Short-Chain Fatty Acid and Organic Acid Concentrations in Feces of Healthy Human Volunteers and Their Correlation with Anaerobe Cultural Counts during Systemic Ceftriaxone Administration

Abstract

Short-chain fatty acid (SCFA) and organic acid concentrations and (an)aerobe cultural counts were determined simultaneously in fresh feces from 10 human volunteers before, during, and after 5 days of single-dose ceftriaxone administration. The changes and the correlation coefficients between these variables were tested to be significant (P < 0.05), to investigate whether significant changes in the intestinal microflora could be predicted by significant changes in SCFA/organic acid concentrations. Multivariate analysis was used with the same objective. Significant decreases in most SCFA, total SCFA (0.01 < P< 0.02), and pyruvic acid (0.02 < P < 0.05) concentrations in feces were found on day 3 of treatment and also on day 5, with the exception of the pyruvic acid concentrations. Lactic acid concentrations, however, were significantly increased (0.01 < P < 0.02) on day 5. All anaerobic cultural counts were significantly decreased (P < 0.05) on days 3 and 5 of treatment except those for Clostridium difficile agar, which were only decreased on day 5. Highly significant correlations were found on day 3 between the total anaerobe counts (P < 0.001), the Bacteroides counts (P < 0.001), and propionic acid, of which the latter had a predictive value during treatment. The results of multivariate analysis were significant but did not have a predictive value. From this study we can conclude that propionic acid concentrations during ceftriaxone treatment in healthy volunteers have a predictive value for the Bacteroides cultural counts. The results of this study must be confirmed by those from patients treated with ceftriaxone.

Key Words:

• Anaerobes
• ceftriaxone
• cultural counts
• fecal flora
• gas-liquid chromatography
• organic acids
• short-chain fatty acids