Antimicrobial Therapy

Flashcards covering key terms and concepts associated with antimicrobial therapy.

Pathogen

A biological agent that causes disease in a host organism.

Antimicrobial

A substance that acts against microorganisms, especially bacteria causing disease.

Gram Stain

A method for classifying bacteria into two groups based on their cell wall, either gram-positive or gram-negative.

Gram positive

bacteria that retain the crystal violet stain in the Gram staining process, appearing purple under a microscope.

• Examples: Streptococcus and Staphylococcus

Gram negative

bacteria that do not retain the crystal violet stain in the Gram staining process, appearing pink under a microscope.

• Examples:Escherichia coli and Salmonella.

Anti-microbial therapy

the use of drugs to kill or inhibit the growth of microorganisms, such as bacteria, fungi, or parasites.

• Over use of this can cause resistance in pathogens, making infections harder to treat.  

• Can cause Diahrrhea, C. difficile infection, and Yeast infection (Candida)

Dose dependency/ Time dependency

Dose-refers to the relationship between the dose of an antimicrobial agent and its efficacy in inhibiting or killing bacteria

Time-where certain agents are effective based on the concentration achieved in the body over time.

Nursing process to admin antimicrobials

• Baseline temp, heart rate,blood pressure,and respiratory rate

• most recent white blood cell count

• and any allergies to medications are assessed. The patient's renal and hepatic function should also be evaluated to ensure appropriate dosing and minimize adverse effects.

Hypersensitivity Reactions

Adverse reactions that may occur with some antibiotics, ranging from mild (itching, hives) to severe (anaphylaxis).

• Anaphylaxis:a severe, potentially life-threatening allergic reaction that requires immediate medical attention and treatment.

• Early signs: itching, rash, difficulty breathing, swelling of the face, tongue, or throat, dizzinesand gastrointestinal symptoms such as nausea or vomiting.

Beta-lactam Antibiotics

A class of antibiotics that share a common chemical structure known as the beta-lactam ring, widely used for bacterial infections.

Penicillin

An antibiotic used to treat various bacterial infections by weakening the bacterial cell wall.

• Indication: Respiratory infections: strep throat, pneumonia, Skin:syphilis, cellulitus, impetigo. Ear, nose, and throat infections, Cardiovascular infections, Gastrointestinal infections, Lyme disease, Anthrax, and Meningitis

• Mechanism of action: involves inhibition of bacterial cell wall synthesis, leading to cell lysis and death.

• Administered: orally, intramuscularly, or intravenously depending on the infection severity. Best taken on empty stomach.

• Common side effects: include nausea, diarrhea, GI upset, black hairy tongue.

• Severe side effects: anaphylaxis, superinfection ( C. diff and Canididiasis, Hyperkalemia, Hypersensitivity. High doses can cause blood clot

• Nursing actions: include monitoring for signs of allergic reactions( discontinue if allergy occurs) and assessing renal function.

• Drug interaction: Watch pt on potassium dieuretics or supplements as it can cause hyperkalemia. Avoid citrus products.

• Patient teaching: should include adherence to prescribed dosage, recognizing signs of allergies, and completing the full course of antibiotics. Space doses evenly.

• Special consideration:  If on oral contraceptive, take additional measures

Cephalosporins

• Indication

• Mechanism of action

• Administered

• Common side effects

• Severe side effects

• Nursing actions

• Drug interaction

• Patient teaching

• Special consideration

  A class of beta-lactam antibiotics used to treat a variety of bacterial infections.

  • Indication: often used for respiratory tract infections:pneumonia, skin infections, soft tissue infections and urinary tract infections.

  • Mechanism of action: Bactericidal ,disrupts bacterial cell wall synthesis, leading to cell death.

  • Effective against: Grouped by generation. Gen 1= active against gram positive= streptococci and staphylococi. Higher gen= Broader spectrum gram negative and gram positive bacilli. 5th gen= Active against MRSA and complicated infections.

  • Administered: orally or intravenously depending on the severity of the infection.

  • Common side effects: include diarrhea, rash, and allergic reactions.

  • Severe side effects: include anaphylaxis,low blood count,hemolytic anemia, elevated INR ,Clostridium difficile infection.

  • Nursing actions: monitor for signs of hypersensitivity and renal function.

  • Drug interaction: may interact with anticoagulants, increasing bleeding risk.

  • Use of alcohol can cause disulfiram like reactions: Headache, Flushing, nausea, and vommiting

  • Patient teaching: adherence to the full course, recognizing allergy signs, and taking with food if gastrointestinal upset occurs.

  • Special consideration: cross-reactivity may occur in patients with penicillin allergy.

Carbapenems

• Indication: Primarily used for serious bacterial infections, including complicated intra-abdominal infections, complicated urinary tract infections, lower respiratory tract infections, skin and soft tissue infections, and bacterial meningitis caused by susceptible organisms, often when other antibiotics are ineffective.

• Mechanism of action: Bactericidal; they inhibit bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), leading to cell lysis and death.

• Administered: Typically administered intravenously, often in hospital settings due to their broad spectrum and severity of infections treated.

• Common side effects: include nausea, vomiting, diarrhea, rash, and injection site reactions.

• Severe side effects: include seizures (especially at high doses or in patients with renal impairment or CNS disorders), anaphylaxis, Clostridium difficile infection, and rare hematologic abnormalities.

• Nursing actions: Monitor for signs of hypersensitivity, especially in patients with a history of penicillin allergy (though cross-reactivity is low). Assess renal and hepatic function, monitor for CNS effects (e.g., tremors, confusion, seizures), and observe for signs of superinfection. Monitor intake and output.

• Drug interaction: Can decrease the serum levels of valproic acid, leading to loss of seizure control. Probenecid can increase carbapenem levels.

• Patient teaching: Advise patients to report any severe diarrhea, rash, or signs of allergic reaction immediately. Emphasize completing the full course of antibiotics as prescribed, even if symptoms improve. Inform about potential neurological side effects.

• Special consideration: Reserved for severe infections or multidrug-resistant bacteria to minimize the development of resistance. Use with caution in patients with a history of seizures or CNS disorders. Cross-reactivity with penicillin allergy is generally low, but caution is still advised.

Monabactams

Indication: Primarily used for serious gram-negative bacterial infections, including urinary tract infections, lower respiratory tract infections, skin and skin structure infections, intra-abdominal infections, and septicemia caused by susceptible organisms like Pseudomonas aeruginosa. Often used in patients with severe penicillin allergies.

• Mechanism of action: Bactericidal; works by inhibiting bacterial cell wall synthesis, specifically targeting penicillin-binding protein 3 (PBP-3) in gram-negative bacteria, leading to cell lysis and death.

• Administered: Typically administered intravenously or intramuscularly. An inhalation solution is also available for specific indications (e.g., in cystic fibrosis patients).

• Common side effects: include nausea, vomiting, diarrhea, rash, and local reactions at the injection site (e.g., phlebitis, discomfort).

• Severe side effects: include anaphylaxis (rare, low cross-reactivity with other beta-lactams), Clostridium difficile infection, seizures (very rare), and transient elevations in liver enzymes.

• Nursing actions: Monitor for signs of hypersensitivity, especially in patients with a history of penicillin allergy (cross-reactivity is very low). Assess renal function and adjust dosage as needed. Monitor for superinfection. Review liver function tests.

• Drug interaction: Probenecid can increase aztreonam levels. Concurrent use with other nephrotoxic drugs should be monitored carefully.

• Patient teaching: Advise patients to report any severe diarrhea, rash, or signs of allergic reaction immediately. Emphasize completing the full course of antibiotics as prescribed. Inform them about potential injection site discomfort.

• Special consideration: Unique among beta-lactams for its monocyclic beta-lactam ring, which results in minimal cross-reactivity with other beta-lactam antibiotics (e.g., penicillins, cephalosporins), making it a valuable option for patients with true IgE-mediated penicillin allergies. Active only against gram-negative aerobic bacteria; it has no activity against gram-positive or anaerobic bacteria.

Sulfonamides

Definition: A class of antibiotics that inhibit bacterial growth by blocking enzymes needed for bacterial metabolism.

• Indication: Used for various bacterial infections, primarily urinary tract infections (UTIs), Nocardiosis, some respiratory infections, and often in combination with Trimethoprim (e.g., Co-trimoxazole/Bactrim) for other infections like Pneumocystis Jirovecii pneumonia (PCP).

• Mechanism of action: Bacteriostatic; they inhibit bacterial synthesis of folic acid by interfering with the enzyme dihydropteroate synthetase, which is crucial for bacterial DNA and RNA synthesis. They compete with para-aminobenzoic acid (PABA).

• Administered: Primarily orally, but also available in topical and intravenous forms.

• Common side effects: Nausea, vomiting, diarrhea, rash, photosensitivity, headache, dizziness.

• Severe side effects: Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), crystalluria (leading to kidney stones or acute kidney injury), hypersensitivity reactions, bone marrow suppression (e.g., agranulocytosis, aplastic anemia), hemolytic anemia (especially in G6PD deficient patients), hyperkalemia.

• Nursing actions: Monitor for allergic reactions (especially severe rashes like SJS). Ensure adequate hydration to prevent crystalluria. Assess renal and hepatic function. Monitor complete blood count (CBC) for potential blood dyscrasias. Assess for signs of superinfection. Document allergies.

• Drug interaction: Can potentiate the effects of oral anticoagulants (e.g., warfarin), increasing the risk of bleeding. May increase the effects of sulfonylureas (leading to hypoglycemia) and phenytoin. Concurrent use with methenamine should be avoided (risk of crystalluria).

• Patient teaching: Advise patients to drink plenty of water to prevent crystalluria. Counsel on avoiding prolonged sun exposure and using sunscreen due to photosensitivity. Educate on immediately reporting any rash, fever, sore throat, unusual bleeding/bruising, or severe diarrhea. Emphasize completing the full course of therapy.

• Special consideration: Contraindicated in the third trimester of pregnancy (risk of kernicterus in neonates) and in infants under 2 months of age. Use with caution in patients with G6PD deficiency due to the risk of hemolytic anemia. High incidence of allergic reactions. Bacterial resistance to sulfonamides is common.

Fluoroquinolones

• Definition: Antibiotics that inhibit bacterial DNA replication, often used for respiratory and urinary tract infections.

  • Indication: Broad-spectrum antibiotics used for a wide range of bacterial infections, including respiratory tract infections (e.g., pneumonia, bronchitis), urinary tract infections (UTIs), skin and soft tissue infections, bone and joint infections, intra-abdominal infections, and certain sexually transmitted infections.

  • Mechanism of action: Bactericidal; they inhibit bacterial DNA gyrase and topoisomerase IV, essential enzymes involved in DNA replication, transcription, repair, and recombination, leading to bacterial cell death.

  • Administered: Available orally, intravenously, and topically (e.g., eye drops, ear drops).

  • Common side effects: Nausea, vomiting, diarrhea, abdominal pain, headache, dizziness, insomnia, and photosensitivity.

  • Severe side effects: Tendonitis and tendon rupture (especially Achilles tendon), peripheral neuropathy (nerve damage), central nervous system effects (e.g., seizures, confusion, hallucinations), QTc prolongation and arrhythmias, Clostridium difficile infection, severe hypersensitivity reactions, dysglycemia (hypoglycemia or hyperglycemia), and aortic dissection or rupture.

  • Nursing actions: Monitor for tendon pain or swelling; advise immediate reporting. Assess for neurological symptoms (numbness, tingling, confusion). Monitor cardiac function (ECG for QTc). Monitor blood glucose levels. Assess renal function. Advise on avoiding sun exposure. Document existing cardiovascular disease.

  • Drug interaction: Antacids, iron supplements, zinc, calcium, magnesium, and sucralfate can significantly decrease absorption (administer fluoroquinolones several hours before or after these agents). Can increase anticoagulant effects of warfarin. May increase risk of QTc prolongation with other drugs (e.g., antiarrhythmics, tricyclic antidepressants). May increase theophylline levels.

  • Patient teaching: Advise patients to report any tendon pain, swelling, numbness, tingling, or muscle weakness immediately. Instruct to avoid sun exposure. Emphasize taking the full course of therapy. Explain interactions with dairy products and mineral supplements. Advise on consuming plenty of fluids.

  • Special consideration: Due to serious side effects, the FDA advises reserving fluoroquinolone use for conditions where other treatment options are not suitable. Contraindicated in patients with a history of myasthenia gravis (may worsen muscle weakness). Use with caution in elderly patients and those with a history of QTc prolongation or uncorrected hypokalemia/hypomagnesemia.

Macrolides

Definition: Antibiotics that inhibit RNA protein synthesis and are used for respiratory infections and certain STDs.

• Indication: Used for respiratory tract infections (e.g., pneumonia, bronchitis), skin infections, sexually transmitted infections (STIs) like chlamydia and gonorrhea, atypical bacterial infections (e.g., Mycoplasma pneumoniae, Legionella pneumophila), and in patients with penicillin allergies.

• Mechanism of action: Bacteriostatic (at lower doses) or bactericidal (at higher doses); they inhibit bacterial protein synthesis by reversibly binding to the 50S ribosomal subunit, thereby blocking the translocation step of protein synthesis.

• Administered: Primarily orally, but also available intravenously (e.g., azithromycin, erythromycin).

• Common side effects: Nausea, vomiting, diarrhea, abdominal pain, and GI upset (especially with erythromycin).

• Severe side effects: QTc prolongation and arrhythmias (especially torsades de pointes), hepatotoxicity (cholestatic hepatitis), Clostridium difficile infection, and allergic reactions.

• Nursing actions: Monitor liver function tests. Assess for cardiac arrhythmias (ECG monitoring in high-risk patients). Administer oral doses with food if GI upset occurs (except azithromycin, which can be taken without regard to food). Monitor for signs of superinfection. Document existing cardiac conditions and allergies.

• Drug interaction: Can inhibit the metabolism of other drugs metabolized by cytochrome P450 enzymes (e.g., warfarin, theophylline, digoxin, carbamazepine, statins), leading to increased drug levels and potential toxicity. Concurrent use with other drugs that prolong the QTc interval should be avoided.

• Patient teaching: Advise patients to take the full course of antibiotics, even if symptoms improve. Report any signs of jaundice, dark urine, severe diarrhea, palpitations, or fainting. Advise on taking with food if GI upset occurs (check specific drug instructions).

• Special consideration: Erythromycin has a higher incidence of GI side effects compared to azithromycin and clarithromycin. Azithromycin has a prolonged half-life, allowing for once-daily dosing and shorter courses of therapy. Use with caution in patients with hepatic dysfunction or pre-existing QTc prolongation.

Tetracyclines

• Definition: - Indication: Broad-spectrum antibiotics used for various bacterial infections, including respiratory tract infections, urinary tract infections, skin infections, sexually transmitted infections (e.g., chlamydia), acne, Lyme disease, Rocky Mountain spotted fever, cholera, and Helicobacter pylori (in combination therapy).

  • Mechanism of action: Bacteriostatic; they inhibit bacterial protein synthesis by reversibly binding to the 30S ribosomal subunit, preventing the attachment of aminoacyl-tRNA to the ribosomal acceptor site.

  • Administered: Primarily orally, but also available in topical and intravenous forms. Doxycycline and minocycline are generally well-absorbed orally.

  • Common side effects: Nausea, vomiting, diarrhea, abdominal pain, photosensitivity (severe sunburn), and esophageal irritation/ulceration (especially with doxycycline).

  • Severe side effects: Permanent tooth discoloration (in children and fetuses), bone growth retardation (in children), hepatotoxicity, nephrotoxicity (especially with outdated tetracyclines), pseudotumor cerebri (intracranial hypertension), Clostridium difficile infection, severe hypersensitivity reactions, and vestibular side effects (dizziness, vertigo with minocycline).

  • Nursing actions: Advise patients to take with a full glass of water and remain upright for at least 30 minutes to prevent esophageal irritation. Monitor for signs of photosensitivity. Assess renal and hepatic function. Monitor for signs of superinfection. Document allergies. Avoid administration with milk, antacids, iron supplements, and other divalent/trivalent cations.

  • Drug interaction: Antacids, iron supplements, calcium, magnesium, aluminum, zinc, and dairy products significantly decrease absorption (administer tetracyclines 1-2 hours before or 2-3 hours after these agents). Can potentiate the effects of oral anticoagulants (e.g., warfarin). May decrease the effectiveness of oral contraceptives. Concurrent use with retinoids (e.g., isotretinoin) can increase the risk of pseudotumor cerebri.

  • Patient teaching: Advise patients to avoid direct sunlight and use protective clothing/sunscreen due to photosensitivity. Instruct to take with plenty of water and not lie down for at least 30 minutes after taking. Emphasize avoiding dairy products, antacids, and iron supplements around administration. Explain the importance of completing the full course of therapy. Report any severe diarrhea, rash, or visual disturbances immediately.

  • Special consideration: Contraindicated in children under 8 years of age and during pregnancy (especially the second and third trimesters) due to the risk of permanent tooth discoloration and impaired bone development. Use with caution in patients with renal or hepatic impairment. Expired tetracyclines can be nephrotoxic.