The distribution of labeled antibiotics in normal and infected rat brain: an autoradiographic study

The penetration and distribution of labeled benzylpenicillin and cefuroxime into normal and infected rat brain was studied. 15 rats were injected intravenously with radiolabeled antibiotic; 5 of these served as uninfected controls and 10 were previously infected by stereotactic deposition of 10(11) B. fragilis in the right frontal lobe inducing bacterial cerebritis. The animals were killed after administration of antibiotic. The brains were immediately frozen and cut into 20/micron sections. Autoradiographic recordings showed that benzylpenicillin was mainly distributed in the cerebrospinal fluid and pial vessels but no activity was found in the deeper grey or white matter. In contrast, cefuroxime was found not only in the surrounding but also in the centre of the infected area. The autoradiographic technique provides a valuable method for studies of the distribution of antibiotics in the brain.