title: Extended-spectrum β-lactamase- and AmpC β-lactamase-producing D-tartrate-positive Salmonella enterica serovar Paratyphi B from broilers and human patients in Belgium, 2008-10.
abstract: OBJECTIVE
  To characterize the genetic determinants responsible for extended-spectrum cephalosporin (ESC) resistance of d-tartrate-positive Salmonella enterica subsp. enterica serovar Paratyphi B (serovar Paratyphi B dT+) strains that have emerged in poultry and humans in Belgium during 2008-10.
  
  
  METHODS
  The ESC resistance genes among non-redundant serovar Paratyphi B dT+ strains were determined using PCR and sequencing. ESC phenotypes were horizontally transferred by conjugation. Extended-spectrum β-lactamase (ESBL)- or AmpC-carrying plasmids were typed by PCR-based replicon typing, plasmid multilocus sequence typing and restriction fragment length polymorphism. The genetic relationship of ESC-resistant strains was assessed by XbaI PFGE and multilocus sequence typing.
  
  
  RESULTS
  Since 2008, the proportion of serovar Paratyphi B dT+ strains from broiler origin has increased significantly to reach 36.5% in 2010. Among 95 non-duplicate serovar Paratyphi B dT+ strains, 35% were resistant to ESCs. At the same time, a few ESC-resistant serovar Paratyphi B dT+ strains from humans were also detected in Belgium. The most prevalent ESBL gene, blaCTX-M-1, and the AmpC cephalosporinase gene blaCMY-2 were identified on various conjugative IncI1 plasmids of different sequence types and with different additional non-β-lactam phenotypes. Interestingly, the blaCTX-M-2 gene was located on large multireplicon IncHI2/P plasmids. In addition, highly ESC-resistant strains contained both the ESBL CTX-M-2 and the AmpC CMY-2 encoded by the IncHI2/P and IncI1 plasmids, respectively. All ESC-resistant serovar Paratyphi B dT+ strains belonged to sequence type 28 and showed the common PFGE pattern X8, as well as the chromosomal class 2 integron cassette array dfrA1-sat2-aadA1 previously described in the European poultry-associated serovar Paratyphi B dT+ clonal population.
  
  
  CONCLUSIONS
  This study showed that the clonal population of multidrug-resistant serovar Paratyphi B dT+, persisting in broilers in Belgium for the last decade, recently acquired various plasmid-borne ESC resistance determinants, constituting a major concern for public health. Further surveillance programmes and research are an absolute necessity to understand their epidemiology and to propose interventions to limit the spread of ESC- and multidrug-resistant Salmonella spp.
authors.affiliation: INRA, UMR1282 Infectiologie et Santé Publique, F-37380 Nouzilly, France.
authors.forename: Benoît
authors.initials: B
authors.lastname: Doublet
authors.forename: Karine
authors.initials: K
authors.lastname: Praud
authors.forename: Tran
authors.initials: T
authors.lastname: Nguyen-Ho-Bao
authors.forename: María Angeles
authors.initials: MA
authors.lastname: Argudín
authors.forename: Sophie
authors.initials: S
authors.lastname: Bertrand
authors.forename: Patrick
authors.initials: P
authors.lastname: Butaye
authors.forename: Axel
authors.initials: A
authors.lastname: Cloeckaert
mesh_terms: D000818:Animals; D001530:Belgium; D003227:Conjugation, Genetic; D016521:Electrophoresis, Gel, Pulsed-Field; D022761:Gene Transfer, Horizontal; D006801:Humans; D010284:Paratyphoid Fever / Q000382:microbiology* / Q000662:veterinary*; D016133:Polymerase Chain Reaction; D011200:Poultry; D012484:Salmonella paratyphi B / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013644:Tartrates / Q000378:metabolism*; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D013644:Tartrates; D001618:beta-Lactamases; C029768:tartaric acid
keywords: CMY; CTX-M; conjugative IncI1 plasmids; extended-spectrum cephalosporins