2. Which of the following sentences can character diarrheagenic E.coli? 1. They have a specific antigenic structure 2. They are lactose -negative 3. They may contain plasmids of virulence 4. They are non-motile aaulated in the Kligler iron agar.

The correct answer is:<br /><br />3. They may contain plasmids of virulence<br /><br />Diarrheagenic E. coli (Enterotoxigenic E. coli or ETEC) are known for their ability to produce toxins that cause diarrhea. These bacteria often contain plasmids encoding these virulence factors, which contribute to their pathogenicity.