The theory is that most environmental niches will already be maxed out in terms of how much MRSA-like bacteria they can support—if they weren’t, the bacteria would just reproduce more.
So say your backyard can support 1e9 bacteria. Of that, 5e8 is antibiotic-resistant bacteria, while 5e8 is regular bacteria. Then you add another 1e9 regular bacteria. Now the backyard is overcapacity, so the 2e9 bacteria will compete for survival until only 1e9 are left. Assuming that the antibiotic-resistant bacteria has no other advantage over regular bacteria, then after the winnowing there will be 2.5e8 antibiotic-resistant and 7.5e8 regular bacteria—a reduction from 50% to 25%. Every subsequent application of the procedure will exponentially decrease the proportion of resistant bacteria.
More to the point though, any time antibiotics are used the bacterium with antibiotic resistance takes over. There is a reason that it is often spread in hospitals, where sick people on antibiotics are, and in pig farms where ridiculous loads of antibiotics are used to increase growth rates.
What is necessary is breaking the chain of spread from antibiotic-treated niche to antibiotic-treated niche, and making sure there aren’t places like said pig farms where the selective pressure is constantly applied.
This would also increase the number of Staphylococcus relative to other bacteria in the ground. And these bacteria can transfer DNA to each other, including resistance genes. So many of your added bacteria would turn into MRSA, and if there is enough antibiotics in the environment to maintain the MRSA prevalence without your intervention, then you just might end up increasing the amount of MRSA in the region.
Soil bacteria, including Staphylococcus aureus, are already everywhere. I don’t see how spreading more of them would reduce the old ones.
The theory is that most environmental niches will already be maxed out in terms of how much MRSA-like bacteria they can support—if they weren’t, the bacteria would just reproduce more.
So say your backyard can support 1e9 bacteria. Of that, 5e8 is antibiotic-resistant bacteria, while 5e8 is regular bacteria. Then you add another 1e9 regular bacteria. Now the backyard is overcapacity, so the 2e9 bacteria will compete for survival until only 1e9 are left. Assuming that the antibiotic-resistant bacteria has no other advantage over regular bacteria, then after the winnowing there will be 2.5e8 antibiotic-resistant and 7.5e8 regular bacteria—a reduction from 50% to 25%. Every subsequent application of the procedure will exponentially decrease the proportion of resistant bacteria.
More to the point though, any time antibiotics are used the bacterium with antibiotic resistance takes over. There is a reason that it is often spread in hospitals, where sick people on antibiotics are, and in pig farms where ridiculous loads of antibiotics are used to increase growth rates.
What is necessary is breaking the chain of spread from antibiotic-treated niche to antibiotic-treated niche, and making sure there aren’t places like said pig farms where the selective pressure is constantly applied.
This would also increase the number of Staphylococcus relative to other bacteria in the ground. And these bacteria can transfer DNA to each other, including resistance genes. So many of your added bacteria would turn into MRSA, and if there is enough antibiotics in the environment to maintain the MRSA prevalence without your intervention, then you just might end up increasing the amount of MRSA in the region.