Nationwide pseudo-outbreak of Salmonella enterica ssp. diarizonae, France

Thiolet, J M; Silva, N. Jourdan-Da; Reggiani, A; Valk, Henriette de; Coignard, B.; Weill, François‐Xavier

doi:10.1111/j.1469-0691.2010.03343.x

Cited by 4 publications

(4 citation statements)

References 9 publications

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“…Only a small number of severe human cases have been described, which mainly affected high-risk groups, such as infants [ 19 ], immunocompromised adults [ 20 ] and the elderly [ 21 ]. No larger outbreak of human infections with SASd has been documented so far and a pseudo-outbreak in France could be traced back to contaminated sheep blood agar [ 22 ]. Given the high prevalence of SASd in sheep and the low number of human infections, Swedish authorities have concluded that the risk management of this serovar in sheep can be exempted without any adverse effect on human health [ 7 ].…”

Section: Introductionmentioning

confidence: 99%

Comparative genomics of Salmonella enterica subsp. diarizonae serovar 61:k:1,5,(7) reveals lineage-specific host adaptation of ST432

et al. 2021

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Unlike most Salmonella enterica subsp. diarizonae , which are predominantly associated with cold-blooded animals such as reptiles, the serovar IIIb 61:k:1,5,(7) (termed SASd) is regarded as host-adapted to sheep. The bacterium is rarely associated with disease in humans but, nevertheless, SASd isolates are sporadically obtained from human clinical samples. It is unclear whether these transmissions are directly linked to sheep or whether transmissions may, for example, occur through other domestic animals also carrying SASd. For this reason, we utilized whole-genome sequencing to investigate a set of 119 diverse SASd isolates, including sheep-associated and human-associated isolates, as well as isolates obtained from other matrices. We discovered that serovar IIIb 61:k:1,5,(7) is composed of two distinct lineages defined by their sequence types ST432 and ST439. These two lineages are distinguished by a number of genetic features, as well as their prevalence and reservoir. ST432 appears to be the more prevalent sequence type, with the majority of isolates investigated in this study belonging to ST432. In contrast, only a small number of isolates were attributed to ST439. While ST432 isolates were of sheep, human or other origin, all ST439 isolates with source information available, were obtained from human clinical samples. Regarding their genetic features, lineage ST432 shows increased pseudogenization, harbours a virB/D4 plasmid that encodes a type IV secretion system (T4SS) and does not possess the iro gene cluster, which encodes a salmochelin siderophore for iron acquisition. These characteristics likely contribute to the ability of ST432 to persistently colonize the intestines of sheep. Furthermore, we found isolates of the lineage ST432 to be highly clonal, with little variation over the sampling period of almost 20 years. We conclude from the genomic comparisons that SASd underlies a microevolutionary process and that it is specifically lineage ST432 that should be considered as host-adapted to sheep.

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Section: Introductionmentioning

confidence: 99%

Comparative genomics of Salmonella enterica subsp. diarizonae serovar 61:k:1,5,(7) reveals lineage-specific host adaptation of ST432

et al. 2021

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“…After some investigations, they revealed that nine of the ten isolates had grown on sheep blood agar from the same manufacturer and that the batch number was similar for three cases. The manufacturer confirmed that the samples of the blood agar were positive to SED, owing to contaminated sheep blood [43].…”

Section: Zoonotic Potential Of Salmonella Enterica Subsp Diarizonae Serotype 61:k:1:5:(7)mentioning

confidence: 89%

“…Diarizonae serotype 61:k:1:5:(7) and the role of sheep in the transmission has been widely discussed [17,26,42], even though there have been no confirmed human cases associated with this specific serotype. In France, in 2008, a pseudo-outbreak in humans associated with SED was reported [43]. After a large number of SED positive samples from humans, trace-back investigations incriminated culture media containing contaminated sheep blood agar.…”

Section: Zoonotic Potential Of Salmonella Enterica Subsp Diarizonae Serotype 61:k:1:5:(7)mentioning

confidence: 99%

Salmonella enterica subsp. diarizonae Serotype 61:k:1:5:(7) a Host Adapted to Sheep

Rubira¹,

Figueras²,

Jiménez³

et al. 2021

Salmonella Spp. - A Global Challenge

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Salmonella genus is widely distributed in nature and causes a spectrum of diseases in man and animals. Salmonella enterica subsp. diarizonae serotype 61: k: 1,5, (7) (SED) is a host adapted to sheep and its presence as saprophytic bacteria in sheep has been described in different countries. Several studies performed in abattoirs reported the presence of SED in healthy sheep in the intestinal content and also in the respiratory tract. In addition, this microorganism has also been isolated from nostril and faecal samples in healthy live animals. For this reason, this microorganism is considered well adapted to sheep, behaving normally these animals as asymptomatic carriers. However, SED has also been reported causing health disorders such as chronic proliferative rhinitis in adult sheep, abortions, testicular lesions in rams or alimentary tract disorders in young animals. The zoonotic potential of this microorganism is also discussed.

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“…Clinical samples, laboratory equipment, stains and media may get contaminated and lead to pseudo-outbreaks. 19 One-time isolation of hitherto zoonotic pathogens may remain inconclusive. Positive isolates may not be associated with clinically manifest infection owing to muted immune response in premature neonates, elderly and immunocompromised patients.…”

Section: Attributing Pathogenicitymentioning

confidence: 99%