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Year 2 PODT > Microbiology D > Flashcards

Microbiology D Flashcards

1
Q

what does selective toxicity mean and how is this achieved

A

Antimicrobials are intended to be drugs that kill microorganisms but do not harm the host cells

Antibacterials Selectively toxic by targeting:

  • Cell wall
  • Protein synthesis
  • Process of DNA supercoiling
  • Folate metabolism
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2
Q

name two bacteria classes that act on the cell wall

A
  1. Beta-lactams

2. Glycopeptides

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3
Q

name two bacteria classes that act on the cell wall

A
  1. Beta-lactams:
    - penicillins
    - Penicillin/ beta-lactamase
    inhibitor combinations
    - Cephalosporins
    - Monobactam
    - Carbapenems
  2. Glycopeptides
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4
Q

name some bacteria classes that are protein synthesis inhibitors

A

macrolides
aminoglycosides
tetracyclines

quinolones - DNA supercoiling

others - folate metabolism

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5
Q

what is a bacterias spectrum activity. what is meant by broad spectrum

A

The range of bacteria that a given antibiotic is able to kill

Antibiotics effective against a large variety of medically important organisms

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6
Q

describe the start smart then focus guidelines for infection treatment

A

Start smart:

  • Do not start antibiotics in the absence of clinical evidence of infection
  • Thorough drug allergy history*
  • Rapid assessment for Sepsis
  • Comply with local guidelines [microguide app
  • Document diagnosis and treatment
  • Document review and stop date
  • Obtain cultures prior to starting treatment
Then focus:
Clinical review, ideally with microbiological results at 48-72 hours:  Document decisions:
		1. Stop
		2. IV to oral switch
		3. change antibiotic
		4. Continue
		5. OPAT (Outpatient Parenteral Antimicrobial Therapy)
Document all decisions
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7
Q

how do you Take a thorough allergy history

A

What drug

When did you take it (i.e. What age were you)

How long after taking the drug did the adverse reaction start (type 1, IgE reactions tend to be immediate)

Describe the reaction (paying attention to the appearance of rash- urticarial rash tends to be caused by histamine and so may be IgE mediated)

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8
Q

what drug is ok to give after a life threatening reaction to penicillin

A

Monobactam Aztreonam

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9
Q

what drugs are ok to give after a non-life threatening reaction to penicillin

A

Cephalosporins
Cefuroxime, Ceftriaxone

Monobactam Aztreonam

Carbapenems
Meropenem, Ertapenem

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10
Q

name two drugs used for Herpesvirus infections and how they work

A

Aciclovir
Ganciclovir

Nucleoside analogues: faulty DNA
Aciclovir: HSV and VZV
Ganciclovir: CMV

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11
Q

name the drug prescribed for influenza and how does it work

A

Oseltamivir

can be used for people with influenza or prophylaxis

Inhibitor of Neuraminadase enzyme:
Neuraminadase promotes viral
release and spread from respiratory cells

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12
Q

name some of the drugs prescribed for Hepatitis B and C and how do they work

A

Hepatitis B:
Tenovovir
Peginterferon alfa

Hepatitis C
Peginterferon alfa
Ribavarin

  • Tenovovir: analogue of adenosine: a nucleoside reverse transcriptase
    inhibitor
  • Peginterferon alfa: naturally
    occurring cytokine with wide variety of antiviral properties
  • Ribavarin: Analogue of
    Guanosine: broad antiviral activity, including RNA viruses. Toxic.
    Multiple modes of action
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13
Q

name two drugs prescribed for Respiratory syncytial virus and how do they work

A

Palivizumab
Ribavarin

Palivizumab: Monoclonal antibody
Given as prophylaxis to children at
risk of serious RSV infection

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14
Q

name some drugs used in treatment of HIV

A 
Reverse transcriptase inhibitors:
- Nucleoside RTI:
Zidovudine
Tenovovir
- Non-nucleoside RTI:
Efavirenz

Protease inhibitors:
Lopinavir
Ritonavir

Integrase inhibitors:
Raltegravir

Fusion inhibitors:
Enfuviritide

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15
Q

describe Highly Active Anti Retroviral Therapy (HAART)

A

management of HIV

Multiple agents limit development of resistance

Backbone of 2 Nucleoside RTI

Plus one other agent (PI, Non Nucleoside RTI, integrase inhibitor)

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16
Q

Define herd immunity, vaccine adjuvant, passive immunotherapy

List the characteristics of a good vaccine.

Distinguish different types of vaccine preparations (live and inactivated) and compare their advantages and disadvantages.

List side effects of vaccine

Identify vaccines on the current UK vaccination schedule

Give examples of patient risk groups that require additional vaccinations

Give examples of post exposure vaccination

A

.

17
Q

Define herd immunity

A

Concept of herd immunity – level of immunity at which an infectious agent can no longer continuously circulate (R becomes <1)

18
Q

what’s the difference between dead or live vaccines

A

All vaccines should contain at least one of the protective antigens of the microbe.

Dead vaccines generally less effective than live

Live:

  • microbes with artificially reduced virulence (‘attenuated’)
  • microbes with naturally reduced virulence for humans

Dead:

  • Inactivated virus
  • subcellular fragments/ Sub-unit vaccines
  • Toxoids
  • Genetically engineered recombinant vaccines.
19
Q

list some Pros and Cons of Live Attenuated Vaccines

A

Advantages:

  • Good immunogens
  • Induce long-lived, appropriate immunity
  • Tend to produce mucosal immunity
  • May offer alternative routes (e.g. oral)

Disadvantages:

  • Labile: Cold chain vital for live vaccines
  • Potentially unstable genetically (possible reversion to virulence)
  • Not possible to produce in all cases - trial and error
  • Contamination possible (e.g SV40 virus) in poliovirus vaccine
  • Inappropriate/accidental vaccination to at risk groups (immunosuppressed and pregnant) may pose risk
20
Q

list some Pros and Cons of Live Attenuated Vaccines

A

Advantages:

  • Good immunogens
  • Induce long-lived, appropriate immunity
  • Tend to produce mucosal immunity
  • May offer alternative routes (e.g. oral)

Disadvantages:

  • Labile: Cold chain vital for live vaccines
  • Potentially unstable genetically (possible reversion to virulence)
  • Not possible to produce in all cases - trial and error
  • Contamination possible (e.g SV40 virus) in poliovirus vaccine
  • Inappropriate/accidental vaccination to at risk groups (immunosuppressed and pregnant) may pose risk
21
Q

list some Pros and Cons of Inactivated Vaccines

A

Inactivated whole virus- Poliovirus, Rabies, inactivated HAV

Advantages:

  • Stable
  • Little or no risk (if properly inactivated)

Disadvantages:

  • Not possible for all viruses; denaturation may lead to loss of antigenicity and adverse affects, e.g. measles, RSV.
  • Not as effective at preventing infection as live viruses (mucosal immunity - IgA).
  • May only protect for a short period protect
22
Q

describe Sub-Cellular (Sub-Unit Vaccines)

A

Subcellular fractions can be used as vaccines if protective immunity is directed against a particular part of an organism

23
Q

list the Pros and Cons of Sub-unit Vaccines

A

Advantages:
Selected virus proteins or peptides used so:
- Completely safe, except for rare adverse reactions.
- Specific Antibody and T cell reactions can be selected.
- Can be made using recombinant DNA techniques

Disadvantages:

  • Tend to be the least effective.
  • (Relatively) poor antigenicity (especially short peptides)
  • Vaccine delivery (carriers/adjuvants needed)
24
Q

describe Toxoid Vaccines

A
  • Bacterial toxins – proteins realised by bacteria which induce inflammatory responses
  • Toxoids: inactivated toxins (usually by formaldehyde) so no longer toxic, but still induce protective antibody
  • Two toxoids: diphtheria and tetanus- among the most successful and widely used of all vaccines.
  • In combination with killed Bordetella pertussis, they constitute the triple vaccine, DTP (diphtheria, tetanus, pertussis).
  • Pertussis acts as an ‘adjuvant’ as well as a specific vaccine.
25
Q

describe some proven concerns with vaccine safety

A

Live attenuated vaccines:

  • Insufficient attenuation - Reversion to wild type
  • Administration to immunodeficient patient & Persistent infection
  • Contamination by other viruses
  • Fetal damage.

Non-living vaccines:

  • Contamination by toxins or chemicals
  • Allergic reactions
  • Autoimmunity.

Genetically engineered vaccines:
??Possible inclusion of oncogenes - hasn’t been proven

26
Q

list some at risk groups for vaccines

A
  • Immunodeficiency
  • HIV positive
  • Asthma
  • Chronic Lung Disease
  • Congenital Heart Disease
  • Definite hypersensitivity- Severe or Generalised Reaction to Preceding Dose
  • Down’s Syndrome
  • Avoid live vaccines in pregnancy
  • Small For Dates infants
  • Premature infants
27
Q

Give examples of post exposure vaccination

A

Examples: MMR in measles exposures, HBV vaccination in HBV exposure

28
Q

describe the use of passive immunisation with immunoglobulin

A

to prevent infection after exposure (e.g. rabies, tetanus)

to minimise its severity (varicella, measles in immunodeficient children).

Primary treatment (e.g diphtheria)

Year 2 PODT (14 decks)

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