Hospital sees bacteria give up

Thursday, June 24, 1999

Scientists view one antibiotic’s comeback as evidence that a germ “sheds its armor.”

By Ron Sylvester

Not feeding antibiotics to disease-causing germs could actually prove to be the bugs’ undoing.
Consider the plight in Springfield of a little character called pseudomonas.

Pseudomonas is an opportunistic infection that can spread via water from sources such as bathtubs, faucets and sponges. It can turn up in hospital patients with compromised immune systems, including infants, the elderly, burn victims and people with cancer.

At St. John’s Regional Health Center, doctors for years used the antibiotic gentamicin as a first line of defense against pseudomonas.

But pseudomonas becomes readily resistant to drugs, and eventually the bacteria learned how to defeat gentamicin.

Drug susceptibility tests performed by the St. John’s microbiology lab showed that by 1990, gentamicin worked against pseudomonas only 31 percent of the time.

“Well, as a result, the doctors decided we’re not going to use gentamicin,” said Dr. Alastair Haddow, infectious disease specialist at St. John’s.

Within four years, the drug’s effectiveness vaulted to 84 percent. It’s now at 89 percent.

“Sure enough, we saw a decrease of resistance to gentamicin,” said Mike Reidle, St. John’s microbiologist.
That decrease came about because bacteria don’t fight what they don’t see.

“If the antibiotic isn’t there, it doesn’t need its coat of armor,” Haddow said. “Over a period of time, the bacterium frequently sheds its armor.”

That could happen with other bugs, too.

“There’s no question that by going back to much simplified regimes, and by using drugs more carefully and more wisely, it’s going to affect the entire health of the community,” Haddow said.

“We could see a reversion of these resistant strains to more simple organisms.”