Scientists discover new antibiotic family in soil


In rats, the agent - which the researchers dubbed malacidin - attacked and broke down the cell walls of methicillin-resistant Staphylococcus aureus and cleared the animals' MRSA skin infections within a day. This then triggers bacterial cell destruction, killing the target bacterium. (Also, "mal" means bad in Latin, and "cide" means to kill.) It is a distant relative of daptomycin, a powerful antibiotic that uses calcium to disrupt bacterial cell walls.

In their study, published as a letter in the journal Nature Microbiology, the authors cautioned that it is only effective against one group of bacteria - the gram positives, which include MRSA.

In a new paper, published February 12 in the journal Nature Microbiology, the scientists described the fruits of their labor: a class of antibiotics made by soil-dwelling microbes that may kill deadly superbugs, or bacteria that no longer succumb to known drugs. While it was taken from daptomycin, is appears to work differently.

Experts have hailed this new antibiotic from soil the next big thing because, a new antibiotic has not been discovered since 1987. The team of researchers used Malacidin against MRS for consecutive 20 days to see if the bacteria could mutate and develop any resistance to the antibiotic.

Professor Brady added: 'Despite the wide availability of antibiotics, infectious diseases remain a leading cause of death worldwide.

The hunt for a new antibiotic candidate has been exhaustive, but the answer could be just beneath our feet in the form of soil. This antibiotic Malacidin, further scores over others because of its ability to prevent development of resistance by the microbes.

Sean Brady, a chemical biologist at Rockefeller University in NY, and a team of colleagues, sequenced bacterial DNA they had taken from 2,000 soil samples collected across the United States.

"In the absence of new therapies, mortality rates due to untreatable infections are predicted to rise more than tenfold by 2050", researchers warned. The result could be new discoveries, and a new way of sifting the soil for compounds that might make good medicine.

Scientists said they used a high-throughput sequencing-based screening method that bypasses the need to grow microorganisms first because the vast majority of bacterial species cannot be cultured in the laboratory, and thus can be used to "quickly mine new drug candidates from diverse environmental sources". When they found what they were after, they cloned the genes, rearranged them and implanted them in a host organism, using fermentation to expand the sample. This was then tried on MRSA-infected rats with success.