# Antibiotic Resistance in the Farming Environment
## 4 Husbandry Wastes as a Reservoir of Antibiotic Resistance and Its Carrier in the Environment
[71] compared the frequency of antibiotic resistance in _Pseudomonas aeruginosa_ strains isolated from the topsoil of a poultry farm where antibiotics were used to raise poultry and bacteria of this species from sites at least 500 m from the nearest poultry farm. They found indicators of antibiotic resistance were present in samples taken from both types of sites. What is interesting, florfenicol-resistant _E. coli_ strains were isolated even from remote, geographically separated farms [46]. There is evidence that the increase in antibiotic resistance genes in the soil environment resulting from fertilization with manure is periodic. It was also observed that the concentration of resistance genes in the soil environment may decrease over time [66]. The results of a study conducted by [PERSON] et al. [72] on Finnish dairy cattle and pig farms showed that despite some resistance genes being found in the manure, their abundance in manure-fertilized soils was gradually reduced. A very similar effect, a decrease in antibiotic-resistant bacteria over time, was observed for stored slurry by [PERSON] et al. [73] However, it is worth noting that 163 genes determining antibiotic resistance were also detected in non-fertil soil, while in manure-fertilized soil, depending on the type of livestock, there were 230-245 genes [74]. It should be noticed that a way to reduce the spread of drug resistance resulting from the use of natural fertilizers can be the use of the composite process. Manure composting promotes the elimination of antibiotic residues at levels as high as 50-99%, with higher temperatures and prolongation of the thermophilic phase having the greatest impact. Unfortunately, some antibiotics such as sulfamethazine, ofloxacin, and ciprofloxacin may not degrade under composting conditions, while their concentration in the final product remains high [21]. There is some evidence to confirm that the competing process can lead to the effective reduction of antibiotic-resistant microorganisms and resistance conditioning genes present in manure [5; 75]. [PERSON] et al. [76] pointed out the possibility of reducing the spread of antibiotic resistance genes by composting pig manure under conditions of appropriate temperature and pH. However, they found that the standard composting process did not provide effective control of antibiotic resistance. Even an increase in temperature in the thermophilic phase only resulted in a periodic decrease in the number of resistance-determining genes detected [77]. Moreover, research results are available indicating that during composting, there can be both a decrease, stabilization in the amount, and an increase in the antibiotic resistance in the composted material [67; 70]. [PERSON] et al. [67] found, a nine-fold increase in the abundance of antibiotic resistance genes (mainly sull, sul2, tetQ, and tetX genes) in sheep manure aerobic heap composting. [PERSON] et al. [78] observed that the frequency of antibiotic resistance genes increased 44-fold during heap composting, especially with regard to macrolide antibiotic resistance. On the other hand, during composting under thermophilic conditions, there was a 92% decrease in antibiotic resistance genes, with tetracycline resistance genes reaching as high as 97%. It was observed that the abundance of tetracycline resistance genes could both decrease and increase during the composting process, depending on microflora activity and environmental conditions (C/N, moisture, pH) [79]. A factor affecting the survival of antibiotic-resistant microorganisms in manure and compost and the persistence of antibiotic resistance genes in microbial communities may be the presence of heavy metals and antibiotic residues [80].