antimicrobials-

Question 1

Chemical substances produced by microorganisms with the capacity to inhibit
(bacteriostatic) or kill (bactericidal) other microorganisms.

Answer 1

antibiotics/antimicrobials

Question 2

produce amphotericin B

Answer 2

streptomyces nodosus

Question 3

produce Nystatin

Answer 3

Streptomyces noursei

Question 4

produce Chloramphenicol

Answer 4

Streptomyces venezuelae

Question 5

produce Bacitracin

Answer 5

Bacillus subtilis

Question 6

produce Polymyxin

Answer 6

Bacillus polymyxa

Question 7

produce Cephalosporins

Answer 7

Cephalosporium

Question 8

produce Gentamicin

Answer 8

Micromonospora purpurea

Question 9

produce Penicillin

Answer 9

Penicillium notatum

Question 10

produce Erythromycin

Answer 10

Streptomyces erythraeus

Question 11

produce Neomycin

Answer 11

Streptomyces fradiae

Question 12

effective against a limited number of pathogens.

Answer 12

narrow spectrum

Question 13

example of narrow-spectrum

Answer 13

Bacitracin, clindamycin, erythromycin, gentamicin, penicillin and
Vancomycin

Question 14

destroy different kinds of organisms.

Answer 14

broad spectrum

Question 15

example of broad spectrum

Answer 15

Ampicillin, cephalosporins, chloramphenicol, ciprofloxacin, rifampicin,
trimethoprim and tetracycline.

Question 16

drugs produced by bacteria or fungi.

Answer 16

natural drugs such as Erythromycin, amphotericin B, vancomycin, tetracycline, penicillin

Question 17

modified drugs with added chemical groups.

Answer 17

semi-synthetic drugs such as Ampicillin, carbenicillin and methicillin.

Question 18

a chemically-produced drugs

Answer 18

synthetic drugs such as Sulfonamides, trimethoprim, ciprofloxacin, isoniazid.

Question 19

inhibit the bacterial growth but generally they do not kill the microorganisms.

Answer 19

Bacteriostatic agents such as Chloramphenicol, erythromycin, clindamycin

Question 20

usually kill or destroy organisms and are used for the treatment of life-threatening infections.

Answer 20

bactericidal agents such as:
Aminoglycosides ( gentamicin,amikacin & streptomycin)
β-lactams ( ceftriaxone, imepenem, penicillin & cefotaxime)
Glycopeptides ( isoniazid, quinolones, bacitracin and metronidazole)

Question 21

Characteristics of Antimicrobial agents

Answer 21

1. Must be in an active form.
2. Must able to achieve concentration at the site of infection that is higher than the
   pathogen’s MIC to be effective.
3. Must have “selective toxicity”.

Question 22

are genetic elements that are capable of integrating genes(cassettes) by an integrin
encoded site-specific recombinase.

Answer 22

integrons

Question 23

lowest concentration of a drug that can still
inhibit bacterial growth.

Answer 23

Minimal-inhibitory concentration (MIC)

Question 24

the lowest concentration of a drug that can kill bacteria.

Answer 24

Minimal lethal concentration

Question 25

are enzymes (transpeptidase or transglycolase) that mediate peptidoglycan cross-linking with reduced affinity for B-lactam antibiotics.

Answer 25

Penicillin-binding proteins

Question 26

the ratio of the toxic dose to the therapeutic dose and as such, the higher the therapeutic index, the more effective the chemotherapeutic agent.

Answer 26

therapeutic index

Question 27

DNA elements that encode transposition and excision functions and which are also able to carry antibiotic resistance genes among plasmids and chromosomes

Answer 27

transposons

Question 28

most selective antibiotics with a high therapeutic index. Inhibits the transpeptidase enzymes in which cell growth stops and the death of the cells occurs.

Answer 28

cell wall inhibitors

Question 29

inhibits the synthesis of peptidoglycan precursors

Answer 29

bacitracin

Question 30

inhibits transpeptidation

Answer 30

β-lactams

Question 31

acts on growing cells & can either be a bactericidal or bacteriostatic agent

Answer 31

isoniazid

Question 32

inhibits the translocation and elongation of peptidoglycan.

Answer 32

vancomycin

Question 33

binds with a 30S subunit that result in the misreading of mRNA and 50S subunit that results in the inhibition of peptidyl transferase and peptide chain elongation.

Answer 33

protein synthesis inhibitors such as Tetracycline, aminoglycosides (30S) Erythromycin,chloramphenicol & clindamycin ( 50S) Linezolid – blocks the initial step in protein synthesis.

Question 34

nucleic acid inhibitors

Answer 34

rifampicin, quinolones, metronidazole

Question 35

inhibits RNA polymerase

Answer 35

Rifampicin

Question 36

interferes with DNA gyrase and topoisomerase IV and highly effective for enteric bacteria.

Answer 36

Quinolones

Question 37

disrupts DNA and is effective against anaerobic bacteria.

Answer 37

Metronidazole

Question 38

cell membrane inhibitors

Answer 38

Polymyxin B and E – Gram- negative bacteria (P.aeuruginosa) also used as a topical antibiotic.

Question 39

Essential metabolite inhibitors

Answer 39

SMZ, Dapsone, Trimethoprin

Question 40

inhibits folic acid and metabolism and has a higher therapeutic index.

Answer 40

Sulfamethoxazole (SMZ)

Question 41

interferes with folic acid synthesis

Answer 41

Dapsone

Question 42

blocks the tetrahydrofale synthesis

Answer 42

Trimethoprim

Question 43

Result of both the use and overuse of antimicrobial agents and may arise within antibiotic-producing microorganism (autotoxicity)

Answer 43

Antibiotic Resistance

Question 44

2 types of A.R

Answer 44

Intrinsic Resistance and Acquired Resistance

Question 45

Result of the biochemical make up of wild type of organism. Depends on the hydrophobic or hydrophilic nature of the antibiotic and on the impermeability of the cell wall to the antibiotic Passed vertically into new cell.

Answer 45

Intrinsic Resistance

Question 46

All Gram-negative bacteria mediate this type of resistance through the inactivation of penicillin

Answer 46

intrinsic resistance

Question 47

enzymes that chemically inactivate β-lactam drugs by disrupting β-lactam ring component of the molecule.

Answer 47

B-lactamases

Question 48

clinically important B-lactamases

Answer 48

Class A enzymes - plasmids found Class C enzymes - chromosomally localed and inducible by exposure to β-lactams.

Question 49

structurally similar with the β-lactam antibiotics and functions as a substrate, thus reducing their harmful effects on the β-lactam antibiotics.

Answer 49

Β-lactamase Inhibitors

Question 50

Present only on a certain isolates that are different from the parental strains and usually expressed as a modification of target sites or enzymatic modification of antibiotics.

Answer 50

Acquired Resistance

Question 51

ex. of Acquired Resistance

Answer 51

Chromosomal mutations (transformation and recombination)