Penicillins and Cephalosporins
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Questions and Answers

What is the reason for using Cefazolin in surgical prophylaxis?

  • Bile excretion
  • Good tissue and fluid penetration (correct)
  • Broad spectrum activity
  • Minimal allergic reactions

    • How is Ceftriaxone primarily excreted from the body?

  • Metabolism in the liver
  • Glomerular filtration
  • Bile excretion (correct)
  • Tubular secretion

    • What is the primary adverse reaction profile of cephalosporins compared to penicillins?

  • Neurotoxicity
  • Hepatotoxicity
  • Well-tolerated (correct)
  • High incidence of diarrhea

    • What is the cross-reactivity rate between penicillin and cephalosporins?

    <p>3% to 5%</p> Signup and view all the answers

    Which organisms are covered by carbapenems?

    <p>β-lactamase-producing G +ve and G –ve organisms, anaerobes, and P. aeruginosa</p> Signup and view all the answers

    Which carbapenem has coverage different from the others?

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

    What factors affect the selection of antimicrobial agents?

    <p>Patient factors, safety and efficacy, and cost of therapy</p> Signup and view all the answers

    What are the properties influencing the frequency of dosing of antimicrobial agents?

    <p>Concentration-dependent killing and time-dependent killing</p> Signup and view all the answers

    What are the chemotherapeutic spectra of antimicrobial drugs?

    <p>Narrow-spectrum and extended/broad-spectrum</p> Signup and view all the answers

    What are the mechanisms of acquired resistance in drug-resistant organisms?

    <p>Altered expression of proteins, modification of target sites, decreased accumulation, and enzymatic inactivation</p> Signup and view all the answers

    What can combinations of antimicrobial drugs lead to?

    <p>Advantages such as synergism, but also disadvantages like risk of antibiotic resistance</p> Signup and view all the answers

    What can capillaries in certain tissues act as, impacting penetration and concentration of antimicrobial agents?

    <p>Natural barriers to drug delivery</p> Signup and view all the answers

    What is the primary mechanism of action of penicillins?

    <p>Interfering with the transpeptidation process</p> Signup and view all the answers

    Which type of penicillin is effective against Pseudomonas aeruginosa when combined with a β-lactamase inhibitor?

    <p>Antipseudomonal penicillins</p> Signup and view all the answers

    What is a common cause of resistance to penicillins?

    <p>β-lactamase production</p> Signup and view all the answers

    Which type of penicillin is used for treating infections caused by penicillinase-producing staphylococci?

    <p>Antistaphylococcal penicillins</p> Signup and view all the answers

    What is the primary function of cell wall inhibitors as antimicrobial drugs?

    <p>Interfere with bacterial cell wall synthesis</p> Signup and view all the answers

    What is the main advantage of semisynthetic penicillins like ampicillin and amoxicillin?

    <p>Extended Gram-negative antimicrobial activity</p> Signup and view all the answers

    Which adverse reaction is associated with penicillins?

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

    Which cephalosporin can cross the blood-brain barrier?

    <p>Cefuroxime sodium</p> Signup and view all the answers

    Which penicillin shows poor oral bioavailability?

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

    Which generation of cephalosporins is effective against Pseudomonas aeruginosa?

    <p>Fourth-generation</p> Signup and view all the answers

    Which cephalosporin is used for treating meningitis and has good penetration into bone?

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

    Which body organ does penicillin have insufficient penetration into?

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

    What are the topics covered in Pharmacology (3)?

    <p>Antimicrobial Drugs, Anticancer Drugs, Thyroid Hormones, Estrogens and Androgens</p> Signup and view all the answers

    What is the principle behind antimicrobial therapy?

    <p>Selective toxicity due to biochemical differences between microorganisms and human beings</p> Signup and view all the answers

    What factors are considered for selecting the most appropriate antimicrobial agent?

    <p>The identity of the organism, the susceptibility of the organism to a particular agent, the site of infection</p> Signup and view all the answers

    What is the purpose of Gram stain and sample culture in antimicrobial therapy?

    <p>To identify the organism causing the infection</p> Signup and view all the answers

    What does MIC stand for in the context of antimicrobial therapy?

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

    What is the significance of selective toxicity in antimicrobial therapy?

    <p>It allows for targeting the microorganism without harming the host</p> Signup and view all the answers

    What is the primary route of excretion for Ceftriaxone?

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

    What is the main reason for avoiding or using caution with 1st generation cephalosporins in individuals with penicillin allergy?

    <p>Potential for cross-reactivity with penicillin</p> Signup and view all the answers

    Which cephalosporin is preferred for surgical prophylaxis due to its good tissue and fluid penetration and activity against penicillinase-producing S. aureus?

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

    What is the primary mechanism of action of carbapenems?

    <p>Disruption of cell wall synthesis</p> Signup and view all the answers

    What is the primary adverse reaction profile of cephalosporins compared to penicillins?

    <p>Greater likelihood of inducing anaphylactic shock</p> Signup and view all the answers

    How are carbapenems primarily eliminated from the body?

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

    Which penicillin has poor oral bioavailability?

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

    Which cephalosporin has the longest half-life?

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

    Which cephalosporin is active against MRSA?

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

    Which cephalosporin has greater stability against beta-lactamases?

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

    Which cephalosporin is effective in treating meningitis and has good penetration into bone?

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

    Which penicillin is primarily excreted through the kidneys?

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

    What influences the selection of the most appropriate antimicrobial agent?

    <p>The identity of the organism</p> Signup and view all the answers

    What is the primary factor considered when selecting the most appropriate antimicrobial agent?

    <p>The site of infection</p> Signup and view all the answers

    What is the significance of selective toxicity in antimicrobial therapy?

    <p>It allows for preferential harm to the microorganism over the host</p> Signup and view all the answers

    What does MIC stand for in the context of antimicrobial therapy?

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

    What is the primary function of cell wall inhibitors as antimicrobial drugs?

    <p>Disrupting the formation of the bacterial cell wall</p> Signup and view all the answers

    What can capillaries in certain tissues act as, impacting penetration and concentration of antimicrobial agents?

    <p>A barrier to antimicrobial penetration</p> Signup and view all the answers

    Which type of penicillin has extended Gram-negative antimicrobial activity and is commonly used for respiratory infections?

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

    What is the primary reason for the increasing resistance of natural penicillins like penicillin G and penicillin V?

    <p>β-lactamase production in many bacteria</p> Signup and view all the answers

    Which mechanism can lead to resistance to penicillins?

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

    What is the primary mode of administration for penicillins?

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

    Which type of penicillin is used to treat infections caused by penicillinase-producing staphylococci?

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

    What is the primary target of cell wall inhibitors as antimicrobial drugs?

    <p>Bacterial cell wall synthesis</p> Signup and view all the answers

    What factors affect the selection of antimicrobial agents?

    <p>Patient factors, safety and efficacy, and cost of therapy</p> Signup and view all the answers

    What are the mechanisms of acquired resistance in drug-resistant organisms?

    <p>Altered expression of proteins, modification of target sites, decreased accumulation, and enzymatic inactivation</p> Signup and view all the answers

    What is the primary function of cell wall inhibitors as antimicrobial drugs?

    <p>Inhibit the synthesis of bacterial cell walls</p> Signup and view all the answers

    What can combinations of antimicrobial drugs lead to?

    <p>Advantages such as synergism and disadvantages like risk of antibiotic resistance</p> Signup and view all the answers

    What is the significance of selective toxicity in antimicrobial therapy?

    <p>It allows the drug to target the pathogen without harming the host</p> Signup and view all the answers

    What is the reason for using Cefazolin in surgical prophylaxis?

    <p>It covers most skin flora and has a long half-life</p> Signup and view all the answers

    What is the primary factor considered when selecting the most appropriate antimicrobial agent?

    <p>The identity of the organism</p> Signup and view all the answers

    What is the significance of selective toxicity in antimicrobial therapy?

    <p>It ensures absolute toxicity to microorganisms only</p> Signup and view all the answers

    What is the primary route of excretion for Ceftriaxone?

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

    What can capillaries in certain tissues act as, impacting penetration and concentration of antimicrobial agents?

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

    What is the reason for using Cefazolin in surgical prophylaxis?

    <p>To prevent surgical site infections</p> Signup and view all the answers

    What are the topics covered in Pharmacology (3)?

    <p>Antimicrobial Drugs, Anticancer Drugs, Thyroid Hormones, Estrogens and Androgens</p> Signup and view all the answers

    What is the primary reason for the increasing resistance of natural penicillins like penicillin G and penicillin V?

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

    Which penicillin shows poor oral bioavailability?

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

    What is the primary route of excretion for Ceftriaxone?

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

    Which body organ does penicillin have insufficient penetration into?

    <p>Central nervous system</p> Signup and view all the answers

    What can capillaries in certain tissues act as, impacting penetration and concentration of antimicrobial agents?

    <p>Selective barrier</p> Signup and view all the answers

    What is the primary mechanism of action of carbapenems?

    <p>Inhibition of folic acid synthesis</p> Signup and view all the answers

    What are the two properties influencing the frequency of dosing of antimicrobial agents?

    <p>Concentration-dependent killing and time-dependent killing</p> Signup and view all the answers

    What are the mechanisms of acquired resistance in drug-resistant organisms?

    <p>Altered expression of proteins, modification of target sites, decreased accumulation</p> Signup and view all the answers

    What are the chemotherapeutic spectra of antimicrobial drugs?

    <p>Narrow-spectrum and extended/broad-spectrum antimicrobial drugs</p> Signup and view all the answers

    What can combinations of antimicrobial drugs lead to?

    <p>Advantages such as synergism, but also disadvantages like risk of antibiotic resistance</p> Signup and view all the answers

    What can capillaries in certain tissues act as, impacting penetration and concentration of antimicrobial agents?

    <p>Natural barriers to drug delivery</p> Signup and view all the answers

    What is the primary cause of drug resistance in antimicrobial therapy?

    <p>Acquired resistance through genetic alterations</p> Signup and view all the answers

    Which adverse reactions are associated with penicillins?

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

    Which cephalosporin is primarily used for treating complicated skin infections and community-acquired pneumonia?

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

    What is the primary route of excretion for penicillins?

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

    Which cephalosporin has the longest half-life among all cephalosporins?

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

    What is the main reason for avoiding or using caution with 1st generation cephalosporins in individuals with penicillin allergy?

    <p>Cross-reactivity</p> Signup and view all the answers

    What is the primary mechanism of action shared by cephalosporins and penicillins?

    <p>Disruption of cell wall synthesis</p> Signup and view all the answers

    What is the primary route of excretion for Ceftriaxone?

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

    What is the highest rate of allergic cross-sensitivity between penicillin and 1st generation cephalosporins?

    <p>5%-10%</p> Signup and view all the answers

    What is the primary mechanism of action of carbapenems?

    <p>Inhibition of cell wall synthesis</p> Signup and view all the answers

    What is the primary adverse reaction profile of cephalosporins compared to penicillins?

    <p>Higher incidence of allergic reactions</p> Signup and view all the answers

    Which cephalosporin is preferred for surgical prophylaxis due to its good tissue and fluid penetration and activity against penicillinase-producing S. aureus?

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

    Which carbapenem has coverage different from the others?

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

    Antimicrobial therapy takes advantage of the biochemical differences that exist between microorganisms and human beings resulting in absolute toxicity.

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

    The selection of the most appropriate antimicrobial agent considers the identity of the organism, the susceptibility of the organism to a particular agent, and the site of infection.

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

    Cefazolin is primarily used for treating complicated skin infections and community-acquired pneumonia.

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

    Natural penicillins like penicillin G and penicillin V show increasing resistance.

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

    Cell wall inhibitors are primarily targeting the ribosomes of microorganisms.

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

    Ceftriaxone is primarily excreted through the kidneys.

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

    Is Cefazolin preferred for surgical prophylaxis due to its good tissue and fluid penetration and activity against penicillinase-producing S. aureus?

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

    Ceftriaxone is primarily excreted through the urine

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

    The cross-reactivity rate between penicillin and cephalosporins is around 3% to 5%

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

    Carbapenems have the same mechanism of action as penicillins

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

    Carbapenems have a narrow spectrum of activity

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

    Cephalosporins have a higher rate of allergic cross-sensitivity with 1st generation cephalosporins than with penicillin

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

    Penicillins are primarily excreted through the liver.

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

    Cephalosporins share the same mechanism of action as penicillins.

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

    First-generation cephalosporins act on Gram-positive and some Gram-negative bacteria.

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

    Third-generation cephalosporins like ceftriaxone have the longest half-life.

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

    Ceftaroline is the only beta-lactam active against MRSA.

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

    Cephalosporins are not effective in treating meningitis.

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

    Capillaries in certain tissues act as natural barriers to drug delivery, impacting penetration and concentration of antimicrobial agents

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

    Factors affecting selection of antimicrobial agents include patient factors, safety and efficacy, and cost of therapy

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

    Concentration-dependent killing and time-dependent killing are properties influencing the frequency of dosing

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

    Combinations of antimicrobial drugs have advantages such as synergism, but also disadvantages like risk of antibiotic resistance

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

    Drug resistance can be caused by naturally inherent resistance or acquired resistance through genetic alterations

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

    Altered expression of proteins in drug-resistant organisms cannot lead to drug resistance

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

    Prophylactic use of antibiotics is necessary in all clinical situations to prevent infections.

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

    Penicillins weaken the bacterial cell wall by interfering with the transpeptidation process, leading to cell death.

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

    Resistance to penicillins can occur through β-lactamase production, decreased drug permeability, and altered penicillin-binding proteins.

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

    Natural penicillins like penicillin G and penicillin V have a narrow spectrum and are not facing increasing resistance.

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

    Semisynthetic penicillins such as ampicillin and amoxicillin have extended Gram-negative antimicrobial activity.

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

    Antistaphylococcal penicillins like methicillin and nafcillin are used to treat infections caused by penicillinase-producing staphylococci.

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

    Study Notes

    Cell Wall Inhibitors: Penicillins and Cephalosporins

    • Oral absorption of some penicillins is hindered by stomach acids, with penicillin V showing poor oral bioavailability and amoxicillin being readily absorbed from the GI tract.
    • Penicillins are distributed well throughout the body, but have insufficient penetration of bone, CSF, and the prostate, and no teratogenic effects when crossing the placental barrier.
    • Penicillins are primarily excreted through the kidneys, and nafcillin and oxacillin are metabolized in the liver.
    • Adverse reactions to penicillins include hypersensitivity, diarrhea, nephritis, neurotoxicity, and hematologic toxicities.
    • Cephalosporins share the same mechanism of action as penicillins and face resistance due to the hydrolysis of the beta-lactam ring by beta-lactamases.
    • The antibacterial spectrum of cephalosporins varies across different generations, with first-generation cephalosporins acting on Gram-positive and some Gram-negative bacteria, and showing resistance to staphylococcal penicillinase.
    • Second-generation cephalosporins like cefuroxime sodium have a longer half-life and can cross the blood-brain barrier, with cefoxitin showing greater activity on Gram-negative bacteria.
    • Third-generation cephalosporins like cefotaxime and ceftriaxone are effective in treating meningitis and have good penetration into bone, with ceftriaxone having the longest half-life of all cephalosporins.
    • Fourth-generation cephalosporins like cefepime are active against Pseudomonas aeruginosa and show greater stability against beta-lactamases.
    • Advanced generation cephalosporins like ceftaroline are the only beta-lactams active against MRSA and are used for treating complicated skin infections and community-acquired pneumonia.
    • Cephalosporins can be administered orally or parenterally and distribute well into body fluids, with ceftriaxone and cefotaxime being used for CSF infections and childhood meningitis.
    • Overall, both penicillins and cephalosporins have unique characteristics and varying antibacterial spectra, making them important in the treatment of bacterial infections.

    Principles of Antimicrobial Therapy by Dr. Osama Abusara

    • Capillaries in certain tissues act as natural barriers to drug delivery, impacting penetration and concentration of antimicrobial agents
    • Factors affecting selection of antimicrobial agents include patient factors, safety and efficacy, and cost of therapy
    • Route of drug administration and rational dosing are determined based on pharmacodynamics and pharmacokinetics of antimicrobial agents
    • Concentration-dependent killing and time-dependent killing are properties influencing the frequency of dosing
    • Properties affecting dosing frequency include concentration-dependent killing, time-dependent killing, and postantibiotic effect
    • Chemotherapeutic spectra include narrow-spectrum and extended/broad-spectrum antimicrobial drugs
    • Combinations of antimicrobial drugs have advantages such as synergism, but also disadvantages like risk of antibiotic resistance
    • Drug resistance can be caused by naturally inherent resistance or acquired resistance through genetic alterations
    • Acquired resistance can result from altered expression of proteins, modification of target sites, decreased accumulation, and enzymatic inactivation
    • Altered expression of proteins in drug-resistant organisms can lead to drug resistance
    • Modification of target sites, decreased accumulation, and enzymatic inactivation are mechanisms of acquired resistance
    • Drug resistance can be caused by genetic alterations and altered expression of proteins in drug-resistant organisms

    Cell Wall Inhibitors: Penicillins and Cephalosporins

    • Oral absorption of some penicillins is hindered by stomach acids, with penicillin V showing poor oral bioavailability and amoxicillin being readily absorbed from the GI tract.
    • Penicillins are distributed well throughout the body, but have insufficient penetration of bone, CSF, and the prostate, and no teratogenic effects when crossing the placental barrier.
    • Penicillins are primarily excreted through the kidneys, and nafcillin and oxacillin are metabolized in the liver.
    • Adverse reactions to penicillins include hypersensitivity, diarrhea, nephritis, neurotoxicity, and hematologic toxicities.
    • Cephalosporins share the same mechanism of action as penicillins and face resistance due to the hydrolysis of the beta-lactam ring by beta-lactamases.
    • The antibacterial spectrum of cephalosporins varies across different generations, with first-generation cephalosporins acting on Gram-positive and some Gram-negative bacteria, and showing resistance to staphylococcal penicillinase.
    • Second-generation cephalosporins like cefuroxime sodium have a longer half-life and can cross the blood-brain barrier, with cefoxitin showing greater activity on Gram-negative bacteria.
    • Third-generation cephalosporins like cefotaxime and ceftriaxone are effective in treating meningitis and have good penetration into bone, with ceftriaxone having the longest half-life of all cephalosporins.
    • Fourth-generation cephalosporins like cefepime are active against Pseudomonas aeruginosa and show greater stability against beta-lactamases.
    • Advanced generation cephalosporins like ceftaroline are the only beta-lactams active against MRSA and are used for treating complicated skin infections and community-acquired pneumonia.
    • Cephalosporins can be administered orally or parenterally and distribute well into body fluids, with ceftriaxone and cefotaxime being used for CSF infections and childhood meningitis.
    • Overall, both penicillins and cephalosporins have unique characteristics and varying antibacterial spectra, making them important in the treatment of bacterial infections.

    Principles of Antimicrobial Therapy and Cell Wall Inhibitors

    • Prophylactic use of antibiotics is necessary in certain clinical situations to prevent infections when benefits outweigh potential risks.
    • Cell wall inhibitors are antimicrobial drugs that interfere with bacterial cell wall synthesis.
    • Penicillins, cephalosporins, carbapenems, monobactams, and β-lactam antibiotics are examples of cell wall inhibitors.
    • Penicillins weaken the cell wall by interfering with the transpeptidation process, leading to cell death.
    • Natural penicillins like penicillin G and penicillin V have a broad spectrum but are facing increasing resistance due to β-lactamases production in many bacteria.
    • Semisynthetic penicillins such as ampicillin and amoxicillin have extended Gram-negative antimicrobial activity and are used for respiratory infections.
    • Antistaphylococcal penicillins like methicillin and nafcillin are used to treat infections caused by penicillinase-producing staphylococci.
    • Antipseudomonal penicillins like piperacillin are effective against Pseudomonas aeruginosa when combined with a β-lactamase inhibitor.
    • Resistance to penicillins can occur through β-lactamase production, decreased drug permeability, and altered penicillin-binding proteins.
    • Penicillins can be administered orally or parenterally, with some forms having a long period of absorption.
    • Resistance to penicillins can also occur through decreased permeability to the drug and altered penicillin-binding proteins.
    • Penicillins are administered orally or parenterally, with some forms having a long period of absorption.

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    Description

    Test your knowledge of cell wall inhibitors with this quiz on Penicillins and Cephalosporins. Explore their mechanisms of action, distribution, excretion, adverse reactions, antibacterial spectra, and clinical applications.

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