4.2.2_Micro

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Author:
sirchubbsalot13
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12351
Filename:
4.2.2_Micro
Updated:
2010-04-04 14:18:13
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Meningitis Encephalitis
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CNS infections
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  1. Causes of primary headaches
    • tension
    • migraine
    • cluster
    • idiopathic
    • exertional
  2. Causes of secondary headaches
    • vascular disorders
    • hemorrhage
    • brain tumor
    • infection
    • head injury
  3. What symptoms imply that you REALLY should worry about a headache?
    • worst ever
    • first severe headache
    • worseing for days
    • abnormal neurological Sxs
    • vomiting
    • fever/systemic Sx
    • pain on bending/lifting/coughing
    • disturbs sleep
    • known systemic infection
    • onset after age 55
    • pain w/ localized tenderness over temple regions
  4. Meningitis or Encephalitis
    bacterial = septic serious
    aseptic usually viral (alternatives are mycobacterial, fungal, noninfectious)

    Meningitis
  5. Meningitis or Encephalitis
    acute, subacute, chronic
    infectious, postinfectious, noninfectious
    Encephalitis
  6. 2.5 cases/100,000/yr10% deaths, 20% survivors w/ sequelae
    Predominantly pediatric dz (75% <15yrs)
    Usual pathogens part of normal upper resp. flora
    Infection is a rare manifestation of colonization
    Bacterial Meningitis
  7. Etiologic agents of bacterial meningits
    a) newborns
    b) most others
    c) >60
    d) post trauma
    e) immune suppressed
    • a) newborns: E coli, Gp B strep, listeria
    • b) others: S pneumo, Nisseria mening, haemophilis
    • c) >60: pneumo, mening, GNB (gram neg. bacteria), pseudomonas, listeria
    • d) post trauma: pneumo, staph aureus, GNB, pseudomonas
    • e) immune suppressed: listeria, cryptoc, CMV, herpes viruses, mycob, toxo, JC virus
  8. Name the illness:
    fever
    headache
    stiff neck
    nausea/vomiting
    lethargy/reduced mental status
    seizures (rarely seen)
    URI symptoms
    Meningitis

    Differential dx: other infections, CV dz, malignancy, medication, other causes of delirium
  9. How would you confirm a suspected meningits?
    • Bacterial meningits: Elevated protein (>100), low glucose (<50), and really high cell count (PMNs) -- obtained via spinal tap (may need to repeat 6-8 hrs later)
    • Then perform a gram stain (rapid test) to confirm the organism (works 80%)
  10. Brain abscess
    Lateral vein thrombosis
    subdural effusion or empyema
    long term sequelae (deafness, hydrocephalitis, mental defects, ataxia, seizures)
    complications of meningitis
  11. collagen vascular dz's like SLE (systemic lupis)
    sarcoidosis
    Behcet's syndrome
    subarachnoid hemorrhage
    malignancy
    durg hypersensitivity (ibuprofin and other NSAIDs, sulfonamides, cipro, heavy metals)
    Noninfectious causes of inflammation in and around the brain (meningitis or encephilitis)
  12. What should the practicing physician do if he suspects bacterial meningitis based on the clincial triad of symptoms?
    give antibiotics immediately (you don't have time to wait for lab results, but send them to confirm diagnosis)

    clinical triad of symptoms: fever, headache, stiff neck
  13. Short chains of cocci
    9 polysaccharide capsule types
    lower GI tract is major reservoir
    Frequent colonizer of female GI tract (10-30%) -- can lead to invasve dz in neonates
    infections in elder too
    Group B streptococcal
  14. What causes:
    Acute infection in neonates: fever, lethargy, poor feeding, resp. distress (meningitis or sepsis present)
    Late onset of neonatal infections (1-3 months)-- meningitis, focal infection of bone/joint
    Adults: women postpartum
    Elderly: pneumonia, meningitis, UTIs
    Group B strep (dz states)
  15. Gram + bacilli
    Colonies on culture plates look like Grp B strep
    Eleven serotypes
    Can grow in cold temps (refrigerators)
    Colonizes many animals
    Transmission to humans often by food (sausage, hot dogs, etc)
    Lysteria monocytogenes
  16. Common cause of food borne outbreaks of diarrhea
    Multiple major meat product recalls
    Serious dz: meningitis/bacteremia in newborns
    Listeria clinically

  17. Short gram + rods (may appear like cocci, may appear in pairs)
    Small zone beta hemolysis
    Catalase positive (all streps are catalase neg.)
    Tumbling motility
    Listeria (lab tests)
  18. Member Enterobacteriaceae
    Neonatal Meningitis (transmitted at time of birth)
    E. coli
  19. Important cause of meningitis in all age groups (predominantly babies and young adults, but all age groups affected)
    Multiple serotypes (A,B,C,Y,W135)
    Associated w/ both individual cases (sporadics) and epidemics
    Outbreaks on college campuses (recommendations for immunization)
    Normal flora in 5-15% of young adults
    Colonization increases in closed pops.
    Recurrent and severe infections associated w/ complement deficiencies of C6,C7,C8
    Neisseria meningitidis
  20. Meningococcal syndrome
    • Meningococcemia
    • Meningits
    • Waterhouse-Frederichsen syndrome (catostrophic)
    • Chronic Meningococcemia
    • Skin rashes we don't see with other pathogens
  21. Vaccine: polysaccharide vaccine against A,C,Y,W135 (not B)
    Antibiotic prophylaxis: intimate contacts in households (Rifampin still used, but antibiotic resistance has been described)
    Meningococcal prevention
  22. Free living ameoba found in shallow, fresh water (like warm weather)
    Miningitis in summer months from swimming
    Traverses nasal mucosa through cribiform plate to CNS
    Starts olfactory bulbs and spreads in tissue
    Severe bifrontal headache, seizure, changes in taste/smell
    Death in days
    Naegleria (50 cases/yr in US)
  23. Intracellular parasite
    Oocysts are the "eggs" and are only created by sexual reproduction in cats (mature in soil)
    Tissue cysts are capsulated collections of the trophozite form of the organism in muscle, brain, heart of intermediate hosts
    Humans can ingest either oocysts (cats) or tissue cysts (undercooked meats) to become infected
    Clinical: congenital dz (transmission in utero, catastrophic CNS dz)
    Normal host dz: 2nd most common cause of mono
    Immunosuppressed host: pneumonitis, myocarditis, encephalitis
    Encephalitis: Multiple cystic lesions in the brain of Pt's-- often seen in HIV dz.
    Toxoplasma
  24. Coxsackie and echovirus
    HHV6 (human herpes virus 6)
    HIV
    Adenovirus
    EB virus
    CMV
    Mumps
    LCM
    Arboviruses
    HSV
    Rabies
    Viruses causing encephalitis
  25. Vaccinia
    Measles
    VZV
    Rubella
    EBV
    Mumps
    Influenza
    Viruses causing postinfectious encephalitis
  26. Acute febrile illness
    headache, fever
    altered consciousness
    disorientation
    bx disturbances (change in personality)
    focal neurological signs
    seizures
    Clinical manifestations of acute encephalitis
  27. Most common cause of sporadic disease
    No seasonal pattern
    1/3 <20, 1/2 >50 have had it
    Not linked to immune status
    70% mortality; few w/ full recovery
    HSV1 the cause (except newborns)
    begins in temporal lobe
    HSV encephalitis (herpes simplex virus)
  28. 25% have hx of cold sores
    insidious or abrupt onset
    fever always
    headache
    temporal signs: personality change, terror, hallucinations, bizarre behavior
    40% get seizures
    1/3 have hemiparesis
    Aphasia (superior visual field cuts, facial parasthesias)
    May have rapid progression to coma and death
    EEG: slow wave activity
    HSV clinical manifestations
  29. Most freq. cause of encephalitis world-wide (not US)
    Mosquito and Ticks are vectors
    Usually transmitted from birds/horses
    Often have asymptomatic seroconversion
    Pathogenesis: subcutaneous inoculation of virus by insect => local replication => spread to endothelial cells and RE system => spread to liver/brain/blood vessels => cell death and inflammation
    Arbovirus (West Nile)
  30. Diagnosis of Encephalitis: Lab
    • in general should see: moderately elevated protein, moderate pleocytosis w/ monocytes, normal glucose (3-5% have normal CSF)
    • Amplification tests (PCR) best for HSV, potentially enteroviruses)
    • Serologies: IgM helpful for arboviruses
    • Cultures of little to no value for viruses
  31. Prevention of Encephalitis
    • Tracking of target reservoirs, cases essential
    • Immunization for preventable dz's
    • Arboviruses: mosquito control, insect repellents
    • Rabies: immunization of pets, control of wild animal contact, postexposure vaccination.
  32. Incidence reported as 10-15% of all cases
    Vaccinia and measles used to cause most
    Resembles other forms, but hx includes: exanthem or prior resp, tract illness
    Is felt to be a form of autoimmune response to recent infection
    Postinfectious Encephalitis
  33. Rabies epidemiology
    • Zoonotic of animals: Raccoons, skunks, bats in US (foxes in europe)
    • Animal exposure is important, but bite is not commonly present
  34. Mania
    hyperactivity followed by somnolence
    paralysis
    hydrophobia
    virtually always fatal
    Manifestations of Rabies
  35. Differences between meningitis and encephalitis
    • Bx changes in enchephalitis
    • Neck stiffness w/ meningitis
    • Quick onset w/ meningitis
    • Encephalitis can take days, weeks and even months
    • Meningitis more likely to be associated w/ rash
    • Lab: # of cells (normal CSF is possible with encephalitis)
    • Anatomy of meninges
    • Infections (bleeding/hematomas) can happen in each of these spaces
  36. Describe the flow of CSF, where it is made, and what purpose it serves.
    • Made in choroid plexus (mostly)
    • Flows through brain ventricles, cord, optic n., and surface of brain to arachnoid granulations, then into venous blood.
    • Makes brain buoyant, reduces trauma, chemical barrier.
  37. What type of infections occur in the
    a. epidural space
    b. subdural space
    c. subarachnoid space
    d. brain
    • a. epidural abscess (from nearby infection-- staff)
    • b. subdural emyema (staph or strep-- mass effects: headaches, fever, seizure, vomting, etc)
    • c. meningitis
    • d. abscess

  38. Has abundant neutrophils in subarachnoid space
    • Bacterial meningits (notice there are no neutrophils in the brain cortex
    • (compare to normal meninges)
    • .
  39. Necrotizing vasculitis (bacterial meningitis)

  40. Necrotizing vasculitis causes this.
    Infarct

  41. Usually self-limited -- resolved in 7-10 days.
    Lymphocytes, not PMNs in blood and CSF
    • Viral meningitis (aseptic simply means the viral agent was never found)
    • Enteroviruses are most common cause

  42. Rare except in immunocompromised
    Headache, effets of edema (minimal inflammation)
    • Fungal meningitis (cryptoccus)
    • confirmed with india ink prep of CSF

  43. In meninges, but also invades brain
    See caseating granulomas as in other sites
    Can have slow or fulminant course, poor prognosis
    TB Meningoencephalitits

  44. 2nd most common serious CNS infection (to meningitis)
    Caused by Hematogenous spread -- bacterial endocarditis, dental extraction, congenital heart dz w/ R to L shunt, immunocompromised.
    Direct spread: penetrating head trauma, sinusitis
    Presentation: mass effects, high intracranial pressure
    Focal Signs: May or may not have features of sepsis
    Treatment: drainage or removal plus antibiotics
    Brain Abscess

  45. From cat feces or raw meat
    causes mild or no illness if healthy (problomatic in AIDS and fetuses)
    Severe necrotizing encephalitis
    Altered mental state, focal neurol changes
    Ring enhancing hypodense on CT
    Intracellular cysts
    • Toxoplasmosis (protozoa)
    • Toxo antigen EIA, serology, biopsy
    • Intracellular cysts and free tachyzoites

  46. Rare in US, common in Latin America, Africa, Asia
    Most common cause of seizures worldwide
    From undercooked pork or pig feces (pig tapeworm)
    • Cysticercosis -- confirmed by western blot

  47. Usually in neutropenic Pts
    Candida Fungal abscess

  48. Angioinvasive, from sinus infection
    Causes infarct
    Aspergillus

  49. Patchy lymphocytic infiltrate in brain (microglial nodules)
    HIV can directly involve CNS, causing dymentia
    Commonly caused by: HSV, Rabies, Arbovirus, Enterovirus, Mumps, Measles, Lymphocytic Choriomeningitis, JC virus and others
    Viral encephalitis --

  50. 70% death rate without Rx
    Severe sequelze common in survivors
    Mostly in temporal lobes
    Fever, HA, personality changes, seizures
    Viral encephalitis -- herpes simplex (oral herpes often absent)

  51. Long incubation (months to a year) while virus climbs to brain from peripheral nerves
    Tingling at bite site, then manic, somnolent, hydrophobic, paralyzed, death (survival is very rare)
    See red inclusions in neurons (negri bodies at arrows)
    Rabies -- Viral Encephalitis (mostly from raccoons, skunks, and bats in US)
  52. Clinical presentation: Fever, malaise, mental status changes, miningeal irritation signs (headache, stiff neck, irritable, n/v)
    Spinal tap: culture. microscopic exam, protein, glucose, Gram stain, sometimes antigen-antibody testing for specific organisms
    Sequelae: immediate & short term: sepsis, DIC, seizures, herniation, sinus thrombosis
    Late: hydrocephalus, seizures, cranial nerve changes, infarcts
    Bacterial Meningitis
  53. Aseptic meningits agents
    • Enterovirus (coxsackie, Echovirus)
    • Arthropod borne agents
    • HSV
    • HIV
    • (measles and mumps)
  54. Reproduce in gut (although they do not necessarily produce GI dz)
    Worldwide distribution (5-10 million symptomatic infections/yr)
    Major cause of aseptic meningitis in children and young adults (90%)
    Enterovirus
  55. 90% of aseptic meningitis in children and young adults
    fever, chills, headache, photophobia, n/v
    Nonspecific: diarrhea, myalgias, rash, pleurodynia
    Rare complications or sequelae
    Encephalitis (rare): lethargy, disorientation, seizures (paralysis, Guillan-Barre have also been seen)
    Enteroviruses in the CNS
  56. Outcomes of Aseptic meningitis
    • a benign dz
    • Death is rare
    • No long term sequelae
  57. Prevalent in dust containing bird droppings
    Different subtypes
    Pathogenesis: capsule that promotes attachment and invasion
    Organism inhaled and disseminates from lung
    Causes Meningitis (other sites: lung, bone skin, prostate)
    Cryptococcus neoformans
  58. Cryptococcus skin rash
  59. Cryptococcus skin abscess

  60. Notice the budding yeast. (organism is black)
    Variable size of yeast cells. Only yeast that causes CNS disease.
    Cryptococcus
  61. Diagnosis of Cryptococcus
    • Direct antigen test of CSF or blood.
    • On india ink (budding yeast)
    • Very wet appearance on agar (cultures easily)
    • The capsule is the clear part around the pathogen.

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