Question

Avoparcin, a glycopeptide antibiotic, was widely used in animal feed in Denmark. Vancomycin is another glycopeptide. In 1995, the percent of vancomycin-resistance Enterococcus faecalis (VRE) isolated from pigs was 100. The use of avoparcin was banned in Denmark in 1995. In 2002, Danish scientists reported that 20% of their E. faecalis isolates was vancomycin resistant. Explain why the percent of VRE decreased and why VRE in pigs is important to humans.

Answer 1

Enterococcus faecalis is a commensal occuring in both animals and humans. It is present in the intestines and feeds on undigested food material present in the intestine.But in humans it also causes urinary tract infections. It also causes bacteremia, endocarditis etc. So antibiotic resistance in such bacterial strain causing diseases is cause for concern.

Vancomycin given the feed of the animal has developed antibiotic resistance in the bacterium. Such a resistance gene in the bacterium can be transferred from one bacterium to another horizontally . This can spread the resistance gene to number of other E. faecalis bacteria. Such resistance spreading in the bacterial species can cause difficulty in treating the diseases in humans. Wide spreading of the resistance gene among bacteria is possible by horizontal gene tranfer from one bacteria to another. HUmans infected with such a resistant varient can't be treated with Vancomycin antibiotic.

Vancomycin and Avoparcin are both glycopeptide antibiotic and also are analogs of each other. So resistance developed for Avoparcin also led to the resistance to Vvancomycin. That is why Banning Avoparcin usage has led to decrease in the resistance to Vancomycin. Avoparcin was used in animals as growth promoter glycopeptide.