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ESA 3 > Infection > Flashcards

Infection Flashcards

0
Q

What are the pharmacodynamic principles of antibacterials?

A

Each has a MIC, minimum inhibitory concentration and MBC, minimum bacteriocidal concentration.

The MIC and MBC decide the potency and effectiveness of the drug

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1
Q

What are the desirable properties of Antimicrobials?

A
  1. Reach the site of infection
  2. No adverse effects
  3. Selective toxicity
  4. Long half life
  5. Oral / IV formulation
  6. No interference with other drugs
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2
Q

What are the mechanisms of antimicrobial resistance?

A
  1. Drug inactivating enzymes
  2. Altered target
  3. Decrease permeability for the drug
  4. Increase efflux
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3
Q

Give an example of an antimicrobial whose resistance is due to drug inactivating enzymes

A

Beta lactams, amino glycosides

B lactamases, amino glycoside enzymes

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4
Q

Give an example of a drug whose resistance is conferred due to altered target, giving the drug a lower affinity for the bacteria

A

Methicillin, macrolides, trimethoprim

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5
Q

Name a drug whose resistance is due to decreased permeability

A

Beta lactams

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6
Q

Name a drug which resistance is due to increased efflux

A

Tetracycline

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7
Q

What is antimicrobial stewardship?

A

Combined interventions designed to improve and measure the appropriate use of antimicrobials

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8
Q

What are the complications of acute sepsis?

A 
Irreversible hypotension 
Respiratory failure
Renal failure
Raised intracranial pressure- compromises cerebral function- chronic problems
Ischaemic necrosis of the extremities
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9
Q

What is SIRS?

A

Response to insult eg ischaemia, trauma, infection

2 or more of the following:
Resp rate >20
Temp 38*C
Heart rate >90bpm
WBC <12x10^9/L
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10
Q

What is sepsis?

A

Systemic response to infection. SIRS with a documented or presumed infection

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11
Q

Define septicaemia

A

Generalised sepsis, usually due to bacteraemia

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12
Q

Define severe sepsis

A

SIRS and organ dysfunction due to organ hypoperfusion. Presents as renal failure with decreased urine output

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13
Q

Define septic shock

A

Severe sepsis with persistently low blood pressure despite IV fluids

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14
Q

What is the sepsis 6?

A
  1. High flow oxygen
  2. Take blood and other cultures, consider source control
  3. Empirical IV antibiotics
  4. Measure serum lactate- indicates oxygen levels
  5. IV fluid resuscitation
  6. Accurate urine output measurement- indicate renal function
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15
Q

State 3 physical barriers against infection

A

Skin
Mucous membranes
Bronchial cilia

16
Q

State 4 physiological barriers against pathogens

A

Diarrhoea
Vomiting
Coughing
Sneezing

17
Q

State 2 chemical barriers against pathogens

A

Low pH of skin, stomach and vagina

Antimicrobial molecules
IgA- secreted by mucus membranes, found in tears and saliva. Prevents attachment
Lysozymes- found in sebum, perspiration, urine. Makes holes in bacteria
Mucus- traps pathogens
Beta defensins- epithelial cells’ defence against viruses
Gastric acid and pepsin

18
Q

Describe the biological barriers against pathogens

A

Commensal microorganisms found in strategic locations (nasopharyngeal, vagina, mouth/ throat, GI tract) compete with pathogens for attachment sites and resources and produce antimicrobial chemicals. Some synthesise vitamins

19
Q

Describe the second line of defence against pathogens

A

PRRs (toll like receptors) on phagocytes recognise PAMPS on the microbe. Phagocytosis occurs, forming a phagosome. A lysosome fuses to form a phagolysosome. Enzymes digest the microbe using the oxygen dependent or oxygen independent intracellular killing mechanism, and the indigestible material forms residual bodies. Waste materials are discharged.

20
Q

What do cytokines do?

A
  1. Act on the liver to produce CRP and MBL - opsonise microbes and MBL activates the complement system
  2. Bone marrow to mobilise neutrophils
  3. Hypothalamus to increase body temperature
  4. Vasodilation
  5. Increase vascular permeability
  6. Adhesion molecules to attract neutrophils
21
Q

How is the complement system activated?

A

Alternative Pathway- initiated by cell surface microbial constituents

MBL Pathway- initiated when MBL (acute phase protein) binds to mannose containing residues of proteins

22
Q

What is the MBL pathway?

A

A way of activating the complement system, initiated when MBL (acute phase protein) binds to mannose containing residues of proteins

23
Q

What does the complement system do?

A 
Produced by hepatocytes, circulate as inactivated precursors. When activated they: 
Opsonise (C3b-C4b)
Chemotaxis (C3a and C5a)
Cell lysis (C5-C9)
Agglutination - clumping of cells

ESA 3 (2 decks)

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