Molecular Typing of Escherichia coli O157:H7 Isolates from Swedish Cattle and Human Cases: Population Dynamics and Virulence

Söderlund, Robert; Jernberg, Cecilia; Ivarsson, Sofie; Hedenström, Ingela; Eriksson, Erik; Bongcam‐Rudloff, Erik; Aspán, Anna

doi:10.1128/jcm.01877-14

Cited by 19 publications

(25 citation statements)

References 25 publications

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“…Subsequent studies have also suggested an association of varying magnitudes between clade 8 and HUS [15, 16]. Lineages IIa and IIb in the present study overlap with clade 8 and show an elevation in risk of HUS only among 10–59 year-olds.…”

Section: Discussionsupporting

confidence: 68%

“…A study in 2008 identified a subtype of E. coli O157:H7, termed clade 8, associated with increased risk of HUS [10]. Although numerous studies have investigated virulence factor expression that may be responsible for this association [11–14], studies confirming the association have been limited, suggesting an effect of varying strength and specificity [15–17]. …”

Section: Introductionmentioning

confidence: 99%

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Importance of case age in the purported association between phylogenetics and hemolytic uremic syndrome inEscherichia coliO157:H7 infections

Tarr¹,

Shringi

Oltean

et al. 2018

Epidemiol. Infect.

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Escherichia coli O157:H7 is the largest cause of hemolytic uremic syndrome (HUS). Previous studies proposed that HUS risk varies across the E. coli O157:H7 phylogenetic tree (hypervirulent clade 8), but the role of age in the association is unknown. We determined phylogenetic lineage of E. coli O157:H7 isolates from 1160 culture-confirmed E. coli O157:H7 cases reported in Washington State, 2004-2015. Using generalised estimating equations, we tested the association between phylogenetic lineage and HUS. Age was evaluated as an effect modifier. Among 1082 E. coli O157:H7 cases with both phylogenetic lineage and HUS status (HUS n = 76), stratified analysis suggested effect modification by age. Lineages IIa and IIb, relative to Ib, did not appear associated with HUS in children 0-9-years-old. For cases 10-59-years-old, lineages IIa and IIb appeared to confer increased risk of HUS, relative to lineage Ib. The association reversed in ⩾60-year-olds. Results were similar for clade 8. Phylogenetic lineage appears to be associated with HUS risk only among those ⩾10-years-old. Among children <10, the age group most frequently affected, lineage does not explain progression to HUS. However, lineage frequency varied across age groups, suggesting differences in exposure and/or early disease manifestation.

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Section: Discussionsupporting

confidence: 68%

Section: Introductionmentioning

confidence: 99%

Importance of case age in the purported association between phylogenetics and hemolytic uremic syndrome inEscherichia coliO157:H7 infections

Tarr¹,

Shringi

Oltean

et al. 2018

Epidemiol. Infect.

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“…Recently cattle and human isolates in Sweden demonstrated the dynamic nature of STEC O157 populations (Söderlund et al ., ). Human isolates were found to share the same MLVA type as cattle isolates.…”

Section: Introductionmentioning

confidence: 97%

Population and evolutionary dynamics of Shiga‐toxin producing Escherichia coli O157 in a beef herd: A longitudinal study

Jones

Octavia

Lammers

et al. 2017

Environmental Microbiology

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Shiga toxin producing Escherichia coli O157:H7 (STEC O157) is naturally found in the gastrointestinal tract of cattle and can cause severe disease in humans. There is limited understanding of the population dynamics and microevolution of STEC O157 at herd level. In this study, isolates from a closed beef herd of 23 cows were used to examine the population turnover in the herd. Of the nine STEC O157 clades previously described, clade 7 was found in 162 of the 169 isolates typed. Multiple locus variable number tandem repeat analysis (MLVA) differentiated 169 isolates into 33 unique MLVA types. Five predominant MLVA types were evident with most of the remaining types containing only a single isolate. MLVA data suggest that over time clonal replacement occurred within the herd. Genome sequencing of 18 selected isolates found that the isolates were divided into four lineages, representing four different 'clones' in the herd. Genome data confirmed clonal replacement over time and provided evidence of cross transmission of strains between cows. The findings enhanced our understanding of the population dynamics of STEC O157 in its natural host that will help developing effective control measures to prevent the spread of the pathogen to the human population.

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“…In addition, one farm was later excluded as no positive individuals were identified in the individual sampling leading to the final 12 farms included in the study. Analysis of isolates by real-time PCR (as described by Söderlund et al 50 ) established that 11 of the farms had the highly virulent type clade 8. The remaining farm was the one associated with a human outbreak of VTEC O157:H7 (eae and vtx1 positive).…”

Section: Methodsmentioning

confidence: 99%

Socially engaged calves are more likely to be colonised by VTEC O157:H7 than individuals showing signs of poor welfare

Tamminen

Hranac

Dicksved

et al. 2020

Sci Rep

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In cattle herds, the transmission and persistence of VTEC O157:H7 (a serotype of verotoxin-producing Escherichia coli-known for its life threatening complications in humans) is dependent on a small proportion of cattle who become colonised and shed high numbers of the bacteria. Reducing the proportion of these animals is considered key for decreasing the prevalence of VTEC O157:H7. In this study, observations of calf behaviour and animal-based welfare indicators were used to explore individual risk factors and underlying drivers of colonisation in Swedish dairy calves. Interdependencies between variables led to three different approaches being used to visualize and explore the associations. Combining the results of all methods revealed similar patterns and suggest that healthy animals, actively grooming and interacting with others calves in the group have a higher risk of colonisation than small dairy calves in poor condition (diarrhoea, poor ruminal fill, poor body condition score and nasal discharge). This lends no support to the hypothesis that reduced welfare is a risk factor for VTEC O157:H7, but implies that individual differences in calf behaviour affect oral exposure to the bacteria so driving the risk of colonisation. This new finding has important implications for understanding of VTEC O157:H7 transmission within farms. The zoonotic pathogen verotoxin-producing Escherichia coli serotype O157:H7 (VTEC O157:H7) causes disease and even deaths among people worldwide and Sweden is over represented, having had several major outbreaks 1-3. Many of the Swedish cases of VTEC O157:H7 are connected to strains circulating in the cattle population 2,4,5 and there are higher numbers of human cases in cattle dense areas 6. Although experimental infection with high doses of VTEC O157:H7 may cause diarrhoea in young calves 7 it is does not appear to be generally associated with disease 8 and the most significant animal reservoirs are cattle asymptomatically carrying VTEC O157:H7 in their intestines 9. The primary site of colonisation is considered to be the recto-anal junction in the terminal rectum and colonisation of this region has been associated with high levels of bacterial shedding 10-12. Shedding of more than 10 4 colony forming units (cfu) per gram has been proposed to indicate a "super-shedder" 13 and modelling has suggested that these individuals are responsible for shedding as much as 90% of total bacteria in a group 14. It has also been shown that high-level shedders increase contamination levels in the environment, on the hide of animals and increase average shedding levels of pen mates 15-17. More recent studies have questioned the focus on super-shedders and suggested that even lower shedding levels (>10 3 cfu/g faeces) are important for on farm persistence and transmission 18. In all cases, reducing the average shedding rate of animals is an important control measure for preventing transmission from cattle to humans 19,20. Although it appears that all calves can be colonised in experimental studies, usi...

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Molecular Typing of Escherichia coli O157:H7 Isolates from Swedish Cattle and Human Cases: Population Dynamics and Virulence

Cited by 19 publications

References 25 publications

Importance of case age in the purported association between phylogenetics and hemolytic uremic syndrome inEscherichia coliO157:H7 infections

Importance of case age in the purported association between phylogenetics and hemolytic uremic syndrome inEscherichia coliO157:H7 infections

Population and evolutionary dynamics of Shiga‐toxin producing Escherichia coli O157 in a beef herd: A longitudinal study

Socially engaged calves are more likely to be colonised by VTEC O157:H7 than individuals showing signs of poor welfare

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