Beta-Lactam Antibiotics Overview
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What is the essential antibacterial component of 𝛽 lactam antibiotics?

  • Fungal component
  • Amino acid
  • Beta-lactam ring (correct)
  • Penicillin nucleus

    • Which of the following penicillins is known to be acid resistant?

  • Benzyl Penicillin
  • Methicillin
  • Phenoxy methyl penicillin (correct)
  • Procaine Penicillin

    • Which structure is the basic component of natural penicillins?

  • Monobactam structure
  • Carbapenem ring
  • 6-aminopenicillanic acid (correct)
  • Cephalosporin structure

    • Which type of penicillin is resistant to both acid and 𝛽 lactamase?

    <p>Nafcillin</p> Signup and view all the answers

    Which of the following penicillins has a very short duration of action?

    <p>Benzyl Penicillin</p> Signup and view all the answers

    Broad-spectrum penicillins are effective against which of the following?

    <p>Gram -ve bacilli including Salmonella and Shigella</p> Signup and view all the answers

    What is a known disadvantage of Benzyl Penicillin?

    <p>Acid sensitive and not effective orally</p> Signup and view all the answers

    What is a pro-drug of ampicillin that is better absorbed from the gut?

    <p>Bacampicillin</p> Signup and view all the answers

    What mechanism allows bacteria to resist the effects of penicillins?

    <p>Production of β-lactamases</p> Signup and view all the answers

    Which of the following is NOT a narrow spectrum penicillin indicated for treating?

    <p>Meningitis</p> Signup and view all the answers

    Which type of penicillin is specifically active against Pseudomonas, Proteus, and Klebsiella?

    <p>Extended spectrum</p> Signup and view all the answers

    Which adverse effect is most commonly associated with penicillin allergies?

    <p>Hypersensitivity reactions</p> Signup and view all the answers

    What causes the maculopapular rash associated with ampicillin use?

    <p>Allopurinol treatment</p> Signup and view all the answers

    How is hypersensitivity to penicillin typically prevented?

    <p>Skin testing and patient history review</p> Signup and view all the answers

    What is the purpose of benzathine penicillin in medical treatment?

    <p>Prophylaxis against streptococcal infections</p> Signup and view all the answers

    Which of the following statements is true regarding cross-allergy with penicillins?

    <p>10% of patients exhibit cross-allergy to other β-lactam antibiotics</p> Signup and view all the answers

    What distinguishes Amoxycillin from Ampicillin?

    <p>It has complete oral absorption and is not affected by food.</p> Signup and view all the answers

    Which of the following is true regarding Antipseudomonal Penicillins?

    <p>They are effective against Pseudomonas aeruginosa.</p> Signup and view all the answers

    What is the mechanism of action of Penicillins?

    <p>They bind to and inhibit penicillin-binding proteins.</p> Signup and view all the answers

    Which type of Penicillins is ineffective against Pseudomonas and Klebsiella?

    <p>Reversed-spectrum penicillins.</p> Signup and view all the answers

    What is the primary route of excretion for Penicillins?

    <p>Renal tubular excretion.</p> Signup and view all the answers

    How do bacteria develop resistance to Penicillins?

    <p>By acquiring plasmids that code for beta-lactamase.</p> Signup and view all the answers

    Which factor does NOT influence the antibacterial activity of Penicillins?

    <p>The metabolic rate of the human host.</p> Signup and view all the answers

    Which of the following Penicillins is stronger than carboxypenicillins and effective against Klebsiella?

    <p>Piperacillin.</p> Signup and view all the answers

    What is the primary treatment for diarrhea and superinfection caused by penicillin therapy?

    <p>Nystatin</p> Signup and view all the answers

    Which penicillin causes local pain and induration due to intramuscular injection?

    <p>Benzathine penicillin</p> Signup and view all the answers

    What is a significant potential adverse effect of large doses or intrathecal injection of penicillins?

    <p>Seizures</p> Signup and view all the answers

    Which of the following penicillins is combined with clavulanic acid to form Augmentin?

    <p>Ampicillin</p> Signup and view all the answers

    Which generation of cephalosporins cannot pass the blood-brain barrier?

    <p>Both 1st and 2nd Generations</p> Signup and view all the answers

    Which type of bacteria are characterized as PEPSI organisms associated with β Lactamase?

    <p>Certain gram-positive and gram-negative bacteria</p> Signup and view all the answers

    What is a key disadvantage of using Imipenem compared to Meropenem?

    <p>Higher risk of seizures</p> Signup and view all the answers

    Which β Lactamase inhibitor is used in combination with Ampicillin to form Unasyn?

    <p>Sulbactam</p> Signup and view all the answers

    What is the primary reason for using Aztreonam in patients allergic to penicillins?

    <p>It is synthetic and shows no cross-allergy with penicillins</p> Signup and view all the answers

    Which cephalosporin generation is most effective against anaerobes?

    <p>2nd Generation</p> Signup and view all the answers

    Which of the following is NOT an indication for Vancomycin?

    <p>Treatment of systemic infections through oral administration</p> Signup and view all the answers

    What is a characteristic of Ertapenem compared to Meropenem?

    <p>It has a longer half-life allowing once daily administration</p> Signup and view all the answers

    Which side effect is associated with Vancomycin administration?

    <p>Ototoxicity and nephrotoxicity</p> Signup and view all the answers

    Which cephalosporin is excreted in bile and does not cross the blood-brain barrier?

    <p>Cefoperazone</p> Signup and view all the answers

    What is the primary advantage of Cefepime over Ceftazidime?

    <p>More resistant to β lactamase enzymes</p> Signup and view all the answers

    Which generation of cephalosporins is indicated for treating meningitis?

    <p>Third and Fourth generations</p> Signup and view all the answers

    Which adverse effect is associated with cefamandole, cefoxitin, and cefoperazone?

    <p>Disulfiram-like reaction</p> Signup and view all the answers

    What is required to prevent nephrotoxicity when administering imipenem?

    <p>Cilastatin</p> Signup and view all the answers

    Which of the following is a common indication for ceftriaxone?

    <p>Respiratory infections</p> Signup and view all the answers

    Which characteristic of imipenem allows it to effectively treat infections during meningitis?

    <p>Ability to pass the blood-brain barrier</p> Signup and view all the answers

    What mechanism of action do both imipenem and penicillin share?

    <p>Binding to penicillin-binding proteins (PBPs)</p> Signup and view all the answers

    Study Notes

    Beta-Lactam Antibiotics

    • Beta-lactam antibiotics have a beta-lactam ring as their essential antibacterial component.
    • This group includes Penicillins, Cephalosporins, Carbapenems, and Monobactams.

    Penicillins

    • Chemistry: The penicillin nucleus contains a beta-lactam ring. The basic chemical structure is 6-aminopenicillanic acid.
    • Source:
      • Natural: derived from molds (fungi), including penicillin G and Penicillin V.
      • Semisynthetic: chemically modified forms.
    • Preparations of Penicillins:
      • 1. Benzyl Penicillin (Penicillin G): Short duration of action (4-6 hours), acid-sensitive, and susceptible to β-lactamases. Limited effectiveness against Gram-negative bacilli.
      • 2. Long-Acting Penicillins: Procaine penicillin G (12 hours), Fortified Procaine Penicillin G (24 hours), and Benzathine Penicillin G (monthly).
      • 3. Acid-Resistant Penicillins: Phenoxymethyl penicillin (Penicillin V).
      • 4. β-Lactamase Resistant: Methicillin (obsolete due to nephrotoxicity), primarily used for diagnosing Methicillin-resistant Staphylococcus aureus (MRSA) infections.
      • 5. Acid & β-Lactamase Resistant: Oxacillin, Cloxacillin, and nafcillin (IV for severe staph infections).
      • 6. Broad-Spectrum: Effective against Gram-positive and Gram-negative bacteria, including Salmonella, Shigella, H. influenza, and H. pylori, but not against Klebsiella, Proteus, and Pseudomonas aeruginosa. These drugs are often lactamase-sensitive and acid-resistant.
      • 6a. Ampicillin: Incomplete oral absorption, affected by food, and has a short duration of action (6 hours). Useful in enteritis, though it distrubs the gut flora.
      • 6b. Pro-drugs of ampicillin: (e.g., Pivampicillin and Bacampicillin). These are better absorbed than ampicillin itself and do not affect the gut flora.
      • 6c. Amoxicillin: Similar to ampicillin but complete oral absorption and less affected by food; also, less effect on the gut flora. Longer duration of action (8 hours).
      • 7. Antipseudomonal: Broad spectrum, effective against Pseudomonas aeruginosa and Proteus, and are β-lactamase sensitive.
      • 8. Reversed-Spectrum: Effective against Gram-negative bacteria (e.g., Salmonella & Shigella), but not Pseudomonas, Klebsiella, or H. influenza.

    Pharmacokinetics of Penicillins

    • Distribution: Do not pass the blood-brain barrier (BBB) readily, but can pass inflamed tissues. Pass the placental barrier, but are not teratogenic. Active renal tubular excretion, which is inhibited by Probenecid. Adjust dosage for patients with impaired renal function, except Nafcillin, which is excreted in bile.
    • Metabolism: Metabolized by bacterial enzymes (penicillinase). This leads to the inactive penicilloic acid, and can cause allergic reactions.

    Antibacterial Activity of Penicillins

    • Mechanism of Action: Penicillins bind to penicillin-binding proteins (PBPs) inhibiting transpeptidase enzymes, which inhibits cross-linking in peptidoglycan. The bacterial cell wall synthesis is affected as a result. This leads to autolytic enzyme activation and cell wall lysis.
    • Activity: Penicillins are bactericidal, mainly acting on growing bacteria.
    • Resistance:
      • Natural: due to the absence of peptidoglycans (e.g., Mycoplasma).
      • Acquired: synthesis of beta-lactamases (penicillinases). Alteration in the PBP binding sites, decreased permeability, and increased efflux.

    Spectrum of Penicillins

    • Narrow Spectrum: Active against Gram-positive bacteria (cocci and bacilli), Gram-negative cocci, anerobes except certain bacteria like Bacteroides fragilis, spirochaetes like Treponema pallidum, and Actinomyces Israeli.
    • Broad Spectrum: Active against Gram-positive and Gram-negative bacilli, but not Pseudomonas, Proteus, or Klebsiella.
    • Extended Spectrum: Active against a broad range including Pseudomonas, Proteus, and Klebsiella.

    Indications of Penicillins

    • Chemoprophylaxis: Prevention of streptococcal infections (rheumatic fever), endocarditis, and before dental procedures in patients with valve disease or prosthetic valves.
    • Treatment: Respiratory tract infections, Urinary tract infections, gastrointestinal infections (e.g., typhoid fever and eradication of H. pylori), meningitis, and gonorrhea. Pyogenic infections (e.g., abscesses, osteomyelitis), endocarditis, diphtheria, tetanus, gas gangrene, anthrax, actinomycosis, and syphilis.

    Adverse Effects of Penicillins

    • Hypersensitivity: Allergic reactions due to penicilloic acid acting as a hapten. Manifests as rash, urticaria, angioedema, or anaphylactic shock. Prevented by history and skin tests. No re-use recommended. Cross-allergy between penicillins and other beta-lactams (e.g., cephalosporins) is seen in about 10% of patients.
    • "Maculopapular rash" due to Allergy, Leukemia, infectious mononucleosis, or treatment by allopurinol can also occur.
    • Jarisch-Herxheimer reaction: due to release of toxins from dead Treponema in syphilitic patients, manifestations are like an allergic reaction and treated with cortisone.
    • Diarrhea and superinfection: Due to Monilia (Candida) or endotoxin, from Staph. or Clostridium difficile (treated with Nystatin or other drugs).
    • Seizures: From large doses, or intrathecal injection.
    • Electrolyte Imbalance: Sodium (Na+) and Potassium (K+) salts used can cause hypernatremia or hyperkalemia
    • Pain, Induration, and Thrombophlebitis: Local effects from IM and IV injection, respectively.
    • Platelet Dysfunction: Carboxypenicillin.
    • Nephrotoxicity: Methicillin and some other penicillins can cause nephrotoxicity. The dose should be adjusted in renal impairment..

    Other Beta-Lactam Antibiotics

    Cephalosporins

    • Chemistry: similar to penicillin.
    • Generations differ based on spectrum, resistance to beta-lactamases, and ability to cross the BBB.
    • 1st Generation: more active on Gram-positive than Gram-negative bacteria; resistant to beta-lactamases, does not cross BBB.
    • 2nd Generation: More active on Gram-negative than Gram-positive; more resistant to beta-lactamases than 1st generation; does not cross BBB except Cefuroxime.
    • 3rd Generation: More active on Gram-negative bacteria than 2nd generation; More resistant to beta-lactamases; crosses BBB except Cefoperazone. Excretion and metabolism varies between drugs.
    • 4th Generation: Similar to Ceftazidime, but more resistant to beta-lactamases.
    • Pharmacokinetics: Active renal tubular excretion, which is inhibited by Probenecid, except for drugs that are primarily excreted through bile (e.g., Ceftriaxone).
    • Spectrum: varies for each generation
    • Indications: Respiratory, urinary tract, meningitis, typhoid, anaerobic, pyogenic infections, and prophylaxis.
    • Adverse effects: Hypersensitivity, Diarrhea, Pain and Induration, formation of insoluble salts, disulfiram-like action, Hypoprothrombinemia, nephrotoxicity (especially with aminoglycosides or loop diuretics), and platelet dysfunction.

    Carbapenems

    • Members: Imipenem, Meropenem, Ertapenem.
    • Source: Synthetic.
    • Chemistry: Beta-lactam antibiotics.
    • Pharmacokinetics: Given IV and can cross the BBB (in meningitis); Imipenem metabolized into a nephrotoxic metabolite in the PCT, so combined with cilastatin, to avoid such toxicity and renal problems.
    • Spectrum: very wide, active against Gram-positive, Gram-negative, aerobes, and anaerobes.
    • Indications: serious hospital-acquired (nosocomial) infections.
    • Adverse effects: Allergy, Gastrointestinal (GI) disturbances, seizures.

    Monobactams

    • Member: Aztreonam.
    • Source: Synthetic.
    • Chemistry: Beta-lactam antibiotic.
    • Pharmacokinetics: Given IM or IV, and excreted in the urine.
    • Action: Bactericidal, inhibiting cell wall synthesis (PBP3).
    • Spectrum: Narrow, active on Gram-negative bacteria (including Pseudomonas), inactive against Gram-positive and anaerobes.
    • Indications: Patients allergic to penicillins.
    • Adverse effects: GI disturbances (generally).

    Vancomycin

    • Source: Natural.
    • Pharmacokinetics: Not absorbed orally; IV for systemic infections; weakly crosses the BBB, except in meningitis; largely excreted unchanged in urine; adjust dose in renal impairment.
    • Spectrum: Gram-positive bacteria (including MRSA, Clostridium difficile, and Enterococci).
    • Indications: Chemoprophylaxis against endocarditis in penicillin-allergic patients; treatment of pseudomembranous colitis, MRSA infections, and UTIs.
    • Adverse effects: Ototoxicity, nephrotoxicity, red man syndrome (rapid IV infusion).

    Beta-Lactamase Inhibitors

    • Some beta-lactam antibiotics are combined with inhibitors to overcome bacterial resistance. Clavulanic acid and Tazobactam are some examples. Such examples include combination with ampicillin, amoxicillin, or piperacillin.

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    Beta Lactam Antibiotics & Vancomycin PDF

    Description

    This quiz covers the essential features of beta-lactam antibiotics, focusing on their chemical structure and classifications such as penicillins, cephalosporins, carbapenems, and monobactams. You'll explore the sources, preparations, and characteristics of various penicillin types, including their pharmacological properties.

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