Antibiotics

Antibiotics

Antibiotics

  • Antibiotics are defined as:
    • Chemicals that inhibit specific bacteria

Types of Antibiotics

  • Bacteriostatic
    • Substances that prevent the growth of bacteria
  • Bactericidal
    • Substances that kill bacteria directly

Signs of Infection

  • Fever
  • Lethargy
  • Slow-wave sleep induction
  • Classic signs of inflammation (redness, swelling, heat, and pain)

Goal of Antibiotic Therapy

  • Decrease the population of the invading bacteria to a point where the human immune system can effectively deal with the invaders

Selecting Treatment

  • Identification of the causative organism
  • Based on the culture report, an antibiotic is chosen that is known to be effective at treating the invading organism

Bacteria Classification

  • Gram-positive
    • The cell wall retains a stain or resists decolorization with alcohol
  • Gram-negative
    • The cell wall loses a stain or is decolorized by alcohol
  • Aerobic
    • Depend on oxygen for survival
  • Anaerobic
    • Do not use oxygen

Aminoglycosides

  • A group of powerful antibiotics used to treat serious infections caused by gram-negative aerobic bacilli
  • Common medications:
    • Amikacin (Amikin)
    • Gentamicin (Garamycin)
    • Kanamycin (Kantrex)
    • Neomycin (Mycifradin)
    • Streptomycin
    • Tobramycin (Nebcin, Tobrex)
  • Bactericidal
  • Indications: treatment of serious infections caused by susceptible bacteria
  • Action: inhibit protein synthesis in susceptible strains of gram-negative bacteria causing cell death
  • Pharmacokinetics
    • Poorly absorbed from the GI tract but rapidly absorbed after IM injection, reaching peak levels within 1 hour
    • Widely distributed throughout the body, crossing the placenta and entering breast milk
    • Excreted unchanged in the urine and have an average half-life of 2 to 3 hours
    • Depend on the kidney for excretion and are toxic to the kidney
  • Contraindications
    • Known allergies, renal or hepatic disease, and hearing loss
  • Adverse effects
    • Ototoxicity and nephrotoxicity are the most significant
  • Drug-to-drug interactions
  • Diuretics and neuromuscular blockers

Cephalosporins

  • Similar to penicillin in structure and activity
  • Action
    • Interfere with the cell-wall–building ability of bacteria when they divide
  • Indication
    • Treatment of infection caused by susceptible bacteria
  • Pharmacokinetics
    • Well absorbed from the GI tract
    • Metabolized in the liver, excreted in the urine
  • Contraindications
    • Allergies to cephalosporins or penicillin
  • Adverse effect
    • GI tract
  • Drug-to-drug interactions
    • Aminoglycosides, oral anticoagulants, and ETOH

Fluoroquinolones

  • Relatively new class of antibiotics with a broad spectrum of activity
  • Indications: treat infections caused by susceptible strains of gram-negative bacteria, including urinary tract, respiratory tract, and skin infections
  • Actions: interferes with DNA replication in susceptible gram-negative bacteria, preventing cell reproduction
  • Pharmacokinetics
    • Absorbed in the GI tract
    • Metabolized in the liver
    • Excreted in the urine and feces
  • Contraindications
    • Known allergy, pregnancy, and lactation
  • Adverse effects
    • Headache, dizziness, and GI upset
  • Drug-to-drug interactions
    • Antacids, quinidine, and theophylline

Macrolides

  • Antibiotics that interfere with protein synthesis in susceptible bacteria
  • Indications: treatment of respiratory, dermatologic, urinary tract, and GI infections caused by susceptible strains of bacteria
  • Actions: bind to cell membranes causing a change in protein function and cell death; can be bacteriostatic or bactericidal
  • Pharmacokinetics
    • Absorbed from the GI tract
    • Metabolized in the liver, excreted in the bile to feces
  • Contraindications
    • Allergy and hepatic dysfunction
  • Adverse effects
    • GI symptoms
  • Drug-to-drug interactions
    • Digoxin, oral anticoagulants, theophylline, and corticosteroids

Lincosamides

  • Similar to macrolides but more toxic
  • Action
    • Similar to macrolides
  • Indications
    • Severe infections
  • Pharmacokinetics
    • Well absorbed from the GI tract or IM
    • Metabolized in the liver and excreted in the urine and feces
  • Contraindications
    • Hepatic or renal impairment
  • Adverse effects
    • GI reactions

Monobactams

  • Unique structure with little cross-resistance
  • Action
    • Disrupts bacteria cell wall synthesis, which promotes the leakage of cellular content and cell death
  • Indications
    • Treatment of infections caused by susceptible bacteria; UTI, skin, intra-abdominal, and gynecologic infections
  • Pharmacokinetics
    • Well absorbed from the IM injection
    • Excreted unchanged in the urine
  • Contraindications
    • Allergy
  • Adverse effects
    • GI and hepatic enzyme elevation

Penicillins

  • First antibiotics introduced for clinical use
  • Action
    • Inhibit synthesis of the cell wall in susceptible bacteria, causing cell death
  • Indications
    • Treatment of infections caused by streptococcal, pneumococcal, staphylococcal, and other susceptible bacteria
  • Pharmacokinetics
    • Well absorbed from the GI tract
    • Excreted unchanged in the urine
  • Contraindications
    • Allergy
    • Caution in patients with renal disease
  • Adverse effects
    • GI effects
  • Drug-to-drug interactions
    • Tetracyclines and aminoglycosides

Sulfonamides

  • Drugs that inhibit folic acid synthesis
  • Action
    • Interfere with the cell-wall–building ability of dividing bacteria
  • Indications
    • Treatment of infections caused by gram-negative and gram positive-bacteria
  • Pharmacokinetics
    • Well absorbed from the GI tract
    • Metabolized in the liver and excreted in the urine
  • Contraindications
    • Allergy and pregnancy
  • Adverse effects
    • GI symptoms and renal effects related to the filtration of the drug
  • Drug-to-drug interactions
    • Cross sensitivity with thiazide diuretics
    • Sulfonylureas

Tetracyclines

  • Developed as semisynthetic antibiotics based on the structure of a common soil mold
  • Action
    • Inhibit protein synthesis in susceptible bacteria, preventing cell replication
  • Indications
    • Treatment of various infections caused by susceptible strains of bacteria and acne, and when penicillin is contraindicated for eradication of susceptible organisms
  • Pharmacokinetics
    • Adequately absorbed from the GI tract
    • Concentrated in the liver and excreted unchanged in the urine
  • Contraindications
    • Allergy, pregnancy, and lactation
  • Adverse effects
    • GI, skeletal: damage to bones and teeth
  • Drug-to-drug interactions
    • Penicillin G, oral contraceptive therapy, methoxyflurane, and digoxin

Antimycobacterials

  • Contain pathogens causing tuberculosis and leprosy
  • Action
    • Act on the DNA of the bacteria, leading to lack of growth and eventual bacterial death
  • Indication
    • Treatment of acid-fast bacteria
  • Pharmacokinetics
    • Well absorbed from the GI tract
    • Metabolized in the liver and excreted in the urine
  • Contraindications
    • Allergy and renal or hepatic failure
  • Adverse effects
    • CNS effects and GI irritation
  • Drug-to-drug interactions
    • Rifampin and INH can cause liver toxicity

Antibiotic Use Across the Lifespan

  • Pediatric population
  • Adult population
  • Geriatric population

Comparison of Prototype Antibiotics

Drug/ Classification Indication Action Route Onset Peak Pharmacokinetics Adverse Effects
Gentamicin/ Aminoglycosides Treatment of serious infections caused by susceptible bacteria Inhibits protein synthesis in susceptible strains of gram negative bacteria IM Rapid 30-90 min T½  – 2-3 h Sinusitis, dizziness, rash, fever, risk of nephrotoxicity
IV Metabolized in the liver,
excreted in the urine
Cefaclor/ Cephalosporins Treatment of respiratory, dermatological, urinary tract, and middle ear infections Inhibits synthesis of bacteria cell wall Oral 30-60 min 8-10 h T ½ 30-60 min Nausea, vomiting, diarrhea, rash, superinfections, bone marrow suppression, risk for pseudomembranous colitis
Excreted unchanged in the urine
Ciprofloxacin/ Fluoroquinolones Treatment of respiratory, dermatological, urinary tract, ear, eye, bone, and joint infections Interferes with DNA replication in susceptible gram negative bacteria Oral Varies 4-5 h T ½  – 3.5-4 h Headache, dizziness, hypotension, nausea, vomiting, diarrhea, fever, and rash
IV 10 min 4-5 h Metabolized in the liver,
excreted in bile and urine
Erythromycin/ Macrolides Treatment of respiratory, dermatological, urinary tract, and GI infections Binds to cell membrane causing change in protein function and cell death Oral 1-2 h 1-4 h T ½ – 3-5 h Abdominal cramping, vomiting, diarrhea, rash, superinfections, liver toxicity, potential for hearing loss
IV Rapid 1h Metabolized in the liver, CONTINUED ON NEXT SLIDE
excreted in bile and urine
Treatment of serious infections caused by susceptible strains of bacteria Inhibits protein synthesis in susceptible bacteria Oral Varies 1-2 h T ½ – 2-3 hours Nausea, vomiting, diarrhea, pseudomembranous colitis, bone marrow suppression, hypotension, cardiac arrest
IV Immed. Min Metabolized in the liver, excreted in bile and urine
IM 20-30 min 1-3 h
Aztreonam/ Treatment of lower respiratory, dermatological, urinary tract, intra-abdominal, and GYN infections Interferes with bacterial cell wall synthesis IM Varies 60-90 min T ½ – 1.5-2 h Nausea, vomiting, diarrhea, rash, superinfections, anaphylaxis, local discomfort at injection site
Monobactams IV Immed. 30 min Excreted in unchanged urine
Amoxicillin/ Treatment of infections caused by susceptible strains of bacteria Inhibits synthesis of the cell wall, causing cell death Oral Varies 1 h T ½  – 1-1.4 h Nausea, vomiting, diarrhea, glossitis, stomatitis, bone marrow suppression, rash, fever, lethargy
Penicillins Excreted unchanged in urine
Sulfasalazine/ Treatment of rheumatoid arthritis, arthritis, and ulcerative colitis Clindamycin/ Oral Varies 1.5-6 h T ½ – 5-10 h Nausea, vomiting, hepatocellular necrosis, hematuria, Stevens-Johnson syndrome, rash, photophobia, fever
Sulfonamides Lincosamides 6-24 h – metab. Metabolized in the liver, excreted in urine
Tetracycline/ Treatment of various infections caused by susceptible bacteria Inhibits protein synthesis in susceptible bacteria Oral Varies 2-4 h T ½ – 6-12 h Nausea, vomiting, diarrhea, discoloration of teeth, bone marrow suppression, photosensitivity
Tetracyclines Excreted unchanged in urine
Isoniazid/ Treatment of tuberculosis Interferes with lipid and nucleic acid synthesis in actively growing tubercle bacilli Oral Varies 1-2 h T ½  – 1-4 h Peripheral neuropathies, nausea, vomiting, hepatitis, bone marrow suppression, fever, gynecomatia, lupus syndrome
Antimycobacterials Metabolized in the liver, excreted in urine

Nursing Considerations—Aminoglycosides

  • Assessment and history
  • Nursing diagnosis
  • Implementation
  • Evaluation

Nursing Considerations—Cephalosporins

  • Assessment and history
  • Nursing diagnosis
  • Implementation
  • Evaluation

Nursing Considerations—Fluoroquinolones

  • Assessment and history
  • Nursing diagnosis
  • Implementation
  • Evaluation

Nursing Considerations— Macrolides & Lincosamides

  • Assessment and history
  • Nursing diagnosis
  • Implementation
  • Evaluation

Nursing Considerations—Monobactam

  • Assessment and history
  • Nursing diagnosis
  • Implementation
  • Evaluation

Nursing Considerations—Penicillins

  • Assessment and history
  • Nursing diagnosis
  • Implementation
  • Evaluation

Nursing Considerations—Sulfonamides

  • Assessment and history
  • Nursing diagnosis
  • Implementation
  • Evaluation

Nursing Considerations—Tetracyclines

  • Assessment and history
  • Nursing diagnosis
  • Implementation
  • Evaluation

Nursing Considerations—Antimycobacterials

  • Assessment and history
  • Nursing diagnosis
  • Implementation
  • Evaluation
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