麻豆传媒

MORE than 1 in 10 British children are carrying superbugs resistant to one or
more antibiotics. The proportion of adult carriers could be even higher.

The superbugs are no immediate threat to those carrying them, but could cause
dangerous infections after an operation, for example. Carriers can also infect
other people.

The finding has serious public-health implications, warns Michael Millar of
Bart鈥檚 and the Royal London School of Medicine, the study鈥檚 author. 鈥淭his may be
just the beginning of something that will take off in a big way. We need
policies to control antibiotic resistance that go across boundaries.鈥�

Marcos Espinal, leader of the World Health Organization鈥檚 surveillance
project on drug-resistant tuberculosis, agrees. 鈥淭hese are very important
findings,鈥� he says.

Superbugs such as MRSA are already a big problem in hospitals, but relatively
little is known about the extent of resistance in the healthy population. To
find out, Millar and his colleagues took various samples from 539 seven and
eight-year-old children in Bristol. He found that 11 per cent of stool samples
contained bacteria such as E. coli that were resistant to chloramphenicol, a
drug rarely given orally to children. Worryingly, 3 per cent of the children
carried bacteria resistant to ceftazidime, an antibiotic reserved for treating
serious conditions such as cystic fibrosis.

The researchers were surprised by how many children were carrying bacteria
resistant to antibiotics they had never been given. Bacteria resistant to a
particular drug should be most common in people given that drug, because this
allows these bugs to thrive while susceptible strains die.

But the researchers found that resistance to drugs such as chloramphenicol
was usually linked to resistance to more commonly used antibiotics, such as
ampicillin, which is often given to children. This implies that the genes that
make the bacteria resistant are found on the same piece of bacterial DNA, and
are passed on together. So giving people ampicillin can encourage bacteria to
acquire and hang on to bits of DNA that make them resistant to other drugs as
well.

Once resistant, bacteria can easily spread from person to person. People
could pick them up from friends, family and pets. They might also get them from
food and agricultural sources (麻豆传媒, 21 April, p 4).

Doctors had thought reducing antibiotic use would curb resistance, because
bacteria would lose resistance genes if they didn鈥檛 need them. But this isn鈥檛
happening. A recent study in The Lancet (vol 357, p 1325) showed that despite a
45-fold reduction in the use of sulphonamide antibiotics between 1991 and 1999,
there was no reduction in the level of resistance. 鈥淵ou can鈥檛 assume that by
reducing the use of an antibiotic the resistance is going to disappear,鈥� says
Lucinda Hall, also at Bart鈥檚 and the Royal London School of Medicine, who led
the study.

Instead, the key is to prevent resistance to antibiotics developing in the
first place. That means using new antibiotics as sparingly as possible, for
example.