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Flashcards in Beta-Lactams Deck (26):
1

what structural component is essential for biological activity of penicillins?

beta-lactam ring

2

how is the problem of gastric acid sensitivity solved?

EWG at the alpha-carbon

3

oxacillin, dicloxacilin, and nafcillin are exceptions to the elimination process of most penicillins (excreted unchanged through the kidneys)
how are these drugs eliminated?

hepatobiliary system

4

explain the mechanism of penicillins

impair develoment of bacterial cell wall
- by inhibited transpeptidase enzymes (Penicillin binding proteins PBP) (covalent, irreversible) required for formation of cross-links between peptidoglycan strands
-normal bacterial growth depends on balance between cell wall deposition and autolysis

5

how do autolysins assist in the antimicrobial mechanism of penicillins?

autolysins are enzymes needed for normal remodeling of cell wall
-they continue to work in the presence of penicillin (ie absence of PBPs)
-cell wall is weakened even further

6

penicillins are ineffective against which types of organisms (lifecycle)

cells with formed cell walls or microbes without cell walls
-must be actively multipying or growing

7

describe the four mechanisms of bacterial resistance to penicillin

beta lactamase - antibiotic is inactivated
mutations - target is altered
pumps - antibiotics pumped out
porins - antibiotic cannot get in

8

what are porins?

gram negative rods
beta-lactam antibiotics enter cells via porins
mutations can alter porins, which makes it more difficult for beta-lactam to enter cell

9

which drugs are part of the penicillins

pen G (natural penicillin)
penicilin V (oral)

10

the penicillins are effective against what species?

gram + and gram - cocci
gram + bacilli
spirochetes
anaerobes

11

what species do the penicillins not cover

gram - bacilli and staph aureus
-beta-lactamase production

12

which penicillin is more stable in an acidic environment

penicillin V

13

which drugs are the beta-lactamase resistant penicillins
(anti-staph penicillins)

methicillin
cloxacillin
dicloxacillin
oxacillin
flucoxacillin (newest, reserved for severe infection)

14

what species do the beta-lactamase resistant penicillins cover?

staphylococcal infections that are resistant to pen G

not useful for gram - bacteria

15

which drugs are the aminopenicillins?

ampicillin
amoxicillin

16

what is the spectrum of the aminopenicillins?

gram + and gram - cocci, gram + and gram - bacilli, spirochetes, anaerobes


(similar to pen G plus gram - bacilli coverage)

17

ampicillin is used for:

acute bacterial meningitis due to listeria

18

the aminopenicillins are often used in combination drug with:

beta-lactamase inhibitors

Ampcillin/amoxicillin + clavulanic acid

19

aminopenicillins are useful for:

H influenzas, ear infections, respiratory infections in children

20

which drugs are antipseudomonal penicillins

carbenicillin
ticarcillin
piperacillin

21

carbenicillin is used for:

UTIs resistant to other antibiotics
only in oral form

22

ticarcillin is almost always given with:

clavulanic acid

23

piperacillin is almost always given with

tazobactam

24

antipseudomonal penicillins are used to treat infections caused by organisms not covered by penicillins including:

pseudomonas aeruginosa, proteus, enterobacter

25

penicillins are sometims given with aminoglycosides (gentamicin, etc). why?

increases the bactiericidal activity and shortens length of treatment because
- penicillins alter cell wall synthesis, increases permeability to other antibiotics

26

beta lactamase inhibitors include

clavulanic acid
sulbactam
tazobactam