Antimicrobial Agents: General Considerations
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Questions and Answers

What is the primary goal of chemoprophylaxis?

  • To stimulate the immune system
  • To promote antibacterial resistance
  • To treat an existing infection
  • To prevent infection or disease development (correct)

    • What is empiric therapy?

  • Therapy based on the clinical presentation of the patient (correct)
  • Therapy based on the results of antibiotic susceptibility testing
  • Therapy based on the type of infection
  • Therapy based on the patient's medical history

    • What is the difference between bactericidal and bacteriostatic antimicrobial agents?

  • Bacteriostatic agents are used for Gram-positive bacteria, while bactericidal agents are used for Gram-negative bacteria
  • Bacteriostatic agents kill bacteria, while bactericidal agents inhibit their growth
  • Bactericidal agents kill bacteria, while bacteriostatic agents inhibit their growth (correct)
  • Bactericidal agents are used for Gram-positive bacteria, while bacteriostatic agents are used for Gram-negative bacteria

    • What is superinfection?

    <p>A secondary infection caused by a different organism</p> Signup and view all the answers

    What is the primary consideration in antimicrobial dosing?

    <p>The type of antimicrobial agent used</p> Signup and view all the answers

    What is the benefit of combination antimicrobial therapy?

    <p>Synergistic effect against the infecting organism</p> Signup and view all the answers

    What is the primary factor affecting the choice of an antimicrobial agent?

    <p>Spectrum of antimicrobial activity</p> Signup and view all the answers

    What is the primary goal of antimicrobial prophylaxis in persons already infected?

    <p>To prevent development of disease</p> Signup and view all the answers

    What is the ideal time to initiate antimicrobial prophylaxis?

    <p>Before the organism enters the body</p> Signup and view all the answers

    What is a situation where antibiotic combination therapy may be used?

    <p>In severe infections where the etiology is not known</p> Signup and view all the answers

    What is an advantage of using antibiotic combination therapy?

    <p>Synergistic effect</p> Signup and view all the answers

    What is a disadvantage of using antibiotic combination therapy?

    <p>Increased toxicity</p> Signup and view all the answers

    What is a factor that affects the choice of antimicrobial agent (AMA)?

    <p>All of the above</p> Signup and view all the answers

    What is an organism-related factor that affects the choice of AMA?

    <p>Resistance to AMA</p> Signup and view all the answers

    What is superinfection?

    <p>A secondary infection that occurs during chemotherapy</p> Signup and view all the answers

    What is a patient factor that affects the choice of AMA?

    <p>All of the above</p> Signup and view all the answers

    What is a disadvantage of using a combination of bactericidal and bacteriostatic antibiotics?

    <p>Decreased antibacterial activity</p> Signup and view all the answers

    Why is combination therapy used in the treatment of tuberculosis (TB) and leprosy?

    <p>To prevent the emergence of resistant organisms</p> Signup and view all the answers

    What is the primary cause of superinfection?

    <p>Alterations in normal microbial flora</p> Signup and view all the answers

    Which of the following organisms is commonly associated with superinfection?

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

    Which antibiotic is commonly associated with Clostridium difficile superinfection?

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

    What is the primary treatment for pseudomembranous enterocolitis?

    <p>Metronidazole and vancomycin</p> Signup and view all the answers

    What increases the incidence of superinfection?

    <p>Broad spectrum of antimicrobial activity</p> Signup and view all the answers

    Which of the following is NOT a factor in determining the duration of antimicrobial therapy?

    <p>Age of the patient</p> Signup and view all the answers

    What is a common cause of failure of antimicrobial therapy?

    <p>Improper selection of drug</p> Signup and view all the answers

    What is NOT a reason for failure of antimicrobial therapy?

    <p>Inadequate supply of antibiotics</p> Signup and view all the answers

    In which of the following conditions is superinfection more common?

    <p>Immunocompromised conditions</p> Signup and view all the answers

    What is an essential characteristic of an ideal chemoprophylactic agent?

    <p>Should achieve plasma concentration above minimum inhibitory concentration (MIC)</p> Signup and view all the answers

    Why is chemoprophylaxis used in patients with heart valve lesions?

    <p>To prevent endocarditis before undergoing surgery</p> Signup and view all the answers

    What is the purpose of antimicrobial drug combination therapy?

    <p>To treat mixed bacterial infections</p> Signup and view all the answers

    What is the advantage of using antimicrobial combinations in intrabdominal infections?

    <p>It is effective against both aerobic and anaerobic organisms</p> Signup and view all the answers

    Why is chemoprophylaxis used in patients with history of rheumatic fever?

    <p>To prevent involvement of heart (carditis) in patients with history of rheumatic fever</p> Signup and view all the answers

    What is the purpose of pre-treating mother with zidovudine during pregnancy?

    <p>To protect the foetus in case of HIV infected pregnant woman</p> Signup and view all the answers

    What is the benefit of using antimicrobial combinations in pulmonary infections?

    <p>It is effective against both aerobic and anaerobic organisms</p> Signup and view all the answers

    Why is chemoprophylaxis used prior to surgical procedures?

    <p>To prevent wound infection after surgery</p> Signup and view all the answers

    What is the characteristic of an ideal chemoprophylactic agent regarding toxicity?

    <p>Should be least toxic</p> Signup and view all the answers

    What is the outcome of the indiscriminate use of antibiotics in human and veterinary medicine?

    <p>The growth of resistant strains</p> Signup and view all the answers

    What is a consequence of bacterial resistance to antibiotics?

    <p>Increase in morbidity and mortality among patients</p> Signup and view all the answers

    What is an example of a multidrug-resistant bacterium?

    <p>Staphylococcus aureus</p> Signup and view all the answers

    How can antibiotic resistance be prevented or reduced?

    <p>By following rational drug therapy and restricting antibiotic use</p> Signup and view all the answers

    What is a mechanism of drug resistance in bacteria?

    <p>Alteration in the target enzyme</p> Signup and view all the answers

    What is the result of inactivation of antibiotics by microbial enzymes?

    <p>Resistance to antibiotics</p> Signup and view all the answers

    What is an example of a mechanism of drug resistance in bacteria?

    <p>Efflux of the drug from the bacterium</p> Signup and view all the answers

    Why is it important to restrict antibiotic combinations?

    <p>To reduce the emergence of resistant strains</p> Signup and view all the answers

    What is the purpose of monitoring resistance patterns in a hospital or community?

    <p>To recommend antibiotics appropriately</p> Signup and view all the answers

    Study Notes

    Antimicrobial Agents

    • Antimicrobial agents (AMA) are used to prevent infection or disease development in infected individuals.
    • Ideal characteristics of a chemoprophylactic agent include: effectiveness, specificity to common pathogens, achieving plasma concentrations above the minimum inhibitory concentration (MIC), low toxicity, and short-duration use.

    Chemoprophylaxis

    • Chemoprophylaxis is the administration of antimicrobial agents to prevent infection or disease development.
    • The ideal time to initiate chemoprophylaxis is before the organism enters the body or before disease signs and symptoms appear.

    Indications for Chemoprophylaxis

    • Prevent endocarditis in patients with heart valve lesions before surgery
    • Prevent carditis in patients with a history of rheumatic fever
    • Prevent infection in patients undergoing organ transplantation
    • Prevent opportunistic infections in immunocompromised patients
    • Prevent wound infection after surgery
    • Prevent infection in patients with burns
    • Prevent tuberculosis in contacts
    • Pre-treat patients undergoing dental extractions who have implanted prosthetic devices
    • Pre-treat HIV-infected pregnant women with zidovudine to protect the fetus

    Antimicrobial Combinations

    • Antimicrobial combinations involve using two or more antimicrobial agents simultaneously to treat certain infections.
    • Advantages of antimicrobial combinations include:
    • Treatment of mixed bacterial infections
    • Increased antibacterial activity
    • Prevention of resistant organism emergence
    • Reduced therapy duration
    • Reduced adverse effects
    • Disadvantages of antimicrobial combinations include:
    • Increased toxicity
    • Increased cost
    • Decreased antibacterial activity
    • Increased risk of superinfection

    Factors Affecting Choice of Antimicrobial Agent

    • Patient factors: age, allergy history, genetic abnormalities, pregnancy, impaired host defense
    • Drug factors: route of administration, spectrum of antimicrobial activity, bactericidal/bacteriostatic properties
    • Organism-related factors: clinical diagnosis, resistance to antimicrobial agents
    • Drug pharmacokinetics and pharmacodynamics

    Superinfection

    • Superinfection is the appearance of a new infection during chemotherapy of another infection.
    • Causes of superinfection include alterations in normal microbial flora, enabling opportunistic organism growth (e.g., Candida albicans and Pseudomonas).
    • Factors contributing to superinfection include:
    • Broad-spectrum antimicrobial agents
    • Prolonged use of antimicrobial agents
    • Immunosuppressed states
    • Treatment of superinfection involves using metronidazole and vancomycin.

    Factors Determining Duration of Antimicrobial Therapy

    • Duration of treatment depends on the infection type, clinical outcome, and laboratory investigations demonstrating organism eradication.

    Failure of Antimicrobial Therapy

    • Failure of antimicrobial therapy can be due to:
    • Improper selection of drug, dose, route, and duration
    • Delay in treatment initiation
    • Failure to take necessary adjuvant measures
    • Treating viral infections with antibiotics
    • Poor host defense

    Bacterial Resistance to Antimicrobial Agents

    • Bacterial resistance to antimicrobial agents can be innate or acquired.
    • Mechanisms of drug resistance include:
    • Altered targets in microbes
    • Inactivation of the drug by microbial enzymes
    • Decreased drug accumulation by the microbe
    • Prevention and reduction of bacterial resistance involves:
    • Rational drug therapy
    • Avoiding indiscriminate use in human and veterinary practice
    • Restricting antimicrobial agent combinations
    • Monitoring resistance patterns and recommending appropriate antimicrobial agents
    • Implementing an antibiotic policy

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