Antibacterial protocols 7.4

Question 1

Cephalosporins and Cephamycins are antibacterial agents that are isolated from?

Answer 1

the mold Cephalosporium

Question 2

Cephamycins are closely related to the

cephalosporins, except that they contain?

Answer 2

oxygen in place of sulfur in the dihydrothiazine ring. THIS renders them more stable to β-lactamase hydrolysis

Question 3

does penicillin or Cephalosporins/Cephamycins have a wider antibacterial spectrum?

Answer 3

Cephalosporins and Cephamycins

Question 4

Cephalosporins and Cephamycins are RESISTANT to?

Answer 4

resistant to many β-lactamases

Question 5

Name antibiotics that interfere with constuction of bacterial cell wall

Answer 5

1) Penicillin
2) Cephalosporins and Cephamycins
3) vancomycin
4) Daptomycin
5) Bacitracin
6) antimycobacterial agents: isoniazid, ethambutol, cycloserine, and ethionamide

Question 6

Vancomycin was originally obtained from?

Answer 6

Streptomyces orientalis

Question 7

Vancomycin disrupts? G- or G+ ?

Answer 7

Disrupts peptidoglycan synthesis in gram-positive bacteria

Question 8

Vancomycin interacts with what in order to form interpeptide bridges?

Answer 8

interacts with D-alanine-D-alanine termini of pentapeptide interfering with formation of interpeptide bridges

Question 9

Vancomycin is inactive against G- or G+ bacteria? why?

Answer 9

inactive against gram-negative bacteria, because its too large for porins

Question 10

what is resistant to Vancomycin?

Answer 10

• *Intrinsic resistance to vancomycin= Leuconostoc, Lactobacillus, Pediococcus, Erysipelothrix, AND Enterococcus gallinarum, Enterococcus casseliflavus
• *aquired resistance

Question 11

Bacitracin Isolated from?
Is a mixture of?
G- or G+ are resistant to Bacitracin?

Answer 11

Bacillus licheniformis
*a mixture of polypeptides
G- are resistant

Question 12

Bacitracin is used in?

Answer 12

creams, ointments, sprays for skin infections caused by gram-positive bacteria (Staphylococcus and group A Streptococcus)

Question 13

Bacitracin Inhibits cell wall synthesis by interfering with?

Answer 13

bactoprenol carrier of peptidoglycan precursors

Question 14

Bacitracin Resistance to antibiotic is caused by?

Answer 14

failure of the antibiotic to penetrate into the bacterial cell

Question 15

Isoniazid, Ethionamide, Ethambutol, and
Cycloserine
1) used for treatment of?
2) bactericidal against actively replicating?
3) synthesis of \_\_\_\_ acid is affect
4) mechanism of action?

Answer 15

1) treatment of mycobacterial infections
2) Bactericidal against actively replicating mycobacteria
3) Synthesis of mycolic acid is affected
4) mechanism of action is unknown

Question 16

Ethambutol interferes with the synthesis of?

Answer 16

arabinogalactan in cell wall

Question 17

Cycloserine inhibits?

Answer 17

D-alanine-D-alanine synthetase

and alanine racemase, for cell wall synthesis

Question 18

What all inhibits nucleic acid synthesis?

Answer 18

Quinolones and Rifampin and Rifabutin,

Question 19

examples of Quinolones?

Answer 19

nalidixic acid, ciprofloxacin, levofloxacin, and moxifloxacin

Question 20

Quinolones have excellent activity against?

Answer 20

gram-positive and gram-negative bacteria, although resistance can develop rapidly

Question 21

newer extended-spectrum Quinolones have significant activity against? Ex?

Answer 21

gram-positive bacteria

Ex:moxifloxacin

Question 22

what is the promary Quinolones target in G- bacteria? G+?

Answer 22

G-= DNA gyrase-A subunit aka topoisomerase type II
G+= topoisomerase type IV

Question 23

What do Quinolones do?

Answer 23

A widely used class of antibiotics that inhibit bacterial DNA topoisomerase type II (gyrase) or topoisomerase type IV, required for DNA replication, recombination, and repair

Question 24

Rifampin and Rifabutin is a semisynthetic derivative of rifamycin B produced by?

Answer 24

Streptomyces mediterranei

Question 25

What does Rifampin and Rifabutin do?

Answer 25

binds to DNA-dependent RNA polymerase and inhibits initiation of RNA synthesis

Question 26

Rifampin and Rifabutin is very active against? Bactericidal for?

Answer 26

aerobic gram-positive cocci, including
staphylococci and streptococci BUT resistance can develope rapidly
**Bactericidal for Mycobacterium tuberculosis

Question 27

why is Gram-negative bacteria are resistant intrinsically to rifampin?

Answer 27

because of decreased uptake of the hydrophobic