title: Emergence of a Clonal Lineage of Multidrug-Resistant ESBL-Producing Salmonella Infantis Transmitted from Broilers and Broiler Meat to Humans in Italy between 2011 and 2014.
abstract: We report the spread of a clone of multidrug-resistant (MDR), ESBL-producing (blaCTX-M-1) Salmonella enterica subsp. enterica serovar Infantis, in the Italian broiler chicken industry and along the food-chain. This was first detected in Italy in 2011 and led to human infection in Italy in 2013-2014.A set (n = 49) of extended-spectrum cephalosporin (ESC)-resistant (R) isolates of S. Infantis (2011-2014) from humans, food-producing animals and meat thereof, were studied along with a selected set of earlier and more recent ESC-susceptible (ESC-S) isolates (n = 42, 2001-2014). They were characterized by macrorestriction-PFGE analysis and genetic environment of ESC-resistance. Isolates representative of PFGE-patterns and origin were submitted to Whole Genome Sequencing. The emerging ESC-R clone, detected mainly from broiler chickens, broiler meat and humans, showed a minimum pattern of clinical resistance to cefotaxime, tetracycline, sulfonamides, and trimethoprim, beside ciprofloxacin microbiological resistance (MIC 0.25 mg/L). All isolates of this clone harbored a conjugative megaplasmid (~ 280-320 Kb), similar to that described in ESC-susceptible S. Infantis in Israel (pESI-like) in 2014. This megaplasmid carried the ESBL gene blaCTX-M-1, and additional genes [tet(A), sul1, dfrA1 and dfrA14] mediating cefotaxime, tetracycline, sulfonamide, and trimethoprim resistance. It also contained genes conferring enhanced colonization capability, virulence (fimbriae, yersiniabactin), resistance and fitness (qacE1, mer) in the intensive-farming environment. This emerging clone of S. Infantis has been causing infections in humans, most likely through the broiler industry. Since S. Infantis is among major serovars causing human infections in Europe and is an emerging non-typhoidal Salmonella globally, further spread of this lineage in primary productions deserves quick and thorough risk-management strategies.
authors.affiliation: Istituto Zooprofilattico Sperimentale del Lazio e della Toscana "M. Aleandri", National Reference Laboratory for Antimicrobial Resistance, Via Appia Nuova 1411, 00178, Rome, Italy.
authors.forename: Alessia
authors.initials: A
authors.lastname: Franco
authors.affiliation: National Food Institute, Technical University of Denmark, WHO Collaborating Center for Antimicrobial Resistance in Food borne Pathogens, and European Union Reference Laboratory for Antimicrobial Resistance, Kgs. Lyngby, Denmark.
authors.forename: Pimlapas
authors.initials: P
authors.lastname: Leekitcharoenphon
authors.affiliation: Istituto Zooprofilattico Sperimentale del Lazio e della Toscana "M. Aleandri", National Reference Laboratory for Antimicrobial Resistance, Via Appia Nuova 1411, 00178, Rome, Italy.
authors.forename: Fabiola
authors.initials: F
authors.lastname: Feltrin
authors.affiliation: Istituto Zooprofilattico Sperimentale del Lazio e della Toscana "M. Aleandri", National Reference Laboratory for Antimicrobial Resistance, Via Appia Nuova 1411, 00178, Rome, Italy.
authors.forename: Patricia
authors.initials: P
authors.lastname: Alba
authors.affiliation: Istituto Zooprofilattico Sperimentale del Lazio e della Toscana "M. Aleandri", National Reference Laboratory for Antimicrobial Resistance, Via Appia Nuova 1411, 00178, Rome, Italy.
authors.forename: Gessica
authors.initials: G
authors.lastname: Cordaro
authors.affiliation: Istituto Zooprofilattico Sperimentale del Lazio e della Toscana "M. Aleandri", National Reference Laboratory for Antimicrobial Resistance, Via Appia Nuova 1411, 00178, Rome, Italy.
authors.forename: Manuela
authors.initials: M
authors.lastname: Iurescia
authors.affiliation: Istituto Zooprofilattico Sperimentale del Lazio e della Toscana "M. Aleandri", National Reference Laboratory for Antimicrobial Resistance, Via Appia Nuova 1411, 00178, Rome, Italy.
authors.forename: Rita
authors.initials: R
authors.lastname: Tolli
authors.affiliation: Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia-Romagna ''Bruno Ubertini", Via Bianchi 9, 25124, Brescia, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: D'Incau
authors.affiliation: Istituto Zooprofilattico Sperimentale dell'Umbria e delle Marche, Sezione di Macerata, Via dei Velini, 15, 62100, Macerata, Italy.
authors.forename: Monica
authors.initials: M
authors.lastname: Staffolani
authors.affiliation: Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise "G. Caporale", Via Campo Boario, 64100, Teramo, Italy.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Di Giannatale
authors.affiliation: National Food Institute, Technical University of Denmark, WHO Collaborating Center for Antimicrobial Resistance in Food borne Pathogens, and European Union Reference Laboratory for Antimicrobial Resistance, Kgs. Lyngby, Denmark.
authors.forename: Rene S
authors.initials: RS
authors.lastname: Hendriksen
authors.affiliation: Istituto Zooprofilattico Sperimentale del Lazio e della Toscana "M. Aleandri", National Reference Laboratory for Antimicrobial Resistance, Via Appia Nuova 1411, 00178, Rome, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Battisti
mesh_terms: D000818:Animals; D018550:Cephalosporin Resistance / Q000235:genetics; D002645:Chickens / Q000382:microbiology*; D003227:Conjugation, Genetic; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D016521:Electrophoresis, Gel, Pulsed-Field; D005798:Genes, Bacterial; D006801:Humans; D007558:Italy; D008460:Meat / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D058885:Multilocus Sequence Typing; D010802:Phylogeny; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D012475:Salmonella / Q000145:classification / Q000235:genetics / Q000502:physiology*; D012481:Salmonella Infections, Animal / Q000235:genetics / Q000382:microbiology*; D001618:beta-Lactamases / Q000096:biosynthesis*
chemical_list: D001618:beta-Lactamases