Flashcards in Micro - Antimicrobials (Penicillins) Deck (31):
What are the major forms of Penicillin? Into what broader class of antibiotics are Penicillins classified?
Penicillin G (IV and IM form); Penicillin V (oral); Prototype Beta-lactam antibiotics.
What is the mechanism of Penicillin? More specifically, list the 3 major components of its mechanism of action.
(1) Bind penicillin-binding proteins (transpeptidases) (2) Block transpeptidase cross-linking of peptidoglycan (3) Activate autolytic enzymes
What is Penicillin mostly used for clinically? What are its other clinical uses?
Mostly used for gram-positive organisms (S. pneumoniae, S. pyogenes, Actinomyces); Also used for Neisseria meningitidis and Treponema pallidum
What enzyme is particularly relevant to Penicillin, and what is the impact of this enzyme?
Penicillin is not penicillinase resistant
Against what kinds of bacteria is Penicillin bactericidal?
Bactericidal for gram-positive cocci, gram-positive rods, gram-negative cocci, and spirochetes
What 2 toxicities are associated with Penicillin?
(1) Hypersensitivity reactions (2) Hemolytic anemia
What kind of resistance should be considered with Penicillin?
Penicillinase (a type of Beta-lactamase) cleaves Beta-lactam ring
What type of Penicillin are oxacillin, nafcillin, and dicloxacillin?
What are 3 examples of Penicillinase-resistant Penicillins?
(1) Oxacillin (2) Nafcillin (3) Dicloxacillin
Again, what are the penicillinase-resistant penicillins? What is their mechanism of action and spectrum?
Oxacillin, Nafcillin, Dicloxacillin; Same as penicillin (i.e., block peptidoglycan cross linking), Narrow spectrum
Are oxacillin, nafcillin, and dicloxacillin penicillinase-resistant? Why or why not?
Yes; Penicillinase resistant because bulky R group blocks access of Beta-lactamase to Beta-lactam ring
For what are penicillinase-resistant penicillins (i.e., oxacillin, nafcillin, dicloxacillin) clinically used?
S. aureus (except MRSA; resistant because of altered penicillin-binding protein target site); Think: "Use NAF (Nafcillin) for STAPH"
What are the 2 toxicities associated with penicillinase-resistant penicillins (i.e, oxacillin, nafcillin, dicloxacillin)?
(1) Hypersensitivity reactions (2) Interstitial nephritis
What are the aminopenicillins?
(1) Ampicillin (2) Amoxicillin
What kind of drugs are Ampicillin and Amoxicillin?
What is the mechanism of action for Aminopenicillins (i.e., Ampicillin and Amoxicillin) and spectrum?
Same as penicillin (i.e., block peptidoglycan cross linking), Wider spectrum; Think: "AMinoPenicillins are AMP-ed up penicillin"
Are Aminopenicillins pencillinase resistant?
No, Penicillinase sensitive
What are Aminopenicillins combined with for therapy, and why?
Also combine with cavulanic acid to protect against Beta-lactamase
Compare of the oral bioavailability of the Aminopenicillins.
AmOxicillin has greater Oral bioavailability than ampicillin
How are Aminopenicillins used clinically?
Extended-spectrum penicillin - Haemophilus influenzae, E. coli, Listeria monocytogenes, Proteus mirabilis, Salmonella, Shigella, enterococci; Think: Coverage: "ampicillin/amoxicillins HELPSS kill enterococci"
What 3 toxicities are associated with Aminopenicillins?
(1) Hypersensitivity reactions (2) Rash (3) Pseudomembranous colitis
What is important to note with regard to resistance of Aminopenicillins?
Penicillinase sensitive; Penicillinase (a type of Beta-lactamase) cleaves Beta-lactam ring
What are 2 of the Antipseudomal penicillins?
(1) Ticarcillin (2) Piperacillin
What kind of drugs are Ticarcillin and Piperacillin?
What is the mechanism of action of Antipseudomonal Penicillins? What is their spectrum?
Same as penicillin (i.e., block peptidoglycan cross linking), Extended spectrum
How are Antipseudomonal Penicillins (e.g., Ticarcillin, Piperacillin) used clinically?
Pseudomonas spp. and gram-negative rods
Are Ticarcillin and Piperacillin resistant to penicillinase?
No; Susceptible to penicillinase;
What is combined with Antipseudomonal Penicillin therapy, and why?
Use with Beta-lactamase inhibitors (e.g., clavulanic acid); Antipseudomonal Penicillins are susceptible to penicillinase
What toxicity is associated with Antipseudomonal Penicillins (i.e., Ticarcillin, Piperacillin)?
What are examples of Beta-lactamase inhibitors?
Include Clavulanic Acid, Sulbactam, Tazobactam; CAST