Infectious Agents Flashcards

1
Q

What are common symptoms of meningitis?

A
  • HA
  • Neck Stiffness
  • Fever
  • Photophobia
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2
Q

What are the most common causes of viral meningitis?

A
  • Coxsackie Virus
  • Echovirus
  • Arbovirus (Mosquito)
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3
Q

If a healthy 34 year old male presents to the ED with a headache with a fever and CT reveals a well-circumscribed lesion, what might be the infectious agent responsible?

A
    • Staph Aureas

- - Strep

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4
Q

What are characteristic findings of brain abscesses to have a confirmatory diagnosis?

A
    • Well-circumscribed lesion with central necrosis
    • Fibrotic Wall of collagen
    • Numerous PMNs surrounding
    • “Ring Enhancement Lesion” on imaging
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5
Q

What might be the CSF findings of TB-associated meningoencephalitis?

A
    • Elevated Lymphocytes

- - Low Blood Glucose

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6
Q

What are unique characteristics of TB-meningoencephalitis?

A
    • Enhancement of the base of brain on MRI + vasculitis
    • Tuberculoma - mass lesion w/ central caseous necrosis with Epithelial Histiocytes / Giant Cells
    • Pott’s Disease - granulomatous process of vertebral bodies leading to cord compression
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7
Q

What chronic infection is manifests with general paresis, meningovascular meningitis, and tabes dorsalis?

A

Treponema Pallidum

    • gradual cognitive impairment
    • chronic multifocal arteritis–infarctions-thickening of vessels walls until occulsion
  • -Lightning pains, loss of positional-vibrational senses
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8
Q

If on an after death autopsy you unconver perivascular lymphocytic infiltrates, microglial nodules, and neuronophagia; what might have been a pathologic process occurring at the time of death?

A

Viral Encephalitis

–Those symptoms are consistant with general viral encephalitis

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9
Q

A 27 year old female presents to the emergency department with abnormal behavior according to friends and erratic moods complaining of a headache several days ago. What might be found on MRI scan?

A

HSV1 Most Likely

  • Focal abnormalities of the Temporal Lobes
  • Hemorrhagic inflammatory necrosis / swelling
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10
Q

If a biopsy what taken of an individual thought to have Herpes Simplex encephalitis what might they find?

A
  • Intranuclear inclusion bodies

- Cowdry Type A Cells

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11
Q

Contrast the patient populations who acquire HSV1 and HSV2 encephalitis?

A

HSV1 – General Population

HSV2 – Neonates who acquire HSV2 from active infection in the mother during birth.

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12
Q

How is Arbovirus acquired and when should you be suspicious of Arbovirus?

A

Mosquitos – Season, most common during the summer.

Epidemic Encephalitis – when several people in the community contract it.

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13
Q

What virus most common affects Microglial cells?

A

HIV

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14
Q

What are the symptoms associated with chronic HIV infection?

A

Infect Microglial Cells

    • develop HIV Encephalitis over time (years)
    • Cognitive/Behavioral deterioration
    • Ataxia / Tremor
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15
Q

What histologic findings is consistent with HIV encephalitis?

A

Microglia Nodule with Multinucleated microglial cells

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16
Q

What conditional affects the oligodendrocytes?

A

Progressive Multifocal Leukoencepholopahty

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17
Q

What is responsible for Progressive Multifocal Leukoencephalopathy?

A

Reactivation of JC Virus

– Immunocompromised individuals

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18
Q

How does Progressive Multifocal Leukoencephalopathy affect the brain?

A
    • Affects white matter
    • numerous irregular small focal areas of demyelination of the white matter
    • oligodendrocyte inclusions
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19
Q

What might you find with Apergillus / Mucor encephalitis?

A

– Vasculitis causing small localized hemorrhage infarcts

if Aspergillus – vessels infiltrated with hyphae

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20
Q

Where does Cryptococcosus come from and how does it end up infecting the brain?

A

Immunocompromised individuals

    • Bird Poop
    • Infects the lungs first, then hemagenously spreads to the brain cauing encephalitis/abscesses
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21
Q

What are histologic findings with Cryptococcus?

A
    • Thickening of the Meninges from chronic inflammation
    • Intraparenchymal cysts – “Soap Bubbles”
    • Yeast form of fungi
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22
Q

If you become infected with Toxoplasma what might the pathologic findings be?

A
  • Very small areas of necrosis throughout the brain

- Organisms free in tissue in pseudocysts

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23
Q

What are the common causes of Epidural / Subdural empyemas?

A

Hematagenous spread from ENT infection

    • Strep
    • Staph
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24
Q

What is the common clinical presentation of Prion Disease?

A

Rapid progression of dementia, ataxia, myoclonic jerking
– EEG = triphasic waves 1-2s
– MRI = increased signal in basal ganglia
Symptom onset progression in months, death within a year.

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25
Q

What are the most common causes of Prion Disease?

A
  • Idiopathic – Creutzfeld-Jakob Disease (50%)
  • Inherited (15%)
  • Acquired from Surgery
  • Eating Cow w/ Mad Cow
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26
Q

What is the mechanism of action of the abnormal proteins in Prion Disease?

A
  • Abnormal PrPsc infiltrates the body and is able to interact with normal PrPc proteins changing them into abnormal versions
  • PrPsc do not degrade normally and aggregate in the brain causing the symptoms
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27
Q

What is the most common cause of meningitis?

A

Strep Pneumoniae

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28
Q

What is the most common types of meningitis in children less than 1 year old?

A

Neisseria Meningitidis

Group B Strep

29
Q

What is commonly found in adults over the age of 50 and/or immunocompromised?

A

Listeria Meningitis

30
Q

What types of bacteria can cause meningitis after surgery or neurosurgery?

A

Skin Bacteria

  • Strep Agalactiae
  • Staph Epidermis
31
Q

What might be the causative agent in an individual with meningitis symptoms progressive over several weeks?

A

Cryptococcus – immune compromised

32
Q

What causative agent might be at fault for development of meningitis during the summer months?

A
    • Enterovirus

- - Arbovirus / Borrelia Burgdorfi / Ricketti – Mosquitos

33
Q

What is the most common etiology of meningitis of a 2 year old who lives in a closed community?

A

– Haemophilus Influenza

34
Q

What are the differences in CSF findings when evaluating for meningitis?

A

Bacteria – Elevated PMNs, Low Glucose
Viral – Elevated Lymphocytes, Normal Glucose
Fungi – Elevated Lymphocytes, Low Glucose

35
Q

What should be started as empiric therapy for a 57 year old male with negative gram staining CSF?

A
  • Ceftriaxone
  • Vancomycin
  • Corticostertiods
  • Ampicillin – only if gram negative and 50+ (Listeria)
36
Q

What are the two most common causes of meningitis?

A
  • Strep Pneumoniae - everyone

- Neisseria Meningitis – under 1 and 16-21 year olds

37
Q

What is the most common means of acquiring meningitis from strep pneumoniae?

A

– Pneumonia first, then has hemagenous spread into the blood brain barrier – Meningitis

38
Q

What serotype is not protected with the Neisseria conjugate vaccine?

A

Serotype B – due to reactivate to human self-antigens

39
Q

Who are most suspectible to Haemophilus Influenza meningitis?

A

Between the ages of 3 months and 3 years

40
Q

What is the the capsule made from of the most virulent strain of Haemophilus?

A

Ribose / Ribitol – Type B

41
Q

Why is an infant not suspectible to Haemophilus immediately after birth?

A

– due to maternal antibodies circulating for up to 3 months

42
Q

What are the characteristics of Haemophilus?

A
  • gram negative

- small coccibacilli

43
Q

What does the Haemophilus vaccine consist of and how does it prevent infection?

A
  • PRP-D + Diptheria (Conjugate Vaccine)

- Induces a T-cell dependent response producing Memory T-cells

44
Q

If a CSF sample gram stains positive with diplococci, what might be the organism?

A

Strep Pneumoniae

45
Q

What are the virulence factors of Neisseria?

A
  • Lipooligosacchride
  • Polysacchride Capsule
  • Fimbriae - attachment
46
Q

How does Neisseria go about causing meningitis?

A

– Fimbriae attaches in the Nasopharynx, then Lipooligosacchride induce immune response and it can slip into the blood-brain barrier

47
Q

Who are the patient populations most susceptible to Neisseria infections?

A
  • Under 1 year old
  • 16 - 21 years old attending college-close quarters
  • Asplenic individuals
48
Q

What patient population is recommended to get the MCV4 vaccine?

A

MCV4 — Neisseria Conjugate Vaccine

– Anyone under the age of 55

49
Q

How is the MPSV4 Vaccine different from the MCV4?

A

MCV4 - Conjugated Vaccine
MPSV4 – Polysacchride Non-conjucated
– Used for 55+ individuals expanded coverage of strains of Neisseria

50
Q

How is the Neisseria presentation unique in meningitis?

A
  • Very Rapid Progression of symptoms and demise after infiltrating the CNS
51
Q

What extra precaution should be taken when dealing with Neissera?

A

– Any contact with the patient should receive prophylaxis Antibiotics

52
Q

What are the characteristics of Strep Pneumoniae?

A
  • Gram Positive diplococci

- Alpha-hemalytic

53
Q

What other regions does Strep Pneumoniae infect besides the CNS?

A
  • Otitis Media
  • Pneumonia
  • Pharyngitis
  • Sinusitis
54
Q

When might you give the PPSV23 vaccine to a patient?

A

After they turn 65 for an expanded spectrum of protection from strep pneumoniae
– polysacchride vaccine

55
Q

What is the PCV13 vaccine used for?

A

Conjugate Vaccine against Strep Pneumoniae

– Given to Everyone

56
Q

What patient population might Strep agalactiae meningitis be found in?

A
    • Neonates / Preterm Infants

- - Bacteria resides in the mothers vagina and can infect the baby as being delivered.

57
Q

You can prevent Strep Group B from infecting a neonate on delivery?

A
    • Prophylaxis can be given to the mother if she previously had a child infected
    • Penicillin
58
Q

Is there a vaccine for Strep Agalactiae? What is the treatment?

A

No there is no vaccine.

– Treat with Penicillin

59
Q

What are the characteristics of Rabies virus?

A
  • Rhabdovirus / Rod Bullet shaped
  • (-)ssRNA
  • Can bind ACh receptors throughout the body getting into the PNS
60
Q

When the rabies virus is replicating, does it cause the host cell to die?

A
  • No.
61
Q

How does the rabies virus go about infecting the CNS?

A
  • enters through an abrasion / bite in the skin / transplant
  • variable latent period
  • enters PNS carried into the CNS
  • once into CNS rapid replication, then spread distally
62
Q

What are the tissues most common associated with rabies infection?

A
  • Eyes
  • Salivary Glands
  • Hair Follicles
63
Q

What site of infection would cause a more rapid progression of rabies disease?

    • Ankle Bite
    • Abdominal Scratch
A

Abdominal Scratch with rabies infected animal, closer to the CNS.
– further away the longer it takes

64
Q

What are the initial symptoms of a rabies infection?

A
  • Nervousness
  • Anxiety
  • HA / Fever/ Nausea
65
Q

What are the end-stage symptoms of Rabies?

A
  • Crazed Behavior / Aggressive
  • Hydrophobia
  • Flaccid Paralysis
66
Q

How can you diagnose an individual with Rabies?

A
    • Most commonly focal neurologic symptom with a history with possible exposure
    • Sometimes: Negri Bodies / Direct Flourescence Antibodies
67
Q

What is the most common exposure to Rabies in North America?

A
  • Bats / Rabid Wild Animals
68
Q

What is the post-exposure prophylaxis when exposed to Rabies? Is it time sensitive?

A
    • Give Passive Immunization HRIG/ERIG (immunoglobin) in order to prevent the spread of the virus from its localized infection point
    • Begin Vaccine at the same time x4 doses
    • Somewhat time sensitive, but sooner rather than later