ID and Antimicrobial Therapy Flashcards Preview

Fall2014 - Pharm ID/Pulm > ID and Antimicrobial Therapy > Flashcards

Flashcards in ID and Antimicrobial Therapy Deck (38):
1

What might cause a falsely positive fever?

-drug induced: beta lactam abx (penicillins and cephalosporins) or phenytoin

2

What might result in a falsely negative fever?

-aspirin (ASA)
-acetaminophen (APAP)
-NSAIDs
-corticosteroids

3

What is the normal WBC count?

4500-10000 cells/mm^3

4

What is a left shift?

increased WBC with increase in immature neutrophils (bands)

5

How high might WBC be in a bacterial infection?

30000-40000

6

What do immature bands indicate?

increased bone marrow response to infection

7

What do bands > 10% indicate?

bacterial infection

8

ESR

erythrocyte sedimentation rate
(how far RBCs fall in 1 hour)

9

CRP Levels

0.5-1.0 normal
1.0-1.5 moderate inflammation
> 10 suggests infection

10

Procalcitonin

-biomarker that becomes elevated during bacterial infection
-appears to reflect the severity of infection

11

Gram Stain

-crystal violet stain
-add iodine to enhance stain
-alcohol decolorization
-safranin counterstain

12

What is the difference between gram + and gram - bacteria? How do they stain?

-Gram +: thicker cell wall w/ lots of peptidoglycans; purple

-Gram -: thinner cell wall w/ more lipids, fewer peptidoglycans; pink

13

What bacteria stain with acid-fast staining?

mycobacteria, nocardia

14

What are gram stains routinely performed for (eg what types of infections)?

-CSF for meningitis
-urethral smears for STIs
-abscesses or effusions

15

What is the gold standard for diagnosis and treatment of infections?

cultures

16

Antibody and Antigen Detection

-detection and quantification of antibodies directed against a specific pathogen or its components

17

How can anthrax be diagnosed?

PCR

18

Bactericidal

kills sensitive organisms

19

Bacteriostatic

inhibits bacteria growth but does not kill them

20

What is meant by antimicrobial spectrum of activity?

-narrow: kills small # of narrow range of bacteria
-broad: kills many different kinds of bacteria

21

Minimum Inhibitory Concentration

MIC = the lowest antimicrobial concentration that prevents visible growth of an organism after 24 hours of incubation

22

Susceptibility Testing: MAcrodilution Method

-mix pathogen w/ serial dilutions of antibiotic
-incubate over night
-1st clear tube is MIC

23

Susceptibility Testing: MIcrodilution Method

-serial dilutions of several abx in a 96 well plate

24

Susceptibility Testing: Kirby Bauer Disk Method

-paper discs impregnated with various abxs are placed on agar plate seeded with lawn of bacteria
-zone of growth inhibition around the discs is related to MIC (sensitivity and susceptibility)

25

Susceptibility Testing: The E-test

-strip with various concentrations of abx placed on agar plate of bacteria
-as [abx] increases, bacterial growth is affected more

26

Susceptibility Testing: What are the automated methods?

-Vitek system: photometric assessment of turbidity
-Microscan system: fluorogenic substrate hydrolysis as indicator of bacterial growth

27

How are the peak serum concentration and MIC related?

peak serum concentration should be 2-4x MIC for the bacteria to be susceptible

28

What factors increase abx resistance?

-overuse
-low dose, inadequate levels
-prolonged exposure
-inappropriate abx
-day care
-abx in animal feed??

29

What must an antibiotic be able to do in order to have antimicrobial activity?

-penetrate cell
-reach target: cell wall, nucleus, ribosomes
-kill organism

30

Name 4 methods of resistance.

-efflux pump
-decreased permeability
-drug inactivation
-altered target (eg penicillin binding proteins on cell surface)

31

Decreased Permeability

-gram - have porin channels in cell walls that abx use to enter
-bacteria will close or reduce # of porin channels

32

Efflux Pump

-the club bouncer
-abx gets in, but is identified as shady impostor and gets kicked out

33

Drug Inactivation

abx gets into cell, but is inactivated (usually by enzymes like beta-lactamase)

34

Altered Target

-example: macrolide abx gets in and normally works at ribosome; bacteria methylates its ribosomes to block abx activity
-example: bacteria alters penicillin binding proteins to block action of penicillins and cephalosporins

35

Concentration Dependent Killing Rate

-more bacteria killed at higher [ ] of abx
-some aminoglycosides and FQs exhibit CDKR
-penicillins and other beta-lactams usually do not show CDKR

36

Post-antibiotic Effect

-persistent effect of an abx on bacterial growth after the abx is removed from a bacterial culture
-most bactericidal abx exhibit PAE against susceptible pathogens

37

What is an advantage of post-antibiotic effect?

allows for less frequent dosing

38

What therapeutic steps are taken when treating infectious disease?

-empiric therapy: based on likely pathogen for site of infection, patient hx
-refine therapy based on culture and sensitivity results
-monitor therapeutic response and adjust therapy as needed