Quiz 1 - Smith - AMDs

Question 1

What is an antibiotic?

Answer 1

Low molecular substance produced by a microorganism that inhibits or kills other microorganisms while causing little or no damage to itself

Question 2

What is an antimicrobial?

Answer 2

A natural, semisynthetic, or synthetic origin that kills or inhibits the growth of microorganisms while causing little or no damage to the host

Question 3

All antibiotics are ____________, but not all antimicrobials are ___________.

Answer 3

Antimicrobials

Antibiotics

Question 4

Antifungals are also called what?

Answer 4

Antimycotics

Question 5

Bacterocidal does what?

Answer 5

Kills

Question 6

Bacteriostatic does what?

Answer 6

Stops growth

Question 7

Broad spec is what?

Answer 7

Drugs that are active against a wide range of microorganisms

*Tetracyclines

Question 8

Narrow spec does what?

Answer 8

Limited activity and are used against particular species of microorganisms

Question 9

No _______ is effective against all microbes.

Answer 9

Antimicrobial

Question 10

With AIDS patients, only use what type of anticmicrobial?

Answer 10

BACTERIOCIDAL

Question 11

What is the MIC and what does it mean?

Answer 11

Minimal inhibitory concentration - based on the diameter of the zone of inhibition

*The minimum lowest conc of an antimicrobial drug that inhibits the growth of the bacterial strain plated

Question 12

What does MBC mean?

Answer 12

Minimum bactericidal concentration

Question 13

What phase of bacterial growth is most sensitivity to antimicrobial intervention?

Answer 13

Log phase - Period of most rapid growth

Question 14

Empiric vs definitive AMT

Answer 14

Empiric - After symptoms, but before pathogen has been identified.

Definitive - When we know what bug it is

Question 15

Pharmacokinetics vs pharmacodynamics?

Answer 15

PK - What the body does to the drug (ADME)

PD - What the drug does to the body

Question 16

What does ADME stand for?

Answer 16

Absorption - Route of administration and determines the compound’s bioavailability

Distribution - Lipid or H2O soluble, bbb crossing?

Metabolism - Usual routes of clearance are thru liver and kidneys. Cytochrome P450 enzymes

Excretion - Low potency drugs are often used for UTI’s since they concentrate in urine b/c their resorption is so low

Question 17

Although MIC is often compared to plasma concentrations, these concentrations may NOT reflect ______ concentrations at the infection site.

Answer 17

Drug

Question 18

Ideally, antimicrobial therapy will be dosed to provide overkill w/o causing what in the host?

Answer 18

Toxicity

Question 19

What distinguishes antimicrobials from disinfectants?

Answer 19

Selective toxicity

*When selectivity is high, the risk of adverse effects are reduced

Question 20

The ideal AMT is defined by what?

Answer 20

It’s specificity of action in host vs bacteria

Question 21

Not all, but many, adverse effects are dependent upon what?

Answer 21

Dosage

Question 22

Therapeutic index is calculated how?

Answer 22

TD50/ED50

Toxic dose / effective dose

*Higher or wider the therapeutic index, the better/safer the antibiotic

Question 23

Adverse effects of AMTs can be __________ to antimicrobial action.

Answer 23

Analogous

Question 24

Adverse effect of AMTs may be ____________ of antimicrobial action.

Answer 24

Independent

*There may be an irritation or an allergy that the patient has

Question 25

AMDs target all essential microbial processes which include what 4 things?

Answer 25

Cell wall synthesis and cell membrane function/permeability Protein synthesis - inhibits the 50s and/or 30s ribosomal subunits Inhibition of metabolic pathways Nucleic Acid synthesis of DNA and/or RNA

Question 26

What are 4 reasons to use combination therapy?

Answer 26

Treat inherently mixed infections - Antimicrobial combos broaden spectrum of coverage Improve efficacy - However, NOT ALL COMBOS INCREASE EFFICACY Initial empiric therapy of uncharacterized serious infection Prevent emergence of resistance - lowers probability of selection of naturally occurring drug-resistant mutants

Question 27

What is a superinfection?

Answer 27

An overgrowth of pathogenic bacteria

Question 28

How are superinfections caused?

Answer 28

Use of broad-spec antimicrobial agents Use of higher than normal concentrations of even narrow-spec antimicrobial agents

Question 29

What is antimicrobial resistance (AMR)?

Answer 29

Natural process by which microbes evolve to resist the effects of the medications used to treat them

Question 30

Bacteria can mutate in 3 main ways. Name them.

Answer 30

By chance By horizontal gene transfer By strong selective evolutionary pressures (like the increased use of antibiotics in both clinical and agricultural settings)

Question 31

What is horizontal gene transfer (HGT)?

Answer 31

Process whereby genetic material in small packets of bacterial DNA are t-ferred b/t individual bacteria of either the same or different species. This material often conveys antimicrobial resistance b/t bacteria.

Question 32

HGT has three mechanisms. Name them.

Answer 32

Conjugation - MAIN MECHANISM FOR HGT - Plasmid transfer (bacterial sex) Transformation - Resistant gene can be taken up from a dead bacteria Transduction - Viral route via bacteriophage

Question 33

What are the major mechanisms of resistance?

Answer 33

Restrict AMD access - Prevent entry, or to pump in back out of the bacterial cell before the desired effect (**efflux pumps**) Modify AMD’s target - Alter target protein or overexpress target protein requiring more drug Modification of the AMD - Inactivate the AMD before affecting its target or Prevent AMD activation - changing expression of bacterial factors/enzymes needed to activate the precursor

Question 34

Antibiotics fit in to their target proteins like a key in a lock, so how do bacteria modify the target?

Answer 34

Change protein sequence Add chemical groups (Methylation, etc.) *Change the key and/or change the lock

Question 35

How are beta-lactams inactivated?

Answer 35

Beta-lactams target PBP (penicillin-binding proteins) by binding them and inactivating them. Bacteria alter the PBP site to prevent binding and normal bacterial function is restored

Question 36

What do beta-lactamase enzymes do?

Answer 36

Destroy the antibiotic by breaking open the beta-lactam ring *The more beta-lactamase produced, the higher the level of resistance

Question 37

Resistance by modifying expression of bacterial factors needed to activate the antibiotic - prodrug

Answer 37

This renders the pro-drug inactive

Question 38

Antimicrobial effects may be classified based on three types. Name and describe them.

Answer 38

Type I - Conc-dependent - Goal maximize concentrations Type II - Time-dependent - Maximize duration of exposure Type III - Time-dependent with persistent effects - Maximize amount of drug