Durham doctor recognized for groundbreaking malaria research

OSHAWA -- Warnings that increased use of antibiotics can cause bacteria to become resistant are nothing new.

But what Durham resident Dr. Michael Silverman discovered about antibiotic resistance while working in the rainforests of Guyana, is.

From 2002 to 2005, the doctor from Lakeridge Health Oshawa and Rouge Valley Ajax was part of a health care team that travelled to remote parts of Guyana to do humanitarian medical work.

While there, they decided it would be interesting to test Amer-Indian villagers living just outside the rainforest, to see if they showed any signs of resistance to a family of antibiotics called quinolones -- especially because they had never been given any.

"We always look at places that use a lot of antibiotics, and find resistance," Dr. Silverman said. "I thought, why not look at a place where they have no antibiotics? It seemed like a unique population to look at."â?¨ The results left the team stunned.

More than 500 villagers were tested for resistance to ciprofloxacin, one of the world's most commonly used antibiotics in the quinolone family.

Researchers found a resistance rate of 4.8 per cent, compared with a 2003 study that said the rate in American intensive care units -- where quinolones are widely used -- was four per cent.

"They are some of the highest rates of resistance to quinolones in the world, yet they don't have antibiotics there," Dr. Silverman said.

The team quickly put two and two together, realizing the villagers had been taking large amounts of malaria tablets containing chloroquine, which has a chemical make-up similar to quinolones.

They theorized that the malaria tablets were responsible for creating the antibiotic resistance, and the results of the study were published in July in PLoS ONE, a prestigious medical journal. The story was also featured by media around the world, including Reuters and the BBC in Britain.

Dr. Silverman said the research is important because it suggests that treating people in the developing world with chloroquine, might boost their resistance to antibiotics, making it harder to treat deadly diseases like tuberculosis, typhoid fever, cholera and dysentery.

"This shows that we have to find another way to control malaria," Dr. Silverman said. "We have to give out nets and find a vaccine, instead of relying on the tablets."

He said the study has implications for people outside the developing world too, saying antibiotic resistant bacteria can be transmitted around the world, and that fluoroquinolones are among the most commonly used antibiotics in North America.

"This has big public health implications, because we're all related," he said.