Bugs never exposed to antibiotics still show resistance against them

June 9th, 2008 - 4:53 pm ICT by ANI  

London, June 9 (ANI): Scientists have found that bacteria that existed in the soil in 1960s and 70s have developed resistance to an antibiotic they have never seen before.

The team looked at three strains of bacteria that showed extreme resistance to six common antibiotics, including ciprofloxacin, which was first sold in 1989.

“You can pretty safely say that there is no way these bacteria have seen them before,” New Scientist quoted Cristiane San Miguel, a microbiologist at Rutgers University in New Brunswick, New Jersey, US, as saying.

Researchers believe that the soil plays a critical role for bugs to develop antibiotic resistance.

It possibly creates such defences as part of the evolutionary change going on for billions of years between soil-dwelling microbes.

For the study, the team led by San Miguel revived three strains, two of them were opportunistic pathogens called Klebsiella pneuomoniae that were isolated from dirt in 1973 and 1974, then frozen and the third one was a bug called Alcaligenes, last tasted agar in 1963.

They found that all the strains thrived when San Miguel exposed them to a range of antibiotics, however, the bacteria became resistant to a lethal dose of rifampicin, an antibiotic introduced in 1967, and Cipro, a 19-year-old drug that resembles nothing seen in nature.

“I was certainly expecting the Cipro to have an impact and it did not,” she said.

“The origins of many of the antibiotic resistance genes that are floating around in the clinic are out in the environment and have probably been out there for thousands and millions of years,” said Gerry Wright, a microbiologist at McMaster University in Hamilton, Ontario, Canada.

San Miguel would be conducting further studies to determine the genes responsible for the resistance

The findings were presented at the American Society for Microbiology’s annual meeting in Boston, US. (ANI)

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