title: Clonal dissemination of Salmonella enterica serovar Infantis in Germany.
abstract: Salmonella enterica serovar Infantis (Salmonella Infantis) is consistently isolated from broiler chickens, pigs, and humans worldwide. This study investigated 93 epidemiologically unrelated Salmonella Infantis strains isolated in Germany between 2005 and 2008 in respect to their transmission along the food chain. Various phenotypic and genotypic methods were applied, and the pathogenicity and resistance gene repertoire was determined. Phenotypically, 66% of the strains were susceptible to all 17 antimicrobials tested, while the others were almost all multidrug-resistant (two or more antimicrobial resistances), with different resistance profiles and preferentially isolated from broiler chickens. A number of phage types (PTs) were shared by strains from pigs, broiler chickens, and humans (predominated by PT 29). One, PT 1, was only detected in strains from pigs/pork and humans. Pulsed-field gel electrophoresis (PFGE) subdivided strains in seven different clusters, named A-G, consisting of 35 various XbaI profiles with coefficient of similarity values of 0.73-0.97. The majority of XbaI profiles were assigned to clusters A and C, and two predominant XbaI profiles were common in strains isolated from all sources investigated. Multi-locus sequence typing (MLST) analysis of selected strains representing the seven PFGE clusters revealed that they all belonged to ST32. The pathogenicity gene repertoire of 37 representative Salmonella Infantis strains analyzed by microarray was also identical. The resistance gene repertoire correlated perfectly with the phenotypic antimicrobial resistance profiles, and multidrug-resistant strains were associated with class 1 integrons. Overall, this study showed that two major closely related genotypes of Salmonella Infantis can transmit in Germany to humans through contaminated broiler meat or pork, and consequently presents a hazard for human health.
authors.affiliation: Federal Institute for Risk Assessment, Biology Safety Department, National Reference Laboratory for Salmonella, Diedersdorfer Weg 1, Berlin, Germany.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Hauser
authors.forename: Erhard
authors.initials: E
authors.lastname: Tietze
authors.forename: Reiner
authors.initials: R
authors.lastname: Helmuth
authors.forename: Ernst
authors.initials: E
authors.lastname: Junker
authors.forename: Rita
authors.initials: R
authors.lastname: Prager
authors.forename: Andreas
authors.initials: A
authors.lastname: Schroeter
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Rabsch
authors.forename: Angelika
authors.initials: A
authors.lastname: Fruth
authors.forename: Anne
authors.initials: A
authors.lastname: Toboldt
authors.forename: Burkhard
authors.initials: B
authors.lastname: Malorny
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015373:Bacterial Typing Techniques; D002645:Chickens; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D015252:Deoxyribonucleases, Type II Site-Specific; D024901:Drug Resistance, Multiple, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D005516:Food Microbiology; D005838:Genotype; D005858:Germany / Q000453:epidemiology; D006801:Humans; D008460:Meat / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D058885:Multilocus Sequence Typing; D011201:Poultry Diseases / Q000453:epidemiology / Q000382:microbiology* / Q000635:transmission; D012480:Salmonella Infections / Q000453:epidemiology / Q000382:microbiology* / Q000635:transmission; D019779:Salmonella enterica / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology / Q000382:microbiology* / Q000635:transmission
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; C025580:endodeoxyribonuclease XBAI; D015252:Deoxyribonucleases, Type II Site-Specific