Bacterial meningitis pathophysiology
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Bacterial meningitis Microchapters |
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Diagnosis |
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Treatment |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Aysha Anwar, M.B.B.S[2]
Overview
Pathophysiology
Pathogenesis of bacterial meningitis is a complex process which may occur due to imbalance between the host immune response and virulence factors of pathogen causing infection. Following steps may explain the underlying process in a comprehensive way:
Transmission
- H. influenza type b and N. meningitides may be transmitted by close contact or prolong contact with patient suffering from meningitis[1]
- It may also spread by exchanging throat and respiratory secretions (couging and kissing)
- Listeria monocytogenes may spread by eating contaminated food.
- Most people are carriers and do not develop the disease.
Colonization and evasion of host immune response
- Colonization of pathogenic organism involves evasion of host immune response mechanism.
- IgA protease produced by bacterial pathogen cleave mucosal IgA antibodies which prevent the bacteria from attachment to the mucosal surface. [2][3]
- Once host immune response is evaded, bacteria attach themselves to the mucosa via fimbriae or pilli which facilitate colonization process.
Invasion and seeding
- Once colonized, the invasion of bacteria occurs via special adhesion proteins called adhesins.[2]
- Adhesins may help bacteria to cross epithelial barrier intracellularly or intercellularly.
- Bacteria seeds transcellularly to enter the intravascular space.
- Surface encapsulation may play important role in entry of bacterial pathogen across epithelium into blood stream
- Blood stream entry of bacterial pathogen may result in activation of complement pathway and inflammatory process[4]
- Bacterial capsule helps evasion of complement system and ultimate entry into the CNS through blood brain barrier[4]
- Individual genetic susceptibility and immune response determine the severity of infection
Meningeal infalmmation
- Meningeal inflammation follows bacterial invasion into the blood.
- Bacterial entry into brain may occur through highly vascularized areas such as leptomeningeal blood vessels or choroid plexus.
- Intracranial entry of bacterial pathogen through tight junctions of blood CSF or blood CNS barrier may occur through special interaction of adhesins and proteins on the surface of choroid epithelial cells[5]
Associated conditons
Following conditions may increase the susceptibility to develop bacterial meningitis:
- Trauma to skull
- HIV
- Diabetes mellitus
- Organ transplant
Role of Genetics
- Genetic polymorphism in the individuals may determine the susceptibility to develop bacterial meningitis, the severity of infection and the ability to recover.[6]
- Single nucleotide polymorphism in the complement system may determine the increased or decreased susceptibility to develop bacterial meningitis in these patients[7][8]
Gross pathology
Microscopic pathology
References
- ↑ https://www.cdc.gov/meningitis/bacterial.html Accessed on 10th Jan, 2017
- ↑ 2.0 2.1 Stephens DS, Farley MM (1991). "Pathogenic events during infection of the human nasopharynx with Neisseria meningitidis and Haemophilus influenzae". Rev Infect Dis. 13 (1): 22–33. PMID 1901998.
- ↑ Plaut AG (1983). "The IgA1 proteases of pathogenic bacteria". Annu Rev Microbiol. 37: 603–22. doi:10.1146/annurev.mi.37.100183.003131. PMID 6416146.
- ↑ 4.0 4.1 Joiner KA (1988). "Complement evasion by bacteria and parasites". Annu Rev Microbiol. 42: 201–30. doi:10.1146/annurev.mi.42.100188.001221. PMID 3059994.
- ↑ Brown EJ, Joiner KA, Gaither TA, Hammer CH, Frank MM (1983). "The interaction of C3b bound to pneumococci with factor H (beta 1H globulin), factor I (C3b/C4b inactivator), and properdin factor B of the human complement system". J Immunol. 131 (1): 409–15. PMID 6223077.
- ↑ Brouwer MC, de Gans J, Heckenberg SG, Zwinderman AH, van der Poll T, van de Beek D (2009). "Host genetic susceptibility to pneumococcal and meningococcal disease: a systematic review and meta-analysis". Lancet Infect Dis. 9 (1): 31–44. doi:10.1016/S1473-3099(08)70261-5. PMID 19036641.
- ↑ Brouwer MC, Read RC, van de Beek D (2010). "Host genetics and outcome in meningococcal disease: a systematic review and meta-analysis". Lancet Infect Dis. 10 (4): 262–74. doi:10.1016/S1473-3099(10)70045-1. PMID 20334849.
- ↑ Adriani KS, Brouwer MC, Geldhoff M, Baas F, Zwinderman AH, Paul Morgan B; et al. (2013). "Common polymorphisms in the complement system and susceptiblity to bacterial meningitis". J Infect. 66 (3): 255–62. doi:10.1016/j.jinf.2012.10.008. PMID 23068452.