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
Sereny test is positive in - 
Select and explain. 
A. Entero-invasive E.coli, B. Entero-pathogenic E.coli, C. Entero-toxigenic E.coli, D. Entero-aggregative E.coli
A: Entero-invasive E.coli
Answer: A: Entero-invasive E.coli 
Explanation: Ans. is 'a' i.e., Entero-invasive E. coliSereny 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.