title: Increased abundance and transferability of resistance genes after field application of manure from sulfadiazine-treated pigs.
abstract: Spreading manure containing antibiotics in agriculture is assumed to stimulate the dissemination of antibiotic resistance in soil bacterial populations. Plant roots influencing the soil environment and its microflora by exudation of growth substrates might considerably increase this effect. In this study, the effects of manure from pigs treated with sulfadiazine (SDZ), here called SDZ manure, on the abundance and transferability of sulfonamide resistance genes sul1 and sul2 in the rhizosphere of maize and grass were compared to the effects in bulk soil in a field experiment. In plots that repeatedly received SDZ manure, a significantly higher abundance of both sul genes was detected compared to that in plots where manure from untreated pigs was applied. Significantly lower abundances of sul genes relative to bacterial ribosomal genes were encountered in the rhizosphere than in bulk soil. However, in contrast to results for bulk soil, the sul gene abundance in the SDZ manure-treated rhizosphere constantly deviated from control treatments over a period of 6 weeks after manuring, suggesting ongoing antibiotic selection over this period. Transferability of sulfonamide resistance was analyzed by capturing resistance plasmids from soil communities into Escherichia coli. Increased rates of plasmid capture were observed in samples from SDZ manure-treated bulk soil and the rhizosphere of maize and grass. More than 97% of the captured plasmids belonged to the LowGC type (having low G+C content), giving further evidence for their important contribution to the environmental spread of antibiotic resistance. In conclusion, differences between bulk soil and rhizosphere need to be considered when assessing the risks associated with the spreading of antibiotic resistance.
authors: Institute for Epidemiology and Pathogen Diagnostics, Braunschweig, Germany.
authors: Sven
authors: S
authors: Jechalke
authors: Christoph
authors: C
authors: Kopmann
authors: Ingrid
authors: I
authors: Rosendahl
authors: Joost
authors: J
authors: Groeneweg
authors: Viola
authors: V
authors: Weichelt
authors: Ellen
authors: E
authors: Krögerrecklenfort
authors: Nikola
authors: N
authors: Brandes
authors: Mathias
authors: M
authors: Nordwig
authors: Guo-Chun
authors: GC
authors: Ding
authors: Jan
authors: J
authors: Siemens
authors: Holger
authors: H
authors: Heuer
authors: Kornelia
authors: K
authors: Smalla
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000235:genetics; D022761:Gene Transfer, Horizontal; D005798:Genes, Bacterial; D008372:Manure; D018517:Plant Roots / Q000382:microbiology; D010957:Plasmids / Q000302:isolation & purification; D006109:Poaceae / Q000382:microbiology; D012988:Soil Microbiology; D013411:Sulfadiazine / Q000627:therapeutic use*; D013552:Swine; D003313:Zea mays / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents; D008372:Manure; D013411:Sulfadiazine