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Flashcards in Exam 1: IS for infectious disease Deck (24):
1

A 17-year-old woman presents to your office with a fever, stiff neck, and photophobia. Patient history reveals recent sexual activity with multiple partners without the use of contraceptives. A physical examination reveals ulcers on the genitals, which only recently appeared. Which of the following is the most likely causative agent?

A. Coxsackievirus

B. Cytomegalovirus

C. Echovirus

D. Herpes Simplex Virus

E. Varicella-Zoster Virus

D.

Herpes Simplex Virus

2

In a patient with Herpes Simplex Virus, when extension to the central nervous system occurs.  What part of the CNS would be preferentially affected?

A. Cerebellum

B. Frontal lobe

C. Occipital lobe

D. Parietal lobe

E. Spinal cord

F. Temporal lobe

F.

Temporal lobe

 

• Herpes simplex has a predilection for the temporal lobe

•  The gross image shows an acute process. The microscopic image shows neurons with intranuclear inclusions

• immunohistochemistry is very helpful in identifying herpes infection.   HSV-1 is the usual infectious agent in adults.

• Neonatal HSV is more widespread; there is not a predilection for the temporal lobe.   HSV-2 is the most common agent.

3

How did the Herpes Simplex Virus likely reach the brain?

A. Direct spread from the oral cavity

B. Hematogenous spread

C. Lymphatic spread

D. Reactivation of virus latent within the brain.

E. Retrograde transport in a nerve

E.

Retrograde transport in a nerve

4

Based on the organism, Herpes Simplex Virus, which of the following is the best treatment option in this patient

A. Amphotericin B

B. Ampicillin

C. Acyclovir

D. Ganciclovir

E. Miltefosine

F. Vancomycin

 

C.

Acyclovir

5

Which of the following is the best description of the taxonomy of Herpesviridae?

A. Enveloped, icosahedral shaped viruses containing double-stranded DNA

B. Enveloped, bullet-shaped viruses containing single-stranded RNA

C. Non-enveloped, icosahedral shaped viruses containing single-stranded RNA

D. Enveloped, icosahedral shaped viruses containing single-stranded DNA

 

A.

Enveloped, icosahedral shaped viruses containing double-stranded DNA

 

6

True or False:

A person can transmit HSV-1 or HSV-2 even when they are asymptomatic.

TRUE!

 

• Even when no symptoms are present, people infected with HSV-2 shed the virus roughly 10% of the time.

• Only 25% of patients with genital herpes realize they have the virus.

• The vast majority of transmission of the virus occurs when the infected is asymptomatic (>50-70%).

• Genital herpes is one of the most common sexually transmitted disease in the world: 536 million infected, with 23.6 million new cases a year

7

During a humanitarian trip to Africa, you treat a 37-year-old man who is experiencing confusion, depression, and a fever, along with progressive paralysis of the limbs. A few days later, the patient slips into a coma and dies. Biopsy of the CNS reveals the following (see picture) Which is the most likely causative agent? What is the name of the body that the arrow is pointing to?

A. Coxsackievirus

B. Cytomegalovirus

C. Echovirus

D. Poliovirus

E. Rabies virus

E.

Rabies virus

 

• The arrow is pointing to a Negri body

Rabies infections feature the Negri bodies.  These are most easily seen in the Purkinje cells of the cerebellum

Immunohistochemistry (right image) shows that Negri bodies are often more numerous than it appears on H&E sections.

8

Based on the organism, Rabies virus, which of the following is the best treatment option in this patient?

A. Acyclovir

B. Ganciclovir

C. Human rabies immune globulin

D. Rabies Vaccine

E. Valganciclovir

C. & D.

Human rabies immune globulin & Rabies Vaccine

9

Which of the following is the best description of the taxonomy of Rabies virus?

A. Enveloped, icosahedral shaped viruses containing double-stranded DNA

B. Enveloped, bullet-shaped viruses containing single-stranded RNA

C. Non-enveloped, icosahedral shaped viruses containing single-stranded RNA

D. Enveloped, icosahedral shaped viruses containing single-stranded DNA

B.

Enveloped, bullet-shaped viruses containing single-stranded RNA

10

During summer camp, a 13-year-old boy develops a severe frontal headache, fever, and nausea. Shortly afterwards, he begins to have seizures and hallucinations. Within 3 days of the start of his symptoms, he slips into a coma and dies.  Staining of the CSF reveals the following. Which of the following is the most likely causative agent?

A. Acanthamoeba

B. Naegleria fowleri

C. T. brucei gambiense

D. T. brucei rhodesiense

E. Toxoplasma gondii

B.

Naegleria fowleri

11

Based on the organism, Naegleria fowleri, which of the following is the best treatment option in this patient?

A. Amphotericin B

B. Ampicillin

C. Acyclovir

D. Ganciclovir

E. Miltefosine

F. Vancomycin

E.

Miltefosine

12

N. fowleri

infections are obtained from _____ to _____

• Only the _____ form is infectious and is frequently isolated from the _____ of patients.

• Under adverse conditions, N. fowleri reverts to the _____ or _____ form.

Symptoms begin _____ days after exposure, death occurs _____ days after symptoms start. Initial symptoms are very similar to _____.

N. fowleri

• infections are obtained from environment-to-person only

• Only the trophozoite form is infectious and is frequently isolated from the CNS of patients.

• Under adverse conditions, N. fowleri reverts to the flagellate or cyst form.

• Symptoms begin 1 - 7 (median is 5.3) days after exposure, death occurs 1 - 12 days after symptoms start (after ~5.3 days). Initial symptoms are very similar to meningitis.

13

Primary Amebic Meningoencephalitis is most commonly associated with?

Naegleria fowleri

 

Primary amebic meningoencephalitis is most strongly associated with Naegleria infections.   Granulomatous forms can be seen with Acanthamoeba

14

A 55-year-old man is rushed to the ER after collapsing in front of his car. Disease onset was acute (<30 mins) and his symptoms include severe muscle spasms, rigid extension of the limbs, and risus sardonicus. An infection by which pathogen commonly causes symptoms similar to these?

A. Clostridium botulinum

B. Clostridium tetani

C. Poliovirus

D. Rabies virus

E. Trypanosoma brucei

B.

Clostridium tetani

 

• While classically associated with puncture wounds (anaerobic environment), tetanus can also be contracted though burns, crushing injuries, necrotic injuries, and I.V. drug use.

Symptoms typically begin 3-21 days after exposure, and include:

Headache, fever, and sweating

Jaw cramping

Sudden, involuntary muscle tightening – often in the stomach (muscle spasms)

Painful muscle stiffness all over the body

Trouble swallowing

High blood pressure and fast heart rate

15

One differential diagnosis of tetanus is _____ poisoning.  

 

• _____ poisoning has a rapid effect, using starting 30 minutes after poisoning

• While the mechanisms are distinct, the overall effect is the same as tetanusTetanus toxin prevents the release of _____ neurotransmitters (_____, _____).

• _____ poisen binds the glycine receptor, _____ glycine from _____ its receptor.

One differential diagnosis of tetanus is Strychnine poisoning

 

Strychnine poisoning has a rapid effect, using starting 30 minutes after poisoning

• While the mechanisms are distinct, the overall effect is the same as tetanus.  Tetanus toxin prevents the release of inhibitory neurotransmitters (GABA, glycine).

Strychnine binds the glycine receptor, preventing glycine from binding its receptor.

16

A 52-year-old man has recently developed insomnia along with panic attacks.  Eventually, he cannot sleep at all and experiences rapid blood pressure, profuse sweating, and vivid hallucinations. After 3 month of complete insomnia, he dies. Brain biopsy reveals extensive damage to the thalamus. What is the most likely causative agent? 

A. Acanthamoeba

B. Prions

C. Naegleria fowleri

D. T. brucei gambiense

E. Toxoplasma gondii

B.

Prions

Fatal Familial/Sporadic Insomnia

 

FFI is caused by prions and results in the progressive destruction of the thalamus.

• Note that the altered form of the protein can cause normal protein to change conformation. 

Early symptoms include moderate insomnia, occasional muscle twitching, spasms, and stiffness.

Within months of the initial symptoms, patients rapidly deteriorate. Symptoms progress and include rapid heart rate, increased blood pressure and sweating profusely.

• In the final stages, complete insomnia occurs. In the case of Michael Corke, he didn’t sleep for 6 months before dying.

17

Genetic analysis was performed on this patient’s blood.  What would be the most likely finding in analysis of the PRNP gene that is associated with the pathogenesis of fatal familial insomnia?

A.

Methionine at Codon 120

Mutant allele at Codon 179

 

*** Note the difference between Fatal Familial Insomnia and Familial CJD ***

Being associated with proteins, genetic forms of the diseases occur  The above figure shows the difference between familial CJD and Fatal Familial Insomnia. Not that the diseases differ at codon 129 on a chromosome with the mutant allele at codon 178. 

This polymorphism at codon 129 can also affect the susceptibility of a patient (non-genetic) to becoming affected with the disease.  If the patient is heterozygous at codon 129 (with no mutation at 178), it is much more difficult for the patient to become infected than if the patient were homozygous at codon 129.

18

Kuru:

Kuru is a _____ disease

• Kuru is the result of the progressive destruction of the _____ by _____ and can have a latent period of 2-23 _____.

• _____ were 9X more likely to get Kuru.

Kuru:

Kuru is a prion disease in cannibalistic tribes of Papua New Guinea.

• Kuru is the result of the progressive destruction of the cerebellum by prions and can have a latent period of 2-23 years.

Women and children were 9X more likely to get Kuru because of the (cant remember; do you know?)

19

In the 1960’s, growth deficiency was sometimes treated with administration of growth hormone derived from donated pituitaries from autopsies.   After a pituitary was donated from a patient with Creutzfeldt-Jakob disease, some of the treated children developed CJD.  What would be the most likely genetic profile of the children who developed CJD?

 

C.

MM or VV at Codon 120

Normal allele at Codon 179

 

*** Note the difference between Fatal Familial Insomnia and Familial CJD ***

Being associated with proteins, genetic forms of the diseases occur  The above figure shows the difference between familial CJD and Fatal Familial Insomnia. Not that the diseases differ at codon 129 on a chromosome with the mutant allele at codon 178. 

This polymorphism at codon 129 can also affect the susceptibility of a patient (non-genetic) to becoming affected with the disease.  If the patient is heterozygous at codon 129 (with no mutation at 178), it is much more difficult for the patient to become infected than if the patient were homozygous at codon 129.

20

What disease or disorder is shown in the image?

CJD

 

• Note the spongiform changeSpongiform change refers to the vacuoles (“holes”) that develop in the cortex of a patient with CJD

Neuronal gliosis and neuronal loss are the other microscopic components.   CJD does not show amyloid plaques.

21

What disease or disorder is shown in the image?

CJD

 

EEG changes are helpful in the diagnosis.  These can range from diffuse slowing to the more specific periodic sharp wave complexes.

22

What disease or disorder is shown in the image?

vCJD (Variant CJD)

 

• The presence of amyloid plaques surrounded  by vacuoles is seen in scrapie.  It is rare in sporadic CJD.   The classic EEG changes (periodic sharp wave complexes) are absent in vCJD

• Seen in patients in UK without a family history; younger than CJD (30’s). Started as psychiatric illness. All ate beef at some point raising question of transmission from Bovine spongiform encephalopathy-infected cattle

• Show amyloid (Kuru) plaques surrounded by spongiform change

• More involvement of thalamus

23

A 25-year-old man presented to a medical complaint with numerous neurologic signs and symptoms.  These included a history of vomiting and headache, extraocular muscle deficits (CN 3 and 6), neck stiffness, and an intermittent fever.  Imaging of his head was performed; see photograph. 

LP had elevated CSF pressure.  CSF examination showed cloudy fluid 150 cells/mm3 (normal lymphocytes 5% neutrophils.  Protein was 180 mg/dl (normal 15-45 mg/dl), glucose was 58 mg/dl (50-75 mg/dl). 

What was the most likely cause of the enlarged ventricles (lateral (both), 3rd, and 4th ventricles)?

A. Agenesis of the cerebral aqueduct

B. Blockage of both foramina of Monro

C. Cerebral abscess

D. Choroid cyst of the 3rd ventricle

E. Meningitis

E.

Meningitis

24

A 25-year-old man presented to a medical complaint with numerous neurologic signs and symptoms.  These included a history of vomiting and headache, extraocular muscle deficits (CN 3 and 6), neck stiffness, and an intermittent fever.  Imaging of his head was performed; see photograph. 

LP had elevated CSF pressure.  CSF examination showed cloudy fluid 150 cells/mm3 (normal lymphocytes 5% neutrophils.  Protein was 180 mg/dl (normal 15-45 mg/dl), glucose was 58 mg/dl (50-75 mg/dl). 

Diagnosed as meningitis. What would be the most likely cause of the meningitis?

A. Enterovirus (non-polio)

B. Mycobacteria tuberculosis

C. Neisseria meningitidis

D. Prion

B.

Mycobacteria tuberculosis

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