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BLOCK 2 > Microbiology > Flashcards

Microbiology Flashcards

1
Q

Obligate intracellular parasites

A

virus

*Rely on host cell for replication

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2
Q

What are the various omponents making a viral capsid?

A

DNA or RNA + structural proteins + enzymes and nucleic acid binding proteins (nucleocapsid)

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3
Q

Virus morphology is divided into 2. We have ______and _____viruses

A
  • Enveloped
  • Non-enveloped (have a capsid component only, no envelope part)-NAKED VIRUSES. (Polio)
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4
Q

These virus types have lipoproteins lining their envelope

A
  • The enveloped viruses
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5
Q

Features of a viral envelope

A

-Glycoproteins (gp 120 n 41 with HIV)
- Lipoprotein

*Glycoproteins are also known as viral antigens

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6
Q

Where does the nuclear envelope of a virus comes from?

A
  • It is derived from the nuclear membrane of the host cell
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7
Q

Protein subunits that make up the capsid of a virus

A

Capsomers

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8
Q

Three forms of capsid symmetry, resulting from arrangement of capsomers

A
  • Icosahedral (triangular arrangement of capsomers around the viral nucleic acid)
  • helical (capsomer subunits arranged in a helical fashion around the viral nucleic acid)—ON RNA VIRUSES ONLY
  • Complex (Found on DNA viruses only)
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9
Q

Viral genome/ nucleic acid is either_________

A

-DNA or RNA never both
- Single or double stranded
- Continuous or segmented

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10
Q

These viruses are all double stranded except parvo viruses

A

DNA viruses

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11
Q

These viruses are all single stranded, except reoviruses

A

RNA viruses

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12
Q

A sense strand that can be directly translated into proteins. It has the same sequence as RNA. It functions like mRNA. Needs no further processing to code proteins.

A

positive sense strand

*+sense mRNA is found on SARS COV2 virus

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13
Q

A sense strand that acts as a temple for a + sense strand or mRNA. Cannot be directly transcribed into proteins. It needs a medium strand to convey it info of what proteins to be encoded

A

Negative sense strand

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14
Q

A classification of viruses based on their genome type and replication strategy (whether they produce mRNA)

A

Baltimore classification

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15
Q

Modes of viral transmission

A
  • Inhalation
  • Ingestion
  • Direct contact with skin or mucous membranes
  • Indirect contact (fomites)
  • Transplacental
  • Organ transplant of blood transfusion
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16
Q

What viruses cause chronic viral infections

A
  • HBV, HCV, HTLV1, HIV
  • They ‘‘flare up’’ (sudden and significant increase in viral replication)
  • May or may not be symptomatic
    -Shedding continues and therefore are infectious in varying degrees
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17
Q

What are latent viral infections?

A
  • Does not cause disease in latency periods with little or no replication
  • Remains relatively undetectable diagnostically and immunologically
  • '’Flare up’’ disease may occur if the virus reactivates (eg: Herpesviridae (eg. zoster)
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18
Q

How does Hepers Simplex Type-1 Virus (HSV-1) spread?

A

-Through close contact with infected person e.g kissing
- Sharing utensils,
- or Touching the affected area
- And through oral sex, causing genital herpes

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19
Q

Pathogenesis of HSV-1?

A

HSV-1 can remain dormant in nerve cells near the site of the initial infection (typically the trigeminal ganglia) and reactivate periodically.

*Latency and reactivation are its features
*Triggers of reactivation: illness, fever, sun exposure, hormonal changes, menstruation, stresss

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20
Q

Two types of HSV

A
  • HSV-1: facial herpes (above the waist; gingivostomatitis, fluid-filled blisters or sores around the mouth or on the lips, herpetic whitlow-skin infection, HSV keratitis-infctn of cornea,
    encephalitis, pneumonitis)
  • HSV-2: associates with genital infections (below the waist – genital herpes, encephalitis,
    meningitis)
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21
Q

HSV infection of newborn within 28 days of birth

*results from transmission of virus during delivery through infected genital secretions from
mother

A

Neonatal herpes

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22
Q

Diagnoses of type 1 HSV

A
  • Clinical presentation (gingivostomatitis-fluid filled blisters around the mouth/on lips)
  • (LAB)
    -Viral culture
    -Immunofluorescence staining
    -Serology
    -Polymerase chain reaction (PCR)
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23
Q

Is there possible cure for HSV?

A

No,

There is no cure for HSV-1, but antiviral medications such as acyclovir, valacyclovir, and famciclovir can help reduce the severity and duration of outbreaks and decrease the frequency of recurrence.

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24
Q

Episodic Topical creams to reduce frequency of HSV

A
  • Acyclovir cream
  • Docosanol cream
  • Penciclovir cream
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25
Q

Different types of HIV diagnostic tests?

A
  • Rapid point-of-care: measures antigens and antibodies
  • At-home tests: measures antibodies
  • Standard point-of-care: measures anitbodies
  • Nucleic acid test: measures HIV RNA
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26
Q

How is adenovirus transmitted from one person to the next?

A
  • Usually enter host by inhalation of droplet
  • Or by oral route
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26
Q

Direct inoculation of _______virus onto nasal or conjunctival mucosa by hands, contaminated towels, or ophthalmic medications may occur

A

Adenovirus

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27
Q

A virus that replicates in epithelial cells, producing cell necrosis and inflammation

A

Adenovirus

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28
Q

Large number of patients are asymptomatic, but mostly presents with features of URTI.
Which virus cud they be infected with?

A

Adenovirus

*Affects multiple organs

29
Q

Diagnostic methods of adenovirus

A
  • PCR routinely done
  • High specificity and sensitivity
  • Respiratory sample – swab or aspirate
30
Q

Adenovirus has no treatment, just a drug helping with symptom management. What drug is this?

A

Cidofovir

31
Q

Infection with this virus is prevented with live-viral vaccine (enclosed-enteric capsules), where viruses are administered orally into your small intestine

A

Adenovirus

32
Q

Diagnostic techniques of adeno-virus

A
  • Serology
  • Molecular
  • Culture
33
Q

What are the 3 analytic stages of microbe diagnostic cycle

A
  • Post-analyticstage
    -Final Reports
    -Doctor interprets report and treats appropriately
    -Record keeping
  • Pre-analytic stage
    -Patient consultation and clinical diagnosis
    -Appropriate specimen collection
    -Transport to lab
    -Registration in the laboratory
  • Analytic stage
    -Direct examination and specimen processing
    -Presumptive Reports
34
Q

The Triumphant Trio

A

Three essential components or approaches that are crucial for effectively identifying microbes and their possible inhibitors:

  • microscopy
  • Culture
  • Susceptibility test
35
Q

What can a doctor learn from microscopy results?

A

The gram stain result will tell her/him whether his choice of antibiotic covers that group
of organisms empirically (fairly broad)

36
Q

What can a doctor learn from culture results?

A

name of the microbe

37
Q

What a doctor can learn from susceptibility testing?

A

the results will tell him if his choice of antibiotics will work on this exact strain of the
organism

38
Q

Normative ways of diagnosing viruses

A

Molecular methods

39
Q

How to possible isolate bacteria and fungi in a single patient sample?

A

Grow them on the surface of solid nutrient media, to get a pure culture of each organism

*Such a medium normally consists of a mixture of protein digests (peptone, tryptone) & inorganic salts,
hardened by the addition of 1.5% agar

40
Q

Culture media used for antibiotic susceptibility testing

A

Mueller Hinton agar plate

41
Q

What is the basic quantitative measure of in vitro activity of antibiotics?

A

MIC

42
Q
  • The lowest concentration of the antibiotic that results in inhibition of visible growth
A

MIC

43
Q

What are the methods used to carry out antimicrobial susceptibility testing?

A
  • Disk diffusion: (Kirby-Bauer)
  • Antibiotic gradient strips: (Etest®)
    -Broth microdilution
  • AUTOMATED- Vitek
44
Q

Remains the gold standard

A

Culture based diagnostic

45
Q

What makes non-culture based samples favorable over culture based samples?

A
  • Non-culture based does not need sample from sites of infection, it uses blood samples.
46
Q

What 3 diagnostic tests are considered non-culture based?

A
  • Molecular tests
  • Antigen detection
  • Immunoassays- antibody tests (serology)
47
Q

Examination of blood serum regarding the response of your immune system to the pathogen

A

Serology test

*We looking at antibodies produced

48
Q

1st antibody to be produced with every pathogen infection, but has a shorter half-life.
*clears sooner

A

IgM

*Produced in 7-10 days after infection, and lasts for 1-3 months

49
Q

An antibody produced with persistent, chronic infections and has a longer half life
*doesn’t clear up for a very long time

A

IgG

50
Q

How many genes does HIV genome have?

A

9 genes

51
Q

What are the 3 structural genes of HIV?

A
  • Gag – encodes group antigen and structure of capsid
  • Env – making of the envelope gene
  • Pol – codes for the polymerase
52
Q

What are the 3 common modes of HIV transmissions?

A
  • Sexual
    -Main mode of transmission
    -Accounts for 70−80% of all HIV infections
  • Parenteral
    -Blood transfusions (estimated risk from a single unit of HIV-infected whole blood is > 90%)
    -Contaminated needle pricks
    -Needle sharing among HIV-infected drug users
  • Vertical (perinatal)
    -In utero, during labour and delivery, and through breastfeeding
53
Q

What cells does HIV targets
And how does it bind to them?

A

-HIV targets CD4 T cells. Binds to their receptor, as well as their co-receptor.
-It also targets macrophages, binding their receptor and core receptor

54
Q

What’s a core receptor of CD4 T cell to which HIV binds?

A

CXCR4

55
Q

What’s a core receptor of macrophage to which HIV binds?

A

CCR-5

56
Q

What’s the HIV entry pathway into the host cell?

A

Endocytosis

57
Q

What’s the host DNA called after it has been integrated with tht of HIV (HIV) by intergrase?

A

proviral DNA

57
Q

What’s the process by which HIV exits the host cell called?

A

Budding

58
Q

Who can have immunity against HIV 1?

A
  • Individual without a CCR5 receptors
  • Homozygous persons: those with two deleted CCR5 gene segments are homozygous for the CCR5Δ32 mutation
59
Q

A cell surface receptor primarily found on immune cells, including T cells, macrophages, and dendritic cells; utilized by the majority of HIV strains during the initial stages of infection

A

CCR-5

60
Q

Which 2 groups of Individuals, may not be on ART treatment (may be excused)?

A
  • Elite Controller: someone who can keep nearly undetectable levels of virus, without antiretroviral therapy
  • Long Term Non-Progressor: someone who maintains a normal count of CD4 and CD8 T-cells for a minimum of 10 years without the aid of antiretroviral therapy
61
Q

What are the 2 main approaches to testing for HIV?

A
  • Antibody based e.g HIV ELISA (Ag/Ab combo), HIV Rapid Test
  • Nucleic Acid Testing e.g HIV DNA PCR

*These 2 are impacted by age of a patient (which one to use depend on patient age)

62
Q

What’s a preferred HIV diagnostic strategy for children <18 months?

A

HIV nucleic acid test

*We cannot use HIV ELISA test coz it tests HIV antibodies. And martenal antibodies take over affecting credibility of the results

63
Q

What’s a preferred HIV diagnostic strategy for individuals > 18 months?

A

-HIV ELISA test

*Detects antibodies to HIV

64
Q

What is the goal of ART?

A

ART must result to viral load below the limit of detection in 3-4 months following initiation

*CD4 count expected to increase by 50 -100 cells/mm3 in the first month and thereafter increase much slower

65
Q

HIV can be measured in blood products. Or, u can measure viral load in patient’s blood. What assay test is best used for this?

A

Quantitative molecular assay/Viral Load Assays

*Predict disease progression
-Assist with deciding when to initiate anti-retroviral therapy
-Monitors response to antiretrovirals

66
Q

What’s the enzyme responsible for reverse transcription of HIV?

A

Reverse transcriptase

67
Q

What are the 2 forms of viral infections?

A
  • Inapparent infections
    -Asymptomatic
  • Apparent infections
    -Acute
    -Chronic (persistent, latent)
68
Q

The process by which viruses are released from infected cells and spread to infect other cells or individuals.

A

Shedding

69
Q

What’s the NUCLEIC ACID TEST used in early neonate diagnoses of HIV, mapping out marternal antibodies?

A

HIV qualitative PCR (HIV 1 DNA PCR)

*Detects virus b4 the viral load is present

70
Q

What are characteristics of ‘slow growing virus’ and its exaple?

A
  • Longer incubation period for like years
  • Virus replicates without causing disease
  • Cause disease years later, at the end of the infectious period

example JC virus

BLOCK 2 (56 decks)

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