated mice, indicating that MAs were effectively cleared at some point during the 4-week treatment (Fig 3B). Thus, direct monitoring of pulmonary MAs can be used to differentiate TB-infected mice from healthy ones.
Affiliation: Yong Loo Lin School of Medicine, Department of Biochemistry, National University of Singapore, Singapore. firstname.lastname@example.org