ҹ1000

Deadly touch

Skin is the perfect breeding ground for rampaging superbugs

HOSPITAL superbugs thrive on sweat, say Danish researchers. They have found
that some antibiotics “leak” out of the body in sweat, and believe that bacteria
on patients’ skin become resistant through unrelenting exposure to the seeping
drugs. Simple physical contact would then be enough to pass on the bugs.

Niels Høiby and his colleagues at the University of Copenhagen suggest that
doctors might have to limit the use of the most leaky antibiotics. These include
two widely used beta-lactam antibiotics called cephalosporins.

Høiby and five other volunteers took five common antibiotics in turn. He then
measured how much came out in sweat samples from the armpit and forearm. Sweat
from all six people contained ceftazidime and ceftriaxone. Both are
“third-generation” cephalosporins, widely used for treating chest and urinary
tract infections.

Høiby says that we all sweat continuously, although most of the time sweat
evaporates without our noticing. So populations of bacteria on the skin would be
reduced to those that survive exposure to the drug. “I think the risk is highest
in the armpit and the perineum around the anus, as this is where you sweat most.
We know that these are areas where we see resistant Staphylococcus
bacteria,” he says.

Antibiotic resistance coincided with the advent of leaky antibiotics, says
H iby. “We’ve found a mechanism which explains why we’ve seen the development of
multiresistant staphylococci in the 1980s and 1990s,” he says. “That’s when
these third-generation cephalosporins were introduced.” Høiby says the only
solution might be to use these drugs much more sparingly in future. “When we
know which antibiotics disturb the flora of the skin, we can choose antibiotics
that don’t,” he says.

In previous experiments on himself with ciprofloxacin, a broad-spectrum
fluoroquinolone antibiotic used to treat urinary tract infections, Høiby showed
that bacteria on the skin developed resistance only three days after he
completed a week-long course of treatment. Høiby says he’s now tested 25
antibiotics, and plans to test the theory further in patients who receive the
drugs as part of their treatment.

“It’s an important observation, no doubt about that,” says Alan Johnson, an
antibiotic resistance expert at Britain’s Public ҹ1000 Laboratory Service in
Colindale, London. He agrees that the phenomenon could be an important
unforeseen factor in the spread of hospital infections. But he warns against
hastily withdrawing the drugs, some of which are vital for intravenous treatment
of serious diseases.

  • Source:
    Antimicrobial Agents and Chemotherapy (vol 44, p 2855)