Exam #4 - Microbials Flashcards Preview

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Flashcards in Exam #4 - Microbials Deck (32):
1

benefits of narrow spectrum ABX

o Most effective on susceptible organism
o Less disturbance of host flora

2

benefits and consequences of broad spectrum ABX

greater scope of activity for initial empiric coverage

more likely to cause superinfections

3

ABX with activity to MSSA

Dicloxacillin **
Amox/Clav-Augmentin **
PIP-TAZ **
Cephalosporins (all) **
Macrolides
Tetracyclines
Clindamycin
SMX/TMP (Bactrim)

4

ABX with activity to MRSA

Vancomycin **
Tetracyclines **
Clindamycin **
SMX/TMP (Bactrim)

Note: possibly 5th Gen cephalosporins

5

ABX that treat Gonorrhea (gram - cocci)

Ceftriaxone (3rd Gen) **
Macrolides
Tetracyclines

6

ABX that treat pseudomonas (gram - rod with tough outer membrane)

PIP-TAZ **
Ceftazidime (3rd Gen) **
Aminoglycosides **
Cipro (uFQ) **
Levo (u+rFQ) **

7

ABX that treat C. Diff (+ anaerobe)

Vancomycin ** (severe)
Metronidazole **

8

ABX that treat B Fragilis (- anaerobe)

Amox/Clav (Augmentin)
PIP-TAZ **
Clindamycin **
Metronidazole **

9

ABX that treat chlamydia (atypical)

Macrolides **
Tetracyclines **
FQs (all) **
SMX/TMP (Bactrim)

10

ABX that treat mycoplasma (atypical)

Macrolides **
Tetracyclines **
FQs (all) **

11

3 determinants of bactericidal vs. bacteriostatic

mechanism of action (target)
concentration in vivo
specific micro-organism

12

targets for antimicrobials

- Inhibition of synthesis/damage to cell wall
- Inhibition of synthesis/damage to cell membrane
- Inhibition/modification of protein synthesis
- Modification of synthesis/metabolism of nucleic acids
- Modification of intermediary metabolism (folate metabolism)

13

bactericidal mechanisms (organisms killed)

o Inhibition of cell wall synthesis
o Disruption of cell membrane function
o Interference with DNA function or synthesis

14

bacteriostatic mechanisms (organisms prevented from growing)

o Inhibition of protein synthesis (exception: aminoglycosides (AGs → -cidal)
o Inhibition of intermediary metabolic pathways (unless combo, TMP/SMX --> -cidal)

15

advantages of bactericidal agents

• Preferred in severe infections
• Act more quickly and action is often irreversible
• Compensate for pts with impaired host defense
• Required for treatment of infections in locations that are not accessible to host immune system responses (e.g., endocarditic vegetations and cerebrospinal fluid / CNS)

16

pharmacodynamics of antimicrobial therapy

ensures that the ABX has antimicrobial activity against the specific infectious organisms

17

pharmacokinetics of antimicrobial therapy

ensures that a sufficient concentration gets to the site of infection and remains active for a sufficient duration
- absorption, distribution, and metabolism / elimination

18

ABX that readily enter CNS

Cephalosporins (3rd/4th): best for use
TMP/SMX (Bactrim)
Metronidazole (DNA inhibitors)
Rifampin (anti-TB)

19

ABX to avoid in pregnancy (cross placenta)

Tetracyclines --> bone/tooth development
Aminoglycosides --> 8th nerve/renal tox
Fluoroquinolones: black box for arthralgia / tendon rupture
Nitrofurantoin: no 3rd trimester (hemolytic anemia)
Metronidazole: no 1st trimester
TMP/SMX → kernicterus

20

selective distribution: beneficial accumulations

Clindamycin into bone (osteomyelitis)

Macrolides into pulmonary cells (URI / pneumonia)

Tetracyclines into gingival crevicular fluid and sebum (periodontitis and acne)

Nitrofurantoin rapid excretion into urine (beneficial in UTIs)

21

selective distribution: toxic accumulations

Amino glycoside: bind to cells of inner ear (ototoxicity) and renal brush border (nephrotoxicity)

Tetracyclines: bind to Ca++ in developing bone and teeth

22

inducers of hepatic metabolism (CYP450) = hepatotoxicity

• Rifampin: anti-tubercular agent
• Isoniazid: anti-tubercular agent

23

inhibitors of hepatic metabolism (CYP450)

Fluoroquinolones (especially Ciprofloxacin)

Erythromycin and Clarithromycin (NOT Azithromycin)

Metronidazole → antabuse rx due to inhibition of liver metabolism of EtOH

Also, anti-fungal agents that inhibit CYP450 drug metabolism (not part of DQ-CRIMES)
• Itraconazole (Triazole)
• Ketaconazole (Imidazole)
• Terbinafine

24

what anti-microbial agent can stain your contacts orange and make you have orange secretions (urine, sweat, tears)

rifampin (anti-TB)

25

which ABX exhibit post-ABX effects (ABXs that continue to kill or inhibit growth of bacteria for several hours after the concentration of the drug falls below the MIC)

aminoglycosides

fluoroquinolones

26

which ABX exhibits concentration-dependent killing

aminoglycosides

27

why is multi-drug regime essential in treatment of TB

3 subpopulations exist and resistance to any one drug is very high
- no practical way to quantitate % in given patient
• Intracellular in caseating granulomas
• Extracellular and rapidly dividing
• Intracellular in macrophages

28

candida - anti-fungal treatment

oropharyngeal/esophageal candidiasis and systemic vulvovaginal candidiasis: fluconazole (Diflucan)

oral and vaginal candidiasis: clotrimazole (Lotrimin) and Miconazole (Monistat): topical only

superficial: Nystatin (topical only)

29

superficial dermatophytosis (athlete's foot, jock itch, etc.) and onychomycosis (nail infection) - anti-fungal treatment

systemic therapy for either: itraconazole

once daily oral dose (nail infections): PO Terbinafine

topical for dermatophytosis: Terbinafine

30

life-threatening systemic fungal infections - anti-fungal treatment

amphotericin B (IV or topical only)
- very toxic: nephrotoxicity and anemia
- pre-dose with Benadryl, Ibuprofen, Prednisone

31

invasive aspergillosis

amphotericin B (1st choice)
itraconazole
caspofungin (if refractory to either of above)

32

recommended premedication before Amphotericin B treatment (very toxic!)

diphenhydramine (Benadryl)
ibuprofen
prednisone