Post on 20-Sep-2020
G L O B A L S Y M P O S I U MO N S O I L
P O L L U T I O N2 - 4 M A Y 2 0 1 8 | F A O - R O M E , I T A L Y
Animal and anthropogenic pressures on agricultural soils from Shiga/Vero-Toxin producing E. coli (STEC/VTEC): impact on
food safety and food securityGianfranco Brambilla, Federica Gigliucci, Valeria Michelacci, Rosangela Tozzoli and
Stefano Morabito - Istituto Superiore di Sanità, EURL-VTEC
INTRODUCTION
The use of biosolids and remediat-ed water from civil wastewater treatment plants (WWTPs) in agri-culture practices can represent a port of entry of pathogenetic E. coli strains including STEC in the food chain. The latter strains have been proven to cause severe Haemolitic Uremic Syndrome (HUS) out-breaks in children, Enterocolitis in adults and provoked food scandals that hampered food security.Additional to the spreading of pathogens to soil, potential genetic re-assortment between strains of human, animal, and environmen-tal origin, may determine the pres-ence of emerging pathotypes show-ing different combinations of viru-lence and resistance factors:• vtx1, vtx2, eae, aggR aaiC, lt, sth,
stp, and ipaH • Antimicrobial Resistance - AMR
METHODOLOGY
Investigation of virulence factors associated with pathogenic E. coli strains and Antimicrobial resis-tance (AMR) genes in a set of dif-ferent Biosolid samples originat-ing from WWTPs in Italy, using a Real Time Polymerase Chain Reac-tion (RT-PCR) and Whole Metag-enomic Sequencing approaches.
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
CO3 CO2 MCO CO1 BSO2 BSO4 BSO3 BSO1
Distributionofthegenetictraitsencodingresistancetocompounds inmetagenomes
Arsenic_resistance Methicillin_resistance_in_Staphylococci Fosfomycin_resistance Multidrug_efflux_pump(CmeABC_operon)
Mercuric_reductase Beta-lactamase Multidrug_Resistance,_Tripartite_Systems Zinc_resistance
Copper_homeostasis:_copper_tolerance Resistance_to_fluoroquinolones Streptothricin_resistance Resistance_to_Vancomycin
Multidrug_Resistance,_2-protein Cobalt-zinc-cadmium_resistance Multidrug_Resistance_Efflux_Pumps Mercury_resistance_operon
Copper_homeostasis Aminoglycoside_adenylyltransferases Streptococcus_pneumoniae_Vancomycin_Tolerance_Locus
Genomic traits related to resistance to compounds, including resistance to heavy metals and antimicrobials
Genetic pool of virulence genes associated with all the pathotypes of Diarrheagenic E. coli.
Positive signals for some virulence genes in some cases appeared only after the enrichment of the samples, suggesting the
presence of viable bacterial cells
Nucleic acid extracted from enriched cultures
vtx1 vtx2 eae aggR aaiC lt sth stp ipaH
MSS 13-0474 - - - - - - - - -MSS 13-0475 - - - - - - - - -MSS 13-0476 - + - + - - - - -DIG 13-0477 - - - - - - - - -MSS 13-0478 - + - - - - - - -MSS 13-0479 - - - - - - - - -MCO 13-0482 + + + - - - - - -MCO 13-0483 - - + - - - - - -MCO 13-0484 - + + - - - - - -GCO 13-0485 - - - - - - - - -MCO 13-0486 - - - - - - - - -GCO 13-0487 - + - - - - - - -MSS 13-0488 - - + - - - - - -MSS 13-0489 - + + - - - - - -MSS 13-0490 - - + - - - - - -MSS 13-0492 - + + - - - - - -MSS 13-0496b - + - - - - - - -MAN 13-0497 - + - - - - - - -MSS 13-0480 - - - - - - - - +MCO 13-0481 - - - - - - - - -MSS 13-0493 - - - - - - - - -MSS 13-0494 - - - - - - - - -MSS 13-0495 - - - - - - - - +MSS 13-0496 - - + - - - - - +
Sample
Representation of a potential super-pathogen E. coli due to the acquisition of virulence and resistance genes from different pathotypes. From Navarro-Garcia F. (2014), modifi ed.
Pathogenic E. coli in human faeces
Animal pathogenic E. coli in manure
Animal pathogenic E. coli in slaughterhouses effluents
Human and Animal Pathogenic E. coli in civil
Waste WaterTreatment Plants
Contaminated sludges Contaminated reclaimed waters
Application on agriculture soil
Irrigation of vegetables
Potential contamination of unprocessed food and well waters
Food exposure leading to Haemorrhagic Colitis in adults and to a severe
Haemolitic Uremic Syndrome in children
Food recall and food insecurity
Potential re-assortment of virulence factors and AMR genes
CONCLUSIONSThe sustainability policies for food production may impact on food safety/food security due to the recycle of former wastes of anthropogenic origin as soil improvers.Pathogenic E. coli should be considered as priority emerging hazards, as far current aerobic/anaerobic fer-mentation to stabilize biosolids can be considered not effective in their abatement.The set up of diagnostic tools based on genomic and metagenomic approaches would be able to identify emerg-ing pathotypes, to design the end-of-waste criteria for the agriculture use of biosolids as well to evaluate the efficacy of the risk management .