pH-mediated potentiation of aminoglycosides kills bacterial persisters and eradicates in vivo biofilms.
BACKGROUND
Limitations in treatment of biofilm-associated bacterial infections are often due to subpopulation of persistent bacteria (persisters) tolerant to high concentrations of antibiotics. Based on the increased aminoglycoside efficiency under alkaline conditions, we studied the combination of gentamicin and the clinically compatible basic amino acid L-arginine against planktonic and biofilm bacteria both in vitro and in vivo.


METHODS
Using Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli bioluminescent strains, we studied the combination of L-arginine and gentamicin against planktonic persisters through time-kill curves of late stationary-phase cultures. In vitro biofilm tolerance towards gentamicin was assessed using PVC 96 well-plates assays. Efficacy of gentamicin as antibiotic lock treatment (ALT) at 5 mg/mL at different pH was evaluated in vivo using a model of totally implantable venous access port (TIVAP) surgically implanted in rats.


RESULTS
We demonstrated that a combination of gentamicin and the clinically compatible basic amino acid L-arginine increases in vitro planktonic and biofilm susceptibility to gentamicin, with 99% mortality amongst clinically relevant pathogens, i.e. S. aureus, E. coli and P. aeruginosa persistent bacteria. Moreover, although gentamicin local treatment alone showed poor efficacy in a clinically relevant in vivo model of catheter-related infection, gentamicin supplemented with L-arginine led to complete, long-lasting eradication of S. aureus and E. coli biofilms, when used locally.


CONCLUSIONS
Given that intravenous administration of L-arginine to human patients is well tolerated, combined use of aminoglycoside and the non-toxic adjuvant L-arginine as catheter lock solution could constitute a new option for the eradication of pathogenic biofilms.
Department of Microbiology, Genetics of Biofilms Unit.
David
D
Lebeaux
Department of Microbiology, Genetics of Biofilms Unit.
Ashwini
A
Chauhan
Department of Microbiology, Genetics of Biofilms Unit.
Sylvie
S
Létoffé
Department of Microbiology, Helicobacter Pathogenesis Unit, Institut Pasteur, Paris, France.
Frédéric
F
Fischer
Department of Microbiology, Helicobacter Pathogenesis Unit, Institut Pasteur, Paris, France.
Hilde
H
de Reuse
Department of Microbiology, Genetics of Biofilms Unit.
Christophe
C
Beloin
Department of Microbiology, Genetics of Biofilms Unit.
Jean-Marc
JM
Ghigo
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001120:Arginine / Q000008:administration & dosage / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D055499:Catheter-Related Infections / Q000188:drug therapy / Q000517:prevention & control; D062905:Central Venous Catheters / Q000009:adverse effects / Q000382:microbiology; D004357:Drug Synergism; D004359:Drug Therapy, Combination; D004926:Escherichia coli / Q000187:drug effects; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000517:prevention & control; D005839:Gentamicins / Q000008:administration & dosage / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D011552:Pseudomonas Infections / Q000188:drug therapy / Q000517:prevention & control; D011550:Pseudomonas aeruginosa / Q000187:drug effects; D051381:Rats; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000517:prevention & control; D013211:Staphylococcus aureus / Q000187:drug effects
D000900:Anti-Bacterial Agents; D005839:Gentamicins; D001120:Arginine
aminoglycoside; biofilm; catheter-related infections; persister; proton motive force