Antibiotics: Bacteriostatic vs Bactericidal
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Questions and Answers

What characterizes a bactericidal effect?

  • Kills bacteria above MIC (correct)
  • Inhibits growth at all concentrations above MIC
  • Requires lower concentration than MIC to be effective
  • Only inhibits growth without killing

    • What type of killing does beta-lactams exhibit?

  • Concentration Dependent Killing
  • Time Above MIC Killing (correct)
  • Peak to MIC Killing
  • Dose Independent Killing

    • Which of the following classes of antibiotics is known for dose dependent killing?

  • Aminoglycosides (correct)
  • Macrolides
  • Beta-Lactams
  • Tetracyclines

    • Above what concentration does a bacteriostatic agent inhibit bacterial growth?

    <p>Above MIC</p> Signup and view all the answers

    Which of the following statements is true regarding the action of antibiotics?

    <p>Bactericidal agents kill bacteria at concentrations above MBC</p> Signup and view all the answers

    What type of antibiotics are known for time-dependent killing?

    <p>Beta-lactam antibiotics</p> Signup and view all the answers

    Which of the following changes facilitates the activity of penicillin against gram-negative aerobes?

    <p>Addition of acyl side chain</p> Signup and view all the answers

    Nafcillin and Oxacillin are primarily eliminated through which route?

    <p>Biliary excretion</p> Signup and view all the answers

    Which penicillin is recognized for high protein binding, typically greater than 90%?

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

    What major issue arises due to the presence of extended-spectrum β-lactamases (ESBL)?

    <p>Resistance to multiple beta-lactam antibiotics</p> Signup and view all the answers

    What limits the penetration of antibiotics into the prostate, eye, and bone?

    <p>Intrinsic structural barriers</p> Signup and view all the answers

    What is a common side effect associated with beta-lactam antibiotics?

    <p>Nausea and vomiting</p> Signup and view all the answers

    Which of the following penicillin derivatives is specifically designed to resist penicillinase?

    <p>Penicillinase-resistant penicillins</p> Signup and view all the answers

    What is the effect of bacteriostatic agents on bacterial growth?

    <p>Inhibits growth at all concentrations above MIC</p> Signup and view all the answers

    Which factor primarily determines clinical success in antibiotic treatment?

    <p>Concentration of drug over time at the site of infection relative to MIC</p> Signup and view all the answers

    What is the area under the inhibitory concentration (AUIC) value associated with better outcomes for Vancomycin use?

    <p>400</p> Signup and view all the answers

    Which of the following is considered a dose-dependent killing antibiotic?

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

    What is the recommended trough concentration of Vancomycin for serious infections?

    <p>15-20 mcg/mL</p> Signup and view all the answers

    Which site of infection is known for poor penetration of aminoglycosides?

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

    Which of the following antibiotics is associated with exposure-dependent killing?

    <p>Beta-Lactams</p> Signup and view all the answers

    What does the acronym MIC stand for in pharmacodynamics?

    <p>Minimum Inhibitory Concentration</p> Signup and view all the answers

    Which of the following describes the mechanism of action of Vancomycin?

    <p>Inhibits cell wall synthesis by binding to D-Ala-D-Ala terminus</p> Signup and view all the answers

    What is a notable characteristic of the pharmacokinetics of Oritavancin and Dalbavancin?

    <p>They are compatible in D5W only and have a half-life of 14-16 days.</p> Signup and view all the answers

    Which condition is most likely associated with the use of all antibiotic classes?

    <p>Pseudomembranous colitis due to Clostridium difficile infection.</p> Signup and view all the answers

    What describes a mechanism of resistance to Vancomycin?

    <p>Use of D-lactate in place of D-Ala by bacteria.</p> Signup and view all the answers

    Which statement regarding Vancomycin's distribution is true?

    <p>It is poorly distributed in the lung tissue, requiring higher doses for optimal effect.</p> Signup and view all the answers

    Which side effect is commonly associated with an allergic reaction to antibiotics?

    <p>Urticaria or hives.</p> Signup and view all the answers

    What is the typical half-life range of Vancomycin?

    <p>6-10 hours, potentially increasing in renal failure.</p> Signup and view all the answers

    Which action describes the pharmacologic property of glycopeptides?

    <p>They primarily inhibit cell wall synthesis.</p> Signup and view all the answers

    Which route of elimination is primarily associated with Nafcillin and Oxacillin?

    <p>Biliary excretion</p> Signup and view all the answers

    What is a common mechanism of resistance to beta-lactam antibiotics?

    <p>Hydrolysis of the beta-lactam ring</p> Signup and view all the answers

    What factor does NOT determine the activity of beta-lactam cell wall agents?

    <p>Activity against anaerobic bacteria</p> Signup and view all the answers

    Which condition can result from the use of all antibiotic classes?

    <p>Pseudomembranous colitis</p> Signup and view all the answers

    Which of the following drugs would likely concentrate in the urine due to renal elimination?

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

    What adverse effect is associated with the use of beta-lactam antibiotics, particularly with Nafcillin or Oxacillin?

    <p>Hemolytic anemia</p> Signup and view all the answers

    Where in the body does beta-lactam absorption face significant challenges?

    <p>Gastric acid environment</p> Signup and view all the answers

    Which factor can enhance the effectiveness of beta-lactam antibiotics against bacteria?

    <p>Activation of autolytic systems</p> Signup and view all the answers

    Which class of antibiotics is known to penetrate poorly in the lungs?

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

    What is a key factor in the activity of beta-lactam cell wall agents?

    <p>Concentration of penicillin-binding proteins</p> Signup and view all the answers

    Which condition is associated with all antibiotic classes, including beta-lactams?

    <p>Pseudomembranous colitis</p> Signup and view all the answers

    Which route of elimination is NOT associated with Nafcillin and Oxacillin?

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

    What is the primary mechanism of resistance for beta-lactam antibiotics?

    <p>Inactivation by beta-lactamases</p> Signup and view all the answers

    What can interfere with the absorption of beta-lactam antibiotics?

    <p>Gastric acid destruction</p> Signup and view all the answers

    Which of the following antibiotics offers significant renal elimination, concentrating in urine?

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

    Which beta-lactam antibiotic is specifically noted for its risk of cross-allergenicity?

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

    Which of the following describes the factors determining the activity of beta-lactam antibiotics?

    <p>Penicillin-binding protein affinity</p> Signup and view all the answers

    Which antibiotics are known to concentrate in the urine due to renal elimination?

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

    What is a significant challenge for the absorption of beta-lactam antibiotics?

    <p>Destruction by gastric acid</p> Signup and view all the answers

    Which statement is true about the penetration of aminoglycosides?

    <p>They penetrate poorly in the lungs</p> Signup and view all the answers

    What is a common side effect associated with Nafcillin and Oxacillin usage?

    <p>Interstitial nephritis</p> Signup and view all the answers

    What is the mechanism of resistance for gram-positive bacteria against beta-lactam antibiotics?

    <p>Hydrolysis of the beta-lactam ring</p> Signup and view all the answers

    Which condition is a precaution for all antibiotic classes, including beta-lactams?

    <p>Pseudomembranous colitis</p> Signup and view all the answers

    What happens to aminoglycosides and vancomycin when administered for lung infections?

    <p>They penetrate poorly into lung tissues</p> Signup and view all the answers

    Which antibiotics are known to poorly penetrate the lungs?

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

    What must be considered for drugs that penetrate the central nervous system (CNS) in terms of dosage?

    <p>Higher doses or intrathecal administration may be required.</p> Signup and view all the answers

    Which factor does NOT determine the activity of beta-lactam cell wall agents?

    <p>Presence of an antibiotic resistance gene</p> Signup and view all the answers

    What is the primary method of excretion for Nafcillin and Oxacillin?

    <p>Primarily through biliary excretion</p> Signup and view all the answers

    Which condition is closely associated with all antibiotic classes, including beta-lactams?

    <p>Pseudomembranous colitis</p> Signup and view all the answers

    What level of quinolone or fluconazole is typically found in urine compared to blood concentrations?

    <p>100 times higher than blood</p> Signup and view all the answers

    What is one of the mechanisms of resistance for beta-lactam antibiotics?

    <p>Inactivation by beta-lactamases</p> Signup and view all the answers

    Which of the following statements regarding absorption of beta-lactam agents is true?

    <p>Many are destroyed by gastric acid.</p> Signup and view all the answers

    Which antibiotics are known to exhibit poor penetration in the lungs?

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

    What is the key factor affecting the activity of beta-lactam antibiotics?

    <p>Cell wall penetration</p> Signup and view all the answers

    Which of the following antibiotics must be given at higher doses due to the blood-brain barrier?

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

    Which antibiotics show significantly concentrated levels in the urine due to renal elimination?

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

    What type of hypersensitivity reaction can occur with the use of penicillin antibiotics?

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

    What is the mechanism by which beta-lactam antibiotics become ineffective against certain bacteria?

    <p>Hydrolysis of the beta-lactam ring</p> Signup and view all the answers

    Which class of antibiotics is associated with the risk of causing interstitial nephritis?

    <p>Beta-lactams</p> Signup and view all the answers

    Which factor is NOT involved in the action of beta-lactam cell wall agents?

    <p>Activation of efflux pumps</p> Signup and view all the answers

    What primarily affects the clinical success of beta-lactam antibiotics?

    <p>Penetration of bacteria's outer membrane</p> Signup and view all the answers

    Which of the following antibiotics is notable for penetrating poorly in the lungs?

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

    What is a significant factor determining the activity of beta-lactam cell wall agents?

    <p>Concentration of penicillin-binding proteins</p> Signup and view all the answers

    What are the effects of beta-lactam antibiotics on the human immune system?

    <p>They bind to human proteins, forming haptens.</p> Signup and view all the answers

    Which condition may arise as a precaution for all antibiotic classes including beta-lactams?

    <p>Pseudomembranous colitis</p> Signup and view all the answers

    What is a common route of elimination for beta-lactam antibiotics?

    <p>Bile ducts</p> Signup and view all the answers

    What can inhibit the effectiveness of beta-lactam antibiotics?

    <p>Presence of beta-lactamases</p> Signup and view all the answers

    Where do aminoglycosides exhibit poor penetration?

    <p>Central Nervous System</p> Signup and view all the answers

    Study Notes

    Bactericidal Agents

    • Bacteriostatic agents inhibit bacterial growth at all concentrations above the Minimum Inhibitory Concentration (MIC).
    • Bactericidal agents inhibit growth above MIC and kill bacteria when concentrations exceed the Minimum Bactericidal Concentration (MBC).

    Mechanisms of Killing

    • : Dose Dependent Killing: This type of killing is characterized by the relationship between drug concentration and its effect on bacteria.

      • Agents such as aminoglycosides, quinolones, and daptomycin demonstrate concentration-dependent killing, where efficacy correlates with the peak concentration relative to the MIC.

    • Exposure (Time) Dependent Killing: Efficacy relies on the duration that the drug concentration remains above the MIC.

      • Beta-lactams exemplify time-dependent killing, with effectiveness primarily determined by the time the drug remains active above the MIC.

    Pharmacodynamics

    • Pharmacodynamics examines the drug's effect on organisms, particularly on bacteria.

    Drug Activity

    • Bacteriostatic drugs inhibit bacterial growth at all concentrations above the minimum inhibitory concentration (MIC).
    • Bactericidal drugs kill bacteria above the minimum bactericidal concentration (MBC) and inhibit growth above the MIC.
    • Killing characteristics can be:
      • Dose-Dependent (Peak: MIC) - efficacy related to drug concentration at peak levels.
      • Exposure-Dependent (Time Above MIC) - efficacy relates to the duration the drug concentration exceeds the MIC.

    Bactericidal Agents

    • Aminoglycosides and quinolones exhibit dose-dependent killing.
    • Beta-lactams demonstrate exposure-dependent killing.
    • Composite measures like AUIC (Area Under Inhibitory Concentration) predict outcomes, with Vancomycin having an AUIC > 400 associated with improved clinical results.

    Site of Infection

    • Drug concentration at the infection site relative to the MIC is crucial for clinical success.
    • Blood is the primary distribution route for antibiotics, regardless of administration method.
    • Blood levels can be easily measured, unlike concentrations in other sites.

    Specific Drug Concentrations

    • Vancomycin:
      • AUIC of 400-600 is optimal.
      • Trough levels for serious infections: 15-20 mcg/mL; for mild infections: 10-15 mcg/mL.
    • Aminoglycosides:
      • Peak concentration varies by infection site (3-13 mcg/mL).
      • Trough levels should be < 2 mcg/mL to minimize nephrotoxicity.

    Historical Context

    • 1929: Alexander Fleming discovered Penicillium notatum inhibits Staphylococcus aureus.
    • 1941: Howard W Florey treated first patients with penicillin for streptococcal and gonococcal infections.
    • Emergence of penicillinase-producing staphylococci led to modifications in penicillin structure, resulting in:
      • Aminopenicillins
      • Carboxypenicillins
      • Ureidopenicillins
      • β-lactamase inhibitors

    Structure and Mechanism of Action

    • Bacterial cell wall structures are primary targets for beta-lactam antibiotics.
    • Key factors influencing activity include:
      • Affinity, type, and concentration of penicillin-binding proteins.
      • Activation of autolysins, enzymes crucial for cell wall remodeling.

    General Pharmacologic Properties of Beta-Lactam Antibiotics

    • Absorption varies, with excellent penetration in some tissues and poor in others (e.g., prostate, eye, bone).
    • CNS penetration is significant only when the meninges are inflamed; can cross placenta and breast milk.
    • Metabolism/Excretion:
      • Biliary excretion for Nafcillin, Oxacillin, and Piperacillin, while Ceftriaxone is both renal and biliary.

    Resistance Mechanisms

    • Inactivation by β-lactamases:
      • Occurs outside the cell wall for gram-positives and in the periplasmic space for gram-negatives.
      • Extended-spectrum β-lactamases (ESBLs) found in K. pneumoniae and E. coli.
    • Decreased cell wall permeability and development of new penicillin-binding proteins enhance bacterial resistance, notably in Streptococcus pneumoniae and MRSA.

    Side Effects

    • Common side effects: nausea, vomiting, diarrhea, and risk of Pseudomembranous colitis (CDAD).
    • Allergic reactions can range from mild rashes to severe anaphylaxis; interstitial nephritis particularly with Nafcillin/Oxacillin.

    Mechanism of Glycopeptide and Lipoglycopeptide Action

    • Vancomycin and analogous agents inhibit cell wall synthesis by binding to the D-Ala-D-Ala termini.
    • Resistance mechanisms include substituting D-Ala with D-lactate (VanH and VanA resistance).

    Agents

    • Vancomycin (Vancocin®): MOA 1,2 (IV, PO, glycopeptide).
    • Telavancin (Vibativ®): MOA 1,2,4 (IV, lipoglycopeptide).
    • Oritavancin (Orbactiv®): Compatible in D5W only; MOA 1,2,3,4 (IV, lipoglycopeptide).
    • Dalbavancin (Dalvance®): Compatible in D5W only; MOA 1,2,4 (IV, lipoglycopeptide).

    General Pharmacologic Properties

    • Absorption: Poor oral absorption; used orally or rectally predominantly for C. diff colitis.
    • Distribution: Vancomycin has poor CNS penetration and lung penetration; trough targeted to achieve systemic effectiveness.
    • Metabolism/Excretion:
      • Vancomycin and Telavancin have a half-life of 6-10 hours; renal adjusting is necessary.
      • Oritavancin and Dalbavancin have a long half-life of 14-16 days, allowing for weekly dosing.

    Lungs

    • Quinolones and macrolides exhibit high concentration in lung tissue.
    • Aminoglycosides and vancomycin, along with daptomycin, have poor penetration in the lungs.

    Central Nervous System (CNS)

    • The blood-brain barrier (BBB) protects the CNS; higher doses and possibly intrathecal (IT) administration are necessary.

    Urine

    • Drugs eliminated through the kidneys concentrate in urine.
    • Quinolones and fluconazole can reach urine levels that are 100 times higher than blood levels.

    Action of Beta-Lactam Cell Wall Agents

    • Beta-lactams are bactericidal and exhibit time-dependent killing.
    • Factors influencing activity include:
      • Cell wall penetration and permeability.
      • Affinity for penicillin-binding proteins (PBPs).
      • Specific type and concentration of PBPs.
      • Activation of autolysins, enzymes that break down cell wall components.

    Absorption and Distribution

    • Most beta-lactam agents are destroyed by gastric acid.
    • CNS penetration occurs only through inflamed meninges.
    • Commonly excreted renally, including via tubular secretion.
    • Biliary excretion occurs for agents like Nafcillin, Oxacillin, Piperacillin, and Ceftriaxone.

    Resistance

    • Resistance can occur through inactivation by beta-lactamases:
      • Beta-lactamases can be found outside the cell wall for gram-positive bacteria.
      • For gram-negative bacteria, they are typically present in the periplasmic space.
      • Hydrolysis of the beta-lactam ring leads to resistance.
    • Development of new penicillin-binding proteins can emerge, notably in:
      • Streptococcus pneumoniae.
      • Methicillin-resistant Staphylococcus aureus (MRSA).

    Adverse Effects

    • Pseudomembranous colitis (CDAD) poses a risk with all antibiotic classes.
    • Hemolytic anemia may occur, evidenced by a positive direct Coombs test, due to penicillin binding to human proteins, forming a hapten that is recognized as foreign.
    • Cross-reactivity can occur among various penicillins and other beta-lactams.
    • Interstitial nephritis is particularly associated with Nafcillin and Oxacillin use.

    Lungs

    • Quinolones and macrolides exhibit high concentration in lung tissue.
    • Aminoglycosides and vancomycin, along with daptomycin, have poor penetration in the lungs.

    Central Nervous System (CNS)

    • The blood-brain barrier (BBB) protects the CNS; higher doses and possibly intrathecal (IT) administration are necessary.

    Urine

    • Drugs eliminated through the kidneys concentrate in urine.
    • Quinolones and fluconazole can reach urine levels that are 100 times higher than blood levels.

    Action of Beta-Lactam Cell Wall Agents

    • Beta-lactams are bactericidal and exhibit time-dependent killing.
    • Factors influencing activity include:
      • Cell wall penetration and permeability.
      • Affinity for penicillin-binding proteins (PBPs).
      • Specific type and concentration of PBPs.
      • Activation of autolysins, enzymes that break down cell wall components.

    Absorption and Distribution

    • Most beta-lactam agents are destroyed by gastric acid.
    • CNS penetration occurs only through inflamed meninges.
    • Commonly excreted renally, including via tubular secretion.
    • Biliary excretion occurs for agents like Nafcillin, Oxacillin, Piperacillin, and Ceftriaxone.

    Resistance

    • Resistance can occur through inactivation by beta-lactamases:
      • Beta-lactamases can be found outside the cell wall for gram-positive bacteria.
      • For gram-negative bacteria, they are typically present in the periplasmic space.
      • Hydrolysis of the beta-lactam ring leads to resistance.
    • Development of new penicillin-binding proteins can emerge, notably in:
      • Streptococcus pneumoniae.
      • Methicillin-resistant Staphylococcus aureus (MRSA).

    Adverse Effects

    • Pseudomembranous colitis (CDAD) poses a risk with all antibiotic classes.
    • Hemolytic anemia may occur, evidenced by a positive direct Coombs test, due to penicillin binding to human proteins, forming a hapten that is recognized as foreign.
    • Cross-reactivity can occur among various penicillins and other beta-lactams.
    • Interstitial nephritis is particularly associated with Nafcillin and Oxacillin use.

    Lungs

    • Quinolones and macrolides exhibit high concentration in lung tissue.
    • Aminoglycosides and vancomycin, along with daptomycin, have poor penetration in the lungs.

    Central Nervous System (CNS)

    • The blood-brain barrier (BBB) protects the CNS; higher doses and possibly intrathecal (IT) administration are necessary.

    Urine

    • Drugs eliminated through the kidneys concentrate in urine.
    • Quinolones and fluconazole can reach urine levels that are 100 times higher than blood levels.

    Action of Beta-Lactam Cell Wall Agents

    • Beta-lactams are bactericidal and exhibit time-dependent killing.
    • Factors influencing activity include:
      • Cell wall penetration and permeability.
      • Affinity for penicillin-binding proteins (PBPs).
      • Specific type and concentration of PBPs.
      • Activation of autolysins, enzymes that break down cell wall components.

    Absorption and Distribution

    • Most beta-lactam agents are destroyed by gastric acid.
    • CNS penetration occurs only through inflamed meninges.
    • Commonly excreted renally, including via tubular secretion.
    • Biliary excretion occurs for agents like Nafcillin, Oxacillin, Piperacillin, and Ceftriaxone.

    Resistance

    • Resistance can occur through inactivation by beta-lactamases:
      • Beta-lactamases can be found outside the cell wall for gram-positive bacteria.
      • For gram-negative bacteria, they are typically present in the periplasmic space.
      • Hydrolysis of the beta-lactam ring leads to resistance.
    • Development of new penicillin-binding proteins can emerge, notably in:
      • Streptococcus pneumoniae.
      • Methicillin-resistant Staphylococcus aureus (MRSA).

    Adverse Effects

    • Pseudomembranous colitis (CDAD) poses a risk with all antibiotic classes.
    • Hemolytic anemia may occur, evidenced by a positive direct Coombs test, due to penicillin binding to human proteins, forming a hapten that is recognized as foreign.
    • Cross-reactivity can occur among various penicillins and other beta-lactams.
    • Interstitial nephritis is particularly associated with Nafcillin and Oxacillin use.

    Lungs

    • Quinolones and macrolides exhibit high concentration in lung tissue.
    • Aminoglycosides and vancomycin, along with daptomycin, have poor penetration in the lungs.

    Central Nervous System (CNS)

    • The blood-brain barrier (BBB) protects the CNS; higher doses and possibly intrathecal (IT) administration are necessary.

    Urine

    • Drugs eliminated through the kidneys concentrate in urine.
    • Quinolones and fluconazole can reach urine levels that are 100 times higher than blood levels.

    Action of Beta-Lactam Cell Wall Agents

    • Beta-lactams are bactericidal and exhibit time-dependent killing.
    • Factors influencing activity include:
      • Cell wall penetration and permeability.
      • Affinity for penicillin-binding proteins (PBPs).
      • Specific type and concentration of PBPs.
      • Activation of autolysins, enzymes that break down cell wall components.

    Absorption and Distribution

    • Most beta-lactam agents are destroyed by gastric acid.
    • CNS penetration occurs only through inflamed meninges.
    • Commonly excreted renally, including via tubular secretion.
    • Biliary excretion occurs for agents like Nafcillin, Oxacillin, Piperacillin, and Ceftriaxone.

    Resistance

    • Resistance can occur through inactivation by beta-lactamases:
      • Beta-lactamases can be found outside the cell wall for gram-positive bacteria.
      • For gram-negative bacteria, they are typically present in the periplasmic space.
      • Hydrolysis of the beta-lactam ring leads to resistance.
    • Development of new penicillin-binding proteins can emerge, notably in:
      • Streptococcus pneumoniae.
      • Methicillin-resistant Staphylococcus aureus (MRSA).

    Adverse Effects

    • Pseudomembranous colitis (CDAD) poses a risk with all antibiotic classes.
    • Hemolytic anemia may occur, evidenced by a positive direct Coombs test, due to penicillin binding to human proteins, forming a hapten that is recognized as foreign.
    • Cross-reactivity can occur among various penicillins and other beta-lactams.
    • Interstitial nephritis is particularly associated with Nafcillin and Oxacillin use.

    Lungs

    • Quinolones and macrolides exhibit high concentration in lung tissue.
    • Aminoglycosides and vancomycin, along with daptomycin, have poor penetration in the lungs.

    Central Nervous System (CNS)

    • The blood-brain barrier (BBB) protects the CNS; higher doses and possibly intrathecal (IT) administration are necessary.

    Urine

    • Drugs eliminated through the kidneys concentrate in urine.
    • Quinolones and fluconazole can reach urine levels that are 100 times higher than blood levels.

    Action of Beta-Lactam Cell Wall Agents

    • Beta-lactams are bactericidal and exhibit time-dependent killing.
    • Factors influencing activity include:
      • Cell wall penetration and permeability.
      • Affinity for penicillin-binding proteins (PBPs).
      • Specific type and concentration of PBPs.
      • Activation of autolysins, enzymes that break down cell wall components.

    Absorption and Distribution

    • Most beta-lactam agents are destroyed by gastric acid.
    • CNS penetration occurs only through inflamed meninges.
    • Commonly excreted renally, including via tubular secretion.
    • Biliary excretion occurs for agents like Nafcillin, Oxacillin, Piperacillin, and Ceftriaxone.

    Resistance

    • Resistance can occur through inactivation by beta-lactamases:
      • Beta-lactamases can be found outside the cell wall for gram-positive bacteria.
      • For gram-negative bacteria, they are typically present in the periplasmic space.
      • Hydrolysis of the beta-lactam ring leads to resistance.
    • Development of new penicillin-binding proteins can emerge, notably in:
      • Streptococcus pneumoniae.
      • Methicillin-resistant Staphylococcus aureus (MRSA).

    Adverse Effects

    • Pseudomembranous colitis (CDAD) poses a risk with all antibiotic classes.
    • Hemolytic anemia may occur, evidenced by a positive direct Coombs test, due to penicillin binding to human proteins, forming a hapten that is recognized as foreign.
    • Cross-reactivity can occur among various penicillins and other beta-lactams.
    • Interstitial nephritis is particularly associated with Nafcillin and Oxacillin use.

    Lungs

    • Quinolones and macrolides exhibit high concentration in lung tissue.
    • Aminoglycosides and vancomycin, along with daptomycin, have poor penetration in the lungs.

    Central Nervous System (CNS)

    • The blood-brain barrier (BBB) protects the CNS; higher doses and possibly intrathecal (IT) administration are necessary.

    Urine

    • Drugs eliminated through the kidneys concentrate in urine.
    • Quinolones and fluconazole can reach urine levels that are 100 times higher than blood levels.

    Action of Beta-Lactam Cell Wall Agents

    • Beta-lactams are bactericidal and exhibit time-dependent killing.
    • Factors influencing activity include:
      • Cell wall penetration and permeability.
      • Affinity for penicillin-binding proteins (PBPs).
      • Specific type and concentration of PBPs.
      • Activation of autolysins, enzymes that break down cell wall components.

    Absorption and Distribution

    • Most beta-lactam agents are destroyed by gastric acid.
    • CNS penetration occurs only through inflamed meninges.
    • Commonly excreted renally, including via tubular secretion.
    • Biliary excretion occurs for agents like Nafcillin, Oxacillin, Piperacillin, and Ceftriaxone.

    Resistance

    • Resistance can occur through inactivation by beta-lactamases:
      • Beta-lactamases can be found outside the cell wall for gram-positive bacteria.
      • For gram-negative bacteria, they are typically present in the periplasmic space.
      • Hydrolysis of the beta-lactam ring leads to resistance.
    • Development of new penicillin-binding proteins can emerge, notably in:
      • Streptococcus pneumoniae.
      • Methicillin-resistant Staphylococcus aureus (MRSA).

    Adverse Effects

    • Pseudomembranous colitis (CDAD) poses a risk with all antibiotic classes.
    • Hemolytic anemia may occur, evidenced by a positive direct Coombs test, due to penicillin binding to human proteins, forming a hapten that is recognized as foreign.
    • Cross-reactivity can occur among various penicillins and other beta-lactams.
    • Interstitial nephritis is particularly associated with Nafcillin and Oxacillin use.

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    Explore the concepts of bacteriostatic and bactericidal activities of antibiotics in this quiz. Learn about dose-dependent and time-dependent killing mechanisms, focusing on aminoglycosides, quinolones, daptomycin, and beta-lactams. Test your understanding of these critical pharmacological principles.

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