Penicillin: Types, Action & Medications

Penicillin: Overview

• Penicillin treats a wide range of infections, including ear and throat infections (broad-spectrum) and urinary tract infections (narrow-spectrum).
• Primarily targets gram-positive cocci and bacilli; some penicillins (e.g., ampicillin) also effective against gram-negative bacteria.
• Amoxicillin, a broad-spectrum penicillin, treats non-penicillinase-producing bacteria and other infections.

Mechanism of Action

• Beta-lactam antibiotics like penicillin weaken and destroy bacterial cell walls by inhibiting transpeptidase (cell wall formation enzyme) and activating autolysin (cell wall-opening enzyme).
• Penicillins are bactericidal, mostly against aerobic gram-positive bacteria; some gram-negative.
• Penicillin G is the active component.
• Human cells lack cell walls, making penicillins safe for humans.

Prototype and other Medications

• Amoxicillin is the prototype penicillin.
• Other penicillins include penicillin G, nafcillin, and piperacillin.
• Addition of clavulanic acid increases the spectrum against bacteria that produce beta-lactamases which destroy the effectiveness of penicillin.

Adverse Drug Reactions

• Penicillins are a common cause of medication allergies.
• Gastrointestinal issues (diarrhea, nausea, vomiting) are possible with oral penicillin.
• Superinfections (candidiasis, Clostridium difficile-associated diarrhea (CDAD)) can occur, particularly with broad-spectrum antibiotics.
• Allergic reactions (rash, hives, anaphylaxis) can be serious and require monitoring.
• Important: Thorough allergy history is crucial prior to administration.
• Cephalosporins can be a suitable alternative for penicillin allergy; however, cross-reactivity is possible, thus careful consideration.

Interventions and Monitoring

• Administer with food to lessen gastrointestinal distress.
• Monitor for diarrhea (watery, bloody stools), which indicates possible C. difficile infection; report immediately.
• Watch for vaginal and oral candidiasis (intense itching, white discharge, oral thrush, mouth sores); treat with antifungal agents.
• Observe for rash, hives, difficulty breathing, and wheezing; if noted, notify the provider immediately.
• Intramuscular or intravenous administration requires observation for at least 30 minutes post-administration.
• Anaphylaxis is more frequent with penicillin than other medications.

Safety Alert

• Clients allergic to penicillin are at risk for anaphylaxis if exposed to penicillin.
• Thorough allergy history is crucial.
• Important: Consider allergy testing, especially with a history of penicillin allergy in childhood or for patients with no recollection of penicillin allergy symptoms.

Administration

• Penicillin comes in extended-release forms that should not be crushed or chewed (except for chewable/child-specific forms).
• Use drops cautiously if giving to infants/young children, and ensure the full dose is administered.
• Timing with meals can help reduce gastrointestinal side effects and improve absorption.
• Probenecid, when co-administered with amoxicillin, delays excretion, increasing amoxicillin's therapeutic blood level.

Client Instructions

• Report watery or bloody diarrhea promptly to the provider.
• Take the medication with or around mealtimes.
• Report mouth pain, difficulty eating, vaginal burning/itching/discharge, rash, or hives, immediately to the provider.
• Seek emergency assistance (911) for severe breathing difficulties, wheezing, or airway swelling.

Contraindications and Precautions

• Contraindicated in patients with a history of penicillin allergy.
• Use cautiously in patients with severe renal impairment; dose adjustments may be necessary.
• Avoid concomitant use with certain bacteriostatic agents.

Interactions

• Probenecid increases penicillin blood levels.
• Concurrent use with bacteriostatic agents is generally not recommended.
• Penicillin may reduce the effectiveness of oral contraceptives.

Learn about penicillin, a beta-lactam antibiotic that weakens bacterial cell walls, its mechanism of action, and its use in treating infections. Understand its prototype, amoxicillin, and other related medications. This antibiotic is effective against a range of gram-positive and some gram-negative bacteria.