Identification of group B streptococci in tissue sections using the peroxidase-antiperoxidase method: a retrospective necropsy study.

The peroxidase-antiperoxidase (PAP) method was used to demonstrate group B streptococci in formalin-fixed, paraffin-embedded tissue sections using commercial group specific streptococcal antiserum. Sections from neonatal necropsies in which postmortem lung cultures were positive for group B streptococci showed positively stained intra- and extra-cellular cocci in the alveolar exudate. Many hyaline membranes contained intact organisms whereas some membranes showed only diffuse positive staining. One case of neonatal death was evaluated in which there was a clinical diagnosis of group B streptococcal infection, but postmortem cultures were not obtained. Group B streptococci were identified in the lung by the PAP method. This method may be of assistance in the postmortem evaluation of certain infectious diseases such as those due to group B streptococci.