INFECTIONS: PENICILLIN, PENICILLASE-RESISTANT Flashcards

1
Q

PENICILLINS, PR: INDICATIONS

A
  • Staphylococcal infection, including:
    1) Skin and soft tissue infections such as cellulitis (in combination with benzylpenicillin for more severe infection)

2) Osteomyelitis and septic arthritis
3) Other infections, including endocarditis.

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2
Q

PENICILLINS, PR: MOA

A
  • Penicillins inhibit the enzymes responsible for cross-linking peptidoglycans in bacterial cell walls
  • This weakens cell walls, preventing them from maintaining an osmotic gradient
  • Uncontrolled entry of water into bacteria causes cell swelling, lysis and death
  • Penicillins contain a β-lactam ring, which is responsible for their antimicrobial activity
  • Side chains attached to the β-lactam ring can be modified to make semi-synthetic penicillins
  • The nature of the side chain determines the antimicrobial spectrum and other properties of the drug
  • For flucloxacillin, an acyl side chain protects the β-lactam ring from β-lactamases, which are enzymes made by bacteria to deactivate penicillin
  • This makes flucloxacillin effective against β-lactamase producing staphylococci.
  • Meticillin-resistant Staphylococcus aureus (MRSA) resists the actions of flucloxacillin by reducing penicillin binding affinity.
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3
Q

PENICILLINS, PR: ADVERSE EFFECTS

A
  • Minor GI upset
  • Penicillin Allergy (acute/delayed)
  • Liver Toxicity - cholestasis and hepatitis
  • CNS toxicity can occur in high doses of penicillin or where severe renal impairment delays excretion
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4
Q

PENICILLINS, PR: WARNINGS

A
  • Generally safe in most situations
  • Dose reduction in renal failure
  • Main CI to Flucloxacillin use is a Hx of Penicillin allergy
  • Prior Flucloxacillin-related hepatotoxicity
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5
Q

PENICILLINS, PR: INTERACTIONS

A
  • MTX
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6
Q

PENICILLINS, PR: EXAMPLES

A
  • Flucloxacillin
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