Electron-capture gas chromatographic–chemical ionization mass spectrometric study of sera from people vaccinated with bacille Calmette–Guerin for characteristic metabolites

Serum samples from 26 individuals vaccinated with bacille Calmette–Guerin (BCG) and from 26 controls (10 patients with pulmonary tuberculosis and 16 non BCG-vaccinated healthy individuals) were analyzed by frequency-pulsed electron-capture gas chromatography (FPEC-GC) and chemical ionization gas chromatography–mass spectrometry (CIGC–MS) for the presence of characteristic metabolites. A distinct pattern consisted of tuberculostearic acid (TSA) and a peak, labeled peak 1, was observed in all BCG-vaccinated individuals, whereas only three of 26 controls generated this chromatography profile. TSA was detected in all patients with pulmonary tuberculosis but peak 1 was absent. Sera drawn from 12 individuals 11 to 14 days after BCG vaccination yielded three transitional FPEC-GC profiles. A permanent FPEC-GC profile consisting of TSA and of a full scale peak 1 appeared 28 days to a few months after BCG vaccination. Peak 1 was tentatively identified by CIGC–MS as 9-methyl-hexacosanol. The findings suggest that peak 1 may serve as a marker to detect Mycobacterium bovis BCG and to distinguish individuals infected with M. tuberculosis from individuals vaccinated with BCG.