Rational antimicrobial therapy Flashcards Preview

Vet - notes > Rational antimicrobial therapy > Flashcards

Flashcards in Rational antimicrobial therapy Deck (46)
Loading flashcards...
1

Gram positive aerobic bacteria

Strep
Staph aureus

2

Gram negative aerobic bacteria

E coli
Helicobacter

3

Anaerobic bacteria 

Clostridium perfringens

4

Atypical bacterial species

Rickettsia
Mycoplasma
Chlamydia
Borrelia
Bartonella
Mycobacterium

5

Bacterial resistance

some bacteria have resistant genes
use of antimicrobials creates a selective pressure

6

When to use antimicrobials?

definitively diagnosed/likely diagnosis
disease likely to progress without medical therapy 
Would cause critical illness if it was not recognised or treated 

7

factors to consider when choosing antimicrobial

likely bacteria involved
likely susceptibility
culture needed/feasible?
pharmacokinetic factors you need to consider?
potential side effects + incr risk in your patient?
client compliance issues?
cost considerations?

8

Factors affecting the success of antibacterial therapy

What bugs live where?
Bacterial susceptibility
Distribution to the site of infection (pharmacokinetic phase)
Local conditions (pharmacodynamic phase)
Client compliance 

9

Bacterial susceptibility

if not susceptible in vitro - resistant in vivo
if susceptible in vitro - may work in vivo
resistance may be overcome by high concs achieved in urine or topical application 

10

MIC

MIC = Minimum inhibitory concentration
Lowest conc of drug that will inhibit bacterial growth
MIC90 usual measure used to determine therapeutic dose - Conc that will inhibit 90% of isolates

11

Inhibition of cell wall synthesis 

penicillins
cephalosporins
bacitracin

12

Inhibition of cell membrane function

polymyxins
amphotericin B
imidazoles
nystatin

13

Inhibition of protein synthesis

chloramphenicol
macrolides
lincosamides
tetracyclines
aminoglycosides

14

Inhibition of nucleic acid synthesis

sulphonamides
trimethoprim
quinolones
metronidazole
rifampin

15

Bacteriostatic - define

Temp inhibit the growth of organisms
Effect is reversible once the drug is removed
drug conc at the site of the infection should stay above the MIC throughout dosing interval
Many bacteriostatic drugs can be bactericidal if drug exposure is sufficiently high or prolonged

16

Bacteriostatic drugs

Chloramphenicol
Lincosamides
Macrolides
Tetracyclines
Non-potentiated sulphonamides
(mostly inhibit protein synthesis)

17

Bactericidal - define

Under ideal conditions kill bacteria
preferred when concern about site of infection or host defence
gram +ve infections - susceptibility of bacteria and ability to 
penetrate tissue more important considerations

18

Bactericidal drugs

Penicillins
Cephalosporins
Aminoglycosides
Fluoroquinolones
Potentiated sulphonamides (TMPS)
Metronidazole

19

why not to give Penicillins, Cephalosporins + TMPS with bacteriostatic drugs

Bacteria need to be multiplying for drugs to be effective

20

concentration dependant drugs

Aminoglycosides
Fluoroquinolones
Metronidazole
Peak concentration achieved or area under the curve predicts therapeutic success
can be given with bacteriostatic drugs

21

drugs v. bad against gram +ve aerobes

Aminoglycosides
Metronidazole

22

drugs v. bad against gram -ve aerobes

Metronidazole
Penicillin G
Lincosamides/Macrolides

23

drugs v.bad against obligate aerobes

Fluoroquinolones
Aminoglycosides

24

drugs v.bad against penicillinase producing staph

Penicillin G
Aminopenicillins
Metronidazole

25

drugs v. good against gram +ve aerobes

Penicillin G
Aminopenicillins
Lincosamides/
Macrolides
Tetracyclines

26

drugs v. good against gram -ve aerobes

Fluoroquinolones
Aminoglycosides
Ticarcillin-clavulanate
Cephalosporins

27

drugs v.good against obligate aerobes

Penicillin G
Amoxy-clav
Clindamycin
Metronidazole
Chloramphenicol
Rifampin

28

drugs v.good against penicillinase producing staph

Amoxy-clav
Cephalosporins
Cloxacillin
Fluoroquinolones
Rifampin

29

drug most good but leaves some important gram +ve aerobes

Fluoroquinolones

30

drug most good but leaves some important penicillinase producing staph

Clindamycin