Cephalosporins and Carbapenems Overview

Carbapenems

• Similar in structure and activity to penicillins
• Exert bactericidal and bacteriostatic effects by interfering with bacterial cell wall synthesis during cell division

Cephalosporins

• First-generation: effective against gram-positive bacteria like penicillin G, as well as gram-negative bacteria like P.mirabilis, K.pneumoniae, and E.coli
• Second-generation: effective against first-generation strains, as well as H.influenzae, E.aerogenes, and Neisseria spp., less effective against gram-positive bacteria.
• Third-generation: effective against all previously mentioned strains, relatively weak against gram-positive bacteria, more potent against gram-negative bacilli and S.marcescens
• Fourth-generation: active against gram-negative and gram-positive organisms including cephalosporin-resistant staphylococci and P.aeruginosa

Cephalosporins Pharmacokinetics

• Oral: onset N/A, peak 30-60 minutes, duration 8-10 hours
• Half-life: 30-60 minutes
• Metabolism: N/A
• Excretion: kidney (urine); unchanged

Cephalosporins Contraindications and Cautions

• Known allergy to cephalosporins or beta-lactams (cross-reactions are common)
• Hepatic or renal impairment (toxic to the kidneys)
• Pregnancy and lactation (potential effects on fetus and infant are not known)
• Reserve cephalosporins for appropriate situations due to increasing cephalosporin-resistant bacteria
• Perform culture and sensitivity tests before starting therapy

Tetracyclines

• Inhibit protein synthesis leading to an inability of bacteria to multiply
• Can be toxic to humans at high concentrations due to similar protein structure to human cells

Tetracyclines Indications

• Treatment of infections caused by susceptible strains: Ricketssiae, M.pneumoniae, B.recurrentis, H.influenzae, H.ducreyi, Bacteroides spp., V.comma, Shigella spp., D.pneumoniae, and S.aureus
• Adjunct in treatment of protozoal infections

Tetracyclines Pharmacokinetics

• Oral: onset varies, peak 2-4 hours, duration N/A
• Topical: minimal absorption occurs, peak N/A, duration N/A
• Half-life: 6-12 hours
• Metabolism: N/A
• Excretion: kidney (urine)

Tetracyclines Contraindications and Cautions

• Known allergies to tetracyclines or tartrazine
• Pregnancy and lactation (effects on developing bones and teeth)
• Fungal, mycobacterial, or viral ocular infections
• Use with caution in children below 8 (can damage developing bones and teeth)
• Hepatic or renal dysfunction (drugs are concentrated in the bile and excreted in urine)

Tetracyclines Adverse Effects

• GI: nausea, vomiting, diarrhea, abdominal pain, glossitis, dysphagia, fatal hepatotoxicity
• Skeletal and bones: weakening structure, staining, and pitting of teeth and bones
• Dermatological: photosensitivity and rash
• Superinfection
• Local: pain and stinging with topical or ocular applications
• Hematologic: hemolytic anemia, bone marrow depression
• Hypersensitivity reactions: urticaria, anaphylaxis
• Intracranial hypertension

Tetracyclines Interactions

• Penicillin G: decreased effectiveness of penicillin G
• Oral contraceptives: decreased effectiveness of oral contraceptives
• Digoxin: increased digoxin toxicity
• Calcium salts, magnesium slats, zinc salts, aluminum salts, bismuth salts, iron, urinary alkalinizers, and charcoal: decreased absorption of tetracyclines

Antimycobacterials

• Used to treat infections caused by pathogens responsible for tuberculosis and leprosy
• Mycobacterium tuberculosis causes tuberculosis, the leading cause of death from infectious disease in the world
• Mycobacterium leprae causes leprosy or Hansen's disease, characterized by skin lesions and respiratory tract damage

Antimycobacterials Therapeutic Action

• Act on bacteria DNA and/or RNA, leading to a lack of growth and eventually bacterial death

Antimycobacterials Indications

• Treatment of tuberculosis and leprosy

Antimycobacterials Pharmacokinetics

• Oral: onset varies, Peak 1-2 hours, duration 24 hours
• Half-life: 1-4 hours
• Metabolism: liver
• Excretion: kidney (urine)

Antimycobacterials Contraindications and Cautions

• Known allergies to antimycobacterials
• Pregnancy (adverse effects on the fetus)

Antimycobacterials Adverse Effects

• GI: nausea, vomiting, potential for pseudomembranous colitis, superinfections, taste alterations, risk for C.difficile diarrhea

Antimycobacterials Interactions

• Ketolides: loss of therapeutic effects if combined with rifampin, phenytoin, carbamazepine, phenobarbital; increased serum levels of digoxin and metoprolol, increased GI toxicity with theophylline
• Lipoglycopeptides: increased risk for prolonged QT interval if combined with drugs that cause prolonged QT interval
• Macrolides: food in the stomach decreases absorption of oral macrolifes, take on an empty stomach 1 hour before or 2-3 hours after meals

Monobactams

• Incompatible in solution with nafcillin, cephradine, and metronidazole

Nursing Considerations for Antibiotics

• Assess for cautions and contraindications to prevent complications
• Perform a thorough physical assessment to establish baseline data, determine effectiveness, and evaluate adverse effects
• Perform culture and sensitivity tests to ensure appropriate drug use
• Conduct orientation and reflex assessment, as well as auditory testing for CNS effects (aminoglycosides)

Nursing Diagnoses for Antibiotics

• Acute pain related to GI or CNS drug effects
• Deficient fluid volume and imbalanced nutrition: less than body requirements due to diarrhea
• Disturbed sensory perception (auditory) due to CNS effects
• Risk for infection due to bone marrow suppression (aminoglycosides) and repeated injections (cephalosporins)

Nursing Interventions for Antibiotics

• Ensure the patient receives a full course of aminoglycosides as prescribed, divided around the clock
• Monitor infection site and presenting signs and symptoms throughout drug therapy
• Provide safety measures to protect the patient if CNS effects occur
• Educate the patient on drug therapy to promote understanding and compliance

Nursing Interventions for Antibiotics - Patient Teaching

• Safety precautions (e.g., changing positions, avoiding hazardous tasks)
• Drinking lots of fluids and maintain nutrition
• Report difficulty breathing, severe headache, fever, diarrhea, and signs of infection

Evaluation of Nursing Interventions

• Monitor patient response to therapy (decrease in signs and symptoms of infection)
• Monitor for adverse effects
• Evaluate patient understanding of drug therapy (name, indication, adverse effects)
• Monitor patient compliance to drug therapy

This quiz covers the structure, activity, and classification of carbapenems and cephalosporins. It explains their bactericidal and bacteriostatic effects, as well as their pharmacokinetics across the different generations of cephalosporins. Test your knowledge on these important antibiotics and their mechanisms of action.