Researchers have discovered previously unknown genes for antibiotic resistance lurking in the human gut.
A story by Bob Grant in The Scientist
reports that Harvard University researchers found more than 90
undiscovered bacterial genes capable of conferring antibiotic resistance
in the intestinal tracts of two healthy adults. Humans have been
exposed to quantities of antibiotics for decades through medicines and
foods as well as by agricultural use and cleaning products. Morten Sommer, lead author of the study, published in Science, says the newly discovered antibiotic resistance in our internal microbiome is likely to result from that exposure. Sommer, a postdoctoral researcher in the lab of Harvard geneticist George Church, told The Scientist "that could be a problem when the microbiome interacts with disease causing microbes."
and colleagues isolated more than 500 bacterial strains in saliva and
fecal samples from two healthy adults who had not taken antibiotics for
at least a year. They cloned the genes from those strains and exposed
them to 13 different antibiotics to discover which genes conferred
antibiotic resistance. Stuart Levy, A Tufts University microbiologist who is president of the Alliance for the Prudent Use of Antibiotics,
said the study highlights the dangers of pervasive irresponsible
antibiotic use. He said pathogenic bacteria could add antibiotic
resistance to their genes by way of horizontal gene transfer from
harmless bacteria that has the resistance trait.
Sommer and colleagues found nearly half the resistant genes isolated
from the human gut are identical to resistant genes found in pathogenic
microbial strains of E. coli and Salmonella enterica. While that
doesn't prove horizontal gene transfer between beneficial gut bacteria
and pathogens, Sommer said it does show a close evolutionary history.
Sommer has also researched another discovery: bacteria that thrives by eating antibiotics.
quotes Gerry Wright
a chemical biologist and infectious disease researcher at McMaster
University, as saying the gut study shows how little is understood
about microbial ecology and how antibiotics work. If resistance is so
rampant, he asks, what makes antibiotics work at all? Cellular Conflict
at the University of Bath and the University of Exeter in the United
Kingdom have developed a new technique that lets them observe microbial cells in action.
While most studies of infection have been done after the death of the
infected organism, these scientists were able to make a movie of a
bacteria infecting a living host. They also created an extraordinary
film debut: the war between immune cells and hostile bacteria.Will Wood,
research fellow and coauthor of the study
explained that cells behave differently in a Petri dish than they do
in their natural environment, so it is important to be able to examine
how bacteria interact with their host.
You can view the movie at the University of Bath website
, and on the NPR where you can see the August 21 Science Roundup reel on Worms, Snorkels and Cell Battles.
The microbial smack down is the last of the brief segments. But do
watch the first two. They are fascinating, as Ira Flatow's Science
Friday presentations generally are.