Antiinfective Agents and Therapy

Antiinfective Agents Overview

• Antiinfectives target foreign organisms that invade and infect the body.
• Some antiinfectives prevent infections in patients at risk of exposure to pathogens, known as prophylaxis.
• Sensitivity testing determines a drug's ability to control or eradicate an infection.
• Common adverse reactions include toxic effects on the kidneys, gastrointestinal tract, and nervous system.
• Antiinfectives exhibit selective toxicity.

Antiinfective Therapy Goals

• Aims to reduce the organism population, allowing the human immune response to manage the infection
• Can have broad or narrow spectrums

Types of Antiinfectives

• Bactericidal: kills bacteria
• Bacteriostatic: inhibits bacterial growth

Resistance to Antiinfectives

• Vancomycin was created for patients intolerant/allergic to penicillin/cephalosporins.
• Some organisms produce penicillinase to inactivate penicillin.
• Minimizing resistance involves correct usage: Don't use for other infections, take as prescribed, and complete the full course.

Systemic Infection Treatment

• Identification of the pathogen is key, which involves culture and the pathogen's sensitivity
• It helps determine effective drug(s)
• Broad-spectrum antibiotics and combination therapy may also be needed

Combination Therapy

• May uses smaller doses with fewer side effects
• Can be more powerful - synergistic
• Can target different pathogens
• May decrease resistant strains

Adverse Reactions - Kidney Damage

• Monitor for signs of renal dysfunction.
• Staying hydrated is important for metabolism and excretion.

Adverse Reactions - GI Toxicity

• Can cause nausea, vomiting, diarrhea, and upset stomach.
• Can include liver toxicity

Adverse Reactions - Neurotoxicity

• Can cause dizziness, vertigo, vision changes, ototoxicity, drowsiness, and hallucinations.

Allergic/Hypersensitivity Reactions

• Delayed reactions can progress to anaphylaxis
• Assess for cross-sensitivity between cephalosporins and penicillins.

Superinfections

• Results from destruction of normal flora
• Common infections include vaginal and GI yeast infections

Bacteria - Gram-Positive

• Retains stain or color with alcohol during testing - purple
• Commonly associated with respiratory and soft tissue infections

Bacteria - Gram-Negative

• Loses color when in contact with alcohol - pink
• Commonly associated with GU and GI infections
• Aerobic and Anaerobic are classifications of bacteria

Aminoglycosides

• Examples: amikacin, gentamicin, neomycin, streptomycin, and tobramycin
• bactericidal
• Indicated when penicillin is contraindicated
• Administer for at least 2 days after symptom resolution to prevent resistance
• Potential for nephrotoxicity, neurotoxicity, and ototoxicity (high with amikacin); hydration can minimize renal toxicity.
• Other adverse effects: confusion, depression, disorientation, numbness, and weakness.

Carbapenems

• Examples: Imipenem-cilastatin, doripenem, and ertapenem
• Bactericidal
• Contraindicated in clients with seizure disorders
• Excreted unchanged in urine; monitor kidney function regularly due to potential toxicity

Carbapenems Adverse Reactions

• GI distress, including C. diff diarrhea, can lead to dehydration, electrolyte imbalances, oral thrush, furry tongue, and vaginal yeast infections

Cephalosporins

• Examples: cefazolin, cefuroxime, ceftriaxone, cefepime, and ceftaroline
• Similar to penicillins, so assess for allergies
• Five generations exist, each generally building upon its predecessor

Cephalosporins Common Adverse Effects

• GI tract issues like nausea, vomiting, diarrhea, anorexia, abdominal pain, and flatulence
• Avoid alcohol for at least 72 hours after use to prevent disulfiram-like reactions

Fluoroquinolones

• Examples: ciprofloxacin, levofloxacin
• Broad-spectrum antibiotic
• Approved for prevention of anthrax infection
• Serious adverse effects include tendonitis, tendon rupture, and peripheral neuropathy; risk increases with corticosteroids
• Photosensitivity may cause skin reactions; advise patients to avoid sun and ultraviolet light exposure, use protective clothing, and sunscreen

Penicillin/Penicillin-Resistant

• Examples: amoxicillin, carbenicillin, nafcillin, oxacillin
• First antibiotic for clinical use
• Penicillinase-resistant drugs were developed to combat resistant organisms
• Assess for cephalosporin allergies
• Monitor renal function; drug is excreted unchanged in urine
• Common adverse effects relate to loss of normal flora: nausea, vomiting, diarrhea, yeast infection, etc.
• Avoid combining penicillin with tetracycline or aminoglycosides
• Monitor for allergic reactions, which may occur within 30 minutes after administration.

Sulfonamides

• Example: Sulfadiazine
• Inhibits folic acid synthesis, preventing susceptible bacteria from producing RNA and DNA
• Assess for sulfa allergies
• Used for ulcerative colitis and rheumatoid arthritis, but not widely
• Adverse effects: loss of normal flora and GI tract irritation

Sulfonamides and Urine Output

• Nursing consideration: Report crystals in urine to the health care provider

Sulfonamides & Urinary Tract Infections

• Trimethoprim-sulfamethoxazole is used for UTIs
• Assess for sulfa, thiazide, and loop diuretic allergies
• Encourage fluid intake for crystallizations causing renal injury

Urinary Tract Analgesic - Phenazopyridine

• Azo dye acts as local anesthetic
• Changes urine to orange-red color and may stain clothes

Cranberry Juice

• Helpful in preventing UTIs but not for treating them.

Tetracyclines

• Examples: demeclocycline, doxycycline, and minocycline
• Decreased use due to resistance and toxicity in large doses
• Contraindicated in patients with tartrazine allergy
• Use cautiously in young children, during pregnancy, and breastfeeding due to potential bone and teeth damage
• Causes GI tract irritation, hepatotoxicity, photosensitivity, and superinfections
• Oral agents can be taken on an empty stomach, and don't take lying down due to risk of esophageal ulceration

Anti-Mycobacterials

• Targets mycobacteria, which cause tuberculosis and leprosy
• These bacteria have an acid coat that protects them.

Anti-Tuberculosis Drugs

• Isoniazid, rifampin, pyrazinamide, ethambutol, streptomycin, and rifapentine are first-line drugs
• Treatment lasts 6 months to 2 years
• Rifampin, rifapentine, and rifabutine can cause orange discoloration of body fluids and may stain
• Combining rifampin and INH increases liver toxicity risk
• In pregnancy, isoniazid, ethambutol, and rifampin are considered the safest combination
• Used in combination to treat various stages of TB infection
• Some drugs are offered in one tablet to help promote compliance

Leprostatic Drug - Dapsone

• Treats leprosy, pneumocystitis pneumonia in AIDS, and brown recluse spider bites
• Inhibits folate synthesis

Antimycobacterials - Pregnancy Question

• Key question before administering rifampin and pyrazinamide to a female client with active tuberculosis: "Are you pregnant?"

Lincosamides

• Examples: clindamycin and lincomycin
• Reserved for severe infections when other antibiotics aren't effective
• Black Box Warning: clindamycin can cause severe colitis

Lipoglycopeptides

• Example: vancomycin
• Can cause transfusion reaction (red man syndrome): flushing, sweating, and hypotension with rapid infusion
• Other adverse effects: GI tract alterations and taste alterations
• Monitor ECG due to risk of arrhythmias (prolonged QT interval)
• Monitor kidney function and vancomycin trough level
• Risk of ototoxicity increases when taken with other ototoxic medications

Macrolides

• Examples: azithromycin, erythromycin, clarithromycin, and fidaxomicin
• Treats many organisms and may prevent endocarditis before dental procedures in high-risk patients
• Treats ocular infections and is used prophylactically against minor skin abrasions

Oxazolidinones

• Example: linezolid
• Used in pneumonia, skin structure infections, and diabetic foot infections without osteomyelitis

Oxazolidinones Risk

• Potential for life-threatening hypertension when combined with tyramine-containing foods (aged cheeses, sausage, beer)

Oxazolidinones Assessment

• Key question: "Are you taking any medications for depression right now?"

Oxazolidinones Black Box Warning

• Linezolid should not be administered with selective serotonin reuptake inhibitors, serotonin–norepinephrine reuptake inhibitors, tricyclic antidepressants, or monoamine oxidase inhibitors
• Linezolid inhibits monoamine oxidase A, leading to serotonin toxicity

General Information - Preventive Measures

• Hand hygiene before/after client contact prevent infection spread
• Recognize invasive procedures increasing infection risk (urinary catheter, IVs, etc.)
• Maintain up-to-date immunizations
• Complete antimicrobial courses to prevent resistance and recurrence
• Use infection-control procedures to prevent transmission of resistant micro-organisms, including applying aseptic technique, following standard and transmission-based precautions, and ensuring careful room assignments
• Evaluate treatment effectiveness
• Check post-treatment cultures for negative results
• Monitor for clinical improvement (clear breath sounds and resolution of fever)