Lesson 11

Question 1

Lowest
concentration of a drug that inhibits bacterial growth

Answer 1

Minimum Inhibitory Concentration (MIC)

Question 2

Ratio of the toxic dose to the
therapeutic dose (Higher TI = Higher Effectivity

Answer 2

Therapeutic Index

Question 3

Lowest concentration of a drug that kills bacterial growth

Answer 3

Minimum Lethal Concentration (MLC)

Question 4

DNA Elements that encode transposition and excision functions

Answer 4

Transposons

Question 5

Enzymes that mediate
peptidoglycan cross-linking

Answer 5

Penicillin-binding proteins

Question 6

Genetic elements capable of integrating genes

Answer 6

Integrons

Question 7

Chemical substances produced by a microorganism with the capacity to inhibit other microorganisms (bacteriostatic) or destroy/kill the organisms (bactericidal)

Answer 7

Antimicrobials

Question 8

Agents that kill bacterial cells

Answer 8

Bacteriocidal

Question 9

Agents that inhibit bacterial growth

Answer 9

Bacteriostatic

Question 10

Naturally found in bacteria
(chromosomal)

Answer 10

Intrinsic Resistance

Question 11

Acquired from exogenous DNA
(Plasmid or through conjugation

Answer 11

Extrinsic Resistance

Question 12

-He knew Arsenic can kill syphillis organism but is toxic to humans
-Systematically tried combinations of Arsenic with organics

Answer 12

Paul Ehrlich

Question 13

He coined the term “Selective Toxicity”

Answer 13

Paul Ehrlich

Question 14

He created Prontosil:
Effective against infections in animals despite a lack of activity in the test tube

Answer 14

Gerhardt Domagk

Question 15

Introduced into field hospitals during WWII and saved countless lives from surgical wound infections

Answer 15

Sulfa Drugs

Question 16

He discovered Penicillin

Answer 16

Sir Alexander Fleming

Question 17

o Work only on gram-positives (cannot penetrate
the outer cell membrane)
o Exception: Doripenem, carbapenem
Used to treat gram-positive and gramnegative bacillus
(including Pseudomonas aeruginosa)

Answer 17

Narrow Spectrum

Question 18

Work on a broad variety of bacteria (can penetrate the outer membrane)

Answer 18

Broad Spectrum

Question 19

Produced by bacteria or fungi

Answer 19

Natural Drugs

Question 20

Chemically modified natural drugs with added extra chemical groups

Answer 20

Semisynthetic Drugs

Question 21

Chemically produced drugs

Answer 21

Synthetic Drugs

Question 22

Basic Structure of Penicillin

Answer 22

Aminopenicillanic Acid

Question 23

o Closely related to Penicillin
o Have a beta lactam ring as part of the basic structure

Answer 23

Cephalosporins

Question 24

Binds to and inhibits the
transpeptidases (Known as Penicillinbinding proteins, PBPs)

Answer 24

B-Lactam Ring

Question 25

o Examples: Vancomycin, Teicoplanin o Blocks the Transpeptidation step o Narrow spectrum antibiotic o Useful for staphylococci, streptococci, and enterococci o Vancomycin Does not bind to PBP but to the DAlanyl-D-Alanine termini of Peptidoglycan precursors. Interference with elongation and cross-linking of the Peptidoglycan weakens the cell wall and the organisms lyse.

Answer 25

Glycopeptides

Question 26

Competitively inhibits Dihydropteroate synthetase Needs constant levels of drug to inhibit enzyme (High therapeutic index)

Answer 26

Sulfonamides

Question 27

Competitively inhibits Dihydrofolate reductase Needs constant levels of drug to inhibit enzyme

Answer 27

Thrimetoprim

Question 28

o Most effective against Gram-Negative organisms o Drug binding is irreversible o Uptake: Dependent on Oxidative Phosphorylation Drug is not active in anaerobes or facultative anaerobes (I.e., Streptococcus pneumoniae)

Answer 28

Aminoglycosides

Question 29

o Broad spectrum, Bacteriostatic o Binding of drug to Ribosome is reversible

Answer 29

Tetracycline

Question 30

o Broad spectrum, Bacteriostatic o Has good penetration into the CSF Use restricted due to side effect (Aplastic Anemia) following or during treatment

Answer 30

Chlorampenicol

Question 31

Synthetic derivative of Rifamycin B, targets DNA transcription Interferes with production of mRNA ✓ Prevents Protein synthesis via blocking of RNA Polymerase Principle therapeutic use: Combination with other antibacterial classes to treat Mycobacterium tuberculosis

Answer 31

Rifampin

Question 32

Interferes with Bacterial Gyrase (Supercoiling of the DNA) Examples: Nalidixic Acid, Norfloxacin, Ciprofloxacin

Answer 32

Quinolones

Question 33

Irreversibly binds to 30S subunit ✓ Prevents docking of Aminoacyl-tRNA Also contributes to misreading the genetic code

Answer 33

Aminoglycosides

Question 34

Binds to 30S subunit ✓ Interferes with the stability of peptidyl tRNA by inhibiting elongation factor

Answer 34

Spectinomycin

Question 35

Natural consequence of drug exposure and results from the use and inappropriate use of antimicrobial agents

Answer 35

Antimicrobial Drug Resistance

Question 36

• Present only on certain isolates that are different from the parental strain. • Result of chromosomal mutations (transformation and recombination), acquisition of extrachromosomal DNA or by horizontal transfer of preexisting resistance genes.

Answer 36

Acquired Resistance