Your microbiota—the trillions of microbes that live in and on your
body—play essential roles in maintaining your health. As they
grow and reproduce, they utilize nutrients that would otherwise go
to pathogens; they excrete vitamins, aid in digestion, and change
the pH of their environment, all of which benefit us. Now, scientists
are on the verge of enhancing the protective role of the microbiota
by giving them genes that code for chemicals that inhibit pathogens
without being deleterious to the normal microbiota or to us.
In one experiment, researchers inserted a gene for an antibody
against a yeast, Candida, into the genome of a benign species of
Streptococcus bacteria—a member of the microbiota. Mice with
candidiasis that received the recombinant Streptococcus recovered
twice as fast as mice that received fluconazole—a standard antifungal
medication. Since Streptococcus is normally in the vagina, it can
reproduce there, maintaining a constant level of protective chemicals
without requiring reinoculation and without harming the mice.
Other researchers have altered strains of Lactobacillus—a common
probiotic—to express cyanovirin, which is a protein that successfully
inhibits HIV. The idea is to colonize the vaginas of women at risk for infection with HIV
with this altered but otherwise
normal member of
the vaginal microbiota. The
modified bacterium would
act as a potent first line of
defense against infection.
Benefits of using microbiota
to deliver antimicrobial
drugs are numerous. Such a drug would be relatively
less expensive to manufacture—bacteria at the site would be
the “factory”—and delivery of the drug would be automatic, not
requiring a prescription to be filled, delivered, or administered
more than once. Further, the concentration of drug at a site could
be maintained without depending on a patient to keep a set
schedule.
Perhaps your future pharmacist will be a microbe that has been
tailored to deliver antimicrobial chemicals precisely to sites of
infection.