Dataset Information

Verification of different methods used for isolating Salmonella enterica serovar Dublin from cattle feces.

ABSTRACT: Salmonella enterica serovar Dublin is a cattle-adapted serovar, and some infected cattle can become asymptomatic carriers. Identification of carrier animals is important for preventing the spread of infection within a farm, but low diagnostic sensitivity of the fecal culture method is problematic. In this study, we investigated isolation methods of four S. enterica Dublin strains. Selective enrichment using the tetrathionate broth showed better performance than Rappaport-Vassiliadis R10 broth, but one of the strains was not detectable. Since isolation of such strains by selective enrichment can be difficult, we designed a method using immuno-plates that concentrates S. enterica Dublin by antigen-antibody reaction. Our method is able to detect approximately 200 clony-forming units of S. enterica Dublin in 0.1 g of cattle feces. If S. enterica Dublin was isolated from cattle with clinical signs, the method to identify carriers in the farm should be based on the growth kinetics of the target S. enterica Dublin strain.

SUBMITTER: Fujihara M

PROVIDER: S-EPMC10600525 | biostudies-literature | 2023 Oct

REPOSITORIES: biostudies-literature

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Verification of different methods used for isolating Salmonella enterica serovar Dublin from cattle feces.

Fujihara Masatoshi M Hayashi Mika M Hara Kiwako K Sakazume Noriko N Tsukuda Takuma T Tagaino Yuuka Y

The Journal of veterinary medical science 20230905 10

Salmonella enterica serovar Dublin is a cattle-adapted serovar, and some infected cattle can become asymptomatic carriers. Identification of carrier animals is important for preventing the spread of infection within a farm, but low diagnostic sensitivity of the fecal culture method is problematic. In this study, we investigated isolation methods of four S. enterica Dublin strains. Selective enrichment using the tetrathionate broth showed better performance than Rappaport-Vassiliadis R10 broth, b ...[more]

PMID: 37673592

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Project description:Salmonella enterica subsp. enterica serovar Dublin is a cattle-adapted serovar that causes enteritis and systemic diseases in animals. In Germany, S. Dublin is not detected or is very rarely detected in some federal states but is endemic in certain regions. Information on detailed genetic characteristics of S. Dublin is not available. An understanding of the paths and spreading of S. Dublin within and between regions and over time is essential to establish effective control strategies. Whole-genome sequencing (WGS) and bioinformatic analysis were used to explore the genetic traits of S. Dublin and to determine their epidemiological context. Seventy-four S. Dublin strains collected in 2005 to 2018 from 10 federal states were studied. The phylogeny was analyzed using core-genome single-nucleotide polymorphisms (cgSNPs) and core-genome multilocus sequence typing. Genomic clusters at 100 cgSNPs, 40 cgSNPs, and 15 cgSNPs were selected for molecular epidemiology. WGS-based genoserotyping confirmed serotyping. Important specific virulence determinants were detected in all strains, but multidrug resistance in German S. Dublin organisms is uncommon. Use of different thresholds for cgSNP analysis enabled a broad view and also a detailed view of the occurrence of S. Dublin in Germany. Genomic clusters could be allocated nationwide, to a limited number of federal states, or to special regions only. Results indicate both persistence and spread of S. Dublin within and between federal states in short and longer time periods. However, to detect possible routes of infection or persistence of S. Dublin indicated by genomic analysis, information on the management of the cattle farms and contacts with corresponding farms are essential. IMPORTANCE Salmonella enterica subsp. enterica serovar Dublin is a bovine host-adapted serovar that causes up to 50% of all registered outbreaks of salmonellosis in cattle in Germany. S. Dublin is not detected or is only rarely detected in some federal states but has been endemic in certain regions of the country for a long time. Information on genetic traits of the causative strains is essential to determine routes of infection. WGS and bioinformatic analysis should be used to explore the genetic characteristics of S. Dublin. Combining the genomic features of S. Dublin strains with information on the management of the cattle farms concerned should enable the detection of possible routes of infection or persistence of S. Dublin. This approach is regarded as a prerequisite to developing effective intervention strategies.

Project description:Salmonella enterica serovar Dublin is a cattle-adapted S. enterica serovar causing both intestinal and systemic infection in its bovine host, and it is also a serious threat to human health. The present study aimed to determine the population structure of S Dublin isolates obtained from Danish cattle herds and to investigate how cattle isolates relate to Danish human isolates, as well as to non-Danish human and bovine isolates. Phylogenetic analysis of 197 Danish cattle isolates from 1996 to 2016 identified three major clades corresponding to distinct geographical regions of cattle herds. Persistence of closely related isolates within the same herd and their circulation between epidemiologically linked herds for a period of more than 20 years were demonstrated. These findings suggest that a lack of internal biosecurity and, to some extent, also a lack of external biosecurity in the herds have played an important role in the long-term persistence of S Dublin in Danish cattle herds in the period investigated. Global population analysis revealed that Danish cattle isolates clustered separately from bovine isolates from other countries, whereas human isolates were geographically spread. Resistance genes were not commonly demonstrated in Danish bovine isolates; only the isolates within one Danish clade were found to often harbor two plasmids of IncFII/IncFIB and IncN types, the latter plasmid carrying blaTEM-1, tetA, strA, and strB antibiotic resistance genes.IMPORTANCES Dublin causes economic losses in cattle production, and the bacterium is a public health concern. A surveillance and control program has been in place in Denmark since 2002 with the ultimate goal to eradicate S Dublin from Danish cattle herds; however, a small proportion of herds have remained positive for many years. In this study, we demonstrate that herds with persistent infection often were infected with the same strain for many years, indicating that internal biosecurity has to be improved to curb the infection. Further, domestic cases of S Dublin infection in humans were found to be caused both by Danish cattle isolates and by isolates acquired abroad. This study shows the strength of whole-genome sequencing to obtain detailed information on epidemiology of S Dublin and allows us to suggest internal biosecurity as a main way to control this bacterium in Danish cattle herds.

Dataset Information

Verification of different methods used for isolating Salmonella enterica serovar Dublin from cattle feces.

Publications

Verification of different methods used for isolating Salmonella enterica serovar Dublin from cattle feces.

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