Micro 2- antimicrobial drugs

Question 1

chemotherapy

Answer 1

the use of chemicals to treat a disease

Question 2

antibiotic

Answer 2

a substance produced by a microbe that, in small amounts, inhibits another microbe
(example: streptomyces)

Question 3

antimicrobial drug

Answer 3

synthetic substances that interfere with the growth of microbes

Question 4

selective toxicity

Answer 4

selectively finding and destroying pathogens without damaging the host

Question 5

narrow spectrum of microbial activity

Answer 5

drugs that affect a narrow range of microbial types

Question 6

broad-spectrum antibiotics

Answer 6

affect a broad range of gram positive and gram negative bacteria

Question 7

bactericidal

Answer 7

kills microbes directly

Question 8

bacteriostatic

Answer 8

prevent microbes from growing

Question 9

what is a superinfection and how is it caused

Answer 9

overgrowth of normal microbiota that is not sensitive to antibiotics (candida albicans)
-growth of target pathogen that has developed resistance to antibiotics

Question 10

superinfection is a disadvantage of

Answer 10

broad spectrum drugs

Question 11

5 ways antimicrobial drugs target essential functions of the microbe

Answer 11

1. inhibition of cell wall synthesis
2. inhibition of protein synthesis
3. inhibition of nucleic acid replication and transcription
4. injury to plasma membrane
5. inhibition of essential metabolite synthesis

Question 12

example of cell wall synthesis inhibitor and how it works

Answer 12

penicillin, contains beta-lactam ring and prevents the cross-linking of peptidoglycan, interfering with cell wall construction (primarily gram-positives)

Question 13

natural penicillins are

Answer 13

• extracted from penicillium cultures, G (injected) and V (oral)
• narrow spectrum of activity
• susceptible to penicillinases (Beta-lactamases)

Question 14

semisynthetic penicillins

Answer 14

contain chemically added side chains, making them resistant to penicillinases

Question 15

list of inhibitors of protein synthesis

Answer 15

1. aminoglycosides (including streptomycin)
2. chloramphenicol
3. tetracyclines

Question 16

aminoglycosides

Answer 16

• amino sugars linked by glycoside bonds
• change the shape of the 30S subunit of the 70S ribosome
• can cause auditory damage
• streptomycin, neomycin, gentamicin

Question 17

chloramphenicol

Answer 17

• inhibits peptide bond formation
• binds to 50S subunit of the 70S ribosome
• synthesized chemically, broad spectrum
• can suppress bone marrow and affect blood cell formation

Question 18

tetracyclines

Answer 18

• produced by streptomyces spp.
• interfere with the tRNA attachment to the ribosome
• broad spectrum, penetrate tissues, making them valuble against rickettsias and chlamydias
• can suppress normal intestinal microbiota

Question 19

what substances injury the plasma membrane

Answer 19

1. lipopeptide

- includes daptomycin and polymixin B

Question 20

daptomycin

type of lipopeptide

Answer 20

• produced by streptomycetes, used for skin infections

- attacks the bacterial cell membrane

Question 21

polymixin B
(type of lipopeptide)

Answer 21

• topical, bacteriocidal, effective against gram negatives

- combined with bacitracin and neomycin in nonprescription ointments

Question 22

how do “inhibiting synthesis of essential metabolites” work

Answer 22

• antimetabolites compete with normal substrate for enzyme
• sulfonamides compete with para-aminobenzoic acid (PABA), stopping the synthesis of folic acid
• folic acid needed for nucleic acid and protein synthesis

Question 23

types of inhibitors of nucleic acid synthesis

Answer 23

-rifamycin
-quinolone and fluoroquinolones
(nalidixic acid, norfloxacin and ciprofloxacin)

Question 24

rifamycin

Answer 24

inhibits mRNA synthesis

-penetrates tissues, antitubercular activity

Question 25

quinolone- | nalidixic acid

Answer 25

synthetic, inhibits DNA gyrase

Question 26

quinolone- | norfloxacin and ciprofloxacin

Answer 26

broad spectrum, relatively nontoxic

Question 27

list 2 types of diffusion methods

Answer 27

1. disk-diffusion method (Kirby-Bauer) | 2. E test

Question 28

disk diffusion method (Kirby Bauer)

Answer 28

- tests the effectiveness of chemotherapeutic agents - paper disks with chemotherapeutic agent are placed on agar containing the test organism - zone of inhibition around the disk determines the sensitivity of the organism to the antibiotic

Question 29

E test

Answer 29

determines the minimal inhibitory concentration (MIC) | -lowest antibiotic concentration preventing bacterial growth

Question 30

broth dilution tests

Answer 30

- determine the MIC and minimal bacterial concentration (MBC) of an antimicrobial drug - test organism is placed into the wells of a tray containing dilutions of a drug, growth is determined

Question 31

what are antibiograms

Answer 31

reports that record the susceptibility of organisms encountered clinically

Question 32

what are persister cells

Answer 32

microbes with genetic characteristics allowing for their survival when exposed to an antibiotic

Question 33

superbugs

Answer 33

bacteria that are resistant to large numbers of antibiotics

Question 34

how are resistance genes spread

Answer 34

often spread horizontally among bacteria on plasmids or transposons via conjugation or transduction

Question 35

list of mechanisms of resistance

Answer 35

- enzymatic destruction or inactivation of the drug - prevention of penetration to the target site within the microbe - alteration of the drug's target site - rapid efflux (ejection) of the antibiotic - variations of mechanisms of resistance