# Antibiotic Resistance in the Farming Environment
## 2 Antibiotics in Farming Practices  
Antibiotics have been used in farming for decades not only for therapeutic purposes but also for prophylaxis and as growth promoters [10; 15; 16]. Today, thousands of tons of antibiotics are used every year for cattle, pig, and poultry farming [4; 17; 18] (Table 1).  
According to the reports concerning European countries, penicillin, oxytetracycline, chlorotetracycline, flavophospholipid, and bactracin were among the most commonly used [1]. Numerous research results confirmed the fact that a wide range of antibiotics are detected in agricultural ecosystems on different continents, including sulfadiazine, sulfamethazine, sulfamethoxazole, erythromycinycin, tylosin, tilmicosin, limomycin, chloramphenicol, florfenicol, chlorotetracycline, doxycycline, oxytetracycline, tetracycline, ciprofloxacin, enrofloxacin, norfloxacin, monensin, and trimethoprim [21]. Due to the long history of the use of macrolide and tetracycline antibiotics in agriculture, it is the genes that determine resistance to these antibiotic groups that are detected most often [22; 23; 24].  
Antibiotics are used both for therapeutic purposes for sick animals, as a metaphylactic treatment, when the entire herd is treated with an antibiotic (to both treat sick individuals and limit the spread of the disease), and for prophylactic purposes (e.g., to avoid transmission of an infection occurring in a particular area) [25; 26] (Figure 1).  
The amounts and types of antibiotics used depend on the stage of breeding and age of the animals [15], for example, they are commonly used during the suckling and post-weaning period [27]. In Belgium, more than 90% of the total antibiotics used in pig farming were used for prophylactic purposes [28]. Currently, the use of antibiotics as growth promoters is banned in many countries, and efforts are being made to limit their use in preventive treatments [13; 25]. However, it should be noted that the ban on the use of antibiotics as growth promoters has not significantly affected the overall quantitative level of consumption of these pharmaceuticals [29].  
The quantities of antibiotics used in animal production significantly exceed those used for human therapy [1; 30; 31]. For example, in the Netherlands, each year about a hundred tons of antibiotics are used for animal treatment [32]. Many of the antibiotics used in animal farming are structurally related to pharmaceuticals used in human medicine, which can contribute to the formation of cross-resistance [13].  
\begin{table}
\begin{tabular}{c c c} \hline
**Type of Livestock** & **Antibiotics** & **References** \\ \hline Swine & Pleuromutilins, tetracyclines, macrolides & [15] \\ Swine & Penicillin, tetracyclines, cephalosporions, lincosamides, fluoroquinolones, & [19] \\ Swine & amoxicillin, tulathromycin, tylosin, colistin & [20] \\ Poultry & Bacitracin, virginamycin, salinomycin, tilmicosin & [20] \\ Cattle & \(\beta\)-lactams, aminoglycos, quinolones, fluoroquinolones, macrolides, & [20] \\  & tetracyclines, sulfonamides, streptograms, lincosamides & \\ Cattle & Penicillins, tetracyclines and macrolides & [15] \\ \hline \end{tabular}
\end{table}
Table 1: Examples of antibiotics used in farming.  
It should be noted that antibiotics are also used in crop production. The use of antibiotics for crop protection involves up to 0.5% of all antibiotics used. Studies from the early 21 st century report on the use of antibiotics on crops and trees in both European countries and the US, as well as Latin American countries and Israel. They address the use of antibiotics such as streptomycin, oxytetracycline, gentamicin, kasugamycin, and oxolinic acid, among others [21]. In recent years, there has been an increase in the use of streptomycin and oxytetracycline in the treatment of citrus plant diseases, which may result in an increase in the prevalence of antibiotic-resistant bacteria and drug resistance determinant genes in plant foods [16].