Penicillins

Question 1

Penicillin structure consists of a fused _ ring and a _ ring

Answer 1

Penicillin structure consists of a fused beta-lactam ring and a thiazolidine ring
* Also has an amide and carboxylic acid

Question 2

Aminopenicillins (ampicillin and amoxicillin) have a positively charged amino group that enhances their _

Answer 2

Aminopenicillins (ampicillin and amoxicillin) have a positively charged amino group that enhances their uptake through porins

Question 3

Carboxypenicillins (ticarcillin) has a _ group in the variable side chain of penicillin

Answer 3

Carboxypenicillins (ticarcillin) has a carboxylic acid group in the variable side chain of penicillin

Question 4

Piperacillin (a type of ureidopenicillin) has an additional _ group

Answer 4

Piperacillin (a type of ureidopenicillin) has an additional urea group

Question 5

Nafcillin and oxacillin have a bulky R group that blocks _

Answer 5

Nafcillin and oxacillin have a bulky R group that blocks beta-lactamase from the beta-lactam ring

Question 6

Most penicillins (can/cannot) cross the blood-brain barrier to penetrate the CNS when the meningest are inflammed; they are then excreted unchanged in the urine

Answer 6

Most penicillins can cross the blood-brain barrier to penetrate the CNS when the meningest are inflammed; they are then excreted unchanged in the urine

Question 7

Which penicillin is mainly excreted in the bile?

Answer 7

Nafcillin is mainly excreted in the bile

Question 8

_ penicillins have poor oral absorption, while _ penicillins have better oral absorption

Answer 8

Penicillin G, Methicillin, Nafcillin have poor oral absorption, while Penicillin V, aminopenicillins have better oral absorption

Question 9

The core beta-lactam ring of penicillins is important because it bind irreversibly to _ and inhibits its action

Answer 9

The core beta-lactam ring of penicillins is important because it bind irreversibly to transpeptidase and inhibits its action
* Otherwise known as penicillin-binding protein

Question 10

The enzyme that beta-lactam of penicillin inhibits an enzyme in the bacterial cell that serves _ function

Answer 10

The enzyme that beta-lactam of penicillin inhibits an enzyme in the bacterial cell that cross-links the linear peptidoglycan chain components of the cell wall
* Cell wall synthesis is halted, bacteria die

Question 11

Penicillin can be used against (gram-positive/ gram-negative/ both)

Answer 11

Penicillin can be used against both gram-positive and gram-negative bacteria because they both have peptidoglycan in their cell walls

Question 12

The beta-lactam pretents to be _ , a normal part of the peptidoglycan

Answer 12

The beta-lactam pretents to be D-Ala-D-Ala , a normal part of the peptidoglycan –> binds to the transpeptidase (PBP) –> blocks normal cross-linking in the cell wall
* In other words, it acts as a structural analogue

Question 13

Beta-lactam antibiotics not only inhibit cell wall cross-linking, but they also activate _ enzymes to cause lesions in the bacterial cell wall

Answer 13

Beta-lactam antibiotics not only inhibit cell wall cross-linking, but they also activate autolytic enzymes to cause lesions in the bacterial cell wall –> rapid digestion of the cell wall –> osmotic death

Question 14

Sometimes beta-lactam and aminoglycosides are prescribed to take together, as synergists; _ operate via time-dependent killing, while _ operate via concentration-dependent killing

Answer 14

Sometimes beta-lactam and aminoglycosides are prescribed to take together, as synergists; beta-lactams operate via time-dependent killing, while aminoglycosides operate via concentration-dependent killing
* Time dependent means the more time spent above the MIC the better
* Concentration dependent means the more the plasma level is above the MIC the better

Question 15

Both gram-positive and gram-negative organisms can produce _ (enzyme) that allows beta-lactam ring cleavage and loss of antimicrobial activity

Answer 15

Both gram-positive and gram-negative organisms can produce beta- lactamase (enzyme) that allows beta-lactam ring cleavage and loss of antimicrobial activity

Question 16

β-Lactamase inhibitors are given in combination with penicillins to create a β-lactamase–resistant combination; Some of the common ones include _ (often paired with amoxicillin), _ , and _

Answer 16

β-Lactamase inhibitors are given in combination with penicillins to create a β-lactamase–resistant combination; Some of the common ones include clavulanic acid (often paired with amoxicillin), sulbactam, and tazobactam

Question 17

Penicillin gets degraded into several metabolites like _ derivatives which elicit an immune response including IgE production

Answer 17

Penicillin gets degraded into several metabolites like benzylpenicilloyl derivatives which elicit an immune response including IgE production

Question 18

Type I hypersensitivity (immediate) to penicillin occur when IgE antibodies on mast cells interact with the penicillin metabolites and cause immediate degranulation of _ cells –> releases histamine

Answer 18

Type I hypersensitivity (immediate) to penicillin occur when IgE antibodies on mast cells interact with the penicillin metabolites and cause immediate degranulation of mast cells –> releases histamine

Question 19

Type II hypersensitivity occurs when IgG reacts with penicillin absorbed on RBCs –> leads to _

Answer 19

Type II hypersensitivity occurs when IgG reacts with penicillin absorbed on RBCs –> leads to hemolytic anemia

Question 20

Type III hypersensitivity can result due to the circulating antibody-antigen complexes that can deposit in the skin, kidneys, and blood vessels and cause tissue damage through _ activation

Answer 20

Type III hypersensitivity can result due to the circulating antibody-antigen complexes that can deposit in the skin, kidneys, and blood vessels and cause tissue damage through complement activation
* Urticaria, diffused lymphadenopathy, arthralgia

Question 21

Type IV hypersensitivity is beleived to cause drug induced _ and presents with fever, eosinophilia, rash, hematuria

Answer 21

Type IV hypersensitivity is beleived to cause drug induced tubular interstitial nephritis and presents with fever, eosinophilia, rash, hematuria

Question 22

_ is a reaction that occurs in patients being treated with penicillin G for spirochete infection (syphilis); it causes flu-like symptoms due to the release of toxins by the killed bacteria

Answer 22

Jarisch-Herxheimer reaction is a reaction that occurs in patients being treated with penicillin G for spirochete infection (syphilis); it causes flu-like symptoms due to the release of toxins by the killed bacteria

Question 23

_ is caused by C diff due to changes in normal bowel flora after penicillin treatment and c diff overgrowth (spores survive despite being sensitive to penicillin)

Answer 23

Pseudomembranous colitis is caused by C diff due to changes in normal bowel flora after penicillin treatment and c diff overgrowth (spores survive despite being sensitive to penicillin)
* Pseudomembranes = areas of white exudate

Question 24

Ampicillin and amoxicillin are known to cause a maculopapular skin rash; patients with _ are more likely to experience this

Answer 24

Ampicillin and amoxicillin are known to cause a maculopapular skin rash; patients with mononucleosis are more likely to experience this