1. In vitro pharmacodynamic models for the study of antibiotic activity against bacterial biofilms
Françoise Van Bambeke, PharmD, PhD Pharmacologie cellulaire et moléculaire Louvain Drug Research Institute Université catholique de Louvain, Brussels, Belgium
20/12/2013
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2. Biofilms in human infections
Biofilms are associated to 65a-80b % of human infections and can colonize virtually all organs …
ear
nose throat mouth & teeth eye lung heart
kidney gall bladder pancreas nervous system skin bone *** implanted medical devices
aCDC 1999; bLewis et al, Nat Rev Microbiol. 2007; 5:48-56
20/12/2013
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3. Antibiotics and biofilms in clinical practice
 Treatment failure is not rare…
20/12/2013
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4. PK/PD parameters in biofilms
nutrients & oxygen
catheter, bone, skin, cardiac valve, …
pharmacokinetics
diffusibility through the matrix
access to bacteria
efflux out of bacteria
pharmacodynamics
bacterial responsiveness (metabolic activity of bacteria)
antibiotic expression of activity (local environment [O2, pH, ..])
20/12/2013
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5. Main pathogens in biofilm-related diseases
Römling & Balsalobre; J Intern Med. 2012; 272:541-61
20/12/2013
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6. Quantifying biomass and metabolic activity in biofilms
biofilm mass
crystal violet
resazurin
resorufin
metabolic activity
fluorescein diacetate
fluorescein
Gram(+) bacteria
Gram(-) bacteria
20/12/2013
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7. S. aureus & S. pneumoniae models
Kinetics of biofilm formation
S. aureus
S. pneumoniae
young biofilm
mature biofilm
young biofilm
mature biofilm
20/12/2013
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8. Pharmacodynamic model for antibiotic activity
An example with young biofilm of S. aureus
C « rel. potency »
Emax « efficacy »
Bauer, Siala et al, Antimicrob Ag Chemother. 2013;57:
20/12/2013
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9. S. aureus (MRSA) mature biofilms
more effective and more potent on viability than on matrix
RIF and DAP more efficient at clinically achievable concentrations
Bauer, Siala et al, Antimicrob Ag Chemother. 2013;57:
20/12/2013
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10. S. aureus (MRSA) mature biofilms
live dead
Bauer, Siala et al, Antimicrob Ag Chemother. 2013;57:
20/12/2013
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11. Moxifloxacin and S. pneumoniae biofilms
maximal efficacy  with maturity
Vandevelde et al, Antimicrob Ag Chemother. 2014; in the press
20/12/2013
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12. Moxifloxacin and S. pneumoniae biofilms
relative potency  with maturity
Vandevelde et al, Antimicrob Ag Chemother. 2014; in the press
20/12/2013
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13. Comparison of PD parameters
Bauer, Siala et al, Antimicrob Ag Chemother. 2013;57:
20/12/2013
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14. S. aureus isolates from persistent infections
reference strain
(ATCC33591)
clinical isolate
(2005/104)
20/12/2013
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15. Antibiotic potency against clinical isolates of S. aureus
20/12/2013
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16. Antibiotic potency against clinical isolates of S. aureus
Bodipy-DAP CTC
651 vs daptomycin-bodipy
104 vs daptomycin-bodipy
20/12/2013
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17. Antibiotic potency against clinical isolates of S. aureus
Bodipy-VAN CTC
ATCC25923 vs vancomycin-bodipy
104 vs vancomycin-bodipy
20/12/2013
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18. Anti-biofilm strategies ….
Kostakioti et al. Cold Spring Harb Perspect Med 2013;3:a010306
20/12/2013
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19. PK-related parameters: improving diffusion
20/12/2013
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20. PK-related parameters: improving diffusion
651 Daptomycin-bodipy
Bodipy-DAP CTC
20/12/2013
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21. PK-related parameters: improving diffusion
651 Daptomycin-bodipy
S028 vs daptomycin-bodipy
Bodipy-DAP CTC
20/12/2013
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22. PK-related parameters: improving diffusion
651 Daptomycin-bodipy
651 Daptomycin-bodipy- norspermine
S028 vs daptomycin-bodipy
Bodipy-DAP CTC
20/12/2013
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23. PD-related parameters: pH effect ?
ATCC33591 (MRSA)
basic acidic
Siala et al, Eurobiofilms 2013
20/12/2013
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24. PD-related parameters: pH effect ?
ATCC33591 (MRSA)
2005/104
basic acidic
Siala et al, Eurobiofilms 2013
20/12/2013
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25. PD-related parameters: pH effect ?
ATCC33591 (MRSA)
2005/104
2005/179
basic acidic
Siala et al, Eurobiofilms 2013
20/12/2013
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26. PD-related parameters: pH effect ?
ATCC33591 (MRSA)
2005/104
2003/651
2005/179
basic acidic
Siala et al, Eurobiofilms 2013
20/12/2013
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27. beef infusion solids, casein hydrolysate, starch
P. aeruginosa biofilms
Kinetics of biofilm formation
mucin, DNA, DTPA, casaminoacids, NaCl, KCl, tris base, egg yolk emulsion.
beef infusion solids, casein hydrolysate, starch
20/12/2013
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28. Antibiotics and P. aeruginosa mature biofilms
classes currently used by inhalation in cystic fibrosis patients
aminoglycosides >> polymyxins
20/12/2013
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29. Antibiotics and P. aeruginosa mature biofilms
classes in development for inhalation in cystic fibrosis patients
fluoroquinolones >> -lactams
20/12/2013
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30. Macrolides and biofilms
quorum sensing
Tateda et al, J Infect Chemother. 2007;13:357-67
20/12/2013
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31. Aminoglycosides in combination with macrolides
MHB
ASM
metabolic activity
synergism
biomass
Basseres et al, Pseudomonas meeting 2013
20/12/2013
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32. Conclusions and perspectives
antibiotic efficacy and relative potency globally reduced against biofilms
effect on viability >> effect against biomass in G(+)
Combination of antibiotics with agents acting on QS or matrix may be useful
MICs do not
predict activity
 appropriate models required for screening
mature biofilms much more resistant
to antibiotics
Strain-specific factors affecting PK (drug access) and PD (bacterial responsiveness)
20/12/2013
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33. Acknowledgments Wafi Siala Julia Bauer Nathalie Vandevelde
Yvan Diaz Iglesias
Eugénie Basseres
20/12/2013
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34. Thank you for your attention and ….
Merry Christmas!
20/12/2013
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