| 1. |
- Nilsson, Anna, 1986-
(author)
-
Characterization of Campylobacter jejuni and Campylobacter coli water isolates
- 2018
-
Doctoral thesis (other academic/artistic)abstract
- Campylobacter jejuni and C. coli are together the most common cause of bacterial gastroenteritis in the European Union. Campylobacter can be transmitted to humans via contaminated water, but it is largely unknown how these bacteria survive in water.The aim of this thesis was to better understand the water survival strategies and pathogenic potential of Campylobacter water isolates. For this purpose, C. jejuni and C. coli, originally isolated from incoming water at surface water plants, were characterized using whole genome sequencing, phenotypical assays, water survival experiments and an in vitro infection model.C. jejuni water isolates included both common and uncommon sequence types for human pathogens, whereas C. coli isolates were assigned to clades 2 and 3, associated with environmental sources. For C. jejuni, comparative genomics revealed genes involved in oxidative and aerobic stress response. In C. coli, various carbon metabolism-related sequences were identified in clade 2 isolates and in clade 3 isolates, oxidative stress and putative virulence genes were detected. All water isolates were motile and the majority of C. jejuni isolates, but none of C. coli isolates, were able to form biofilm. C. jejuni survived better than C. coli in untreated well and lake water. Furthermore, in contrast to C. coli, a seasonal difference in survival was observed for C. jejuni with better survival in lake water collected during autumn than in spring. When tested in an in vitro infection model, all water isolates adhered to and induced IL-8 response in HT-29 cells indicating pathogenic potential. However, C. coli clade 3 isolates demonstrated a strong cytotoxic effect on human HT-29 cells leading to rapid cell death. This novel phenomenon was not observed for C. coli clade 2 or C. jejuni isolates.This is, to the best of our knowledge, the first study on Campylobacter water isolates characterized using genomic, phenotypical and in vitro infection analyses. These findings suggest that some Campylobacter isolates might survive better than others in water and water survival patterns shown here help us further understand the seasonality and predominance of water-related C. jejuni infections.
|
|
| 2. |
- Nilsson, Anna, et al.
(author)
-
Characterization of Swedish Campylobacter coli clade 2 and clade 3 water isolates
- 2018
-
In: MicrobiologyOpen. - : Wiley. - 2045-8827. ; 7:4
-
Journal article (peer-reviewed)abstract
- Campylobacter jejuni and Campylobacter coli are important bacterial enteropathogens. Poultry is the best-known reservoir for Campylobacter infection but natural bodies of water have also been shown to be important pathways for transmission. Campylobacter can survive in cold water but most of the studies have focused on C. jejuni only. In this paper, we take a closer look at the biology and water survival strategies of C. coil. Eight C. coil isolates cultivated from raw (incoming) surface water at water plants in Sweden were characterized using whole-genome sequencing and phenotypical assays. Phylogenetic analysis assigned the Swedish water isolates to clades 2 and 3, known to include C. coil of environmental origin. In addition, 53 earlier published sequences of C. coil clade 2 and 3 from environmental waters were included for in silico analyses. Generally, clade 2 isolates had larger genomes, which included a functional tricarballylate utilization locus, while clade 3 isolates contained different genes involved in oxidative stress as well as putative virulence factors. The Swedish water isolates of clade 2 formed large, blurry bacterial colonies on agar, whereas clade 3 colonies were smaller. All Swedish isolates were motile, but clade 3 isolates formed larger motility zones on soft agar, and none of these isolates produced biofilm. Although water survival varied between the analyzed isolates, there were hardly any clade-specific significant differences. Our results highlight the diversity of C. coil in general, and show differences in metabolic capabilities and ways to handle oxidative stress between clade 2 and 3 water isolates.
|
|
| 3. |
- Nilsson, Anna, et al.
(author)
-
Genomic and phenotypic characteristics of Swedish C. jejuni water isolates
- 2017
-
In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 12:12
-
Journal article (peer-reviewed)abstract
- Campylobacter jejuni is the most common cause of bacterial gastroenteritis. Major reservoirs are warm-blooded animals, poultry in particular, but Campylobacter can also be transmitted via water. In this paper, we have taken a closer look at the biology and potential virulence of C. jejuni water isolates. Seven C. jejuni isolates from incoming surface water at water plants in Sweden were characterized with whole genome sequencing and phenotypical testing. Multi locus sequence typing analysis revealed that these isolates belonged to groups known to include both common (ST48CC) and uncommon (ST1275CC, ST683, ST793 and ST8853) human pathogens. Further genomic characterization revealed that these isolates had potential for arsenic resistance (due to presence of arsB gene in all isolates), an anaerobic dimethyl sulfoxide oxidoreductase (in three isolates) and lacked the MarR-type transcriptional regulator gene rrpB (in all but one isolate) earlier shown to be involved in better survival under oxidative and aerobic stress. As putative virulence factors were concerned, there were differences between the water isolates in the presence of genes coding for cytolethal distending toxin (cdtABC), Type VI secretion system and sialylated LOS, as well as in biofilm formation. However, all isolates were motile and could adhere to and invade the human HT-29 colon cancer cell line in vitro and induce IL-8 secretion suggesting potential to infect humans. This is, to the best of our knowledge, the first study where C. jejuni water isolates have been characterized using whole genome sequencing and phenotypical assays. We found differences and shared traits among the isolates but also potential to infect humans.
|
|
| 4. |
- Nilsson, Anna, et al.
(author)
-
Survival of Campylobacter jejuni and C. coli water isolates in lake and well water
- 2018
-
In: Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS). - : Wiley. - 0903-4641 .- 1600-0463. ; 126:9, s. 762-770
-
Journal article (peer-reviewed)abstract
- The role of water for transmission of Campylobacter jejuni and C. coli to humans might be underestimated, as factors important for bacterial viability in water are largely unknown. We have studied water survival of seven C. jejuni and eight C. coli isolates originally isolated from Swedish waters, together with selected reference strains, over eight days at 4 °C in the dark in untreated water collected from a local lake and a private well. To study seasonality, lake water samples were collected during spring and autumn. Samples for culturable bacterial counts were taken on days 2, 4, 6, and 8 and compared to the start inoculum. For C. jejuni, a significantly better survival was observed in autumn than in spring lake water. Furthermore, C. jejuni had a significantly better survival than C. coli in autumn lake and well water samples; the rate of culturability loss was almost double for C. coli in autumn lake water. These findings contribute to a better understanding on the seasonality of waterborne Campylobacter infections and the general predominance of C. jejuni.
|
|
| 5. |
- Skarp, Astrid, et al.
(author)
-
Accessory genetic content in Campylobacter jejuni ST21CC isolates from feces and blood
- 2017
-
In: International Journal of Medical Microbiology. - : Elsevier BV. - 1438-4221 .- 1618-0607. ; 307:4-5, s. 233-240
-
Journal article (peer-reviewed)abstract
- Campylobacter jejuni is an important foodborne pathogen and the most commonly reported bacterial cause of gastroenteritis. C. jejuni is occasionally found in blood, although mechanisms important for invasiveness have remained unclear. C. jejuni is divided into many different lineages, of which the ST21 clonal complex (CC) is widely distributed. Here, we performed comparative genomic and in vitro analyses on 17C. jejuni ST21CC strains derived from human blood and feces in order to identify features associated with isolation site. The ST21CC lineage is divided into two large groups; centered around ST-21 and ST-50. Our clinical strains, typed as ST-50, showed further microevolution into two distinct clusters. These clusters were distinguished by major differences in their capsule loci and the distribution of accessory genetic content, including C. jejuni integrated elements (CJIEs) and plasmids. Accessory genetic content was more common among fecal than blood strains, whereas blood strains contained a hybrid capsule locus which partially consisted of C. jejuni subsp. doylei-like content. In vitro infection assays with human colon cell lines did not show significant differences in adherence and invasion between the blood and fecal strains. Our results showed that CJIEs and plasmid derived genetic material were less common among blood isolates than fecal isolates; in contrast, hybrid capsule loci, especially those containing C. jejuni subsp. doylei-like gene content, were found among many isolates derived from blood. The role of these findings requires more detailed investigation.
|
|
| 6. |
- Skarp, Astrid, et al.
(author)
-
Campylobacteriosis : the role of poultry meat
- 2016
-
In: Clinical Microbiology and Infection. - : Elsevier BV. - 1198-743X .- 1469-0691. ; 22:2, s. 103-109
-
Research review (peer-reviewed)abstract
- The incidence of human infections caused by Campylobacter jejuni and Campylobacter coil, the main bacterial agents of gastrointestinal disease, has been increasing worldwide. Here, we review the role of poultry as a source and reservoir for Campylobacter. Contamination and subsequent colonization of broiler flocks at the farm level often lead to transmission of Campylobacter along the poultry production chain and contamination of poultry meat at retail. Yet Cainpylobacter prevalence in poultry, as well as the contamination level of poultry products, vary greatly between different countries so there are differences in the intervention strategies that need to be applied. Temporal patterns in poultry do not always coincide with those found in human infections. Studies in rural and urban areas have revealed differences in Campylobacter infections attributed to poultry, as poultry seems to be the predominant reservoir in urban, but not necessarily in rural, settings. Furthermore, foreign travel is considered a major risk factor in acquiring the disease, especially for individuals living in the northern European countries. Intervention strategies aimed at reducing Campylobacter colonization in poultry and focused at the farm level have been successful in reducing the number of Campylobacter cases in several countries. Increasing farm biosecurity and education of consumers are likely to limit the risk of infection. Overall, poultry is an important reservoir and source of human campylobacteriosis, although the contribution of other sources, reservoirs and transmission warrants more research.
|
|
| 7. |
- Skarp, Astrid, et al.
(author)
-
Comparative genomics and genome biology of invasive Campylobacter jejuni
- 2015
-
In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 5
-
Journal article (peer-reviewed)abstract
- Campylobacter jejuni is a major pathogen in bacterial gastroenteritis worldwide and can cause bacteremia in severe cases. C. jejuni is highly structured into clonal lineages of which the ST677CC lineage has been overrepresented among C. jejuni isolates derived from blood. In this study, we characterized the genomes of 31 C. jejuni blood isolates and 24 faecal isolates belonging to ST677CC in order to study the genome biology related to C. jejuni invasiveness. We combined the genome analyses with phenotypical evidence on serum resistance which was associated with phase variation of wcbK; a GDP-mannose 4,6-dehydratase involved in capsular biosynthesis. We also describe the finding of a Type III restriction-modification system unique to the ST-794 sublineage. However, features previously considered to be related to pathogenesis of C. jejuni were either absent or disrupted among our strains. Our results refine the role of capsule features associated with invasive disease and accentuate the possibility of methylation and restriction enzymes in the potential of C. jejuni to establish invasive infections. Our findings underline the importance of studying clinically relevant well-characterized bacterial strains in order to understand pathogenesis mechanisms important in human infections.
|
|
| 8. |
- Wahab, Tara, et al.
(author)
-
GIFeGSH : A New Genomic Island Might Explain the Differences in Brucella Virulence
- 2017
-
In: Open Journal of Animal Sciences. - : Scientific Research Publishing, Inc.. - 2161-7597 .- 2161-7627. ; 7, s. 141-148
-
Journal article (peer-reviewed)abstract
- An imported dog was confirmed to be positive with canine brucellosis in Sweden in 2010. The whole genome of Brucella canis SVA10 was subjected to phage analysis (WGS-PA) and was assigned to the Asian B. canis cluster. Further analysis indicated that the genome of B. canis SVA10 is smaller compared to genomes of the same species. A 35,781 bp genomic island (GI) was found to be absent in strain SVA10 which was detected by read mapping the paired reads to the genome of B. canisATCC 23,365T. The lacking genes of genomic island GIFeGSH are mainly coding for iron uptake enzymes and parts of the glutathione pathway. A screening of all available whole genome sequences of Brucella strains confirmed that GIFeGSH is also missing in four more strains of B. canis but present in several strains of B. abortus, B. melitensis, B. suis, B. ovis, B. microti, B. pinnipedialis, and B. ceti. Parts of the GI were present, but scattered in two other B. canis strains. The aim of this study was to find differences in the genomes of Brucella which might explain former described differences in virulence. The analysis was extended to all available Brucella genomes after the detection of a genomic island in strain SVA10.
|
|
