# Antibiotic Resistance in the Farming Environment
## 4 Husbandry Wastes as a Reservoir of Antibiotic Resistance and Its Carrier in the Environment  
Some of the antibiotics used in animal husbandry end up in livestock waste. The level of metabolization of antibiotics in the body varies widely, ranging from 10 to 90% of the ingested dose, and most likely depends on the age and species of the animal [1]. Hence, the waste contains both the antibiotics themselves and the products of their metabolism. A French study found that solid waste from animal production contained 241 mg/kg d.w. of ciprofloxacin and about 12 mg/kg d.w. of doxycycline. For liquid waste, the concentrations of these antibiotics were 0.006 mg/L and 0.505 mg/L, respectively [5]. Comparing these values with the concentrations of these antibiotics suggested to cause resistance selection (0.064 mg/L for ciprofloxacin and 2 mg/L for doxycycline [58]), it can be concluded that these wastes pose a real threat in terms of pressure toward antibiotic resistance of the inhabiting microflora. Bacteria isolated from livestock waste are characterized by resistance to numerous antibiotics. The addition of antibiotics to feed for prophylactic or therapeutic purposes causes not only an increase in drug-resistant intestinal microflora but also an increase in the number of drug-resistant bacteria in the manure of these animals [7]. Consequently, the agents responsible for the phenomenon of drug resistance are often detected in farming waste [25; 59] (Table 3). [PERSON] et al. [61] identified a number of factors determining the role of manure as a potential hotspot for the spread of antibiotic resistance traits through horizontal gene transfer: the abundance of nutrients, the presence of antibiotic residues that can act as a selection factor, the large number and diversity of microorganisms. The abundance of antibiotic resistance genes in manure can reach 10% relative to the number of 16S rRNA genes [62]. A number of pathogenic bacteria, including _Klebsiella pneumoniae_ and bacteria from genera _Campylobacter_, _Salmonella_, _Listeria_, _Coxiella_, and _Mycobacterium_ showing antibiotic resistance traits, have been isolated from manure of farm animals [64]. The use of manure sourced from antibiotic-treated animal farms as fertilizer is one of the factors promoting the development of drug resistance in the soil environment [62; 63; 65; 66; 67; 68; 69]. There are studies confirming the presence of tetracycline, sulfonamide, fluoroquinoline, and chloramphenicol resistance genes in manure-fertil soils [15; 19]. [PERSON] et al. [70], in a study of antibiotic resistance conducted on Finnish cattle and pig farms, found that even when only small amounts of antibiotics were typically used in animal husbandry, soils amended with manure contained elevated amounts of resistance genes towards carbapenem (blaOXA-58), sulfonamide (sull), and tetracycline (tetM). It was observed that drug-resistant microorganisms may persist in the environment for a relatively long time. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Type of Wastes** & **Antibiotic Resistance** & **Resistance Genes** & **References** \\ \hline \multirow{3}{*}{Poultry manure} & & ermB, sul2, tetA, sul1, and & \multirow{3}{*}{[60]} \\  & Tetracyclines, sulfonamides, aminoglycoside, & & \\ \cline{3-3 The conditioning factors are climate, soil type, frequency of fertilization, and also the type of microflora inhabiting the soil [5]. A separate aspect is the potential for further spread of antibiotic resistance in the environment. An interesting phenomenon is an increase in the abundance of detected antibiotic resistance genes in the soil already some time after manure fertilization, which may indicate the transfer of these genes in the environment [15]. Antibiotics in manure may be an additional selection factor in soil bacteria for antibiotic resistance [59]. [PERSON] et al.