Listeria monocytogenes, a food-borne, human-infecting pathogen, is widespread in nature and has been isolated from soil, human and animal feces. Since the incidence of human listeriosis is not well-known and placentitis has a nonspecific morphological aspect, usually uninvestigated for this etiologic factor, we decided to implement immunohistochemistry (IHC) to diagnose listeriosis in placentas or abortion specimens by using an anti-Listeria polyclonal antibody (Biodesign®). A pilot study was conducted with the material obtained from ten placentas from abortions or preterm deliveries at Hospital de Clínicas de Porto Alegre in the year 2000. The slides were analyzed by conventional HE staining and IHC. The results revealed listeriosis in five (50%) of the ten studied cases. All cases showed alterations suggestive of acute suppurative inflammatory process. These findings show that it is important to consider IHC-detected listeriosis as a tool for the diagnosis of abortion pathogenesis or perinatal infections, as this can contribute towards the treatment of newborns or pregnant women. The microscopic characteristics of listeriosis in the placenta, albeit nonpathognomonic, allow for a presumptive diagnosis, which is then confirmed by IHC.
Abortion; Listeria infections; Placentitis; Pathology
