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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