Penicillin

Question 1

MOA of penicillin?

Answer 1

bactericidal– inhibits the with the last step of synthesis of cell wall by three ways
Penicillin binding Proteins
inhibition of transpeptidation reaction(inhibibtion of cross linkage)
Production of autolysin

Question 2

Where are PBP located?

Answer 2

bacterial cytoplasmic memberane

Question 3

why is staph resistant to methicillin

Answer 3

due to alterations in PBP

Question 4

how does production of autolysin effect the bacterial cell?

Answer 4

Many bacteria, particularly the grampositive
cocci, produce degradative enzymes (autolysins) that
participate in the normal remodeling of the bacterial cell wall. In
the presence of a penicillin, the degradative action of the autolysins
proceeds in the absence of cell wall synthesis. Thus, the
antibacterial effect of a penicillin is the result of both inhibition
of cell wall synthesis and destruction of the existing cell wall by
autolysins.

Question 5

how are penicillins excreted out of the body?

Answer 5

excreted by kidney (excreted unchanged in urine)

Question 6

what is the mechanism of excretion of penicillins through kidney?

Answer 6

Active tubular Excretion

Question 7

the excretion of penicllin is effected by which drug?

Answer 7

probenecid(causes inhibition of active tubular excretion)

Question 8

the excretion of penicllins is effected by which drug?

Answer 8

probenecid(causes inhibition of active tubular excretion)

Question 9

what is the only penicllin that is excreted by a route other than kidney

Answer 9

Nafcillin (excreted by a biliary route)

Question 10

absorption of penicillin after oral administration

Answer 10

incompletely absorbed (amoxicillin is completely absorbed)

Question 11

antibacterial spectrum of penicillins

Answer 11

G+ve: → cell wall is easily penetrated.
G-ve: → envelope around cell wall, however porins permit entrance of penicillins.

Question 12

which microorganism lacks porins that makes it very resistant to penicillin action?

Answer 12

pseudomonas aeruginosa

Question 13

Penicillins in “Natural pencillins”?

Answer 13

Penicllin G
Penicillin V

Question 14

Which is more acid stable G or V

Answer 14

V

Question 15

which gram + cocci is natural penicillin active against?

Answer 15

Streptococcus(Pneumonia, pyrogenes, viridans)

Question 16

which gram - cocci is natural penicillin active against?

Answer 16

neisseria (gonorrhea, meningitides)

Question 17

is natural penicillin active against spirochetes?

Answer 17

treponema palladium(syphilis)

Question 18

which anerobic is natural penicillin active against?

Answer 18

clsostridium pefringens

Question 19

which gram + bacilli is natural penicillin active against?

Answer 19

corynebacterium diptheria
bacillus anthracis

Question 20

the class Anti Staphylococcal penicllins include which antibiotics?

Answer 20

Methicillin
Oxacillin
Nafcillin
Dicloxacillin
MOND

Question 21

Are antistaphylococcal penicillins (MOND) resistant to penicillanase (Beta lactamase)?

Answer 21

Yes

Question 22

what toxicity does methicillin cause?

Answer 22

interstitial nephritis

Question 23

What is MRSA and its treatment?

Answer 23

Methicillin resistant Staph Aureus

treated with vancomycin

Question 24

antibiotics in Extended spectrum

Answer 24

Ampicillin and amoxicillin

Question 25

spectrum of extended spectrum antibiotics?

Answer 25

same as penicillin g but with more effect on gram- bacilli( H influenza, E coli)

Question 26

drug of choice in listeria monocytogenes(Gram +)

Answer 26

Amoxicillin

Question 27

which drug is used as a prophylactic agent to prevent bacterial endocarditis

Answer 27

Amoxicillin

Question 28

what is done to extended spec antibiotics to inc their activity against Beta lactamase producing organisms

Answer 28

sulbactam and clavulanic acid

Question 29

what drug are included in antipseudomonal penicillins?

Answer 29

(Carbenicillin, Piperacillin, Ticarcillin) [CPT]

Question 30

which organism do (Carbenicillin, Piperacillin, Ticarcillin) [CPT] acts on

Answer 30

pseudomonas aeruginosa

Question 31

to enhance the activity of piperacillin what is it combined with

Answer 31

Tazobactam

Question 32

to enhance the activity of ticarcillin what is it combined with

Answer 32

clavulinic ACID

Question 33

Penicillins + Aminoglycosides

Answer 33

Synergistic effect as penicillins inhibit cell wall synthesis & A.G. inhibits protein synthesis with enhanced permeability.
*Caution: penicillin + A.G not in the same vial as: → (+ve) A.G. + (-ve) penicillin→ ppt

Question 34

Routes of administration:*
*CPT & their combination

Answer 34

IV & IM

Question 35

Route of administration
Penicillin V, Amoxicillin & Ampicillin +Clavulonic acid

Answer 35

oral

Question 36

Route of administration
Procaine penicillin G& benzathine penicillin G

Answer 36

depot IM slowly absorbed into the circulation

Question 37

route of administraion
*MOND→

Answer 37

given before food(30-60 min)

Question 38

adverse effects of penicillins

Answer 38

Hypersensitivity → most common.
The metabolite penicilloic acid reacts with proteins→ Hapten that causes immune Rx.
2) Diarrhea→ pseudomembranous colitis.
3) Nephritis→ mainly Methicillin.
4) Neurotoxicity→ epileptic patients at risk.
5) Hematologic toxicities→ ↓ coagulation (CPT).
6) Cation toxicity: penicillins are administered as Na+ or K+ salt.

Question 39

*Test of penicillins Hypersensitivity:

Answer 39

Penicilloyl- polylysine skin test

Question 40

ticarcillin causes what as a disodium salt

Answer 40

inc risk of HTN
also has an antiplatelet effect

Question 41

why is ticarcillin preferred over carbenicillin in pts with CHF

Answer 41

Because dose of Ticarcillin is 1/2 that of Carbenicillin.

Question 42

patient with penicillin allergy don’t shift to cephalosporin but shift to

Answer 42

erythromycin

Question 43

cross hypersensitivity risk bw penicillin and cephalosporin

Answer 43

10%