4 - Intro to Antimicrobial.txt

  1. Reminder: You may have to scroll up on some of the answers! And please let me know if you find any mistakes!
    Thank you!
  2. Antimicrobial subgroups:
    Chemotherapeutic agents: Chemically synthesized

    Antibiotics: Drugs that act against bacteria, made from natural substances PRODUCED BY MICROORGANISMS (usually fungus).

    Semisynthetic antibiotics: Molecular version produced by the microbe, THEN MODIFIED.
  3. T/F: ALL antibiotics have ADRs.
  4. T/F: Clinicians often avoid antibiotics due to ADRs.

    They rarely avoid due to ADRs. Just have to monitor pts more closely.

    Unless specifically mentioned, NEVER avoid recommending the BEST or MORE EFFECTIVE antibiotic option based on potential ADR…COMMON or RARE!!!

    Only avoid due to CONTRAINDICATIONS!!!
  5. PharmacoKINETICS (PK)
    Time course of antimicrobial concentration in the body.
  6. PharmacoDYNAMICS (PD)
    Relationship between antibiotic concentration and the antimicrobial effect.
  7. TRADITIONALLY dosing regimens have been determined by PK parameters only, but (blank)
    • PD plays an equal, if not MORE IMPORTANT, role.
    • - Can influence pt response to therapy (i.e. success or failure)
    • - Can prevent pathogens from becoming resistant.
  8. If killing activity is CONCENTRATION-dependent, what are the parameters and goals of therapy?
    PK/PD parameters: Peak/MIC

    Goal of therapy: Maximize CONCENTRATION
  9. If killing activity is TIME-dependent, what are the parameters and goals of therapy?
    PK/PD parameters: Time > MIC

    Goal of therapy: Maximize DURATION of exposure.
  10. If killing activity is BOTH time and concentration-dependent (hybrid), what are the parameters and goals of therapy?
    PK/PD parameters: AUC/MIC

    Goal of therapy: Maximize AMOUNT of drug.
  11. Antibiotic prescribing methodology (Community):
    • 1. Determine viral vs bacterial
    • - Onset of SX (acute vs chronic)
    • - Course oc illness
    • - Local epidemiology

    2. Write Rx for 1 of the PO antibiotics commonly used.

    3. Hope it works.
  12. Antibiotic prescribing methodology (Hospital):
    • Day 1:
    • Infection suspected
    • (Gram stain, culture and sensitivity)
    • Start empiric antibiotics
    • (Evaluate pt for clinical response to abx therapy)

    • Day 3:
    • De-escalation: Change abx based on culture results
    • - If improving: D/C abx AFTER RESOLUTION of infection based on clinical SX and/or follow-up negative cultures.
    • - If NOT improving: Evaluate abx choice. Look for superinfection, abscess, non-infectious cause.
  13. Empiric therapy: Hospital-associated vs Community-associated:
    • HA:
    • - Must cover MDR-P (Multi-Drug Resistant Pathogens)
    • - MRSA
    • - Pseudomonas aeruginosa

    • CA:
    • - More dependent on SITE if infection
    • - i.e. UTI vs pneumonia
    • - "Fewer" and less resistant pathogens in community setting.
  14. What do you do if culture results came back NEGATIVE?
    • 1. Re-evaluate infectious or non-infectious cause
    • - Allergic reactions can look like infectious diseases (rash, fever, elevated white count)
    • - If NON-infectious reason found, STOP abx!


    • 2. Stop abx; BOLD DECISION!!!
    • - If pt improves clinically (NOT infectious)
    • - If pt stays the same clinically (NOT infectious)
    • - If pt declines clinically (MAYBE infectious)


    3. Continue therapy
  15. What do you do if culture is negative and pt is not improving at 48 - 72 hour window, and you're fairly sure infection is present?
    • Options:
    • - Change abx
    • - Change abx dose and/or frequency (MAXIMIZE PD parameters)
    • - Look for undrained focuses of infection
    • - Abscess
    • - Foreign body (prosthetic joint, catheter)
  16. Penicillin is often referred to as (blank 1) but it's actually quite (blank 2). But it's NOT often used due to (blank 3)
    1. narrow spectrum

    2. quite broad, because it kills GN, GP, spirochetes, anaerobes, etc

    3. high rates of resistance.
  17. Empiric therapy is base on:
    • Host factors:
    • - Site of infection
    • - Renal function
    • - age
    • - pregnancy, etc
    • - Where pt acquired infection (ICU, nursing home, school)

    • Institutional/community resistance patterns:
    • - Ex: High rates of FQ resistance to e. coli
    • - Ex: Outbreak of CA-MRSA in community
    • - Determined by antibiogram: The result of a lab testing for the sensitivity of an isolated bacteria to different abx. It is by definition an "in vitro-sensitivity."
  18. Shaded box in antibiogram indicates (blank)
    organism/antimicrobial combo not tested routinely
  19. Numbers on the antibiogram refers to:
    The % of susceptibility of efficacy
  20. De-escalation is based on:
    • Host factors:
    • - Site of infection
    • - Renal function
    • - Age
    • - Pregnancy
    • - Allergies, etc

    • Culture and sensitivity results:
    • - Ex: Pan-sensitive Proteus sp. in the urine.
    • -De-escalate from cefepime to cefazolin, cipro, or TMP/SMX
  21. De-escalation Examples:
    • 1. Switching from an anti-pseudo t or anti-MRSA abs to one that does not have pseudo or MRSA activity.
    • - Ex: cefepime to cefazolin
    • - Ex: meropemem to ceftriaxone
    • - Ex: vancomycin to nafcillin
    • 2. Switching from IV to PO
    • 3. Decreasing the # of abx
    • 4. Stopping abx
Card Set
4 - Intro to Antimicrobial.txt
Forgive me for any typos. I was typing like a mad man! Use at your own risk! Don't blame me if you don't catch my mistakes! :P