Influence of bacitracin on microbial functions in the gastrointestinal tract of horses.

This research explored how zinc bacitracin affects the gut microbes in horses. This antibiotic was found to momentarily impact certain microbial functions, but unlike humans and rats, horses quickly regained normal gut activity after treatment with bacitracin.

Methods of the Study

• The investigation involved six horses being treated with zinc bacitracin, an antibiotic. The antibiotic’s impact on these horses’ intestinal flora — which refers to the community of microorganisms living in the intestines — was studied.
• The researchers conducted various processes to analyze samples, including gas chromatography, spectrophotometry, gel electrophoresis, and paper chromatography. These techniques were used to identify and examine biochemical markers, which can show the activities of different parts of the intestinal flora.

Studied Flora-Related Functions

• Five different functions of intestinal flora were studied in both fecal samples and intestinal samples, sourced from various sections of the hindgut.
• These functions included the conversion of cholesterol into a substance called coprostanol, the conversion of bilirubin to urobilinogens, the breakdown of mucin (a protein that makes up mucus), the breakdown of another protein called beta-aspartylglycine, and the stopping of tryptic activity (which relates to the action of a type of enzyme).

Effect of Zinc Bacitracin on Flora Functions

• The study found that zinc bacitracin treatment impacted three out of the five studied functions. Specifically, it affected the conversion of cholesterol to coprostanol, the conversion of bilirubin to urobilinogens, and the breakdown of mucin.
• The function most sensitive to the zinc bacitracin treatment was the conversion of cholesterol to coprostanol.

Normalization of Flora Functions

• However, all disrupted functions were quickly normalized in these horses — a contrast to the effects seen in humans and rats.
• The study speculates that this difference might be due to diverse environmental exposures, suggesting that these differences could be why horses’ intestinal flora functions return to normal more quickly after being disturbed by antibiotic treatment.