Enterobacteriaceae is a family of bacteria commonly found in the human gut. There are several species of bacteria within the Enterobacteriaceae family, which include but are not limited to Escherichia, Klebsiella, Enterobacter, Salmonella, Shigella, Citrobacter and Yersinia. Many species of Enterobacteriaceae are necessary for digestion and are usually harmless when contained in the gut.
CRE stands for carbapenem-resistant Enterobacteriaceae. Specifically, three species of the Enterobacteriaceae family - Klebsiella, Enterobacter and Escherichia - have developed resistance to a group of antibiotics called carbapenems. Carbapenems are often used as the last line of treatment when other antibiotics are not effective in treating Enterobacteriaceae infections.