# Antibiotic Resistance in the Farming Environment
## 3 Farmed Animals as Reservoirs of Antibiotic Resistance  
Intensive animal husbandry is seen as one factor in the spread of antibiotic resistance in the environment. Livestock is considered an important reservoir of antibiotic-resistant bacteria and genes responsible for drug resistance, while animal husbandry facilities are considered antibiotic resistance hotspots [33; 34; 35; 36; 37; 38; 39]. Livestock farms are also one of the sources of environmental emissions of bacteria showing increased tolerance to antibiotics [29]. It has been observed that the prevalence of multi-resistant _Escherichia coli_ strains and resistance to extended-spectrum \(\beta\)-lactam antibiotics can be higher in animal isolates compared to strains isolated from humans [40]. The occurrence of antibiotic-resistant bacteria has been reported in various types of livestock [26]. The recent data concerning the resistance level and profile in different source animals are presented in Table 2. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Type of Livestock** & \
\begin{tabular}{c} **Bacteria under** \\ **Study** \\ \end{tabular} & **Resistance Level** & **Antibiotics** &
\begin{tabular}{c} **Detected** \\ **Genes** \\ \end{tabular} & **References** \\ \hline Poultry & _E. coli_ & 35\% & 3 rd generation cephalosporins & [16] \\ Poultry and swine & _E. coli_ & 29.5–54.7\% & ampicillin, sulfonamide, & [41] \\  & & tetracycline & & [41] \\ Poultry & _E. coli_ & 57.6\% & Ciprofloxacinacin & [41] \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Examples of antibiotic resistance of bacteria isolated from livestock. Figure 1: The main reasons for antibiotics applications in farming. [PERSON] et al. [33] demonstrated the presence of 149 unique genes responsible for antibiotic resistance on three large-scale industrial pig farms in China using antibiotics in animal husbandry. [PERSON] et al. [51] reported that one of the genes commonly found in livestock is blaCTX-M-1 encoding extended-spectrum \(\beta\)-lactamases (ESBL). The presence of tetracycline resistance genes on pig farms was found both in the animals themselves and in the soil or water at the site [19]. [PERSON] et al. [52] identified as many as 34 new antibiotic resistance genes in soil samples contaminated with antibiotics used in animal production such as sulfamethazine, chlortetracycline, and tylosin. The results of studies on the relationship between the use of antibiotics in animal husbandry and the prevalence of drug resistance are not entirely clear. On the one hand, the relationship between antibiotic use and the presence of resistant bacteria and antibiotic resistance determinant genes has undoubtedly been demonstrated [35]. The results of [PERSON] et al. [33] showed that the use of antibiotics in pig production can increase the frequency of drug resistance genes by up to 3-4 orders of magnitude. [PERSON] et al. [26], on the other hand, cited findings also confirming the occurrence of antibiotic resistance in pig farms where antibiotics were not used, suggesting the natural origin of antibiotic resistance. [PERSON] et al. [38] found the surprising fact that antibiotic resistance genes: blaTEM, qnrS, sul2, and tetA were present in the broiler farm, where antibiotics were never used, and