M5

• Antibacterial agents


  Any compound - natural, synthetic or semisynthetic - that is able to inhibit other microorganisms
• Anti-infective agents


  Agents that fight against infections
• Learning objectives


  • Explain the concepts of Antibacterial and Anti-Infective Agents
  • Identify the different types of antibacterial and anti-infective agents
  • Apply the nursing process for patients receiving Anti-bacterial and Anti-Infective Agents
• Cell nucleus


  • Contains all genetic material that is necessary for cell reproduction and for regulation of cellular production of protein
• Cell membrane


  • Thin barrier in the cell which separates the ICF from the ECF that maintain homeostasis
• Other important parts of a cell

  • Cytoplasm contains various organelles that are important for cellular function
  • Mitochondria produce energy for the cell
  • Endoplasmic Reticulum contains ribosomes that produce proteins
  • Golgi apparatus packages proteins
  • Lysosomes contain protein-dissolving enzymes that are important for digestion and the recycling of nature
• Cell cycle


  All cells progress through a cell cycle, which allow them to reproduce
• Phases of the cell cycle

  • G0 (Resting phase)
  • G1 (Gathering phase, when the components needed for cell division are collected by the cell)
  • S (Synthesizing phase, when the DNA and other components are produced)
  • G2 (Final gathering phase, when the last substances needed for division are collected and produced)
  • M (Phase when actual cell division occurs, producing two identical daughter cells)
• Antibiotic


  A substance produced by a microorganism, which, in minute amounts, is able to inhibit other microorganisms
• Bacteriostatic agents


  • Chloramphenicol
  • Clindamycin
  • Ethambutol
  • Macrolide
  • Nitrofurantoin
  • Linezolid
  • Sulfonamides
  • Tetracyclines
  • Trimethoprim
• Bactericidal agents


  Agents that significantly reduce (99.9%) the number of viable bacteria in the culture (killing effect)
• Examples of bactericidal agents

  • Aminoglycosides
  • Beta-lactam
  • Isoniazid
  • Metronidazole
  • Pyrazinamide
  • Quinolones
  • Rifampicin
  • Vancomycin
• Narrow spectrum antibiotics


  Are preferentially active against either gram-negative or gram-positive bacteria
• Broad spectrum antibiotics


  Are active against both gram-positive and gram-negative bacteria
• Classes of antibiotics

  • Sulfonamides
  • Penicillins
  • Cephalosporin
  • Tetracyclines
  • Aminoglycoside
  • Fluoroquinolones
  • Macrolides
  • Miscellaneous
• Mechanisms of antibacterial action

  • Inhibits Cell Wall Synthesis
  • Inhibits Protein Synthesis
  • Inhibits Nucleic Acid Synthesis
• Cell wall synthesis inhibitors

  • Beta-lactams inhibit the cell wall synthesis of the bacteria by binding to and inactivating beta lactamase, thus preventing degradation of the penicillin by the enzymes
  • Cephalosporins inhibit cell wall synthesis by blocking bacterial enzyme called transpeptidase
  • Monobactams/Monocytic B Lactam are closely related to aminoglycoside medications
  • Carbapenems are synthetic beta lactams which have a similar mechanism of action to penicillin and have a wider spectrum of activity than most beta lactams
  • Vancomycin binds to a cell wall precursor called peptidoglycan, inhibiting the transfer from plasma membrane to the cell wall
• Protein synthesis inhibitors

  • Aminoglycosides bind reversibly to around 30 ribosomal subunits, causing misreading of the mRNA to prevent protein synthesis
  • Chloramphenicol binds reversibly to around 50 ribosomal subunits, preventing access of aminoacyl (tRNA) to the ribosomal subunit
  • Tetracyclines bind reversibly to around 30 ribosomal subunits, preventing access of aminoacyl (tRNA) to the a-acceptor site
  • Macrolides bind reversibly to around 50 ribosomal subunits, preventing the translocation of polypeptide, and may interfere with binding of chloramphenicol and clindamycin
  • Clindamycin reverses the ribosomal subunit near the binding site of chloramphenicol and macrolides
• Nucleic acid synthesis inhibitors

  • Sulfonamides affect folic acid synthesis
  • Trimethoprim inhibits DNA gyrase, involved in replication and transcription
  • Quinolones inhibit DNA gyrase to cleave and reseal the DNA strand, mostly in DNA replication
• Penicillins


  Inhibit cell wall synthesis of microorganisms and are bactericidal
• Indications for penicillins


  • Systemic infections of gram-positive cocci (e.g. Staphylococcus Aureus, Syphilis)
  • Prophylaxis for Rheumatic Fever
  • Antigen-antibody complex
  • Respiratory, skin, and ear infections
• Adverse reactions to penicillins

  • Hypersensitivity (developing allergic reactions)
  • GI upset
  • Nephritis
  • Anemia
  • Leukopenia
  • Thrombocytopenia
• Nursing responsibilities for penicillins

  • Monitor for any adverse reactions in early stage of taking the medication
  • Prior to the administration, do skin testing
  • Always prepare emergency medication such as epinephrine and hydrocortisone for any hypersensitivity
• Classes of penicillins

  • Natural Penicillin
  • Aminopenicillin
  • Penicillinase-resistant
  • Extended G neg coverage
• Natural penicillins


  • No additives, effective in most gram positive bacteria except staphylococcus aureus (e.g. Penicillin G, Penicillin VK)
• Aminopenicillins


  • Good for some gram negative bacteria including e. coli (e.g. UTI), have an amino group added to restructure the chemical to combat gram negative bacteria (e.g. Amoxicillin, Ampicillin)
• Penicillinase-resistant penicillins


  • Effective with penicillinase-producing organisms (e.g. staphylococcus aureus), also work in gram negative bacteria (e.g. Oxacillin, Cloxacillin, Methicillin)
• Extended G neg coverage penicillins


  • Have broader range, are anti-pseudomonal penicillinase (pseudomonas infections) (e.g. Carboxypenicillins like Carbenicillin, Ticarcillin, and Ureidopenicillins like Piperacillin)
• Nursing responsibilities for penicillins


  • Most given IM or IV
  • If po, give on empty stomach
  • Penicillin G procaine and benzathine (Bicillin) - deep IM (sometimes, we administer Lidocaine for anesthetic purpose)
  • Cross-sensitivity to cephalosporins
  • Oral penicillin except amoxicillin is given at mealtime
  • Give amoxicillin 1 hour before or 2 hours after meal
• Generations of cephalosporins

  • First generation (indication: against gram-positive cocci, mechanism: inhibits bacterial cell wall synthesis, adverse reactions: hypersensitivity, nephrotoxicity, hepatotoxicity, bone marrow depression, cross-allergy with penicillin)
  • Second generation (indication: gram-negative and gram-positive bacteria, adverse reactions: same as first generation)
  • Third generation (indication: serious gram-negative or gram-positive infections like neonatal sepsis and meningitis, gonorrhea, commonly given IV, photosensitive, avoid combining with aminoglycosides)
• Monobactams


  • Used for patients allergic to penicillins (e.g. Aztreonam)
• Carbapenems


  • Synthetic beta lactams with similar mechanism of action to penicillin but wider spectrum of activity, adverse reactions include hypersensitivity, cross-sensitivity to penicillins, and excessive levels in renal failure may lead to seizures (Meropenem < Imipenem)
• Vancomycin


  • Effective against gram-positive cocci like staphylococcus, interferes with cell membrane activities, can be bacteriostatic or bactericidal (used for MRSA), administered IV as poorly absorbed orally, adverse reactions include ototoxicity, nephrotoxicity, thrombophlebitis, and "Red-neck / Red Man syndrome"
• Chloramphenicol


  • Mechanism of action is inhibiting protein synthesis, can be bacteriostatic or bactericidal, used for Haemophilus influenzae meningitis and salmonella (typhoid fever), alternative to beta lactams for meningitis, adverse reactions include bone marrow suppression, aplastic anemia, gray baby syndrome, severe vomiting, stomach distention, irregular respirations, and circulatory collapse
• Aminoglycosides


  • Bactericidal, prevent protein synthesis, first defense against very serious gram-negative infections, also effective for gram-negative eye infections, adverse reactions include ototoxicity, nephrotoxicity, and neuromuscular blockage
• Tetracyclines


  • Inhibit bacterial cell wall synthesis and protein synthesis, are bacteriostatic, reduce fatty acids from triglycerides, used for acne vulgaris, gonorrhea, and spirochetes, adverse reactions include photosensitivity, hepatotoxicity, chelating to teeth and new bones, and permanent discoloration of teeth in children
• Fluoroquinolones


  • Bactericidal, effective against many gram-positive and gram-negative organisms, used for bronchitis, bacterial gastroenteritis, and gonorrhea (e.g. Ciprofloxacin, Ofloxacin, Levofloxacin)
• Macrolides


  • Inhibit protein synthesis in bacterial cells, used in persons with penicillin allergy, indicated for acne, streptococcal and staphylococcal infections (e.g. Erythromycin, Azithromycin)
• All of them are nephrotoxic
• TETRACYCLINE

  • Inhibits bacterial cell wall synthesis
  • Inhibits protein synthesis - bacteriostatic
  • Reduces fatty acids from triglycerides