Lesson 16: Antimicrobial Therapy and Resistance

Question 1

defined as that which minimizes the development of resistance as well as resulting in a therapeutically successful outcome.

Answer 1

antimicrobial therapy

Question 2

Factors relevant to the Pathogenic Organism

Answer 2

✓ type
✓ number of organisms
✓ virulence
✓ pathogenic mechanism
✓ ability to acquire resistance to drug
✓ susceptibility to chemotherapy

Question 3

Factors relevant to the infectious drug

Answer 3

✓ spectrum of activity
✓ route of administration
✓ dosage and frequency of administration
✓ duration of treatment
✓ distribution in body fluids
✓ direct drug toxicity
✓ effect on normal flora
✓ tissue residues

Question 4

Factors relevant to the host

Answer 4

✓ species
✓ age
✓ immune status
✓ nutritional status
✓ nature and severity of infection
✓ site and duration of infection
✓ intercurrent infection

Question 5

can be initiated as soon as specimens are collected and empirical chemotherapy can if necessary be modified when laboratory data are at hand

Answer 5

chemotherapy

Question 6

depends on the susceptibility of the pathogen, pharmacokinetic characteristics of the drug, the amount of drug given at one time, the route, frequency of administration and the duration of treatment

Answer 6

effective antimicrobial therapy

Question 7

others variables relating to chemotherapy;

Answer 7

✓ toxicity of the drug for the host
✓ half-life
✓ concentration and persistence at the site of infection
✓ effect on the normal flora of the host

Question 8

antibiotic in food producing animals

Answer 8

chloramphenicol

Question 9

Antimicrobial drugs can be classified in a number of ways, each of which has clinical importance. what are these?

Answer 9

✓ spectrum of activity against class of microorganisms
✓ antibacterial activity
✓ bacteriostatic or bactericidal
✓ pharmacodynamic activity
✓ mechanism of action

Question 10

are narrow spectrum, because they inhibit only bacteria

Answer 10

penicillins

Question 11

are broader because they inhibit both bacteria and protozoa

Answer 11

sulfonamides, trimethoprim, lincosamides

Question 12

only inhibit fungi

Answer 12

polyenes

Question 13

inhibit both gram positive and gram negative bacteria

Answer 13

tetracyclines

Question 14

inhibit only gram positive

Answer 14

bacitracin and vancomycin

Question 15

they inhibit only gram negative bacteria

Answer 15

polymyxin

Question 16

are most active against gram-positive bacteria but will inhibit some gram-negatives

Answer 16

penicillin G or lincosamides

Question 17

this distinction is an approximation that depends on drug concentrations and the organism involved.

Answer 17

bacteriostatic or bactericidal

Question 18

bactericidal at high concentrations and bacteriostatic at lower ones

Answer 18

penicillin

Question 19

antibacterial action is concentration or time dependent

Answer 19

pharmacodynamic activity

Question 20

this is dependent on the drug class. this is probably the most useful of the classifications, since it determines the previous four classification approaches

Answer 20

mechanism of action

Question 21

Four categories of Mechanism of Action of Antimicrobial Drugs

Answer 21

✓ inhibition of cell wall synthesis
✓ damage to cell membrane function
✓ inhibition of nucleic acid synthesis
✓ inhibition of protein synthesis

Question 22

inhibition of cell wall synthesis example;

Answer 22

✓ penicillins and cephalosporins
✓ bacitracin and vancomycin

Question 23

it inhibits cross-linkage between peptidoglycans in the cell wall, inhibiting division, and creating weak points during active growth and cell division

Answer 23

inhibition of cell wall synthesis

Question 24

antibiotics that damage cell membrane function include the?

Answer 24

✓ polymyxins
✓ monensin
✓ antifungal polyenes
✓ imidazoles

Question 25

antifungal polyenes

Answer 25

amphotericin and nystatin

Question 26

imidazoles

Answer 26

✓ fluconazole
✓ itraconazole
✓ ketoconazole
✓ miconazole

Question 27

example of drugs that inhibit nucleic acid function are;

Answer 27

✓ nitroimidazoles
✓ nitrofurans
✓ nalidixic acid
✓ flfluoroquinolones
✓ novobiocin
✓ rifampin
✓ sulfonamides
✓ trimethoprim
✓ 5-flflucytosine

Question 28

drugs with greater selective toxicity, which inhibit the synthesis of folic acid

Answer 28

sulfonamides and trimethoprim

Question 29

examples of drugs that inhibit protein synthesis are;

Answer 29

✓ tetracyclines
✓ aminoglycosides
✓ aminocyclitols
✓ chloramphenicol
✓ macrolides

Question 30

antibiotics affecting protein synthesis can be divided into those affecting the 30S ribosome

Answer 30

✓ tetracyclines
✓ aminoglycosides
✓ aminocyclitols

Question 31

antibiotics that affect the 50S ribosome

Answer 31

✓ chloramphenicol
✓ macrolides
✓ lincosamides