1. Introduction
The four drugs furazolidone, furaltadone, nitrofurazone and nitrofurantoin (Fig. 1) belong to the group of nitrofuran antibacterial agents (antibiotics), which have been widely used in the form of food additives for the treatment of gastrointestinal infections (bacterial enteritis caused by Escherichia coli and Salmonella) in cattle, pigs and poultry.