INFD3012 Infectious Diseases: LT 7 Central Nervous System Infections 2024 PDF

INFD3012 Infectious Diseases: LT 7 Central Nervous System Infections Dr Megan Steain Infection, Immunity and Inflammation School of Medical Sciences Faculty of Medicine and Health [email protected] The University of Sydney...

INFD3012 Infectious Diseases: LT 7 Central Nervous System Infections Dr Megan Steain Infection, Immunity and Inflammation School of Medical Sciences Faculty of Medicine and Health [email protected] The University of Sydney Page 1  Copyright COMMONWEALTH OF AUSTRALIA Copyright Regulation WARNING This material has been reproduced and communicated to you by or on behalf of the University of Sydney pursuant to Part VB of the Copyright Act 1968 (the Act). The material in this communication may be subject to copyright under the Act. Any further reproduction or communication of this material by you may be the subject of copyright protection under the Act. Do not remove this notice The University of Sydney Page 2  Learning Objectives – Describe how pathogens access the CNS – Compare and contrast the features of meningitis, encephalitis and brain abscesses and give examples of the pathogens responsible for each – Describe a prion and how it can be transmitted and lead to disease – Explain how different infectious agents can cause damage to the CNS – Recall methods to diagnose and treat different types of CNS infections The University of Sydney Page 3  Divisions of the nervous system Nervous System Central Peripheral Nervous System Nervous System (CNS) (PNS) Brain Spinal Cord Somatic Autonomic http://visual.merriam-webster.com/human-being/anatomy/nervous-system/central-nervous-system_1.php The University of Sydney Page 4  Protection against CNS infection – Bones of skull and vertebral column – Meninges – Dura mater – Arachnoid mater Subarachnoid space: CSF and major arteries – Pia mater – The blood-brain barrier Kristensson, 2011, Nature reviews Neuroscience The University of Sydney Page 5  The blood-brain-barrier – Specialised endothelial cells that line blood vessels in brain – Form tight junctions with adjacent cells – Wrapped by astrocytes and pericytes Dahm et al., 2016, Mediators of Inflammation The University of Sydney Page 6  Pathogen entry into the CNS – Direct invasion via bloodstream – Cross endothelial cells Direct infection e.g. Poliovirus Transit between tight junctions e.g. Neisseria meningitidis Disrupt BBB e.g. Nipah virus – Trafficking via infected blood cells E.g. HIV, L.monocytogenes The University of Sydney Page 7  Pathogen entry into the CNS – Retrograde axonal transport from peripheral nerves The University of Sydney Page 8  Pathogen entry into the CNS – Olfactory route Olfactory neurons are exposed to external environment Allows for axonal transport of pathogens Kristensson 2011. Nature reviews: Neuroscience, Vol 12. The University of Sydney Page 9  The olfactory system and Naegleria fowleri The University of Sydney Page 10 https://onlinelibrary.wiley.com/doi/full/10.1111/j.1574-695X.2007.00332.x?sid=nlm%3Apubmed Pathogen entry into the CNS – Direct spread Contiguous infection e.g. sinuses, mastoid Following surgery or trauma Charlton et al.m BMJ Case Rep 2019; 12 The University of Sydney Page 11  Patterns of CNS infection – Meningitis Infection of arachnoid mater and cerebrospinal fluid (CSF) in subarachnoid space and cerebral ventricles Inflammation of meninges – Encephalitis Widespread infection within brain or spinal cord Characterised by abnormalities of brain function – Myelitis Infection of spinal cord – Abscess Localised collection of pus The University of Sydney Page 12  Meningitis – Bacterial (pyogenic) or Viral (aseptic) – Symptoms include: Fever Headache Neck stiffness Photophobia Others: focal neurological deficits, seizures, skin rash (meningococcal) – Absence of both parenchymal brain involvement and spinal cord inflammation The University of Sydney Page 13  Bacterial meningitis – Bacterial pathogens responsible vary with age of patient – High morbidity and mortality – Neonates (