Invasion of the Central Nervous System by Intracellular Bacteria

Abstract

Infection of the central nervous system (CNS) is a severe and frequently fatal event during the course of many diseases caused by microbes with predominantly intracellular life cycles. Examples of these include the facultative intracellular bacteria Listeria monocytogenes, Mycobacterium tuberculosis, and Brucella and Salmonella spp. and obligate intracellular microbes of the Rickettsiaceae family and Tropheryma whipplei. Unfortunately, the mechanisms used by intracellular bacterial pathogens to enter the CNS are less well known than those used by bacterial pathogens with an extracellular life cycle. The goal of this review is to elaborate on the means by which intracellular bacterial pathogens establish infection within the CNS. This review encompasses the clinical and pathological findings that pertain to the CNS infection in humans and includes experimental data from animal models that illuminate how these microbes enter the CNS. Recent experimental data showing that L. monocytogenes can invade the CNS by more than one mechanism make it a useful model for discussing the various routes for neuroinvasion used by intracellular bacterial pathogens

Antigen presentation by monocytes and monocyte-derived cells

“…However, more recently Ly-6C lo monocytes were observed to patrol blood vessels continuously by crawling on the endothelial lining, allowing them to rapidly extravasate during inflammation, and now they are proposed to coordinate further recruitment of inflammatory cells [30]. Thus, the role of Ly-6C lo monocytes during inflammation should not be discounted, though there is ample evidence that these monocytes figure quantitatively less significantly in inflammation than their Ly-6C hi monocyte counterparts [17][18][19]25,26,[32][33][34][35]. Beyond these studies, where much remains to be resolved, another body of work raises the possibility that Ly-6C lo monocytes may have a key role in presenting antigen for the purposes of driving T-independent antibody production by B cells, as we now discuss.…”

The Interaction of N-Glycans in Fcγ Receptor I α-Chain with Escherichia coli K1 Outer Membrane Protein A for Entry into Macrophages

“…This mechanism of direct binding of OmpA to Fc␥RIa NG sites is quite contrary to the mechanisms used by several other bacteria, which utilize a "Trojan horse" mechanism to enter the central nervous system (30). S. aureus avoids macrophage recognition by binding to IgG via protein A, whereas other microbes manipulate macrophage activity by secreting effector proteins (1,4).…”

Severe Condition of Scrub Typhus Meningo-Encephalitis in a Child:A Case Report from Delhi, India

“…In a report of Drevets DA shows in 5.7%-13.5% of patients suffers from Meningismus or meningitis [11]. Mahajan etal retrospectively analyzed data of scrub typhus positive cases for CNS involvement from 2004-2006 from India.…”

“…Several reports of Rickettsial diseases in India are well documented stating the disease outbreak periodically. A main diagnostic criterion includes presence of eschar at site of tick bite along with patients travel history in the endemic region [11].…”