This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteriology, Subject name: Microbiology
[{'content': 'A 20-year-old male had pain in abdomen and mild fever followed by gastroenteritis. The stool examination showed the presence of pus cells and RBC&;s on microscopy. The etiological agent responsible is most likely to be \nSelect and explain. \nA. Enteroinvasive E. Coli., B. Enterotoxigenic E. Coli., C. Enteropathogenic E. Coli., D. Enteroaggregative E. Coli.', 'role': 'user'}, {'content': "Answer: A \nExplanation: `Enteroinvasive E.coli: invade intestinal cells in vivo. The ability to penetrate the cell is determined by the large plasmid. Clinically EIEC infection resembles shigellosis, the passage of bloodstained mucopurulent stools. HeLa and HEp-2 cell invasion in culture can also be used as a diagnostic test. Reference: Textbook of Microbiology; Anathanarayan and paniker's; 10th edition; Page no: 285", 'role': 'assistant'}]