Biomedical Engineering Reference
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Fig. 1
Synergistic antibacterial efficacy of combination treatment with tobramycin and quorum-
sensing inhibitors against
Pseudomonas aeruginosa
in an intraperitoneal foreign-body infection
mouse model. Clearance of implants pre-colonized with wild-type
P. aeruginosa
inserted in the
peritoneal cavity of BALB/c mice treated with either placebo (
open circles
), QSI (
filled triangles
),
tobramycin (TOB) (
open triangles
), or a combination of TOB and QSI (QSI + TOB) (
filled
squares
).
Squares
,
triangles,
and
circles
represent cfu/implant in individual mice and
horizontal
bars
represent the medians. The QSIs depicted are furanone C-30 (
a
), Ajoene (
b
+
d
), and
Horseradish extract (
c
+
e
). Adopted from Christensen et al. (
2012
)
infection model. Significant clearance was found with all tested QSIs (C-30,
Ajoene, and horseradish juice), and the authors stressed the point that the best
application of this treatment was on early initiation (Christensen et al.
2012
) (see
Fig.
1
). The authors speculated that the effect seen was due to a reduction in
extracellular DNA (eDNA). eDNA has been shown to reduce the effect of
aminoglycoside via cation chelation (Mulcahy et al.
2008
; Chiang et al.
2013
),
and the release of eDNA has been shown to be controlled by QS (Allesen-Holm
et al.
2006
). Further, QS controlled virulence factors (e.g., rhamnolipid) are known
to lyse immune cells which leads to release of the host DNA (Jensen et al.
2007
;
Alhede et al.
2009
). The presence of eDNA from both bacteria and host seems to be
suppressed by QSIs and could thus explain the higher susceptibility to tobramycin.
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