DETECTION OF SEPTATA-INTESTINALIS (MICROSPORIDIA) CALI ET-AL. 1993 USING POLYMERASE CHAIN-REACTION PRIMERS TARGETING THE SMALL-SUBUNIT RIBOSOMAL-RNA CODING REGION

Background: The microsporidian Septata intestinalis, recently suggeste d to be reclassified as Encephalitozoon intestinalis, is probably the second most common microsporidian isolated from AIDS patients after En terocytozoon bieneusi. S. intestinalis causes a disseminated disease, including infections of the gastroin-testinal tract, whereas E. bieneu si is confined strictly to the gastrointestinal tract. It is important to differentiate between these two microsporidians, as only infection s caused by S. intestinalis can, at this time, be effectively treated. Currently, diagnosis of infections caused by S. intestinalis can be a chieved only by transmission electron microscopy. Methods and Results: In this study are described specific polymerase chain reaction primer s for diagnosis of S. intestinalis infections based on the region codi ng for the small subunit ribosomal RNA cloned from a S. intestinalis i solate. These primers were tested for specificity on cloned ribosomal RNA sequences of different species of microsporidia, as well as on cul tured samples of E. bieneusi, Encephalitozoon cuniculi, Encephalitozoo n hellem, and Vittaforma corneae (Nosema corneum), without showing any cross-amplification. By use of these polymerase chain reaction primer s, eight different microsporidian isolates grown in culture and one di agnostic sample, collected as an ethanol-fixed duodenal-jejunal segmen t, were identified as S. intestinalis. Conclusion: These primers are p owerful diagnostic tools and can enhance or replace traditional method s used to diagnose this microsporidian.