Biology Reference
In-Depth Information
plants may avoid the problems associated with antibiotic resistance but may be
disadvantaged by their broad specificity. A bifunctional diaryl heptaniod iso-
lated from
Alpinia officinarum
, displays bactericidal activity against EPEC and
suppresses EPEC LPS-induced inflammation. However, it is predicted that the
antimicrobial function is derived from its ability to interact with the A subunit
of
E. coli
gyrase (
Subramanian et al., 2009
). Hence, the non-specificity of this
potential drug may present some challenges in its use. Alkaloids from
Holar-
rhena antidysenterica
(AHA) seeds are antibacterial and antidiarrheal. AHA
has been shown to inhibit EPEC in both disk diffusion and agar well diffusion
assays, and to inhibit bacterial attachment to host epithelial cells (
Kavitha and
Niranjali, 2009
). In addition, these compounds were shown to reduce EPEC-
induced apoptosis (
Kavitha and Niranjali, 2009
). However, no assessment of
AHA alkaloids on commensal strains has been performed. A novel approach
towards biocontrol and treatment of both EHEC and EPEC was described with
the identification of two coliphages (MVBS and MVSS) that demonstrate speci-
ficity against pathogenic strains of
E. coli
(
Viscardi et al., 2008
). A number
of characteristics are specific to EPEC and related strains; these include auto-
aggregation, intimate attachment and translocation of effector proteins. One
approach targeting the T3SS with a linear polyketide compound inhibits secre-
tion of EspB, EspF, and MAP by EPEC. This study also detailed improved sur-
vival using the
C. rodentium
murine model of EPEC infection (
Kimura et al.,
2011
). Benefiting from the emergent field of miRNA, one study identified three
miRNA that target tight junction proteins and indirectly modulate the junctional
complexes. The levels of these miRNA were altered by the probiotic
E. coli
strain Nissle 1917 to enhance barrier integrity and may potentially be exploited
for drug therapy in the future (
Veltman et al., 2012
).
Other indirect methods of treating EPEC infections include the use of probi-
otic bacterial strains and factors produced by them. Both the whole cells and the
isolated surface-associated proteins (SAP) of
Lactobacillus fermentum
demon-
strate inhibition of enteropathogenic bacterial attachment (
Varma et al., 2010
).
The surface layer adhesive protein (SLAP) of
L. plantarum
also decreases EPEC
adhesion, in addition to up-regulating the expression of TJ proteins (
Liu et al.,
2011
). However, few clinical studies have been performed. One study using
Saccharomyces boulardii
proved this strategy to be of social and economic ben-
efit, demonstrating slight improvement to disease progression. Children treated
with
S. boulardii
and oral rehydration solution displayed a reduction in mean
duration of diarrhea of 1.6 days compared with children who received oral rehy-
dration solution alone (
Htwe et al., 2008
).
Immune response
Whilst volunteer studies have provided some information on the immune
response to EPEC, much of our knowledge has been acquired from the murine
model of A/E infection, which utilizes the murine EPEC homolog
C. rodentium
.
Search WWH ::
Custom Search