Indicated only in minor infections because of its relatively poor

Indicated only in minor infections because of its

This preview shows page 4 - 7 out of 18 pages.

Indicated only in minor infections because of its relatively poor bioavailability, the need for dosing four times a day, and its narrow antibacterial spectrum
Amoxicillin is often preferred Narrow-Spectrum Penicillin [Penicillinase-resistant (anti-staphylococcal PCN)] o 1940s: Penicillin introduced o All strains of S. aureus were sensitive o 1960: 80% of S. aureus isolates in hospitals displayed penicillin resistance o Penicillin derivative (methicillin) developed; resistant to actions of beta-lactamases o Methicillin-resistant Staphylococcus aureus (MRSA) has a unique mechanism of resistance ‒ it produces PBPs (penicillin binding protein) with a low affinity for penicillin and all other beta-lactam antibiotics o MRSA developed this ability by acquiring genes that code for low-affinity PBPs from other bacteria o Anti-staphylococcal penicillin: chain altered to create resistance to inactivation by enzyme Nafcillin, Oxacillin, Dicloxacillin Very narrow spectrum Broad-Spectrum Penicillin (aminopenicillins) Ampicillin (po or IV), Amoxicillin and Amoxicillin-clavulunate ie: Augmentin (both are po) - From cartoon o Bactericidal to susceptible organisms o Used for: skin infection, respiratory infections, GU & GI infections, peptic ulcer, H. pylori, Otis media o Adverse effects: rash, diarrhea; anaphylaxis, n/v, oral/diaper/vaginal candidiasis Extended-Spectrum Penicillin [Antipseudomonal penicillins] ticarcillin-clavulunate (Timentin), piperacillin tazobactam (Zosyn) (both IV) o Broad-spectrum, but penicillinase sensitive o Effective against organisms susceptible to the aminopenicillins plus Pseudomonas aeruginosa, Enterobacter species, Proteus (indole positive), Bacteroides fragilis, and many Klebsiella species Beta-lactamase inhibitors (combined with PCN) o Extends antimicrobial spectrum when combined with penicillinase-sensitive antibiotics o Resemble beta-lactam antibiotic structure o Bind to beta-lactamase and protect the antibiotic from destruction o Most successful when they bind the beta-lactamaze irreversibly o Three important in medicine Clavulanic acid Sulbactam Tazobactam o Beta-lactam/beta-lactamase inhibitors Ampicillin/sulbactam Amoxicillin/clavulanate Ticarcillin/clavulanate Piperacillin/tazobactam Penicillin Allergy PCN is most common cause of drug allergy : up to 7% experience reaction Types o Immediate (reaction in 2 to 30 minutes) o Accelerated (reaction in 1 to 72 hours) o Late (takes days or weeks to develop) Assess for penicillin allergy in each patient – who will be receiving penicillin Consider skin tests for penicillin allergy, consider desensitization Anaphylaxis-EMERGENCY!!!
o Laryngeal edema o Bronchoconstriction o Severe hypotension Management of patients with a history of penicillin allergy: o Mild = rash/hives (raised, extremely itchy spots that come and go over a period of hours), OR tissue swelling under the skin, typically around the face (also known as angioedema) o If history of mild reaction: consider cephalosporin o If history of anaphylaxis

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture