Antibiotic Resistance and Transmission Risk of Escherichia coli during the Application of Chicken Manure Fertilizers to Cropland
Application of manure fertilizers to cropland is commonly used to recover manure from farms.In order to investigate the influence of chicken manure fertilizers in different forms on antibiotic resistance of bacterial strains in farmland soil as well as possible risk of resistance transmission,open land for growing field crops was selected to simulate the process of application of manure to cropland,and Escherichia coli(E.coli)was isolated from farmland soil applied with fresh chicken manure and organic fertilizer samples as well as with the two types of manure,and the isolates were tested for drug resistance using broth microdilution methods and identified by PCR for MLST typing.The results showed that 57 strains were isolated and identified from 220 samples,with a total isolation rate of 49.5%in the fresh manure group and 4.8%in the organic manure group.In the drug sensitivity test for 21 strains,the isolates were resistant to 14 antimicrobial drugs under 9 categories to different extent,with a multi-drug resistance rate of 95.2%,and the drug resistance rate of E.coli tended to decrease generally in soil over time.33 ST subtypes were identified,including ST10 as a relatively dominant genotype(9/56),and ST10,ST8774,ST8900 and ST533 subtypes were common.In conclusion,the risk of E.coli contamination was higher in the fresh manure group than that in the organic manure group,E.coli and its resistance genes contained in manure could be transmitted to soil,but their resistance rate decreased over time.It was recommended to process manure prior to its application to cropland to reduce possible risk of E.coli contamination and resistance transmission.
application of manure to croplandE.colidrug resistancemultilocus sequence typing
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