Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

3151 Infection > IC1&3 Clinical Microbiology + Systematic Approach > Flashcards

IC1&3 Clinical Microbiology + Systematic Approach Flashcards

1
Q

What is our Normal Microbiota?

A
  1. Skin – staphylococcus epidermis and aureus, streptococcus
  2. Mouth and teeth – staphylococci, streptococcus mutans, bacteroides
  3. Throat – staphylococci, streptococcus pneumonia & pyogenes, hemophilus, Neisseria, bacteroides, candida
  4. Paranasal sinuses – streptococcus pneumonia, hemophilus, bacteroides
  5. Upper bowel – e. coli, other Enterobacteriaceae, enterococcus, yeasts
  6. Lower bowel – bacteroides, clostridium
  7. Vagina – streptococci, mycoplasma, yeasts
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the usual sterile sites in the body?

A
  1. CV system
  2. Central Nervous system
  3. Lower respiratory tract
  4. Genitourinary tract (except for urethra and vagina)
  5. Bone, joint
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the different Microbiology test? (Total 8) Link them to microbial classification and identification

A
  1. Macroscopic
    a. Pseudomonas: blue green
    b. Staphylococcus aureus: golden colonies
  2. Gram stain
    a. Positive (purple)
    b. Negative (pink)
  3. MaConkey agar (Metabolize bile)
    a. Positive: enteric gram negatives
    i. Lactose fermenters (red): e. coli, klebsiella, Enterobacter
    ii. Non-lactose fermenters (yellow): proteus
    b. Negative: gram positives (no colour)
  4. Hemolysis (streptococcus)
    a. Full: beta hemolysis (Group A,B,C,D)
    b. Partial: alpha hemolysis (Srep pneumonia)
    c. No: gamma hemolysis
  5. Catalase
    a. Positive (bubbling): staphylococcus
    b. Negative: streptococcus, enterococcus
  6. Coagulase
    a. Positive (clumping): Staphylococcus Aureus
    b. Negative: Staphylococcus epidermis
  7. Oxidase
    a. Positive (have cytochrome C, purple colour): pseudomonas
    b. Negative: E. coli, klebsiella, Enterobacter
  8. Fermenters of carbohydrates
    a. Positive: E. coli, proteus
    b. Negatives: Pseudomonas, acinetobacter
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the 3 Antimicrobial susceptibility testing methods? Describe them

A
  1. Agar or broth dilution
    MICs
    - Minimum inhibitory concentration: the lowest concentration that is needed to inhibit the microbe growth (use dilutions and broths
    - MBC: use agar plates (Bactericidal: MBC within one 2-fold dilutions of MIC), e.g. MIC is 2 while MBC is 4
  2. Zone of inhibition
    o The greater the zone, the greater the microbes susceptibility to antibiotics
  3. E-test
    o MIC read where the growth intersects the plastic strip
    o Always want to round off to the higher reading to not underestimate the MIC
    o The lower the number, the more susceptible the microbe is
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are breakpoint and antibiogram? What are their use?

A

Breakpoints:
Critical concentrations which predict susceptibility/resistance
Cannot compare MIC of different drugs for the same indication
- Susceptible
- Intermediate
- Resistant

Antibiogram:
- Local susceptibility rates
- Monitor resistance
- Guide empiric therapy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What comprises the Systematic Approach of using and monitoring antimicrobial therapy?

A
  1. Presence of infection
    a. Risk factors
    b. Subjective evidence
    c. Objective evidence
    d. Site of infecton
  2. Identity of pathogen
    a. Colonizer, contaminant, pathogen
    b. Culture
    c. AST
  3. Choice of antimicrobial (choice, dose, ROA, duration)
    a. Empiric, prophylaxis, culture-directed
    b. Host, drug, organism factors
  4. Monitor response
    a. Efficacy
    b. ADR
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the possible objective evidences?

A

Objective evidence:
1. Fever (>38 degree Celsius)
2. Hypotension (<100mmHg)
3. Tachypnea (normal: 15-22bpm)
4. Tachycardia (>90 bpm)
5. WBC (normal: 4-10)
6. Neutrophils (normal: 45-75%)
7. CRP (normal<10, infection>40mg/L)

  1. Procalcitonin
    a. More specific marker for infection than CRP
    b. ESRF and traumatic brain injury (TBI) can have high procalcitonin (not related to infection)

c. Start:
i. <0.25: highly discourage to start
ii. 0.25-0.5: discourage
iii. 0.5-1: encourage
iv. >=1: highly encourage

d. Change therapy:
i. <0.25: highly encourage to stop
ii. 0.25-0.5/decrease by >80%: encourage to stop
iii. >0.5 and decrease by <80%: encourage to continue
iv. >0.5 and increase: highly encourage to change antibiotics

  1. Radioactive imaging (x-ray, CT scan, MRI, ultrasound)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are Colonizer, contaminant, pathogen?

A
  1. Colonizer: normal flora, or pathogenic organism that does NOT elicit host response
  2. Contaminant: from improper sample collection or handling, usually use midstream catch for urine sample, alcohol swab surface before getting blood sample
  3. Pathogen: grow and invade and damage the tissues + eliciting a host response
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the host factors affecting choice of therapy?

A

Host factors:

  1. Age
  2. Allergies
  3. Cross reactivity:
    a. If have the same R side chain
    b. E.g. Ampicillin + cephalexin
    c. E.g. Cefepime + ceftriaxone
    d. E.g. Ceftazidime + aztreonam
    e. Cefazolin has no shared side chains with other drugs
  4. G6PD deficiency
  5. Pregnancy and lactation
  6. Renal and hepatic impairment (to see whether need dose adjustment)
  7. Status of immune function
  8. Severity of illness
  9. Recent antimicrobial use
  10. Healthcare-associated risk factors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the drug factors affecting choice of therapy?

A
  1. Active against organism
  2. Reach site of infection
  3. Dosing based on PK and PD
    a. Concentration dependent:
    i. Cmax/AUC (peak is 8-10x above MIC)
    ii. E.g. Aminoglycosides, FQ
    iii. Have post-antibiotics effect
    iv. Prevents adaptive resistance
    v. Less nephrotoxicity
    vi. Less cost
    vii. Use total body weight if TBW < 130% of iBW
    viii. Use adjusted body weight if TBW > 130% of IBW

b. Time dependent (no persistent effect/short t1/2):
i. %T > MIC (40-70% of dosing interval is above MIC)
ii. E.g. pernicillins, carbapenems, cephalosporins
iii. More frequent dosage administration
iv. Continuous IV infusion / prolong intermittent infusion
v. Block excretion by adding probenecid

c. Time dependent (persistent effect):
i. 24hrAUC/MIC
ii. E.g. vancomycin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the organism factors affecting choice of therapy?

A
  1. What type of microbe
  2. Susceptible to which antibiotics
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the advantages and disadvantages of using combination therapy?

A

Advantage
1. Extended spectrum of activity
2. Synergistic bactericidal effect
3. Prevent development of resistance

Disadvantage
1. More SE
2. Possible allergic reaction
3. DDI
4. Increase cost
5. Selection of resistant microbes
6. Superinfections
7. Possible antagonistic effects

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the Reasons for unsatisfactory response?

A
  1. Inappropriate diagnosis
    a. Non-infectious cause
    b. Non-bacterial cause
  2. Inappropriate choice of agent
    a. Resistance
    b. Development of resistance
  3. Subtherapeutic concentration
    a. Non-compliance
    b. Improving renal function (cleared faster)
    c. DDI
  4. Collection of abscesses (need drainage)
  5. Impaired host defense
  6. Superinfection
  7. Toxicity of drug
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What does your macConkey agar test for? Link them to microbial classification and identification

A
  1. MacConkey agar (e.g. have bile salts)
    a. Positive: enteric gram negatives
    i. Lactose fermenters (red): e. coli, klebsiella, Enterobacter
    ii. Non-lactose fermenters (yellow): proteus
    b. Negative: gram positives (no colour, pink agar)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What does your hemolysis test for? Link them to microbial classification and identification

A
  1. Hemolysis (streptococcus)
    a. Full: beta hemolysis (Group A,B,C,D)
    b. Partial: alpha hemolysis (Strep pneumonia)
    c. No: gamma hemolysis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does your catalase test for? Link them to microbial classification and identification

A

Catalase
a. Positive (bubbling): staphylococcus
b. Negative: streptococcus, enterococcus

17
Q

What does your coagulase test for? Link them to microbial classification and identification

A
  1. Coagulase
    a. Positive: Staphylococcus Aureus
    b. Negative: Staphylococcus epidermidis
18
Q

What does your oxidase test for? Link them to microbial classification and identification

A
  1. Oxidase
    a. Positive (have cytochrome C): pseudomonas
    b. Negative: E. coli, klebsiella, Enterobacter
19
Q

What does your carbo fermenters test for? Link them to microbial classification and identification

A
  1. Fermenters of carbohydrates
    a. Positive: E. coli, proteus
    b. Negatives: Pseudomonas, acinetobacter

3151 Infection (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions