<prompt> Sereny test is positive in -Entero-invasive E.coliEntero-pathogenic E.coliEntero-toxigenic E.coliEntero-aggregative E.coli  <response>: 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. 