Bacteria in food 'may cause rise in superbugs'

[Pastor Dale Morgan]

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Plagues, Pestilences and Diseases

Bacteria in food 'may cause rise in superbugs'*

By Roger Highfield, Science Editor
Last Updated: 2:19am BST 24/05/2007

Food could be contributing to the rise of antibiotic-resistant
infections caused by superbugs, according to a study released yesterday.

Antibiotic resistance is a global problem with Britain particularly hard
hit as organisms such as Methicillin-resistant Staphylococcus aureus, or
MRSA, become ever less susceptible to drugs.

Harmless and even beneficial bacteria in food may also be carrying genes
that, when ingested, could transmit resistance to disease-causing
bacteria, say researchers.

Tests were carried out on a variety of ready-to-eat food samples
including seafood, meats, dairy, items from delicatessens and fresh
produce purchased from several grocery chain stores. With the exception
of processed cheese and yogurt, bacteria carrying antibiotic resistance
genes were found in many foods.

"The data indicates that food could be an important avenue for
antibiotic-resistant bacterial evolution and dissemination," said Hua
Wang of the Ohio State University, at a meeting of the American Society
for Microbiology in Toronto.

"The role of commensals (bacteria that live in the body that do not
usually cause disease), especially food-borne microbes, in transmitting
resistance genes is becoming a concern to the scientific community," she
said.

Dr Mark Enright of Imperial College London said: "The source of many
important antibiotic resistance genes is unknown. For example, the mecA
gene that makes an MRSA an MRSA has come from an as yet undiscovered
source. It is perfectly plausible that the gut or stomach could be an
important locus where important gene transfer events occur."

The mechanism by which the genes spread is a well understood process
known as horizontal gene transfer, the microbe equivalent of sex, in
which bacteria share genetic information, including genes for antibiotic
resistance. This has already been recognised as an important avenue for
the exchange of antibiotic-resistance genes among pathogens in hospitals.

The human digestive system is home to about 100 trillion bacteria -
around 10 times the number of human cells in the body - and they carry
out useful jobs such as making vitamins, breaking down plant sugars and
helping keep our immune systems well tuned.

Research has also already demonstrated that pathogenic bacteria can swap
genes with various harmless bacteria and even beneficial bacteria,
including those from the food chain.

What concerns scientists is that the size and diversity of the gene pool
in the gut increases the likelihood of gene transfer.

"Once we no longer limit ourselves to food-borne pathogens and look at
commensal bacteria, we will find that the magnitude of
antibiotic-resistant bacterial contamination in the food chain is
tremendous," said Dr Hua.

"While further research is needed to establish the direct correlation
between the antibiotic-resistant microbes from foods and the
antibiotic-resistant population in host ecosystems, it is evident that a
constant supply of antibiotic-resistant bacteria, partnered with
occasional colonisation and horizontal gene transfer, are at least
partially responsible for the increased antibiotic resistance profiles
seen in humans."