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Term 3/4 Flash Cards > Micro - CNS > Flashcards

Micro - CNS Flashcards

1
Q

Herpes Virus 1&2

A

All
All
None

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2
Q

West Nile Virus

A

All
Older adults
Summer - Fall

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3
Q

EEE Virus

A

Atlantic & Gulf Coast and Great Lakes
Children
Summer - Fall

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4
Q

WEE Virus

A

Western US & Canada
Infants & Older adults
Summer - Fall

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5
Q

California Encephalitis Virus

A

Midwest & NE US; S. Canada
Older children
Summer - Fall

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6
Q

Enteroviruses

A

All
Infants & children
Summer

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7
Q

Varicella-Zoster Virus

A

All
Children & Immunocompromised
Winter

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8
Q

Hematogenous (Important for abscesses)

A
  • Meningococci from respiratory epithelium
    - West Nile virus through insect bite
  • Rubella virus via transplacental transmission
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9
Q

Neural

A

- Rabies peripheral nerves to nerve axons to
ganglia and spinal cord to brain
- Human Herpes viruses 1-3 through nerves

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10
Q

Direct inoculation through trauma or

injury - Penetrating head trauma and surgery

A

- Most common- Staph. aureus

- Immunodeficient or HIV infections- Nocardia, Aspergillus, Candida

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11
Q

Most common bacterial etiology

A 
 Aerobic and anaerobic streptococci,
 Bacteroides
 Enterobacteriaceae  Psudomads
 Fusibacterium
 Peptococcus
Mouth- mixed biota
Lungs- Streptococci, Fusibaterium,
Corynebacterium, Peptococcus sp.
Heart- Strep. viridans, Staph. aureus
Urinary tract- Enterobacteriaceae, Pseudomonas
Wounds- Staph. aureus
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12
Q

CNS Syndromes

A

Meningitis
- Acute Meningitis- viral or bacterial
- Chronic Meningitis- fungi and tubercle bacilli

Encephalitis- viral

Brain Abscesses
- Acute Brain Abscess- generally poly microbial
- Chronic Brain Abscess- tubercle bacilli, fungi and protozoa

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13
Q

Tests for Meningism

A

- Demonstrate inability to flex the neck and touch the chin to the chest
- Demonstrate inability to oppose the nose with the knees
- Tripod sign- inability to sit without making a tripod with hands
- Kernig’s sign- patient’s leg can not be straightened because of hamstring spasm
- Brudzinski’s neck sign- patient retracts the legs when neck is lifted

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14
Q

Dx of CNS infxns - Neuroimaging

A

Helpful in partial differentiation of viral
encephalitis
- Japanese B virus: grey matter involvement
- Nipah virus: multiple, small, white matter lesions
- Human herpes virus-1: hemorrhages
- Abscesses and empyema differentiation

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15
Q

Causes of aseptic meningitis

A

Common

  • Viruses - Enteroviruses (ECHO), Arboviruses*, HHV-2
  • Bacteria - Borrelia burgdorferi, inadequately tx’ed bacterial meningitis

Uncommon
- Viruses - Mumps, HHV-5 (CMV), HHV-6,
HIV
- Bacteria - Mycobacterium tuberculosis, Leptospira sp*, Mycoplasma pneumoniae

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16
Q

Enteroviruses

A

Picornaviridae. Class IVa, ss (+) RNA Naked icosahedral viruses
Resistant to pH 3-9, detergents, and heat
Transfecting viruses
Eradicated from W Hemisphere through OPV

Over 90% of viral meningitis d/t Enteroviruses
Other syndromes caused by Enteroviruses include;
Hand-foot and mouth dz, Herpangina, Myocarditis, Pleurodynia, Acute hemorrhagic conjunctivitis

Worldwide distribution. Humans are the only reservoir
Asx infxns are common
Show seasonality;
Temperate climates- Summer to Fall (water)
Tropical climates- year-round (fecal-oral)
Infants and children MOST susceptible

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17
Q

Polioviruses

A

Picornaviridae, same viral characters as Enteroviruses
Spreads through fecal-oral route by consuming contaminated food and water
Direct contact with infected stool or throat secretions

Clinical syndrome:
Acute Flaccid Paralysis, due to infxn of ant horn of grey matter

Pathogenesis
Infects enterocytes of GIT. Transverses intestinal wall through BM
Moves into gut-associated lymphoid tissue, e.g. Peyer’s patches (site of primary replication)
Viremia seeds peripheral tissue, virus enters the neurons of the PNS that innervates the peripheral tissues, and the virus traffics to CNS using retrograde axonal transport.

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18
Q

Polioviruses - outcomes of infxn

A
  • Inapparent infxns - 95% asx, virus in RES
    Dx: virus isolation from feces and oropharynx, and by specific serum Abs
  • Abortive polio (minor illness)- flu like sx’s. Similar to any systemic viral infxn
  • Polio encephalitis- RARE
  • Non-paralytic polio (aseptic meningitis) Similar to other enteroviral meningitis
  • Paralytic polio (<2% of cases) - Viral spread nmlly restricted* d/t:
    Limited rep of virus in PNS
    Insuff retrograde axonal transport in PNS
    Innate resistance through IFN α/β production
    When these barriers are breeched outcome is paralytic:
    Spinal- Flaccid paralysis d/t lysis of ant horn cells
    Bulbar- paralysis of CNs IX and X, medullar/respiratory centers
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19
Q

Poliovirus vaccines

A

Live oral vaccine- Sabin vaccine stable at room temperature w/ MgCl2. Produces secretory Abs.
Virus can spread to contacts and enhance herd immunity and may cause paralytic polio (~1 in 4 million)

Inactivated vaccine - Formalized Salk vaccine injected i.m.
Local Ab is not produced. Mostly used in W. Hemisphere (where polio is considered eradicated)

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20
Q

Birth to 3 months

A

Most common: Streptococcus agalactiae

Others: Escherichia coli, L. monocytogenes

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21
Q

3 to 60 months

A

Most common: Streptococcus pneumoniae

Others: Neisseria meningitidis H. influenzae type b

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22
Q

> 60 months

A

Most common: Streptococcus pneumoniae

Others: Neisseria meningitidis, L. monocytogenes, Other Gram negative organisms

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23
Q

Any age (cranial surgery)

A

Most common: Staphylococcus aureus

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24
Q

Any age (immunosuppressed)

A

Others: L. monocytogenes, Other Gram negatives (including P. aeruginosa)

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25
Q

Very young

A

Neonates- Strep agalactiae, Coliforms and Listeria monocytogenes
Infants- Streptococcus pneumoniae, Neisseria meningitidis, and H. influenzae
Children- Strep. pneumoniae, N. meningitidis and Listeria monocytogenes
Streptococcus pneumoniae most common except neonates
More than 75% of total cases are caused by N. meningitidis, Strep. pneumoniae and H. influenzae, combined

26
Q

Bacterial virulence factors

A
  • Neisseria meningitidis - Capsule, IgA protease, pili, and endotoxin
  • Haemophilus influenzae - Capsule, IgA protease, pili, and endotoxin
    - Streptococcus pneumoniae - Capsule, and IgA protease only
27
Q

Neisseria meningitidis

A

Gram neg, intracellular (PMNs), human pathogen
Members of genus can be commensals of URT
Transmission via droplet inhalation
>1/3 of cases occur in neurologic or other sequelae

Dx: Signs- rash (Tumbler test), sepsis, fever,
nuchal rigidity, CSF tap, Culture- fastidious organism requires 5-10% CO2
Blood or CSF sample- plate on chocolate agar
Nasopharyngeal swab- plate on to Modified Martin-Thayer agar (contains abxs to inhibit normal biota)
Rapid techniques Latex agglutination, PCR

Tetravalent vaccine composed of Grps A, C, Y, and W135 (Grp B is weakly immunogenic)
Protection is grp-spec, lim to ~3 years. Does not protect from carrier status. Poorly immunogenic for infants under 2 years of age

28
Q

Strep agalactiae

A

Gram pos Grp B Strep, Beta hemolytic, Taxos A resistant.
Nml female genital organism (~40% colonized))
60% mortality for babies who develop meningitis during first wk of life -> Premat birth is imp risk factor

Neonates - lethargy, fever, sepsis and resp distress
Children and adults - puerperal fever at delivery and other skin and soft tissue infxns

29
Q

Strep pneumoniae

A

MOST COMMON cause of bacterial meningitis
Gram pos, lancet shaped, alpha hemolytic, Taxos P sensitive cocci (Optochin). Part of nml biota of 20% adults and >75% healthy children

Highest cause of infantile meningitis. Mort rate for pneumococcal meningitis ~25%
Neurological sequelae is ~50% In elderly, may follow pneumonia, otitis media, sinusitis

30
Q

Strep pneumoniae pathogenesis

A

• Hydrogen peroxide - d/t absence of catalase, large amounts accum and enhance apoptosis
• Pneumolysin
• pore forming toxin
• Potent neurotoxin; can trigger cellular apoptosis
• In mouse models, invasion can occur through
nasopharynx (not hematogenous)
• Teichoic and lipoteichoic acids of cell wall mediate binding to gangliosides on neurons (confused as normal cargo)
• Subsequent travel via retrograde axonal transport along olfactory neurons

31
Q

Haemophilus influenzae

A

Gram neg, fastidious encapsulated pleomorphic organisms
Spread via blood from resp tract to brain
Infxn opportunity between 4 mos to 3 yrs
Greater risk of perm neurologic dmg than any other bacterial meningitis
Vaccines made with type B capsular polysaccharide

32
Q

Escherichia coli K1

A

Gram neg, facultative anaerobes
During preg, increased colonization of K1 strain with 8% mortality
Spreads from nasopharynx to meninges

Sx’s
 <1 month old- irritability, lethargy, vomiting, lack of appetite and seizures
 4-18 months - nuchal rigidity, tense fontanelles, and fever
 Older children & adults- headache, vomiting, confusion, lethargy, seizures and fever

33
Q

Klebsiella pneumoniae

A

Gram neg rods, high incidence in cockroach infested areas
Early onset - s - Lethargy, poor feeding, little cry, fever, sclerema
Culture from blood, CSF, urine. C-reactive protein positive

34
Q

Listeria monocytogenes

A

Gram pos, non-spore-forming, aerobic, motile rods

Epidemiology
- Food-borne (dairy and deli). Soil, water, decaying vegetation
- Human intestines may be reservoir, 2-12% humans carry the organism
- Can be transmitted to baby during delivery (may cause spont abortions)

Dx
- Intracellular gram pos rods in macs and neutrophils
- CSF culture - looks like β-Strep, but catalase + , and “tumble”

35
Q

Listeria monocytogenes pathogenesis

A

- Grows in macs
- Releases “Internalin A & B”- cell attachment molecule which trigger entry
- Hemolysins- pore-forming toxin. Allows escape from phagosome to the phagosol.
- Listeriolysin O - prot that helps movement w/in cell
- 2 Phospholipase Cs- help break cell mem
- ActA - Uses host cell actin to move to new cells

36
Q

Spirochetes: Treponema pallidum

A
  • Early stages are infectious w/no CNS involvement
    - Takes about 10+ yrs for non-tx’ed cases
    - Neurosyphilis is Tertiary stage of dz and no longer infectious
    - DTH is part of pathologic mechs of tissue dmg
    - Commonly found in diff tissues as “Gummas”
  • Infxn of CNS via meningovascular route

Sx’s: CNS degen chg -> mental changes. May have frank psychosis. Shuffling gait. Tabes dorsalis

Dx: Spinal fluid. Elevated WBCs and protein. VDRL positive

37
Q

Leptospira interrogans

A

Animals are reservoirs. Spreads through animal urine, contaminated water and food (survives weeks in water)

No body of water in the US is free from it
Sensitive to Acid pH, drying and soap
Sewer workers, miners, vets and meat packers at risk

Sx’s

  • Incubation 7-13 days (range 5 days - 4 weeks)
  • Bacteremic phase - influenza-like sx’s and fever (bacteria NOW enter the CNS)
  • 2nd Phase- ~3+weeks
  • HA w/ “aseptic” meningitis
  • Sometimes hemodynamic collapse

Dx: blood culture, CSF analysis and culture, rise in Ab between acute and convalescent stages

38
Q

Borrelia burgdorferi

A

~15% neurologic abnormalities, rarely fatal

Sx’s
Classic “bull’s eye” rash, fever, joint pain, meningeal irritation
- 2nd Stage- dissemination system wide
- 3rd Stage- mild neurologic or frank encephalitis

Dx: loose irreg spirals, silver or immunofluorescent stain. Difficult to culture. CDC recommends Ab screen using ELISA

39
Q

Cryptococcus gattii

A

 Associated with Eucalyptus trees and/or seeds, foliage
 Not associated with pigeons
 Inflicts immunocompetent people
 Children and elders killed in a week
 Mainly a pulmonary disease (75%) but causes meningitis in ~9-10% of the cases
 Blindness through optic neuropathy

40
Q

Naegleria fowleri

A

Freshwater amoeba
 Reported cases in Kansas, Virginia and Florida
 1 death in South Carolina Diagnosis by CSF microscopy

 In contrast, meningoencephalitis caused by Acanthamoeba spa., Balamuthia mandrillaris, and Sappinia diploidea are more slowly evolving and usually require a brain biopsy with PCR to diagnose the infection.

41
Q

Encephalitis etiology

A

 Viral: Herpes viruses, enteroviruses, arboviruses, rabies virus, HIV, HTLV-1, Paramyxoviruses (Nipah virus, mumps, rubeola virus) and arenaviruses
 Bacterial (RARE) - Exceptions: Legionella pneumophilia, Borrelia burgdorferi, Treponema pallidum
 Fungal - Cryptococcus neoformans and C. gattii
 Parasitic - Plasmodium falciparum, Trypanosomes

Encephalitis - inflam of brain parenchyma. Encephalitis is considered clinically a more severe syndrome than viral meningitis

Sx’s
 HA, Fever, Altered consciousness-lethargy to confusion and coma, Behavioral and speech disturbance, Sz’s

42
Q

Encephalitis - Arboviruses

A

 Arthropod-borne viral infections, worldwide. Transmitted by mosquitoes and ticks. Sporadic and epidemic encephalitis

 Seizures are generally the complications in children.

 All arboviruses env viruses w/icosahedral nucleocapsid and contain transfecting RNA
Major families of arboviruses (Togaviridae and Flaviviridae)
 Togaviridae - Belongs to Baltimore Class IVb. Early and late proteins made. Virus buds at the plasma membrane

43
Q

Venezuelan Equine Encephalitis (VEE)

A

 Togaviridae (alphavirus)
 Spread through Culex and Aedes mosquitoes
 Sx’s: Prodrome- fever, chills, weakness, headache, myalgia (due to viral replication). Rapid progression- nuchal rigidity, confusion, somnolence, seizure in 50% of cases and coma (d/t spread through microvascular permeability of brain, then cell-to-cell occurs via axon and dendrites)
 NO DEATHS in humans , 80% mortality in horses

44
Q

Eastern Equine Encephalitis (EEE)

A

 Togaviridae Common in North America
Spreads through Aedes and Culiseta sp
 Humans are dead-end hosts but Aedes may spread from horse to human
 Clinical symptoms similar to that of VEE
 HIGH MORTALITY in humans

 Large number of active virus entering in brain parenchyma. Affects perikaryon and dendrites of neurons w/minimal glial cell infiltration

45
Q

Western Equine Encephalitis (WEE)

A

 Togaviridae Spreads through Culex and Culiseta
 Common in rural areas of US in summer months
 Fatality rate 3-4%, death in 1-2 days. Children have a 30% chance of CNS sequelae

 Dme mediated by large number of immunologically active cells that enter brain
 Cell death by apoptosis primarily in the glial and inflammatory cells

46
Q

Encephalitis - Flaviviruses

A 
 Belongs to Baltimore class IVa
 Polyprotein is translated first which cleaves into many individual proteins
 Virus buds inside cytoplasmic vesicles and the virus is released through exocytosis
47
Q

St. Louis Encephalitis virus (SLE)

A

Flavivirus. Transmitted by culex mosquitoes
 Overt infection depends upon:
Efficacy of replication at extra neural sites
 Degree of viremia
 Age of the host
 Pathophysiology
 Virus enters through BBB (astrocyte complex)
 Or cross fenestrated endothelium (choroid plexus)

Sx's
 Mortality 2-20% (higher in elderly)
 Malaise and fever only 20% develop sequelae (irritability, mem loss, movement d/os, motor deficits)
 Seizures and coma COMMON
 No chronic illness
48
Q

Japanese B Encephalitis virus (JBE)

A

 Flavivirus. Spread through Culex mosquitoes. Incubation 4-14 days.
Rural areas of Asia
 Sx’s
 Viral prodrome- fever by 2nd week
 Encephalitis syndrome with tremors NOT seizures
 Low CSF IgG/IgM ratio= higher death rate

49
Q

West Nile Encephalitis virus (WNV)

A

 Flavivirus.
 Epidemiology
 Wild birds are reservoir, spreads through Aedes mosquitoes. 3-15% fatal. Very RARE person to person transmission.
 Sx’s:
 Viral prodrome with maculopapular rash on
trunk and extremities
Headache, HIGH fever, nuchal rigidity, stupor, tremor and seizures, paralysis, Guilline-Barre` syndrome

50
Q

Bunyaviridae

A

 Enveloped viruses containing single-
d RNA
 Spreads through mosquitoes, ticks and flies
 California Encephalitis virus  La Crosse virus

51
Q

Lyssavirus: Rabies

A

Rhabdoviridae. Bullet shaped virus. Single-stranded, negative polarity RNA. Helical nucleocapsid in an envelope
 5 proteins- N,P,M,G and L
 Surface glycoprotein attaches to cell receptors including Acetylcholine receptor at neuromuscular junctions

Pathophysiology
Viral entry into cell via endocytosis. Preference for nerve and salivary gland cells (travels via axons to CNS)
 Spreads from brain to salivary glands, kidneys and conjunctival cells (virus in tears)

Sx’s
 Incubation 20-90 days, may extend to a year
 Nonspecific – general malaise, fever, HA
(tingling pain and weakness at bite site)
 Progressive - neurologic sx’s, including insomnia, confusion, slight or partial paralysis, agitation, hypersalivation, dysphagia (hydrophobia)
 Paralytic –disorientation, stupor
 Death w/in days after sx’s (~7 days)

 Dx:
 Saliva- virus isolation, RT-PCR
 Serum and CSF for rabies Abs (FA and ELISA)
 Brain tissue- Negri bodies, Babes nodules consisting of glial cells

52
Q

Polyoma virus (JC virus)

A

Papovaviridae. PML (Progressive Multifocal Leuko-encephalopathy)
Viral DNA in majority of healthy humans
 Multifocal signs including; hemiparesis, visual loss, sz’s, dementia, personality changes and gait problems
 Characteristic white matter lesions common in posterior occipital area

53
Q

Paramyxoviridae

A

Class V, single-strand, linear, negative polarity RNA viruses.
 Hendra virus; affecting horses
 Nipah virus (Barking pig syndrome)  Mumps virus
 Rubeola virus

54
Q

Nipah virus

A

Paramyxoviridae. Belongs to genus Henipavirus. Endemic in Malaysia, Singapore, and Bangladesh.
 Spreads through bats feces/urine /saliva contaminated fruit juices.

55
Q

Rubeola virus

A

Paramyxoviridae. SSPE (Subacute Sclerosing Pan Encephalitis)
 Slow fatal condition after more than 10 years of
measles
 Worldwide, more common in boys (3:1) than girls
 Behavior changes in school age children
 Fulminant course- 10% of cases death in 3 months
 Chronic course- death in 4-10 years

56
Q

Other virus infxns of CNS

A

 Arenaviridae- Lymphocytic Choriomeningitis
 Togaviridae- Rubella virus
 Herpesviridae- Human Herpes virus 1-8
 Retroviridae- HIV-1

57
Q

Frontal brain abscess

A

Predisposing factors: sinusitis, dental sepsis

Organisms:
Streptococci, Bacteroides, Staph. aureus, Hemophilus spp.

58
Q

Temporal brain abscess

A

Predisposing factors: Otitis media, Mastoiditis

Organisms:
Streptococci, Bacteroides, Enterobacteriaceae

59
Q

Frontal,Temporal,Parietal etc brain abscesses

A

Predisposing factors: Trauma, penetrating wound

Organisms:
Staph. aureus, Clostridia

60
Q

Multiple brain abscesses

A

Predisposing factors: Infective endocarditis, Congenital heart disease, Lung abscess

Organisms: Staph. aureus,
Streptococci (viridans gp) Fusibacteria, Nocardia

61
Q

Fungal brain infxns

A

 Disseminated hematogenously from remote
sites (lungs and oropharynx)
 Create multiple areas of infection within brain
 Meningoencephalitis occurs early through
vascular invasion
 Etiology
 Aspergillus,Cryptococcus,Candida

Term 3/4 Flash Cards (7 decks)

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