Penicillins Flashcards
Penicillin structure consists of a fused _ ring and a _ ring
Penicillin structure consists of a fused beta-lactam ring and a thiazolidine ring
* Also has an amide and carboxylic acid
Aminopenicillins (ampicillin and amoxicillin) have a positively charged amino group that enhances their _
Aminopenicillins (ampicillin and amoxicillin) have a positively charged amino group that enhances their uptake through porins
Carboxypenicillins (ticarcillin) has a _ group in the variable side chain of penicillin
Carboxypenicillins (ticarcillin) has a carboxylic acid group in the variable side chain of penicillin
Piperacillin (a type of ureidopenicillin) has an additional _ group
Piperacillin (a type of ureidopenicillin) has an additional urea group
Nafcillin and oxacillin have a bulky R group that blocks _
Nafcillin and oxacillin have a bulky R group that blocks beta-lactamase from the beta-lactam ring
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
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
Which penicillin is mainly excreted in the bile?
Nafcillin is mainly excreted in the bile
_ penicillins have poor oral absorption, while _ penicillins have better oral absorption
Penicillin G, Methicillin, Nafcillin have poor oral absorption, while Penicillin V, aminopenicillins have better oral absorption
The core beta-lactam ring of penicillins is important because it bind irreversibly to _ and inhibits its action
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
The enzyme that beta-lactam of penicillin inhibits an enzyme in the bacterial cell that serves _ function
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
Penicillin can be used against (gram-positive/ gram-negative/ both)
Penicillin can be used against both gram-positive and gram-negative bacteria because they both have peptidoglycan in their cell walls
The beta-lactam pretents to be _ , a normal part of the peptidoglycan
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
Beta-lactam antibiotics not only inhibit cell wall cross-linking, but they also activate _ enzymes to cause lesions in the bacterial cell wall
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
Sometimes beta-lactam and aminoglycosides are prescribed to take together, as synergists; _ operate via time-dependent killing, while _ operate via concentration-dependent killing
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
Both gram-positive and gram-negative organisms can produce _ (enzyme) that allows beta-lactam ring cleavage and loss of antimicrobial activity
Both gram-positive and gram-negative organisms can produce beta- lactamase (enzyme) that allows beta-lactam ring cleavage and loss of antimicrobial activity
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 _
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
Penicillin gets degraded into several metabolites like _ derivatives which elicit an immune response including IgE production
Penicillin gets degraded into several metabolites like benzylpenicilloyl derivatives which elicit an immune response including IgE production
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
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
Type II hypersensitivity occurs when IgG reacts with penicillin absorbed on RBCs –> leads to _
Type II hypersensitivity occurs when IgG reacts with penicillin absorbed on RBCs –> leads to hemolytic anemia
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
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
Type IV hypersensitivity is beleived to cause drug induced _ and presents with fever, eosinophilia, rash, hematuria
Type IV hypersensitivity is beleived to cause drug induced tubular interstitial nephritis and presents with fever, eosinophilia, rash, hematuria
_ 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
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
_ 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)
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
Ampicillin and amoxicillin are known to cause a maculopapular skin rash; patients with _ are more likely to experience this
Ampicillin and amoxicillin are known to cause a maculopapular skin rash; patients with mononucleosis are more likely to experience this
