University:
University of Alberta
Course:
MMI 133 | Medical Microbiology for Health Care Professionals
Academic year:

2024
Views:

491

Pages:

2
Author:

Ali O

Lecture 2 Meningitis: inflammation of the meninges ↳ usually caused by microbes infecting the cerebral spinal fluid (CSF) Meninges: coverings of the brain and spinal cord Neisseria meningitidis (one type) Sometimes called meningococcus (sing.) (pl. meningococci) · microbial, contagious, only affects humans · Gram negative diplococcus (pink) with capsule ↳ the capsule protects the bacteria from white blood cells · >12 serotypes ↳ serotypes are groups or subtypes of a single species of microorganism which share distinctive surface structures · Most epidemics are caused by 6 Serotypes (A, B, C, W-135, X, Y) Transmission: droplet (cough, sneeze, saliva) ~1m Virulence: capsules, endotoxin, pili, IgA protease ↳ endotoxin has Lipid A as part of the molecule (this is the endotoxin) Pathogenicity: - attaches to epithelial cells in the throat. - invades and can go to the bloodstream and /or CSF - endotoxin activates blood clotting, leads to DIC, hemorrhage, and shock - Bacteria evade phagocytosis due to capsule to survive and reproduce in the CSF Meningococcal meningitis: (inflamation/infection of the meninges) · increased pressure to the brain · influx of white blood cells to CSF · death if untreated, if treated early has very good prognosis Meningococcal sepsis: (replication of bacteria in the bloodstream) · disseminated infection, can occur quickly, gram negative sepsis, intravascular coagulation (clotting), may need amputation · death if untreated, or if treated too late 90-95% chance of survival if diagnosed and treated early Meningitis symptoms Symptoms and Disease Meningitis: headache, stiff neck, photosensitivity, nausea, sore throat, petichiae, coma, death Sepsis: fever, petichiae/purpura, shock, hemorrhage, DIC -internal organ meltdown, eventual death Diagnosis Treatment · Gram stain CSF and report to physician specimens (NOT BEFORE! ) · serogroup for epidemiology (public health) culture confirmation · Aspirate CSF and/or blood · Administer antibiotics directly after taking culture · Culture and/or EIA or PCR · Empirical antibiotic treatment: best guess before · ascertain susceptibility to antibiotics · Administer correct drugs after culture confirmation Vaccine (3 types) · Testing done on cultures ① Polysaccharide (uses capsule material as a vaccine) Public Health Issues · 90% protection for 2-5 years · Rapid ID of contacts ② Conjugated · Vaccination of susceptible · good for children < 2 years and immunosuppressed individuals · Health prevention info · effective against 4/15 types (A. C, Y, W-135) · Rapid ID of disease · cannot be used for children < 2 years · Prophylactic antibiotics · polysaccharide combined with a protein individuals · serogroups (A, C, W, Y) · Reportable disease used the most because they last longer better immune response ③ Type B Vaccine · based on proteins in cell wall NOT capsule Textbook page 382-386 for more info and types