This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
All are true about enterohemorrhagic E.coli Except? 
Select and explain. 
A. Sereny test positive, B. May cause diarrhoea, C. Can cause hemolytic uremic syndrome, D. Verocytotoxin is produced
A: Sereny test positive
Answer: A: Sereny test positive 
Explanation: Ans. is 'a' i.e., Sereny test positive . Sereny test is positive in Enteroinvasive E. coli (EIEC) not in Enterohemorrhagic E. coli (EHEC). . EHEC can cause :- i) Severe diarrhea ii) Hemorrhagic colitis iii) Hemolytic uremic syndrome . It produces verocytotoxin (VT) or shiga like toxin (SLT). Sereny test . Sereny test is done for EIEC and shigella. . In this test, instillation of a suspension of freshly isolated ETEC or shigella into the eyes of guinea pigs leads to mucopurulent conjuctivitis and severe keratitis.