Antimicrobial Therapy 1 Basic Principles

Front 1

antibiotic

Back 1

natural compound produced by bacteria or fungi to suppress growth of other microorganisms

Front 2

antimicrobial

Back 2

synthetic agents to suppress growth of microorganisms

Front 3

bactericidal

Back 3

kills organism directly

Front 4

bacteriostatic

Back 4

prevents reproduction.

*must have competent host immune system to help, this merely gives time for the system to kill bacteria

Front 5

what are some of the targets of antimicrobials? (5)

Back 5

1. effects on the cell wall
2. effects on the cell membrane
3. effects on protein synthesis
4. effects on bacterial metabolism
5. modification on DNA or nucleic acid synthesis

Front 6

what are some of the factors influencing selection of antimicrobial agent? (7)

Back 6

1. identification of organism
2. microbial susceptibility
3. bactericidal vs. bacteriostatic
4. bug-drug specific
5. knowledge of patient
6. pharmacokinetics and metabolism
7. allergies, prior adverse drug rxn, contraindications

Front 7

what information do you need to know about the patient?

Back 7

site of infection
status of immune system
age
physiological status

Front 8

what causes the gray baby syndrome? and why?

Back 8

chloramphenicol, b/c it needs to be glucoronidated before they can be excreted, babies cant glucoronidate until 1 yr or 2

Front 9

what does a patient's physiological status include?

Back 9

renal (altered excretion)
hepatic (altered metabolism)
diabetes (limited wound healing)
pregnancy (passed to fetus)

Front 10

too much penicillin to the brain can cause what?

Back 10

clonic-tonic seizures

Front 11

what is time-dependent killing?

Back 11

the ability of a drug to kill a bacteria is dependent on a blood conc

*you need a certain blood conc. for antibiotic to be effective, so may be used multiples times a day.

Front 12

what is concentration dependent killing?

Back 12

even if the drug falls below a therapeutic window, it can still have activity, you can just give a big dose, usually QD

Front 13

when do you use combination therapy? (5)

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1. treatment of life-threatening infections
2. treatment of polymicrobial infections (abdominal contamination during surgery)
3. enhanced antimicrobial activity
4. treatment of resistant strains
5. permit lower doses of antimicrobial agents

**possibly reduce emergence of resistant strains (not proven clinically

Front 14

how does resistance develop?

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1. selection (spontaneous mutations)
2. enzymes to destroy active drug (penicillinase, carbepenemases, cephalosporinases)
3. change permeability to drug
4. change in efflux pathway
5. change affinity of site of active drug
6. develop altered metabolic pathways
7. develop altered enzyme with less affinity

Front 15

what are the 3 origins of resistance?

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1. microorganism is in dormant stage
2. specific target structure is lost after several replications
3. genetic changes

Front 16

what are some of the methods for genetic changes?

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1. mutational resistance
2. conjugation
3. transduction
4. transformation

Front 17

what is conjugation most common in?

Back 17

gram negative bacteria

Front 18

what is transduction?

Back 18

bacterial DNA transferred through phages, important in S.Aureus

Front 19

what is transformation?

Back 19

free DNA absorbed from environment

Front 20

when can antibiotics be used prophylacticly?

Back 20

heart valves replacement people, surgery

Front 21

how are antimicrobial agents misused?

Back 21

1. treatment of nonbacterial infections
2. fever of undertermined origin
3. improper dosage
4. omission of surgical drainage
5. lack of adequate bacteriological information
6. prolonged treatment after cure