Nervous System Infections Lecture Notes 2024 PDF

Lecture Overview: Nervous system infections  Overview of the nervous  Norman-McKay assigned system readings:  Bacterial Meningitis  Chapter 18  Neisseria meningitidis  Abbreviations used in...

Lecture Overview: Nervous system infections  Overview of the nervous  Norman-McKay assigned system readings:  Bacterial Meningitis  Chapter 18  Neisseria meningitidis  Abbreviations used in  Streptococcus pneumoniae lecture notes:  Haemophilus influenzae  Gram positive cocci (GPC)  Listeria monocytogenes  Gram positive bacillus  Bacterial Infections (GPB) affecting PNS  Gram negative cocci (GNC)  Mycobacterium leprae  Gram negative coccobacillus (GNCB)  Clostridium botulinum  Acid-fast bacteria (AFB)  Clostridium tetani 1 MMG1650 2024 Overview of the Nervous system  Peripheral nervous system (PNS)  Nerves  Central nervous system (CNS)  Brain and spinal column  Meninges  three layers of tissue that surround the brain and spinal cord  Blood-brain barrier Figure 18.1, 18.4 Norman-McKay. Microbiology: Basic and Clinical Principles. 2019 2 MMG1650 2024 Overview of the Nervous system  Cerebrospinal fluid (CSF)  Blood-brain barrier  Produced by structures  Specialized blood vessels that within the brain deliver nutrients, O2 to CNS  Acts as a cushion  Selective barrier  Only certain molecules pass into the CNS  Only small subset of pathogens can penetrate Figure 18.5. 18.6 Norman-McKay. Microbiology: Basic and Clinical Principles. 2019 3 MMG1650 2024 Infections of CNS and PNS  The nervous system contains no resident microbiota  Any microbes within CNS/PNS are considered abnormal  Gut-Brain Axis  Influence of gut microbiota on brain function  Altered gut microbiota in:  Patients with depression  Parkinson’s Disease  many others… Figure 18.3 Norman-McKay. Microbiology: Basic and Clinical Principles. 2019 4 MMG1650 2024 Infections of the CNS and PNS  Meningitis  Routes of infection:  Inflammation of the  Hematogenous meninges  Most common route  Viral, bacterial, fungal,  Contiguous spread protozoan  Organisms can spread from  Encephalitis an adjacent site  Inflammation of the brain  Trauma  Viral, bacterial, fungal,  Breach of CNS protective protozoan barriers; injury  Meningoencephalitis  Surgery and shunts  Inflammation of the brain and meninges  Viral, bacterial, fungal, protozoan 5 MMG1650 2024  Specimen collection: Lumbar puncture  Aseptic technique; avoid skin flora  4 tubes collected:  #1 (glucose/protein levels)  #2 (microbiology tests)  #3 (cell counts)  #4 (hold/storage)  Immediate transport – do not refrigerate! https://www.cancer.gov/publications/diction aries/cancer-terms/def/lumbar-puncture https://www.thelancet.com/journals/lancet/ article/PIIS0140-6736(17)32480-7/fulltext 6 MMG1650 2024 Laboratory tests appropriate for CSF:  Cell count and differential (< 1 hour)  Normal = few WBC and rare (or none) RBC  Glucose and protein levels (< 1 hour)  NAAT testing for common viral causes (2-3 hours)  VZV, HSV, and enterovirus  If common agents are ruled out consider serology for rare agents  Bacterial culture and smear (routine c/s); 2-3 days  Positive smear considered critical result; must be called to clinician immediately  Fungal culture and smear; 2-4 weeks  Recommended only if fungal pathogen is suspected 7 MMG1650 2024 Common causes of meningitis Viral meningitis Bacterial meningitis  Common agents  Common agents  Enteroviruses, HSV, VZV  NEME, SXPN, HAIN, GBS, LIMO  Signs and symptoms  Signs and symptoms  Fever, headache, stiff neck,  Fever, headache, stiff neck, nausea/vomiting nausea/vomiting  Lab testing  Purpura and/or petechiae  CSF: cell count, glucose/protein  Lab testing levels, NAAT  CSF: cell count, glucose/protein  Prognosis levels, Bacterial culture/smear  good  Prognosis  poor 8 MMG1650 2024 Diagnosing bacterial meningitis vs. viral meningitis  Examination of CSF  Cell count  CSF protein and glucose levels  Bacterial culture and smear  NAAT testing Test Results and Bacterial Agents Viral Agents Observations Lumbar puncture High pressure released on puncture Low or no pressure released White blood cell High; Elevated, (usually 60 yrs  Transmission  Foodborne  Dairy products, deli meats, fruits/vegetables  Signs and symptoms  In healthy adults:  Mild cold symptoms  In some, acute but short-lived gastrointestinal problems  In immunocompromised individuals, pregnant people, and neonates:  More serious  Can develop into nervous system infections 16 MMG1650 2024 Listeria Meningitis (Listeriosis)  Listeria monocytogenes  GPB  Grows at low temp. (