Recovery of six anaerobic and five aerobic pathogens from viscose swabs and polyurethane swabs (Culturette EZ) was evaluated quantitatively, and transport in aerobic dry tubes, aerobic Amies transport medium (Transwab), and anaerobic universal transport medium (Port-a-Cul) was compared. The Culturette EZ in aerobic dry tubes gave the highest recovery levels. Data obtained with clinical specimens confirmed these results.

The normal flora of the intestinal tract, mainly consisting of anaerobic bacteria, protects the host against colonization by pathogenic microorganisms. Antimicrobial treatment with ceftriaxone may influence the colonic microflora and as a consequence, the protective effect. Ten healthy volunteers received 1 g of ceftriaxone intramuscularly for five days. This resulted in a significant decrease (p less than 0.05) of the mean cultural counts (+/- SEM) of total anaerobes from 10.67 (0.11) (prior to treatment) to 9.02 (0.45) and 8.97 (0.46) at days 3 and 5, respectively (during treatment). After treatment (days 10 and 15-19), the cultural counts of anaerobes returned to 10.17 (0.16) and 10.44 (0.18), respectively. Bacterial enzymes may serve as an indicator of protective microflora. beta- aspartylpeptidase and deoxycholate hydrolase activity was determined in faecal supernatants of the volunteers and compared with anaerobic culturing. Both enzymatic activities show a significant correlation with the total number of anaerobes present at day 3 of deftriaxone treatment. At day 5 and 8 only beta-aspartylpeptidase showed significant correlations with cultural counts of total anaerobes, Bacteroides spp. or bifidobacteria. At day 15 to 19 (ten to 14 days after treatment) beta-aspartylpeptidase showed only a significant correlation with the number of Bacteroides spp. This indicates that changes in the indigenous bacterial flora during and shortly after treatment with ceftriaxone can be monitored by determination of beta-aspartylpeptidase. Recovery of the intestinal flora is difficult to assess in this manner.

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Short-chain fatty acids (SCFA) and succinate in fresh feces from 10 healthy human volunteers were detected with gas-liquid chromatography and were correlated with their fecal cultural counts. The SCFA content of feces did not change significantly after freezing, but the cultural counts of total anaerobes and bifidobacteria showed significant changes (0.001 less than P less than 0.01). A significant negative correlation (r = -0.78; 0.01 less than P less than 0.02) was found between the bifidobacteria cultural counts and the succinic acid concentration in fresh feces, which disappeared after freezing of the samples. Because of the significant differences in cultural counts and the shift in significant correlations after freezing, it is important to use fresh fecal samples for these correlation studies. Lactic acid and i-caproic acid were not found in the fecal samples. The results show that SCFA and organic acid concentrations cannot replace (an)aerobe cultural counts in fecal flora studies of healthy human volunteers because of the low rate of significant correlations between these two.

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 less than 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 less than P less than 0.02), and pyruvic acid (0.02 less than P less than 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 less than P less than 0.02) on day 5. All anaerobic cultural counts were significantly decreased (P less than 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 less than 0.001), the Bacteroides counts (P less than 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.