Characterization of antibiotic-resistant and potentially pathogenic  Escherichia coli  from soil fertilized with litter of broiler chickens fed antimicrobial-supplemented diets.
The objective of this study was to characterize antimicrobial resistance and virulence determinants of  Escherichia coli  from soil amended with litter from 36-day-old broiler chickens ( Gallus gallus domesticus ) fed with diets supplemented with a variety of antimicrobial agents. Soil samples were collected from plots before and periodically after litter application in August to measure E. coli numbers. A total of 295 E. coli were isolated from fertilized soil samples between August and March. Antibiotic susceptibility was determined by Sensititre, and polymerase chain reaction was performed to detect the presence of resistance and virulence genes. The results confirmed that E. coli survived and could be quantified by direct plate count for at least 7 months in soil following litter application in August. The effects of feed supplementation were observed on E. coli numbers in November and January. Among the 295 E. coli, the highest antibiotic resistance level was observed against tetracycline and β-lactams associated mainly with the resistance genes tetB and bla(CMY-2), respectively. Significant treatment effects were observed for phylogenetic groups, antibiotic resistance profiles, and virulence gene frequencies. Serotyping, phylogenetic grouping, and pulsed-field gel electrophoresis confirmed that multiple-antibiotic-resistant and potentially pathogenic E. coli can survive in soil fertilized with litter for several months regardless of antimicrobials used in the feed.
Pacific Agri-Food Research Centre, Agriculture and Agri-Food Canada, Agassiz, Canada.
Laura E
LE
Merchant
Heidi
H
Rempel
Tom
T
Forge
Tissa
T
Kannangara
Shabtai
S
Bittman
Pascal
P
Delaquis
Edward
E
Topp
Kim A
KA
Ziebell
Moussa S
MS
Diarra
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002645:Chickens / Q000502:physiology; D004032:Diet / Q000662:veterinary*; D019587:Dietary Supplements; D024881:Drug Resistance, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D008372:Manure / Q000382:microbiology; D010802:Phylogeny; D011156:Population Density; D011891:Rain; D012703:Serotyping; D012988:Soil Microbiology; D013696:Temperature; D037521:Virulence Factors / Q000235:genetics
D000900:Anti-Bacterial Agents; D008372:Manure; D037521:Virulence Factors