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IPFC 2 Midterm 1 > Intro to infectious disease > Flashcards

Intro to infectious disease Flashcards

1
Q

Define normal flora & colonization & pathogen

A

Normal flora:
- microorganisms usually found in the human body

Colonization (transient flora):
- Microorganisms on the human body not considered normal flora

Pathogen
- a microorganism that can cause disease
- can be from normal or colonized flora

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2
Q

T/F presence of microorganisms indicate infection

A

False

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3
Q

What are factors that influence the likelihood of infection? (3)

A
  1. Size of inoculum
    - someone sneezing in air vs. directly in your face
  2. Virulence of pathogen
    - how effective the bacteria causes the infection
  3. Effectiveness of host defenses
    - strength/deficiencies in immune system
    - chemo, transplant, older patients have weak immune systems
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4
Q

What are the 2 types of ways that your body defends against pathogens (immune system)

A
  1. Innate (always turned on)
    - physical barriers: skin, mucous membranes, digestive enzymes, stomach acidity
    - Internal defenses: phagocytic cells, killer cells
  2. Adaptive (takes a while to turn on)
    - Antibodies and cell-mediated response
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5
Q

How does normal flora protect against infection? (3)

A

Protect against infection
1. Produce toxins
2. Compete for nutrients/resources (with pathogens) in a non-dangerous way
3. Stimulates low-level activation of immune system (occasional attack from normal flora keeps the immune system sharp)

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6
Q

What occurs to normal flora when you use antimicrobials

A

Weakens the protection provided by normal flora –> inc likelihood of superinfection by opportunistic pathogens

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7
Q

Differentiate between antimicrobial and antibiotic

A

Antimicrobial
- natural, semisynthetic, synthetic substance that destroys or inhibits the growth of bacteria, fungi etc..

Antibiotic
- substances produced by NATURAL microorganisms with activity against ONLY bacteria

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8
Q

Differentiate between Intrinsic resistance and acquired resistance?

A

Intrinsic:
- ability of a bacteria to oppose activity of an agent because of its structure or function (will always be resistant)

Acquired:
- Strain or subpopulation of a species that GAINS the ability to oppose activity (previously susceptible)
- transfer of resistance genes or natural mutations

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9
Q

How does antimicrobial resistance occur?

A
  1. 2 types of bacteria exist
    a. wildtype (majority, susceptible)
    b. Random mutations (minority, resistant)
  2. Administer antibiotic:
    - kills all wildtype but leaves the resistant bacteria alive
  3. Usually immune system destroys remaining resistant pathogens
    - if resistant bacteria is not causing problems, immune system will not kill it and it will thrive and multiply
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10
Q

Define collateral damage and superinfection

A

Collateral damage
- normal flora unintentionally harmed by antimicrobial therapy

Superinfection
- treat infection 1 –> kill a lot of normal flora –> resistant pathogen can thrive now –> new infection (superinfection)

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11
Q

What are the 3 golden rules of antimicrobial stewardship

A
  1. Limit collateral damage
  2. Avoid unnecessary antimicrobial use
  3. Use the shortest effective duration of therapy
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12
Q

Does not finishing your course of antibiotics cause resistance?

A

No
Patient should contact clinician when feeling better to see if it is reasonable to stop.

Reason why we used to say finish your course is because we didn’t know how long it will take for the bacteria to die.

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13
Q

What is the spectrum of infection?
What is the severity of clinical presentation determined by?

A

Spectrum of infection
1. Localized inflammatory response
2. Systemic inflammatory response
3. Sepsis
4. Septic shock

Severity of clinical presentation determined by degree of host’s inflammatory response

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14
Q

What is the 1st step that occurs in the inflammatory response to a nail penetrating subcutaneous tissue? symptoms?

A
  1. Pro-inflammatory mediators are released by damaged and phagocytic cells in area
    - Blood vessels become leaky to travel more WBC into the area + release fluids into interstitial space

Local symptoms:
- erythema (redness), warmth, edema, pain

**No defensive bacteria here

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15
Q

What is the 2nd step that occurs in the inflammatory response to a nail penetrating subcutaneous tissue? symptoms?

A

If local inflammatory response not contained, mediators SPILL into bloodstream

Systemic
- fever, tachycardia, tachypnea, leukocytosis, bandemia

**you can get a systemic inflammatory response w/o bacteria

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16
Q

Define bandemia. What occurs in the bands during an infection ?

A

Bandemia: systemic inflammation –> increased demand for WBCs –> increased levels of immature WBC

Left shift occurs

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17
Q

What is the 3rd step that occurs in the inflammatory response to a nail penetrating subcutaneous tissue? symptoms?

A

If systemic inflammatory reaction is not contained, it may become dysregulated
If host response is dysregulated = sepsis
- uncontrolled vascular permeability (BV are very leaky) –> inc fluid loss –> dec organ perfusion with/without hypotension

18
Q

What is the 4th step that occurs in the inflammatory response to a nail penetrating subcutaneous tissue? symptoms?

A

Sepsis –> septic shock + multisystem organ failure
- 40%+ mortality

19
Q

Are all inflammations infectious?

A

No,
can be caused by Drug, fever, malignancy, collagen vascular disease

20
Q

Can you have fever without bacteremia? what about bacteremia without fever?

A

Yes
Yes

21
Q

Do all infections go through each stage? Depends on what?

A

No,
Depends on:
- virulence of pathogen
- Size of inoculum
- Health status
- Effectiveness of therapies

22
Q

What are 3 things to check to make sure antimicrobials are INDICATED

A
  1. Localizing features of inflammation
    - symptoms that line up with diagnosis (pneumonia = shortness of breath)
  2. Evidence of systemic inflammation
  3. Diagnostics: imaging, fluid analysis, microbiology
23
Q

What are some reasons for false negatives? (3)

A
  1. Insufficient volume
  2. Fastidious organism
  3. Drawn after antimicrobial administration
24
Q

What are reasons for false positives?

A
  1. Collection technique
  2. Storage and transportation
25
Q

Does a positive culture mean diagnosis?

A

No, treat the patient not the lab report

26
Q

Why do doctors prescribe “just-in case” (3)

A
  1. Lack of diagnostic certainty
  2. Fear of bad result if infection not adequately treated
  3. Perception that antimicrobial therapy is benign
27
Q

How to determine if antimicrobials are going to be effective?

A

Find out if therapy is empiric or targeted?

28
Q

What is empiric therapy? (3)
When is it used (2)

A

Empiric therapy: BROAD Antimicrobial therapy used W/O definitive knowledge of:
- which infection or if there even is one
- What pathogen is causing it
- What antimicrobials the pathogen is susceptible to

When is it used
1. Definitive microbiology is not available/practical for the infections
2. If it is a serious infection where delay of therapy could cause poor outcomes

29
Q

What are 5 requirements for making an educated guess about which pathogens are likely present when giving empiric therapy?

A
  1. Use literature (pneumonia = strept. pneumo)
  2. Has my patient been exposed to anything (vectors, other humans, environment, covid)
  3. Make a guess about what my patient might be colonized with
  4. How much resistance does my patient have?
  5. Do I have to cover all these pathogens in my patient? (undertreat vs. overtreat)
30
Q

What are some guesses to make about what your patient may be colonized with? Reason for an inc or dec suspicion for certain pathogens? (3)

A
  • Immunization status
  • Exposure to hospitals (contains a lot of resistant bacteria)
  • Recent antibiotic exposure (can increase risk for opportunistic pathogens)
31
Q

What 2 risk factors to consider how much resistance is likely in the patient (#4)

A

Population risk
- based on epidemiological studies, antibiograms (shows susceptibility, NOT effectiveness)

Individual risk
- recent use of antibiotics (gram-negative more resistant) (FQ have 1 year resistance)
- Colonization of resistance organisms from environment (travel, hospital, agriculture)

32
Q

How long does colonization take to go away?

A

3-6 months

33
Q

What is targeted therapy? (3)
Advantages? (3)

A

Targeted therapy
- antimicrobial therapy that is more certain to be effective

Advantages
Allows clinicians to:
- stop unnecessary therapy
- Narrow spectrum of activity
- Limit duration to shortest effective

34
Q

What are requirements of targeted therapy?

A

Culture result

35
Q

What are considerations for EFFICACY of the antibiotic (3)

A
  1. Consider spectrum activity
  2. Consider Penetration (does it reach the area)
  3. Consider evidence
36
Q

What are considerations for SAFE use the antibiotic

A
  • Age
  • Allergies
  • Pregnancy
  • Comorbidites
  • Available routes of administration
  • Collateral damage
37
Q

Which is more safe parental antibiotics or oral?

A

Oral is more safe

38
Q

What if agent appears ineffective? What are possible errors

A
  • Diagnosis, dose, identification of pathogens needed to kill
  • Source control
  • Identifying resistance
39
Q

In time dependant antimicrobials what does efficacy correlate with?

A

correlates with % time that site of infection is greater than MIC
eg. B-lactam

40
Q

In concentration-dependant antimicrobials, what does efficacy correlate with?

A

correlates with ratio of peak (site of infection to MIC
eg. aminoglycoside

IPFC 2 Midterm 1 (8 decks)

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