Early hydrocephalus in Listeria meningitis: Case report and review of the literature

Listeria monocytogenes is a gram-positive bacterium with a predilection to infect the central nervous system, often affecting immunocompromised or elderly patients. The most common manifestations are meningitis and rhomboencephalitis. We report two cases of Listeria meningitis complicated by acute hydrocephalus several days after presentation and we further review the literature of similar cases. We conclude that acute hydrocephalus is a significant, not often recognized, complication of Listeria meningitis, usually occurring several days from onset when coverage did not include anti-Listeria antimicrobials. In high risk patients, meningitis combined with acute hydrocephalus is suggestive of LM infection.

Modulation (inhibition and augmentation) of complement receptor-3-mediated myelin phagocytosis

The removal of damaged myelin is central to repair after injury to axons and in autoimmune demyelinating diseases. Complement receptor 3 (CR3/MAC-1) plays a major role in mediating the phagocytosis of damaged myelin by macrophages and microglia. We studied the modulation (inhibition and augmentation) of CR3/MAC-1 mediated myelin phagocytosis by mAbs that bind to distinct epitopes of subunits alphaM and beta2 of CR3/MAC-1. mAb M1/70 anti-alpha(M) and mAb 5C6 anti-alpha(M) inhibited, whereas mAb M18/2 anti-beta2 augmented myelin phagocytosis. This mAb-induced modulation of myelin phagocytosis occurred in the presence and absence of active complement. Inhibition induced by M1/70 or 5C6 did not add when the two were combined. Combining M1/70 or 5C6 with M18/2 reduced the augmentation induced by M18/2 alone. CR3/MAC-1-mediated myelin phagocytosis may thus be subjected to modulation between efficient and inefficient functional/activation states. These observations and conclusions may offer an explanation for the observed discrepancy between efficient myelin phagocytosis in experimental allergic encephalomyelitis and inefficient myelin phagocytosis after injury to CNS axons, although in both instances macrophages/microglia express CR3/MAC-1.