Intro to Antibiotics

Question 1

3 general ways to use antibiotics

Answer 1

Empiric
Definitive
Prophylaxis

Question 2

Source control

Answer 2

When all the infection that can be removed is removed

By drainage or surgically

Question 3

Antibiogram

Answer 3

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

Question 4

4 routes of delivery

Answer 4

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

Question 5

3 times we should use IV antibiotics

Answer 5

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

Question 6

6 reasons why patients fail antibiotic therapy

Answer 6

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

Question 7

Bacteriostatic

Answer 7

Drugs slow or stop replication so immune system can eliminate bacteria

Question 8

Bactericidal

Answer 8

Drugs can kill bacteria directly

Question 9

Synergy (and classic example)

Answer 9

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

Question 10

Minimal inhibitory concentration

Answer 10

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

Question 11

Time-dependent antibiotic

Answer 11

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

Question 12

Concentration-dependent antibiotic

Answer 12

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

Question 13

3 general targets of antibiotics

Answer 13

Cell wall synthesis
Nucleic acid synthesis
Protein synthesis

Question 14

Where do
1. Beta Lactams
2. Tetracyclines
3. Macrolides
4. Quinolones 
target?

Answer 14

1. cell wall
2. 30S ribosomal subunit
3. 50S ribosomal subunit
4. DNA gyrase

Question 15

4 general types of beta lactams

Answer 15

Penicillins
Cephalosporins
Carbapenems
Monobactams

Question 16

General info about beta lactams

Answer 16

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

Question 17

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

Answer 17

Alteration of PBP

Question 18

Efflux pumps

Answer 18

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

Question 19

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

Answer 19

B-lactamase

Question 20

2 B-lactamase inhibitors

Answer 20

Tazobactam

Clavulanate

Question 21

What do you use to treat Pseudomonas

Answer 21

Pip-Tazo

Question 22

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

Answer 22

Gram positive

Question 23

3 main bacteria treated with penicillin

Answer 23

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

Question 24

Main resistance mechanism to penicillin

Answer 24

Penicillinase

Question 25

How do you get MRSA

Answer 25

mecA gene causes alteration of a PBP (PBP2a)

Question 26

Cloxacillin can be used to treat...

Answer 26

Methicillin susceptible Staph aureus

Question 27

Drugs for MRSA 1. PO (4) 2. IV (3)

Answer 27

1. TMP-SMX, Linezolid, Doxycycline, +/- Clindamycin | 2. Vanco, Daptomycin, Ceftaroline

Question 28

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

Answer 28

Streptococci Enterococcus faecalis Listeria

Question 29

Cephalosporins do NOT treat which 2 types of bacteria

Answer 29

Enterococcus | Anaerobes

Question 30

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

Answer 30

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

Question 31

``` What are 1. first gen 2. second gen 3. third gen 4. fourth gen 5. fifth gen cephalosporins main clinical uses? ```

Answer 31

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

Question 32

Which generation of cephalosporin is best for pseudomonas? | And which carbapenems?

Answer 32

Third gen | Meropenem and Imipenem

Question 33

Carbapenems are used for...

Answer 33

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

Question 34

4 adverse events from B-lactams

Answer 34

Hypersensitivity Gastrointestinal Renal (rare) Hematologic (rare)

Question 35

Fluoroquinolones 1. Mechanism 2. 3 bacteria it covers 3. Resistance mechanisms

Answer 35

1. Inhibits DNA gyrase and topoisomerase 4 2. Mycoplasma, Chlamydophila, Leigonella 3. Efflux pumps, alteration of target DNA enzyme and membrane porins

Question 36

4 adverse events from Fluoroquinolones

Answer 36

``` Tendonitis Prolonged QTc Gastrointestinal CNS (dizziness, insomnia, delirium) ```

Question 37

Macrolides 1. Mechanism 2. Resistance 3. 2 examples

Answer 37

1. Binds and prevents translocation of peptide chain 2. Efflux pumps, alteration of ribosomal target 3. Clarithromycin, azithromycin

Question 38

Tetracyclines 1. Mechanism 2. 3 examples 3. Works on...

Answer 38

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

Question 39

2 adverse events from macrolides

Answer 39

GI | Prolonged QTc

Question 40

3 adverse events from tetracyclines

Answer 40

Tooth discolouration Erosive esophagitis Photosensitivity

Question 41

4 main resistance mechanisms

Answer 41

Efflux pumps Porin membrane mutations Alterations in PBPs Beta lactamases

Question 42

Drugs for pseudomonas

Answer 42

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

Question 43

Drug for ESBL

Answer 43

Carbapenems