• Antibiotic resistance can be passed between bacteria found in the soil, researchers, including one of Indian origin, have found.
• Researchers from North Carolina State University in the US studied antibiotic resistance and how it can persist and spread among food animals, humans and the environment they all share.
• The study found that spreading manure on the ground as fertiliser can also spread antibiotic resistance to bacteria in the soil.
• Bacteria contain small DNA molecules known as plasmids. 
• These plasmids are separate from the bacterias actual DNA, and can pick up and exchange genes between bacteria.
• The researchers took soil samples from a swine farm prior to and for three weeks after a manure spread.
• They had previously tested the manure for antibiotic resistant strains of salmonella, a pathogen responsible for causing the highest number of bacterial food borne illnesses in the US every year.
• After sampling the soil, researchers found that antibiotic-resistant salmonella bacteria were still present in the manure up to 21 days after it had been spread.
• They also discovered that a particular plasmid associated with the antibiotic-resistant salmonella from the manure, which weighed around 95 kilo-base (kb), was now turning up in different salmonella serotypes from the soil samples and every serotype with plasmid 95 kb was now resistant to antibiotics.
• This tells us that this particular plasmid is shuttling across different serotypes.
• It could explain why we find antibiotic resistant salmonella strains even on farms that do not use antibiotics. 
• It seems that once antibiotic resistance takes hold, it doesn’t go away. 
• These bacteria are simply better equipped to survive and so they prosper.

Source:TH