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Medical Microbiology > Lecture 8: HIV Infection in the Immunocompromised > Flashcards

Lecture 8: HIV Infection in the Immunocompromised Flashcards

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USMLE® Step 1 flashcards Biology 101 flashcards
1
Q

HIV

transmission (4)
dx (3)

A

T: 1. blood contaminated needles

  1. unprotected sexual contact
  2. mother-fetus
  3. breast milk

dx: 1. ELISA type antibody screening- test for patient’s anti-HIV antibodies
2. Western blot-test for viral proteins in blood
3. RT-PCR to detect virus RNA in blood

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2
Q

PCR vs. RT-PCR

A

PCR detecs pathogen’s DNA

RT-PCR can detect pathogen RNA by adding a step to convert the RNA to DNA and then doing PCR

**PCR amplifies DNA nor RNA

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3
Q

HIV epidemic

A

ardor in the late 19th-early 20th century

  1. social changes and urbanization
    - disruption in tribal values that favored cause; sexual practices with multiple partners
  2. vaccination practices assoc. with colonialism
  3. increased bushmeat hunting
  4. forced labor (extreme stress depresses immune system)
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4
Q

HIV structure (5)

  • family
  • virulence
  • structure
A
  1. member retroviridae
  2. lipid-enveloped with viral gp120/gp41 envelope glycoprotein with cylindrical psuedoicosahedral capsid
    - gp120-attachment to host cell
    - gp41-promotes fusion of viral envelope with host plasma membrane
  3. 2 copies single-stranded RNA
  4. genome packed with several enzymes
  5. reverse transcriptase copies single-stranded RNS into double stranded DNA
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5
Q

Reverse transcriptase

A

enzyme capable of making a DNA copy with RNA template

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6
Q

Replication HIV (4)

A
  1. attachment and entry
    - gp20, gp41 fusion protein
    - *typically infected helper T cells
  2. Reverse transcription and integration
    - forms provirus which can remain latent
  3. Biosynthesis
    - active provirus transcribed into multiple copies now viral RNA
  4. Assembly and release
    - new capsid forms around each viral RNA genome and fever transcriptase
    - new nucleocapsids bud off plasma membrane taking up viral envelope spikes as each virion is released from the cell
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7
Q

Stage I: Primary HIV infection` (4)

A
  1. may be asymptomatic
  2. can have flu-like illness
  3. occurs within 1-2 months exposure
  4. seroconversion occurs
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8
Q

Stage II: Asymptomatic stage HIV (4)

A
  1. viral load rises
  2. as CD4T cells decline
  3. skin rashes, night sweats
  4. Diarrhea, fever, weight loss
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9
Q

Stage III: HIV infection/AIDS (4)

A
  1. steep rise in viral load
  2. CD4 count < 200 cells/mm sqared
  3. opportunistic infection
  4. death from opportunistic infection
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10
Q

Opportunistic Infections

A
  1. As immune system deteriorates due to HIV, opportunistic infections develop
  2. CD4T cells count falls bellow 200 cells/mm squared
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11
Q

Viral opportunistic diseases in HIV pts. (5)

A
  1. HIV encephalopathy
  2. progressive multifocal leukoencephalopathy
  3. shingles
  4. cytomegalovirus
  5. recurrent HSV
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12
Q

Bacterial opportunistic disease in HIV pts. (4)

A
  1. persisten pneumonia
  2. tuberculosis
  3. mycobacterium avian complex
  4. salmonella septicemia
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13
Q

Fungal opportunistic diseases in HIV pt. (5)

A
  1. cryptococcus
  2. candidiasis
  3. histoplasmosis
  4. coccidioidmycosis
  5. pneumocystis pneumonia
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14
Q

Protozoal Opportunistic Diseases HIV pts. (2)

A
  1. toxoplasmosis

2. chronic cryptosporidium diarrhea

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15
Q

Cancers in HIV Pts. (2)

A
  1. lymphomas of brain, lympatic tissue

2. Kaposi sarcoma

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16
Q

Misc. conditions affected HIV pts. (5)

A
  1. persistent dairrhea
  2. persistent generalized lymphadenopathy
  3. wasting syndrome
  4. night sweats
  5. persistent fever
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17
Q

HIV tx

A
  1. antivirals: Azodiothymidine
    - interferes with reverse transcriptase
    - chain terminator-inhibiting DNA synthesis
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18
Q

HIV resistance

A
  1. many variants become resistant to antivirals
  2. monotherapy= resistant viruses selected
  3. resistant variant becomes dominant-dishes progression
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19
Q

HAART

A

Highly Active Antiretroviral Therapy

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20
Q

HAART tx (4)

A
  1. fusion inhibitors
    - intefere with virus binding CD4
  2. reverse transcriptase
    - inhibits viral RNA conversion to DNA
  3. DNA Polymerase
    - inhibits production of a DNA copy of a virus
  4. Integrase
    - inhibits integration of viral DNA into host genome

*can keep disease from progressing indefinitely

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21
Q

Long-term Non-Progressives Def.

A
  1. indv. infected with HIV many years, w/o therapy maintain CD4 count > 500, and low viral loads
    - eventually can get AIDS if they remain untreated
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22
Q

Elite Controllers

A

HIV infected individuals with even lower viral loads and LTNP pts.

  • HLA allele allows CD8 T cells to efficiently recognize HIV infected cells
  • immume response to gag unusually strong
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23
Q

Stem cell transplant

A

transplant using CCR5 homozygous mutant has achieved “cure” of HIV in 2 patients

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24
Q

CCR5

A

co-receptor for HIV and crucial for infection in some strains

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25
Q

most common causes fungal lung infections (4)

A
  1. Histoplasma capsulatum
  2. Cryptococcus neoformans
  3. blastomyces dermatitidis
  4. coccidioides immitis
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26
Q

2 most important rx factors assoc. w acquiring fungal infection in lung

A
  1. immunosuppression
    * particularly susceptible to poor outcomes from fungal infection
  2. environmental exposure
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27
Q

Endemic Mycoses Causative agents (3)

A
  1. Coccidioides Immitis
    - coccidioidomycosis
  2. Histoplasma Capsulatum
    - histoplasmosis
  3. Blastomyces dermatitidus
    - blastomycosis pulmonary (cough, fever, chest pain, SOB)
    • skin, bone, CNS involvement
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28
Q

Where are fungi found?

A

air, soil, droppings of birds and bats

29
Q

Dimorphic Fungi

A

grow as hype in soil and yeast in vivo

30
Q

Coccidioidomycosis- fungal lung infection

pathogen (2)
found where?
transmission
sx (3)
tx
A
  1. coccidioides immitis and c. posadasii
  2. valley fever: southwest US (az and ca), mexico, central/south america
  3. typically found in soil growing as hyphae
  4. spores released when soil turned up
  5. develop into spherules in diaphragm
  6. no human-human transmission
  7. sx: cough, chest pain, fever
    - most recover in a few weeks
    - if immuncompromised, can become disseminated beyond lungs
  8. tx: amphotericin B for 6 months
31
Q

Histoplasmosis - fungal lung infection

pathogen
sx
dx
tx

A
  1. histoplasmosis capsulate
  2. found in bat guano, often asymptomatic
  3. some develop severe pulmonary and/or systemic infections
  4. sx: flu-like sx, HA, cough, chest pain, shortness breath
  5. Macrophage can ingest but cannot kill-disseminate to other organs
  6. dx: culture, antigen detection (EIA), serology
  7. tx: amphotericin B (severe) or itraconozole
    * Ohio river valley/mississippi valley
32
Q

Aspergillus- fungal lung infection

pathogens
disease
dx

A
  1. causes opportunistic mycoses
  2. Aspergillus fumigateurs, aspergillus niger, others
  3. common both indoors and outdoors, most people breath in fungal spores everyday
  4. disease= aspergillosis
  5. sx: cough, brown mucous, fever, flu-like sx, wheezing, coughing up blood, weight loss, fatigue, disseminated forms to skin, brain, eyes, liver, kidneys-poor prognosis
33
Q

Cyptococcus Neoformans

found where?
causes what disease?
sx

A
  1. opportunistic mycosis
  2. found in soil, decaying wood, tree hallows, or bird droppings
  3. causes cryptococcosis
    - affects lungs or CNS
  4. sx: shortness of breath, rales, cough, HA, nausea, nuchal rigidity, photophobia
34
Q

Cyrptococcus Neoformans lifecycle (5)

A
  1. spores
  2. inhalation in lungs
  3. lodging in alveoli
  4. dissemination to CNS
  5. positiv Culture
35
Q

Pneumocystis Jirovecii

A

*fungus

  1. life threatening infection of immunocompromised
    - also immunosuppressive medications of conditions (TNS inhibitors, cancers)
  2. acuis= person to person, from people with normal immune systems via aerosols
  3. sx: HIV= severe respiratory failure, fever, dry cough
    non-HIV= mild to moderate pneumonia
  4. dx: id organism in sample, detect DNA via PCR
    - beta-D-glucan in serum (presumptive)
  5. tx: TMP-SMX orally or IV for 21 days
36
Q

Sterilization

A

destruction ALL living microbes, spore, and viruses

-sterilized objects become contaminated when exposed to air and surroundings

37
Q

Sanitization

A

reduced the numbers of pathogens or discourages their growth

38
Q

Control

A

limiting exposure to agents

  • microorganisms are part of our environment
  • microbes can be controlled by either eliminating them or reducing their numbers
39
Q

-static

A

remains in place, reduce microbial numbers or inhibit their growth

-bacteriastatic

40
Q

-cide

A

kill

-bacteriacidal

41
Q

Heat

A

physical control method

  • fast, reliable, inexpensive
  • temperative about growth range: proteins and nucleic acids are destroyed/denatured
  • water is removed
42
Q

Autoclave Sterilization

A
  1. Pressurized stream
    - most dependable method sterilization
    - blankets, bedding, utensils, instruments, IV solutions, etc
43
Q

Limitation of autoclave (3)

A
  • plastic ware can melt
  • metal ware can become dull in heat
  • chemical breakdown can occur in the process
44
Q

Prevaccum autoclave

A
  1. draws air out of sterilizing chamber at the beginning of cycle
  2. decreases cycle time
  3. decreases exposure of sensitive materials to steam
45
Q

Pasteruization

A
  1. uses moist heat to reduce bacterial populations in liquid
  2. destroys mycobacterium tuberculosis
  3. bacterial spores not affected*
46
Q

holding/batch method

A

heats at 63 degrees C for 30 minutes in pasteurization

47
Q

flash pasteurization

A

heating at 71.6 degrees celsius for 15sec

-regular milk, only pathogens killed

48
Q

Ultra high temp method

A

heating at 140 celsius for 3sec, pastuerization
-only method capable of sterilization liquid if it is performed under aseptic conditions

-organic milk, completely sterile

49
Q

filtration

A
  1. mechanic method used to remove microorganisms suspended in liquids or gases
    - as fluid passes through filter, size threshold draped in pores
50
Q

HEPA

A

High-Efficiency Particulate Air filter

51
Q

UV light to control microbial growth

A
  1. exposure to UV light causes thymine molecules to link together-disrupts DNA replication
    - errors in protein synthesis and impairment of chromosome replication occur
52
Q

Ionizing radiation to control Microbial growth

A

x-rays and gamma rays (ionizing radiations) force electrons out of microbial molecules

  • ions combine with cellular water and form free radicals, which damage proteins and DNA in cells
  • affects cell metabolism and physiology
  • often used for preserving food
53
Q

Radiation to control microbes in food

A

radiation can control microbes in food, hopeful step for CDC in eradicating foodborne ilness

54
Q

General principles of chemical control (4)

A
  1. medicine chemicals came into widespread use in 1800s
  2. chemical agents rarely achieve sterilization
  3. but they do disinfect/destroy pathogens
  4. disinfection-process of eliminating or reducing pathogens
55
Q

Antiseptics

A

used to destroy pathogens on living tissue

-sepsis refers to contamination by microorganisms

56
Q

disinfectants

A

for non living surfaces

57
Q

sanitizing

A

reducing microbial population to a safe level

58
Q

Degermins

A

removing organisms from an object’s surface

59
Q

Antiseptics/disinfectsns properties (6)

A
  1. able to kill or slow growth of microbes
  2. nontoxic to humans and animals
  3. soluble in water
  4. storable
  5. effective quickly and at low concentration
  6. important in choosing agent
    - pH
    - temp
    - conctentration of agent
    - time-duration disinfection
60
Q

Soaps

A
  1. surface-active agents

2. remove mircobes my emulsifying and solubilizing particle on skin

61
Q

Detergents

A

surface-active agents

  1. can kill some microbes
  2. cause cytoplasm leakage from microbial membranes
  3. Quaternary ammonium compounds react with cell membranes and destroy some bacteria and viruses
62
Q

alcohol based hand sanitizer

A
  1. use when soap and water unavailable

2. at least 60% alcohol (ethyl)

63
Q

H2O2

A
  1. damages microbial components
  2. come microbes have catalase to protect them
  3. catalyst is in wounded tissue and transforms h202 to oxygen and water
  4. the oxygen is effective against anaerobic bacteris
  5. not receomned as antiseptic for open wounds
64
Q

Alehydes

A

cause cross-linking that inactivates proteins and nucleic acids

-ex0 hcutaraldehyde-sterilize medical and dental equipment, toxic and strong irritant

65
Q

ethylene oxide gas

A

effective microbicidal and sporicidal, but is carcinogenic and explosive

66
Q

chlorine dioxide gas

A

non-toxic non-carcinogenic agent

-used to decontaminate anthrax-exposed mail in 2001

67
Q

gp120

A

virulence factor HIV

allows attachment to host cell

68
Q

Gp41

A

virulence factor HIV

promotes fusion of viral envelope with host plasma membrane

69
Q

Stages HIV infection (3)

A
  1. Primary
  2. Asymptomatic
  3. AIDS

Medical Microbiology (11 decks)

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