Rational antimicrobial therapy

Question 1

Grampositiveaerobicbacteria

Answer 1

Strep

Staphaureus

Question 2

Gramnegativeaerobicbacteria

Answer 2

E coli

Helicobacter

Question 3

Anaerobicbacteria

Answer 3

Clostridiumperfringens

Question 4

Atypical bacterial species

Answer 4

Rickettsia
Mycoplasma
Chlamydia
Borrelia
Bartonella
Mycobacterium

Question 5

Bacterialresistance

Answer 5

some bacteria have resistant genes

use of antimicrobials creates a selective pressure

Question 6

Whentouseantimicrobials?

Answer 6

definitivelydiagnosed/likelydiagnosis
diseaselikelytoprogresswithoutmedicaltherapy
Wouldcausecriticalillnessifitwasnotrecognisedortreated

Question 7

factors to consider when choosing antimicrobial

Answer 7

likelybacteriainvolved
likelysusceptibility
cultureneeded/feasible?
pharmacokineticfactorsyouneedtoconsider?
potentialsideeffects+incrriskinyourpatient?
clientcomplianceissues?
costconsiderations?

Question 8

Factors affecting the success of antibacterial therapy

Answer 8

Whatbugslivewhere?
Bacterialsusceptibility
Distributiontothesiteofinfection(pharmacokineticphase)
Localconditions(pharmacodynamic phase)
Clientcompliance

Question 9

Bacterialsusceptibility

Answer 9

if not susceptible in vitro - resistant in vivo
if susceptible in vitro - may work in vivo
resistancemaybeovercomebyhighconcsachievedinurineortopicalapplication

Question 10

MIC

Answer 10

MIC=Minimuminhibitoryconcentration
Lowestconcofdrugthatwillinhibitbacterialgrowth
MIC90 usualmeasureusedtodeterminetherapeuticdose - Concthatwillinhibit90%ofisolates

Question 11

Inhibitionofcellwallsynthesis

Answer 11

penicillins
cephalosporins
bacitracin

Question 12

Inhibition of cell membrane function

Answer 12

polymyxins
amphotericinB
imidazoles
nystatin

Question 13

Inhibition of protein synthesis

Answer 13

chloramphenicol
macrolides
lincosamides
tetracyclines
aminoglycosides

Question 14

Inhibition of nucleic acid synthesis

Answer 14

sulphonamides
trimethoprim
quinolones
metronidazole
rifampin

Question 15

Bacteriostatic - define

Answer 15

Tempinhibitthegrowthoforganisms
Effectisreversibleoncethedrugisremoved
drugconc atthesiteoftheinfectionshouldstayabovetheMICthroughoutdosinginterval
Manybacteriostaticdrugscanbebactericidalifdrugexposureissufficientlyhighorprolonged

Question 16

Bacteriostatic drugs

Answer 16

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

Question 17

Bactericidal - define

Answer 17

Underidealconditionskillbacteria
preferredwhenconcernabout siteofinfectionorhostdefence
gram+veinfections - susceptibility ofbacteriaandabilityto
penetratetissuemoreimportantconsiderations

Question 18

Bactericidal drugs

Answer 18

Penicillins
Cephalosporins
Aminoglycosides
Fluoroquinolones
Potentiatedsulphonamides(TMPS)
Metronidazole

Question 19

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

Answer 19

Bacterianeedtobemultiplyingfordrugstobeeffective

Question 20

concentration dependant drugs

Answer 20

Aminoglycosides
Fluoroquinolones
Metronidazole
Peakconcentrationachievedorareaunderthecurvepredictstherapeuticsuccess
can be given with bacteriostatic drugs

Question 21

drugs v. bad against gram +ve aerobes

Answer 21

Aminoglycosides

Metronidazole

Question 22

drugs v. bad against gram -ve aerobes

Answer 22

Metronidazole
Penicillin G
Lincosamides/Macrolides

Question 23

drugs v.bad against obligate aerobes

Answer 23

Fluoroquinolones

Aminoglycosides

Question 24

drugs v.bad against penicillinase producing staph

Answer 24

Penicillin G
Aminopenicillins
Metronidazole

Question 25

drugs v. good against gram +ve aerobes

Answer 25

``` Penicillin G Aminopenicillins Lincosamides/ Macrolides Tetracyclines ```

Question 26

drugs v. good against gram -ve aerobes

Answer 26

Fluoroquinolones Aminoglycosides Ticarcillin-clavulanate Cephalosporins

Question 27

drugs v.good against obligate aerobes

Answer 27

``` Penicillin G Amoxy-clav Clindamycin Metronidazole Chloramphenicol Rifampin ```

Question 28

drugs v.good against penicillinase producing staph

Answer 28

``` Amoxy-clav Cephalosporins Cloxacillin Fluoroquinolones Rifampin ```

Question 29

drug most good but leaves some important gram +ve aerobes

Answer 29

Fluoroquinolones

Question 30

drug most good but leaves some important penicillinase producing staph

Answer 30

Clindamycin

Question 31

drug most good but leaves some important gram -ve aerobes

Answer 31

Amoxy-clav

Question 32

cephalosporins, cefovicin and amoxycillin

Answer 32

50/50 susceptible/resistant - obligate anaerobes + -ve aerobes

Question 33

TMPS

Answer 33

50/50 susceptible/resistant all quadrants

Question 34

Tetracyclines 

Answer 34

50/50 susceptible/resistant all quadrants except gram positive  aerobes

Question 35

Difficult to access areas

Answer 35

``` Brain Eye Prostate Bronchus Mammary gland Intracellular Poorly vascularised tissues - Bone fragments, Heart valves ```

Question 36

Intracellular bacteria

Answer 36

``` Bartonella  Brucella Chlamydophila Mycobacterium Rickettsia Staphylococcus ```

Question 37

poor penetration

Answer 37

``` Penicillins Cephalosporins Beta lactamase inhibitors Polymixins Aminoglycosides ```

Question 38

good penetration

Answer 38

``` Sulphonamides Trimethoprim Lincosamides Macrolides Tetracycline ```

Question 39

great penetration

Answer 39

``` Chloramphenicol Fluoroquinolones Lipophilic  tetracyclines minocycline doxycycline Metronidazole Rifampin ```

Question 40

Environmental conditions - Foreign material 

Answer 40

phagocytes degranulate to try to destroy the foreign material inefficient in killing bacterial pathogens can protect bacteria from antibacterial drugs and phagocytosis - bacteria can form a biofilm

Question 41

Penicillin activity reduced in presence of 

Answer 41

haemoglobin

Question 42

Post operative infection risk factors

Answer 42

Clinical status of patient - Incr risk for shocked/emaciated patients Nature of surgery - Incr risk for emergency procedures Use of implants Experience of surgeon duration of operation Administering propofol - 3.8x more at risk Clipping - before induction 3x more likely poor BCS concurrent endocrinopathies

Question 43

when to use prophylactic antimicrobials

Answer 43

non-clean surgery dental procedures?  patients with leukopenia (viral, drug induced) orthopaedic and major abdominal and thoracic surgery surgical time > 90 mins consequences of infection would be disastrous

Question 44

Antibiotics can not compensate for

Answer 44

gross contamination Local tissue trauma Compromised patient health

Question 45

Surgical prophylaxis ‐ timing

Answer 45

Administer before procedure  drug must be present in the wound at the time of bacterial contamination LA formulation of amoxycillin takes 12 hours to reach therapeutic concs

Question 46

situations when antimicrobials are inappropriate

Answer 46

Dogs presenting for vomiting d/t acute gastritis Young cats with signs of LUT disease Blood in faeces Routine surgery