INFECTION

Infection Pharmacology N201

Bactericidal vs. Bacteriostatic

  • Bactericidal: Agents that directly kill bacteria by disrupting cellular processes, such as protein synthesis and cell wall integrity, leading to bacterial cell death. Common bactericidal antibiotics include penicillins and cephalosporins.

  • Bacteriostatic: These antibiotics inhibit bacterial growth and reproduction without killing the organisms. They do this by preventing protein synthesis, thereby allowing the host's immune system to eliminate the pathogens. Examples include tetracyclines and macrolides.

  • Beta-lactam: A class of antibiotics that work by destroying bacterial cell walls through inhibition of cell wall synthesis, leading to cell lysis and death. This class includes penicillins, cephalosporins, and carbapenems.

Gram-Negative vs. Gram-Positive

  • Gram-Negative: Bacteria that do not retain the crystal violet stain used in the Gram staining procedure, resulting in a red or pink appearance. They have a thin peptidoglycan layer surrounded by an outer membrane, which often makes them more resistant to certain antibiotics. Examples include Escherichia coli and Pseudomonas aeruginosa.

  • Gram-Positive: These bacteria retain the crystal violet stain and appear purple under a microscope due to their thick peptidoglycan layer. Gram-positive bacteria often respond well to antibiotics like penicillins and vancomycin. Examples include Staphylococcus aureus and Streptococcus pneumoniae.

Clostridium difficile (CDIFF):

  • A gram-positive, spore-forming bacterium that causes antibiotic-associated diarrhea and colitis. It is a significant healthcare-associated infection.

  • Precautions: Patients diagnosed with C. difficile infection must be placed on Contact Precautions to prevent transmission.

  • Symptoms: Commonly presents with watery diarrhea, abdominal pain, and fever. In cases of diarrhea of unknown origin, healthcare providers should assume it could be C. difficile until proven otherwise.

  • Visitors: Must wear personal protective equipment (PPE), and patients should be educated on hygiene practices to avoid spreading infection to visitors.

  • Cleaning: Environmental cleaning should involve bleach-based products as alcohol-based sanitizers are ineffective against C. difficile spores. Hand hygiene should be performed with soap and water, as alcohol-based hand sanitizers do not eliminate spores.

  • Fluid Intake: Clients should increase fluid intake to prevent dehydration, which is a common complication during infection.

Aminoglycosides:

  • Examples: Gentamicin, Tobramycin, Streptomycin

  • Action: Primarily bactericidal against aerobic Gram-negative bacilli, and used for complex infections due to resistant organisms. Streptomycin is specifically effective in treating tuberculosis and plague infections.

Aminoglycosides Side Effects and Interventions:

  • Ototoxicity: Causes hearing loss or balance issues. Regular monitoring of hearing is essential.

  • Renal Toxicity: Can lead to nephrotoxicity, necessitating monitoring of renal function through I & O, BUN, and creatinine levels.

  • Teaching: Emphasize the importance of completing the prescribed antibiotic course, avoid mixing with penicillin, and be cautious of other ototoxic drugs.

Macrolides:

  • Examples: Erythromycin, Clarithromycin

  • Action: Generally bacteriostatic but can be bactericidal at higher doses.

  • Uses: Effective for patients with penicillin allergies, providing coverage for various infections, including respiratory tract infections, and for prophylaxis against rheumatic fever and bacterial endocarditis.

Macrolides Side Effects and Interventions:

  • GI Discomfort: Common side effects include nausea and abdominal pain; administering these with food may help alleviate discomfort.

  • Drug Interactions: Can inhibit the metabolism of Warfarin and Digoxin; close monitoring of INR is crucial for patients on anticoagulants.

  • Prolonged QT Interval: May cause dysrhythmias; monitor patients with a history of cardiac issues.

  • Hepatotoxicity: Liver function tests should be monitored, and patients should report signs of liver dysfunction, such as jaundice or clay-colored stools.

Additional Patient Teaching for Macrolides:

  • Contraception: Advise patients to use additional non-hormonal contraception as antibiotics may reduce the efficacy of oral contraceptives.

  • Sexual Activity: For patients receiving treatment for sexually transmitted infections (STIs), advise abstaining from sexual intercourse until the course is complete, and partners should also seek treatment.

Tetracyclines:

  • Examples: Doxycycline

  • Action: Broad-spectrum antibiotics that are bacteriostatic.

  • Uses: Commonly prescribed for acne, STIs, pneumonia, Lyme disease, Rocky Mountain spotted fever, and more. Cdiff

Tetracycline Side Effects and Interventions:

  • GI Discomfort: Advise taking with meals to minimize discomfort; avoid dosing at bedtime to reduce the risk of esophageal ulceration.

  • Photosensitivity: Patients should avoid sun exposure and utilize sun protection (SPF 30 or higher).

  • Dental Effects: Tetracyclines can cause tooth discoloration; contraindicated in pregnant women and children under 8 years old.

  • Yeast infections

Cephalosporins:

  • Examples: Cephalexin, Cefazolin, Ceftriaxone, Cefepime, Cefotaxime

  • Action: Beta-lactam antibiotics that are usually more effective against Gram-negative organisms as the generations progress.

  • Uses: Often utilized for a broad range of infections requiring potent antibiotic therapy.

Cephalosporins Side Effects and Interventions:

  • Allergic Reactions: Patients with penicillin allergies may have cross-reactivity; discontinuation and provider notification is necessary.

  • Bleeding: monitor PG, antidote is vitamin K (Phytonadione)

  • Diarrhea and Thrush: Monitor for signs of superinfection and diarrhea, which may require further intervention.

  • Disulfiram reaction to alcohol

Penicillins:

  • Examples: PCN G potassium, Amoxicillin, Nafcillin, Piperacillin-Tazobactam

  • Action: Effective against Gram-positive cocci and some Gram-negative cocci.

  • Uses: Indicated for various infections and prophylaxis against bacterial endocarditis.

Penicillins Side Effects and Interventions:

  • Renal Monitoring: Kidney function should be tracked to prevent complications; use cautiously in patients with existing renal issues.

  • Electrolyte Disturbance: Monitor for hypernatremia and hyperkalemia, especially in vulnerable populations.

Penicillins Allergic Reaction:

  • Monitoring Post-Administration: Observe patients for at least 30 minutes after administration to catch any immediate allergic reactions. Have emergency support readily available.

Vancomycin:

  • Action: Broad-spectrum antibiotic effective against gram-positive organisms, including MRSA and C. difficile.

  • Monitoring: Careful monitoring of peak and trough levels is necessary; peak should be drawn 30 minutes post-infusion, and trough just before the next dose.

  • Side Effects: Potential for ototoxicity and renal failure; close monitoring is warranted.

Vancomycin - Red Man Syndrome:

  • A reaction characterized by flushing, rash, discomfort, tachycardia, and hypotension, typically due to rapid infusion. Infusions should be given slowly to prevent this condition.

Sulfonamides:

  • Example: Sulfamethoxazole-trimethoprim

  • Action: Inhibit bacterial growth by obstructing folic acid synthesis, a critical component for bacterial reproduction.

  • Uses: Effective against urinary tract infections, otitis media, and some respiratory infections.

Sulfonamides Adverse Effects:

  • Blood Dyscrasias: Risk of conditions like hemolytic anemia necessitates monitoring of complete blood counts (CBC).

  • Crystalluria: Encourage plenty of fluid intake (at least 2000 mL daily) to prevent crystal formation in the kidney and urinary tract.

Sulfonamides - Steven-Johnson Syndrome:

  • Severe skin reaction that can occur; contraindicated in patients with sulfa allergies.

Fluoroquinolones:

  • Examples: Ciprofloxacin, Levofloxacin

  • Action: Bactericidal mechanism through the inhibition of DNA replication enzymes, effective against both Gram-positive and Gram-negative bacteria.

  • Uses: Frequently prescribed for various infections, including those requiring intravenous therapy and prevention of anthrax.

Fluoroquinolones Side Effects and Interventions:

  • GI Discomfort: Recommend administration with food but caution against dairy to ensure proper absorption.

  • Photosensitivity: Patients should employ protective measures against sun exposure.

  • Achilles Tendon Rupture: Monitor for pain or swelling in the Achilles region; contraindicated in pediatrics unless absolutely necessary.

  • Increased risk for Cdiff

Most Common Risks with Antibiotics and Vaccinations:

  • Kidney Function: Monitor I&O, BUN, creatinine for signs of nephrotoxicity during treatment.

  • IV Complications: Be vigilant about infiltration or extravasation during IV therapy; immediate action is necessary if tissue damage is suspected.

Thrush and Allergic Reactions:

  • Thrush: Fungal infection displayed as white patches in the oral cavity, commonly medicated with Nystatin.

  • Allergic Reactions: A thorough history of allergies should be obtained; any signs of anaphylaxis must prompt immediate cessation of the medication and activation of emergency procedures.

Antifungals:

  • Examples: Amphotericin B, Nystatin, Miconazole, Fluconazole

  • Action: Antifungals disrupt fungal cell membranes, leading to cell death (fungicidal) or inhibit growth (fungistatic).

  • Uses: Indicated for various fungal infections, including candidiasis.