Molecular characterization of <i>Salmonella enterica</i> subsp. <i>enterica</i> serovar Typhimurium DT1 isolates

Lindqvist, Nanna; Heinikainen, Sirpa; Siitonen, Anja; Pelkonen, Sinikka

doi:10.1017/s0950268803001614

Cited by 8 publications

(7 citation statements)

References 31 publications

(40 reference statements)

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“…In addition, the phage types circulating among the animals are well known [ 32 , 33 ]. For example, STM DT1 which was the most common cause of domestic human salmonella infections in this study, is endemic in Finland and isolates with this phage type have been isolated from production animals (poultry and cattle) and wild animals since the 1980s [ 3 , 33 , 34 ]. Phage types DT40 and U277 have been isolated from domestic turkey, wild birds, hedgehogs and regularly from human infections as well [ 32 ].…”

Section: Discussionmentioning

confidence: 99%

Characterization of Salmonella Typhimurium isolates from domestically acquired infections in Finland by phage typing, antimicrobial susceptibility testing, PFGE and MLVA

et al. 2015

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BackgroundSalmonella enterica spp. enterica serotype Typhimurium (STM) is the most common agent of domestically acquired salmonellosis in Finland. Subtyping methods which allow the characterization of STM are essential for effective laboratory-based STM surveillance and for recognition of outbreaks. This study describes the diversity of Finnish STM isolates using phage typing, antimicrobial susceptible testing, pulsed-field gel electrophoresis (PFGE) and multilocus variable-number tandem repeat analysis (MLVA), and compares the discriminatory power and the concordance of these methods.ResultsA total of 375 sporadic STM isolates were analysed. The isolates were divided into 31 definite phage (DT) types, dominated by DT1 (47 % of the isolates), U277 (9 % of the isolates) and DT104 (8 % of the isolates). Of all the isolates, 62 % were susceptible to all the 12 antimicrobials tested and 11 % were multidrug resistant. Subtyping resulted in 83 different XbaI-PFGE profiles and 111 MLVA types. The three most common XbaI-PFGE profiles (STYM1, STYM7 and STYM8) and one MLVA profile with three single locus variants accounted for 56 % and 49 % of the STM isolates, respectively. The studied isolates showed a genetic similarity of more than 70 % by XbaI-PFGE. In MLVA, 71 % of the isolates lacked STTR6 and 77 % missed STTR10p loci. Nevertheless, the calculated Simpson’s diversity index for XbaI-PFGE was 0.829 (95 % CI 0.792−0.865) and for MLVA 0.867 (95 % CI 0.835−0.898). However, the discriminatory power of the 5-loci MLVA varied among the phage types. The highest concordance of the results was found between XbaI-PFGE and phage typing (adjusted Wallace coefficient was 0.833 and adjusted Rand coefficient was 0.627).ConclusionsIn general, the calculated discriminatory power was higher for genotyping methods (MLVA and XbaI-PFGE) than for phenotyping methods (phage typing). Overall, comparable diversity indices were calculated for PFGE and MLVA (both DI > 0.8). However, MLVA was phage type dependent providing better discrimination of the most common phage types. Furthermore, 5-loci MLVA was a less laborious method and easier to interpret than XbaI-PFGE. Thus, the laboratory-based surveillance of the Finnish human STM infections has been conducted with a combination of phage typing, antimicrobial susceptibility testing and 5-loci MLVA since January 2014.

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Section: Discussionmentioning

confidence: 99%

Characterization of Salmonella Typhimurium isolates from domestically acquired infections in Finland by phage typing, antimicrobial susceptibility testing, PFGE and MLVA

et al. 2015

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“…The human S. Typhimurium DT104 and DT104b cases in Finland have in absolute and relative numbers been low compared to other countries (Helms et al, 2005) and the number of DT1 cases has remained relatively stable (statistics of the EBL, KTL). DT1 has been the most common DT among isolates from Finnish cattle (Lindqvist et al, 2004) that is considered an endemic reservoir of S. Typhimurium DT1 strains. Lindqvist et al (2004) studied isolates from different animal sources and S. Typhimurium DT1 with PFGE profile 10 was the most common type in Finland.…”

Section: Discussionmentioning

confidence: 99%

“…DT1 has been the most common DT among isolates from Finnish cattle (Lindqvist et al, 2004) that is considered an endemic reservoir of S. Typhimurium DT1 strains. Lindqvist et al (2004) studied isolates from different animal sources and S. Typhimurium DT1 with PFGE profile 10 was the most common type in Finland. The profile 10 is indistinguishable from the PFGE type STYMXB.0098, found in our study to be the most common PFGE type among S. Typhimurium strains in 2003 and specific to DT1.…”

Section: Discussionmentioning

confidence: 99%

Genomic Diversity Within Phage Types ofSalmonella entericassp.entericaSerotypes Enteritidis and Typhimurium

Lukinmaa¹,

Nakari²,

Liimatainen³

et al. 2006

Foodborne Pathogens and Disease

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The diversity among 1354 strains of Salmonella enterica subsp. enterica, serotype Enteritidis (n = 847) and Typhimurium (n = 507) isolated in Finland in 1991-2002 (n = 608) and in 2003 (n = 746) were studied. The former strains were studied retrospectively by phage typing and pulsed-field gel electrophoresis (PFGE) harmonized in the European Salm-gene project. The latter strains were studied prospectively, and the results correlated to their antimicrobial susceptibility and association with travel to popular tourist destinations. During both periods, S. Enteritidis phage types (PTs) PT1 and PT4, and S. Typhimurium definite types (DTs) DT1 and DT104 were the major phenotypes. SENTXB.0001 was the dominating single PFGE type among S. Enteritidis strains (40% in 1991-2002; 57% in 2003), and accounted correspondingly for 23% and 63% of the PT1 strains, and 81% and 88% of the PT4 strains. No PFGE types dominated among the S. Typhimurium strains but a correlation was found between certain phage and PFGE types: among DT1 strains, STYMXB.0098 accounted for 66% (1991-2002) and 98% (2003) and among the DT104 strains STYMXB.0001 accounted for 84% and 97% in the two time periods, respectively. Of the S. Enteritidis strains isolated in 2003, 91% were associated with travel, most commonly to Spain, Greece, and Bulgaria. SENTXB.0001 was the major Salmonella PFGE type in these countries. In contrast, most (55%) S. Typhimurium strains were of domestic origin. While only 1.3% of the S. Enteritidis strains were multiresistant and 24% were resistant to nalidixic acid only, 30% of the S. Typhimurium strains were multiresistant. Among the multiresistant S. Typhimurium strains, R-type ACSSuT and PFGE type STYMXB.0001 of the DT104 complex dominated.

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“…[38][39][40] In the present study, PFGE was used because it is typically highly discriminatory and because a standardized protocol 22 is available that allows for generation of subtyping data, which can be compared between studies. Pulsed-field gel electrophoresis has been used to characterize Salmonella subtypes from human and animal sources and in outbreak investigations, and differences in the discriminatory power of PFGE have been reported for various serovars.…”

Section: Discussionmentioning

confidence: 99%

Fecal shedding of, antimicrobial resistance in, and serologic response to Salmonella Typhimurium in dairy calves

Alexander

Warnick²,

Cripps³

et al. 2009

javma

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Molecular characterization of Salmonella enterica subsp. enterica serovar Typhimurium DT1 isolates

Cited by 8 publications

References 31 publications

Characterization of Salmonella Typhimurium isolates from domestically acquired infections in Finland by phage typing, antimicrobial susceptibility testing, PFGE and MLVA

Characterization of Salmonella Typhimurium isolates from domestically acquired infections in Finland by phage typing, antimicrobial susceptibility testing, PFGE and MLVA

Genomic Diversity Within Phage Types ofSalmonella entericassp.entericaSerotypes Enteritidis and Typhimurium

Fecal shedding of, antimicrobial resistance in, and serologic response to Salmonella Typhimurium in dairy calves

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