K. E. Norin

Intestinal microbial conversion of cholesterol to coprostanol in man

The intestinal microbial conversion of cholesterol to coprostanol has been measured in groups of healthy subjects before, during and after they received the antibiotics ampicillin, bacitracin, clindamycin, co‐trimoxazole, doxycycline, erythromycin, metronidazole, nalidixic acid, ofloxacin or vancomycin orally for 6 days. Before they received antibiotics, the subjects demonstrated two distinct patterns of cholesterol conversion. One pattern was characterised by extensive conversion of cholesterol, the other by little or no conversion. Intake of bacitracin, clindamycin, erythromycin, metronidazole and vancomycin significantly reduced the conversion to coprostanol. In the groups receiving ampicillin or doxycycline, marked reductions were found in most of the subjects. No alterations were found in the groups receiving co‐trimoxazole, nalidixic acid or ofloxacin. In 6 subjects no conversion of cholesterol to coprostanol was found up to 5 weeks after the end of the antibiotic intake. We conclude that orally given antibiotics may cause alterations in the intestinal conversion of cholesterol, reflecting changes in the anaerobiC., Gram‐positive component of the gut flora.

Influence of antibiotics on intestinal mucin in healthy subjects

To determine the effect on microbial breakdown of intestinal mucin healthy volunteers were treated orally with ten different antibiotics. The most pronounced effects were seen after administration of bacitracin, clindamycin or vancomycin: the electrophoretic mucin pattern in faeces changed from a normal conventional pattern to a specific pattern similar to that found in germ-free rats. Disturbed patterns were also observed in some of the subjects treated with ampicillin, doxycycline, erythromycin, metronidazole or nalidixic acid. In most cases the electrophoretic mucin pattern normalized within five weeks after the end of treatment. There were no effects on the microbial breakdown of intestinal mucin in the groups treated with ofloxacin or trimethoprim/sulfamethoxazole. Thus, administration of antimicrobial drugs in clinically recommended doses may cause long-term disturbances in one microflora-associated characteristic, the breakdown of intestinal mucin.

Effect of Olestra Upon Intestinal Microecology as Reflected by Five Microflora Associated Characteristics in Man

To determine the effect of olestra on microbial ecology of the gut five microflora associated characteristics (MACs) were assessed in 93 subjects in a 36 d parallel, placebo-controlled, double-blind study. Degradation of tryptic activity, β-aspartylglycine and mucin, and conversion of cholesterol to coprostanol and bilirubin to urobilinogen were determined in faecal samples collected at the end of an 8 d low fibre baseline period and 28 d treatment period. The test meal consisted of either a moderate (7 g) or high (24 g) level of fibre and olestra (24 g) or an equivalent amount of conventional fat. Olestra had no effect on degradation of tryptic activity or β-aspartylglycine, and no consistent effect on mucin degradation. Olestra reduced significantly the conversion of cholesterol to coprostanol and urobilin to urobilinogen although the individual values were all within the range of healthy population after treatment. The lipophilic nature of cholesterol and urobilin is the most likely reason for the find...

Enteral nutrition and the function of the intestinal microflora in healthy adults

An oral feeding formula was given to 5 healthy volunteers for 8 days. Faecal samples were collected before, during and after the feeding period. The effect of enteral nutrition (EN) on the following seven intestinal microflora-associated characteristics (MACs) was studied: formation of urobilinogen, coprostanol and deoxycholic acid, degradation of mucin and beta-aspartylglycine, faecal tryptic activity, and production of short-chain fatty acids (SCFAs). None of the microbial functions studied were lost during the study. The urobilinogen level increased during EN (P < 0.05) but it seems reasonable to assume that this was a concentration effect due to a decrease in stool mass. The concentration of SCFAs decreased during EN (P < 0.05) and this reflects the absence of dietary fibre in the feed used.