2000 ASCB Annual Meeting Press Book - page 10

Probiotics: Enlisting
‘Good’ Microbes to Fight
Drug-Resistant Pathogens
The human gut, or GI tract, teems with hundreds of
species of microbial life. Many of these probiotic or ‘good’
strains of bacteria help us survive and thrive. Lactobacillus,
for example, favorably influences the ‘microflora’ of the
colon and urogenital tract, and protects people against a
number of chronic ailments, including colon cancer and
urinary tract infections. Lactobacillus is also famous for
turning milk into cheese and yogurt.
However, other strains of bacteria pose a serious
threat. In 1998, the World Health Organization estimated
that infectious diseases caused over 13 million deaths per
year. Moreover, we are seeing a global rise in pathogens
such as Staphylococcus aureus that are becoming resistant
to antibiotics. A group of Canadian researchers at the
University of Western Ontario, led by Jeffrey Howard, now
have intriguing evidence that probiotic bacteria such as
Lactobacillus could be used to defend against pathogenic
intruders.
The Canadian researchers placed a small piece of surgi-
cal material under the skin of a rat, which they then infect-
ed with S. aureus. As expected, the wound site became
severely infected within days. However, if the implant and
surgical site were treated with a high dose of living
Lactobacillus (strain RC-14), acute infection was significant-
ly inhibited. Even more remarkable, the lactobacilli did
not have to be alive to achieve these results. Treating the
implant and surgical site with ‘biosurfactant’, a mixture of
factors naturally secreted by strain RC-14, also inhibited S.
aureus infection by 90 percent.
How the RC-14 biosurfactant works is not entirely clear.
However, one key may be the presence of proteins that
specifically bind to extracellular matrix molecules.
Invading pathogens like S. aureus express adhesion pro-
teins that allow them to cling to traumatized tissues and
initiate infection. Howard and colleagues propose that the
RC-14 biosurfactant contains similar molecules that com-
pete with the pathogen for a limited number of binding
sites in the host tissue. Although further study is needed,
anti-infective agents such as the RC-14 biosurfactant may
provide important new ways to outwit drug-resistant
microbes.
40th Annual Meeting
December 9-13, 2000
Moscone Convention Center, San Francisco
5
Contact:
Jeffrey Howard
519-646-6000 x64167
Probiotics: A Novel Source of Anti-Infective
Agents
Authors:
Jeffrey C. Howard
1
,
4
, Bing S. Gan
1
,
2
,
Gregor Reid
3
,
4
,
Departments of Surgery
1
, Pharmacology &
Toxicology
2
, Microbiology and Immunology
3
Hand & Upper Limb Centre
4
, Lawson Health
Research Institute, University of Western
Ontario, 268 Grosvenor, London, ON N6A
4V2, Canada
At The ASCB Meeting
Poster Session Halls A/B/C
P109 - Cell Attachment to the Extracellular
Matrix
Author Presents
Tuesday, December 12, 1:30 PM-3:00 PM
Program # 2035
Board # B308
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