Intro to Antibiotics Flashcards

1
Q

3 general ways to use antibiotics

A

Empiric
Definitive
Prophylaxis

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2
Q

Source control

A

When all the infection that can be removed is removed

By drainage or surgically

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3
Q

Antibiogram

A

A summary of all the bacterial isolates over a given period of time and what % of them are susceptible to which antibiotics
Every hospital has one

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4
Q

4 routes of delivery

A

PO (by mouth)
IV
IM
PR (by rectum)

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5
Q

3 times we should use IV antibiotics

A

When patients cannot take oral antibiotics
When there is no oral option
When rapid peak serum antibiotic levels are critical

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6
Q

6 reasons why patients fail antibiotic therapy

A
Wrong bug
Wrong drug
Drug is not getting to bug
Wrong diagnosis
Inadequate source control
Too much/too little immune system
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7
Q

Bacteriostatic

A

Drugs slow or stop replication so immune system can eliminate bacteria

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8
Q

Bactericidal

A

Drugs can kill bacteria directly

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9
Q

Synergy (and classic example)

A

2 drugs together have higher bactericidal activity than either alone
Ex: Beta lactam and aminoglycoside

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10
Q

Minimal inhibitory concentration

A

Minimal concentration of the antibiotic needed to inhibit the growth in vitro

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11
Q

Time-dependent antibiotic

A

Activity depends on the duration of time the concentration is over the MIC
Higher dose will not enhance activity
Need to be frequently dosed

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12
Q

Concentration-dependent antibiotic

A

Activity depends on the absolute concentration greater than MIC
A higher dose = higher activity

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13
Q

3 general targets of antibiotics

A

Cell wall synthesis
Nucleic acid synthesis
Protein synthesis

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14
Q
Where do
1. Beta Lactams
2. Tetracyclines
3. Macrolides
4. Quinolones 
target?
A
  1. cell wall
  2. 30S ribosomal subunit
  3. 50S ribosomal subunit
  4. DNA gyrase
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15
Q

4 general types of beta lactams

A

Penicillins
Cephalosporins
Carbapenems
Monobactams

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16
Q

General info about beta lactams

A

Most common antibiotics
Core beta lactam ring with unique side chain
Time-dependent killing (so need to be frequently doses)
Bactericidal
Safe in pregnancy and for children

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17
Q

What is the major mechanism of resistance in gram positive organisms?

A

Alteration of PBP

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18
Q

Efflux pumps

A

Major resistance mechanism in all bacteria
Active transmembrane pump that expels antibiotics
Can be chromosomal or acquired

19
Q

What is the major mechanism of resistance in gram negative organisms?

A

B-lactamase

20
Q

2 B-lactamase inhibitors

A

Tazobactam

Clavulanate

21
Q

What do you use to treat Pseudomonas

A

Pip-Tazo

22
Q

Can penicillin be used on gram positive or gram negative bacteria?

A

Gram positive

23
Q

3 main bacteria treated with penicillin

A

Group A strep (strep pyogenes)
Strep pneumoniae (when sensitive)
Syphillis (treponema pallidum)

24
Q

Main resistance mechanism to penicillin

A

Penicillinase

25
Q

How do you get MRSA

A

mecA gene causes alteration of a PBP (PBP2a)

26
Q

Cloxacillin can be used to treat…

A

Methicillin susceptible Staph aureus

27
Q

Drugs for MRSA

  1. PO (4)
  2. IV (3)
A
  1. TMP-SMX, Linezolid, Doxycycline, +/- Clindamycin

2. Vanco, Daptomycin, Ceftaroline

28
Q

The amino penicillins (amoxicillin and ampicillin) can be used to treat which 3 bacteria

A

Streptococci
Enterococcus faecalis
Listeria

29
Q

Cephalosporins do NOT treat which 2 types of bacteria

A

Enterococcus

Anaerobes

30
Q

As you go down the generations of cephalosporins… (3)

A

More resistant to beta lactamases
Better activity against gram negative organisms
Better ability to cross into tissue spaces

31
Q
What are
1. first gen 
2. second gen
3. third gen
4. fourth gen
5. fifth gen
cephalosporins main clinical uses?
A
  1. Skin and soft tissue infections, surgical prophylaxis
  2. Better H, influenzae activity, mild CAP
  3. Gonorrhea, serious infections requiring hospitalization, CAP, meningitis, pylonephritis, pseudomonas
  4. Empiric for nosocomial infections and neutropenic gever
  5. Serious MRSA and ESBL infections
32
Q

Which generation of cephalosporin is best for pseudomonas?

And which carbapenems?

A

Third gen

Meropenem and Imipenem

33
Q

Carbapenems are used for…

A

Severe life threatending infections in which ESBL infections are likely
(Nosocomial pneumonia, sepsis)

34
Q

4 adverse events from B-lactams

A

Hypersensitivity
Gastrointestinal
Renal (rare)
Hematologic (rare)

35
Q

Fluoroquinolones

  1. Mechanism
  2. 3 bacteria it covers
  3. Resistance mechanisms
A
  1. Inhibits DNA gyrase and topoisomerase 4
  2. Mycoplasma, Chlamydophila, Leigonella
  3. Efflux pumps, alteration of target DNA enzyme and membrane porins
36
Q

4 adverse events from Fluoroquinolones

A
Tendonitis
Prolonged QTc
Gastrointestinal
CNS (dizziness, insomnia, delirium)
37
Q

Macrolides

  1. Mechanism
  2. Resistance
  3. 2 examples
A
  1. Binds and prevents translocation of peptide chain
  2. Efflux pumps, alteration of ribosomal target
  3. Clarithromycin, azithromycin
38
Q

Tetracyclines

  1. Mechanism
  2. 3 examples
  3. Works on…
A
  1. Binds and prevents translocation of peptide chain
  2. Doxycycline, tetracycline, minocycline
  3. Gram positive (including MRSA), gram negative, plasmodium, intracellular bacteria and bacteria without walls
39
Q

2 adverse events from macrolides

A

GI

Prolonged QTc

40
Q

3 adverse events from tetracyclines

A

Tooth discolouration
Erosive esophagitis
Photosensitivity

41
Q

4 main resistance mechanisms

A

Efflux pumps
Porin membrane mutations
Alterations in PBPs
Beta lactamases

42
Q

Drugs for pseudomonas

A

PO: ciprofloxacin
IV: pip-tazo, ceftazidime, cefepime, meropenem, imipenem

43
Q

Drug for ESBL

A

Carbapenems