title: Molecular characterization of Salmonella enterica serovar 4,[5],12:i:- DT193 ASSuT strains from two outbreaks in Italy.
abstract: Salmonella enterica subsp. enterica serovar 4,[5],12:i:- DT193 is recognized as an emerging monophasic variant of Salmonella Typhimurium in many European countries. Resistance to ampicillin, streptomycin, sulphonamides, and tetracycline (R-type ASSuT) is described as one of the most common profiles of resistance within this clone. Recently, strains presenting such features were isolated from two unrelated outbreaks in Italy. Strains were characterized by pulsed-field gel electrophoresis (PFGE), performed with XbaI, BlnI, and SpeI, and multiple-locus variable-number tandem repeat analysis (MLVA). XbaI-PFGE showed strains related to the two outbreaks as indistinguishable. Conversely, both BlnI-PFGE and MLVA characterized the strains related the two outbreaks as different. XbaI-PFGE identified two profiles, differing by one band, within strains isolated from one of the two outbreaks. Also BlnI-PFGE and MLVA generated different profiles among the strains related to that outbreak. Combining the PFGE profiles obtained by XbaI and BlnI and comparing them with the MLVA profiles, the two methods grouped the same isolates based on identity. Moreover, genomic deletions of the genes included in the operon fljAB, the flanking iroB gene, and the closely located STM2757 gene were investigated. For all strains, the same profile of deletion characterized by the absence of fljA, fljB, and hin genes and the presence of STM2757 and iroB genes was identified. This profile of deletion represents a mixture between two profiles of Salmonella 4,[5],12:i:- described as the "Spanish" and the "U.S." clones. This study demonstrated that although strains of Salmonella 4,[5],12:i:- DT193 ASSuT are highly clonal, minor differences between strains may be seen during the same outbreak by using in parallel PFGE with different restriction enzymes, MLVA, and the analysis of molecular markers related to the operon fljAB. The combination of these different molecular approaches was essential to clarify the epidemiological relationship among the strains.
authors: 1 World Organization for Animal Health (OIE), National Reference Laboratory for Salmonella, Istituto Zooprofilattico Sperimentale delle Venezie , Legnaro (Padova), Italy .
authors: Lisa
authors: L
authors: Barco
authors: Elena
authors: E
authors: Ramon
authors: Enzo
authors: E
authors: Cortini
authors: Alessandra
authors: A
authors: Longo
authors: Maria Cristina
authors: MC
authors: Dalla Pozza
authors: Antonia Anna
authors: AA
authors: Lettini
authors: Anna Maria
authors: AM
authors: Dionisi
authors: John Elmerdahl
authors: JE
authors: Olsen
authors: Antonia
authors: A
authors: Ricci
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics; D002645:Chickens; D002874:Chromosome Mapping; D004269:DNA, Bacterial / Q000235:genetics; D004196:Disease Outbreaks; D016521:Electrophoresis, Gel, Pulsed-Field; D005243:Feces / Q000382:microbiology; D005408:Flagellin / Q000235:genetics; D005506:Food Contamination / Q000032:analysis; D005516:Food Microbiology; D005517:Foodborne Diseases / Q000453:epidemiology* / Q000382:microbiology; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008461:Meat Products / Q000382:microbiology*; D012097:Repressor Proteins / Q000235:genetics; D019779:Salmonella enterica / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification*; D012486:Salmonella typhimurium / Q000235:genetics / Q000302:isolation & purification; D013552:Swine
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; C079830:FljA protein, Salmonella; C094427:FljB protein, Salmonella; D012097:Repressor Proteins; D005408:Flagellin