Pharm II Antimicrobial Therapy (copy)

Antimicrobial Therapy

Key Terms

• Culture and Sensitivity: A laboratory test to determine the specific bacteria causing an infection and to assess its susceptibility to various antibiotics.

• Prophylaxis: Use of antibiotics to prevent infection, particularly in patients undergoing surgery or with compromised immune systems.

• Peak and Trough: Refers to the highest (peak) and lowest (trough) concentrations of a drug in the blood after administration. Important for dosage adjustments.

• Stevens-Johnson Syndrome (SJS): A rare and serious skin reaction involving an immune system overreaction to a drug or infection, potentially fatal.

• Blood Dyscrasias: Disorders affecting the blood components, including those associated with bone marrow and clotting proteins.

• Steady State: The condition when the overall intake of a drug is fairly in dynamic equilibrium with its elimination.

• Superinfection: A secondary infection that occurs when the normal microbial flora are disturbed by antibiotic treatment.

• Ototoxicity: Toxicity that affects the ear, potentially leading to hearing impairment.

• Nephrotoxicity: Toxic effects on the kidneys, which can impair their function.

• Crystalluria: The presence of crystals in urine, which can cause various renal complications.

Stevens-Johnson Syndrome (SJS)

• Description: Rare, serious skin reaction resulting from an immune system overreaction to various triggers, including medications or infections.

• Symptoms:

  • Skin Rash: Painful red rash that starts on the upper body and spreads, may blister and peel, leading to painful sores.

  • Mucous Membrane Involvement: Affects lining of mouth, airways, urinary tract, and genitals, causing difficulty with swallowing, breathing, or urination.

  • Eye Involvement: Affects conjunctiva and cornea, resulting in irritation, redness, pain, and vision issues.

  • Flu-like Symptoms: Fever, headache, joint pain, cough, sore throat, and generalized aches.

Antibiotic Therapy Basics

• Pre-medication Steps:

  • Check for allergies.

  • Obtain cultures before the first antibiotic dose.

  • Ensure to finish the entire course of antibiotics.

  • Report significant side effects to the healthcare provider.

  • Complete periodic lab testing if ordered.

• Interactions:

  • Some antibiotics may reduce the effectiveness of oral contraceptives (OC); alternative contraception may be necessary.

  • Certain antibiotics can cause photosensitivity; patients should wear sunscreen and avoid excessive sun exposure.

Penicillins

• Prototype: Ampicillin

• Characteristics:

  • Effective and generally safe.

  • Low incidence of side effects but high incidence of allergic reactions.

• Indications: Bacterial infections.

• Adverse Effects:

  • Allergies: Symptoms include dyspnea and rash; anaphylaxis possible.

  • GI Symptoms: Abdominal pain, diarrhea, gastritis, nausea, and vomiting.

  • Superinfections: Risk of yeast infections and Clostridium difficile infections.

• Contraindications: History of allergies to penicillins or cephalosporins.

• Nursing Administration:

  • Administer on an empty stomach.

  • Avoid taking orally with acidic fluids.

  • Monitor for allergic reactions and bowel function.

• Route: PO, IM, IV.

• Interactions: Check for compatibility with other antibiotics like tetracyclines and aminoglycosides.

Cephalosporins

• Prototype: Cephalexin (1st generation), Ceftriaxone, Ceftazidime, Cefepime (Generations 1-5).

• Characteristics: Related closely to penicillins.

• Uses: Surgical prophylaxis, commonly the drug of choice for numerous surgical procedures; a single dose is often effective.

• Adverse Effects: GI disturbances, allergic reactions, and superinfections (e.g., Clostridium difficile).

• Contraindications: Hypersensitivity reactions and history of penicillin allergy.

• Patient Teaching: Avoid alcohol while on therapy.

• Nursing Administration:

  • Monitor for rash, GI effects, and abdominal pain, especially with bloody diarrhea.

  • Assess BUN and creatinine (Cr) levels as they may indicate renal impairment.

  • Be aware of many drug-drug interactions; anticoagulants may have their prothrombin time decreased due to vitamin K depletion.

Aminoglycosides

• Prototype: Gentamicin.

• Mechanism of Action (MOA): Inhibits protein synthesis in bacteria, bactericidal.

• Indications: Serious bacterial infections.

• Adverse Effects:

  • Ototoxicity (potential hearing loss and tinnitus).

  • Nephrotoxicity, particularly in the elderly, as well as vertigo, ataxia, and neurotoxicity.

• Nursing Administration:

  • Monitor peak and trough drug levels to ensure therapeutic ranges are met; peak levels measured 30-60 minutes post-administration, trough levels drawn before the next dose.

  • IV is the preferred route since the drug is not absorbed in the GI tract; monitor kidney functions (creatinine, BUN, urinalysis).

  • Maintenance doses should be based on serum drug concentrations.

Fluoroquinolones

• Prototype: Ciprofloxacin (Cipro), Levofloxacin.

• Uses: Effective against various bacterial infections, including respiratory, UTIs, bone/joint infections, and anthrax.

• Adverse Effects:

  • Common: Diarrhea, superinfections, photosensitivity, increased liver enzymes (AST, ALT, LDH, bilirubin), severe skin reactions.

  • Black Box Warning: Risk of tendon rupture and tendonitis.

• Nursing Administration:

  • Advise avoidance of sun exposure and to wear sunscreen due to photosensitivity.

  • Caution in elderly patients and monitor renal function closely.

  • Administer with food to lessen GI side effects, except with antacids, multivitamins, sucralfate, calcium, iron, or zinc.

  • Monitor bowel function closely.

Tetracyclines

• Prototype: Doxycycline, Tetracycline.

• Uses: Broad range of bacterial infections, including acne, Lyme disease, STIs, Rocky Mountain Spotted Fever.

• Contraindications: Not for children <8 years or during pregnancy due to adverse effects on tooth development (may cause discoloration).

• Adverse Effects:

  • Common: GI upset, hepatotoxicity, photosensitivity, risk of superinfections.

• Nursing Administration:

  • Sun protection is essential (wear sunscreen).

  • Do not use past expiration date as the drug may cause severe kidney damage.

  • Administer on an empty stomach (1 hour before or 2-3 hours after meals).

  • Avoid dairy products, antacids, or iron supplements (2 hours before or 4 hours after).

  • Patients taking oral contraceptives (OCP) should use another form of birth control as effectiveness may be reduced.

Sulfonamides

• Prototype: Bactrim (Trimethoprim-sulfamethoxazole).

• Uses: Effective against bacterial infections, particularly UTIs in both adults and children, and topical treatments for burns or E.coli related diarrhea, pneumonia, bronchitis, otitis media in children.

• Contraindications: Sulfa allergies.

• Adverse Effects:

  • GI upset, blood dyscrasias, risk of Stevens-Johnson syndrome, photosensitivity, crystalluria.

• Nursing Administration:

  • Instruct patients to take with 8 oz of water and encourage a fluid intake of 2-3L/day.

  • Sun protection advised (wear sunscreen).

  • Monitor renal function and signs of blood marrow suppression and liver injury.

  • Caution due to cross-sensitivity with thiazide diuretics; it is teratogenic and should not be used during pregnancy or lactation.

Macrolides

• Prototype: Erythromycin, Azithromycin.

• Uses: Effective against bacterial infections and serves as a PCN substitute for those with penicillin allergies.

• Adverse Effects:

  • Common: GI upset, risk of dysrhythmias, potential ototoxicity (especially at high doses), rash, photosensitivity.

• Nursing Administration:

  • Take on an empty stomach, ideally 1 hour before or 2 hours after meals.

  • Accompany doses with 8 oz of water.

  • Patients should avoid grapefruit juice or St. John's wort and delay consuming dairy or antacids for at least 2 hours after taking the drug.

  • Monitor liver function due to potential for hepatotoxicity.

Vancomycin

• Drug Class: Glycopeptides.

• Indication: Used for serious bacterial infections and antibiotic-associated C. difficile infections.

• Adverse Effects:

  • Ototoxicity, nephrotoxicity, infusion reactions (including red man syndrome), and phlebitis.

• Nursing Considerations:

  • Administer slowly over 1-2 hours. Monitor peak and trough levels and check creatinine levels.

  • Alert the prescriber for any infusion reactions and adjust the infusion rate accordingly.

Antifungal: Azoles

• Prototype: Fluconazole (Diflucan), Ketoconazole, Amphotericin B.

• Routes: PO, topical, oral suspension, IV.

• Uses: Effective for topical and systemic fungal infections, including oropharyngeal, esophageal, vaginal, and systemic candidiasis.

• Adverse Effects:

  • Generally well tolerated, but example include:

  • Fluconazole can cause hepatotoxicity, GI upset, and rash.

  • Ketoconazole can lead to hepatotoxicity, GI upset, and arrhythmias.

  • Amphotericin B is highly toxic, used primarily for life-threatening infections, and can cause fever, chills, nausea and vomiting, nephrotoxicity, increased liver enzymes, and phlebitis.

• Nursing Administration:

  • Monitor for numerous drug-drug interactions.

  • Avoid taking with grapefruit juice.

  • Check renal function tests weekly and hepatic function tests monthly (ALT and AST).

  • Encourage small, frequent meals to mitigate GI side effects.

  • Monitor skin rash closely.

  • Report changes in stool or urine, noting any abnormalities such as pale stools, dark urine, nausea/vomiting, fatigue, or jaundice, particularly with Amphotericin B, where a test dose is recommended prior to full administration to observe liver function.