Two major clonal MRSP lineages have disseminated in Europe (ST71-J-t02-II-III) and North America (ST68-C-t06-V). Regardless of their geographical or clonal origin, the isolates displayed resistance to the major classes of antibiotics used in veterinary medicine and thus infections caused by MRSP isolates represent a serious therapeutic challenge.

We report the spread of a clone of multidrug-resistant (MDR), ESBL-producing (bla CTX-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 bla CTX-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.

Salmonella Infantis is one of the five serovars most frequently causing human salmonellosis in Europe, mainly associated with poultry. A clone harbouring a conjugative plasmid of emerging S . Infantis (pESI)-like megaplasmid, carrying multidrug resistant (MDR) and extended-spectrum beta-lactamases (ESBL) genes, has spread in the Italian broiler chicken industry also causing human illness. This work is aimed at elucidating the molecular epidemiology of S . Infantis and pESI-like in Europe using whole-genome sequencing and bioinformatics analysis, and to investigate the genetic relatedness of S . Infantis clones and pESI-like from animals, meat, feed and humans provided by institutions of nine European countries. Two genotyping approaches were used: chromosome or plasmid SNP-based analysis and the minimum spanning tree (MST) algorithm based on core-genome multilocus sequence typing (cgMLST). The European S . Infantis population appeared heterogeneous, with different genetic clusters defined at core-genome level. However, pESI-like variants present in 64.1 % of the isolates were more genetically homogeneous and capable of infecting different clonal lineages in most of the countries. Two different pESI-like with ESBL genes ( n =82) were observed: bla CTX-M-1 -positive in European isolates and bla CTX-M-65 -positive in American isolates (study outgroup). Both variants had toxin-antitoxin systems, resistance genes towards tetracyclines, trimethoprim, sulphonamides and aminoglycosides, heavy metals ( mer A) and disinfectants ( qac EΔ). Worryingly, 66 % of the total isolates studied presented different gyr A chromosomal point mutations associated with (fluoro)quinolone resistance (MIC range 0.125–0.5 mg/L), while 18 % displayed transferable macrolide resistance mediated by mph , mef and erm (B) genes. Proper intervention strategies are needed to prevent further dissemination/transmission of MDR S . Infantis and pESI-like along the food chain in Europe.

We report the first diagnostic test for the identification of Staphylococcus pseudintermedius involving a simple PCR-restriction fragment length polymorphism approach. The method allows discrimination of S. pseudintermedius from the closely related members of the Staphylococcus intermedius group and other important staphylococcal pathogens of humans and dogs.Until recently, Staphylococcus intermedius was considered responsible for most cases of canine pyoderma, a major skin disease of dogs (8). However, using a multilocus sequencing approach, independent research groups have demonstrated that isolates phenotypically identified as Staphylococcus intermedius consist of three distinct species, including S. intermedius, Staphylococcus pseudintermedius, and Staphylococcus delphini, which together represent the S. intermedius group (SIG) (1a, 4). Importantly, it was discovered that S. pseudintermedius, not S. intermedius, is the common canine pyoderma pathogen and that S. delphini, isolated from a variety of different animals, may be more clinically important than was previously thought (1a, 4). The recently identified S. pseudintermedius (5) is occasionally isolated from serious human infections, and the emergence and spread of methicillin-resistant S. pseudintermedius strains are major veterinary and public health issues (1a, 3, 4, 7, 11-13). Sasaki et al. could biochemically differentiate S. intermedius from the other SIG species but was unable to identify phenotypic markers to discriminate S. pseudintermedius, the most clinically relevant species, from S. delphini (12), and DNA sequencing is currently required to identify S. pseudintermedius (1a, 12). In order to address the need for a method of discriminating clinical isolates of S. pseudintermedius, we have developed a rapid, simple, and robust PCR-restriction fragment length polymorphism (RFLP) approach which has been validated independently in laboratories in separate countries.Our previous population genetic study of SIG isolates examined sequence diversity at five gene loci among 104 isolates (1a). In the current study, sequence analysis of one of the loci, pta, which encodes the enzyme phosphoacetyltransferase, revealed the presence of an MboI restriction site in all S. pseudintermedius isolates, which was absent in all S. intermedius and S. delphini isolates examined. Based on this discovery we have designed a simple, robust, and inexpensive PCR-RFLP diagnostic test for the identification of S. pseudintermedius. Staphylococcal genomic DNA isolation was carried out as previously described (1a). PCR amplification of a 320-bp fragment of the pta gene was carried out in a 50-l volume with a 0.2 M concentration of each oligonucleotide primer (pta_f1, AAA GAC AAA CTT TCA GGT AA, and pta_r1, GCA TAA ACA AGC ATT GTA CCG), a 0.2 mM concentration of the de-* Corresponding author. Mailing address:

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