| 1. |
- Ellström, Patrik, et al.
(författare)
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Lipooligosaccharide locus classes and putative virulence genes among chicken and human Campylobacter jejuni isolates
- 2016
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Ingår i: BMC Microbiology. - : Springer Science and Business Media LLC. - 1471-2180. ; 16
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Tidskriftsartikel (refereegranskat)abstract
- Background: Campylobacter cause morbidity and considerable economic loss due to hospitalization and post infectious sequelae such as reactive arthritis, Guillain Barr-and Miller Fischer syndromes. Such sequelae have been linked to C. jejuni harboring sialic acid structures in their lipooligosaccharide (LOS) layer of the cell wall. Poultry is an important source of human Campylobacter infections but little is known about the prevalence of sialylated C. jejuni isolates and the extent of transmission of such isolates to humans. Results: Genotypes of C. jejuni isolates from enteritis patients were compared with those of broiler chicken with pulsed-field gel electrophoresis (PFGE), to study the patterns of LOS biosynthesis genes and other virulence associated genes and to what extent these occur among Campylobacter genotypes found both in humans and chickens. Chicken and human isolates generally had similar distributions of the putative virulence genes and LOS locus classes studied. However, there were significant differences regarding LOS locus class of PFGE types that were overlapping between chicken and human isolates and those that were distinct to each source. Conclusions: The study highlights the prevalence of virulence associated genes among Campylobacter isolates from humans and chickens and suggests possible patterns of transmission between the two species.
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| 2. |
- Johansson, Cecilia, et al.
(författare)
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Campylobacter coli clade 3 isolates induce rapid cell death in vitro
- 2019
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Ingår i: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 85:5
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Tidskriftsartikel (refereegranskat)abstract
- Campylobacter are major human enteropathogens. C. coli show less genetic diversity than C. jejuni and cluster into three clades, of which clade 1 includes most human and farm animal isolates while environmental C. coli mainly belong to clades 2 and 3. Recently, we whole genome-sequenced eight C. coli clade 2 and 3 isolates cultivated from water, and here we studied their interaction with human HT-29 colon cancer cells compared to clinical clade 1 isolates. All C. coli clade 3 isolates caused cell necrosis already 1-2 hours after inoculation, whereas none of the clade 1 and 2 isolates analyzed induced cell death. Isolates from clades 2 and 3 adhered better than clade 1 isolates to epithelial cells but all isolates induced similar levels of IL-8. Alignment and phylogenetic analysis of translated putative virulence genes cadF, flpA, iamA, ciaB and ceuE revealed clade-specific protein sequence variations with clade 1 and 2 sequences more closely related and clade 3 sequences further apart in general.Moreover, when RNA levels were measured, clade 3 isolates showed a significantly lower expression of cadF, iamA and ceuE than clade 2 isolates, while flpA levels were higher in clade 3 isolates. The cytolethal distending toxin genes were also expressed in clades 2 and 3 although there was no difference between clades. Our findings demonstrate differences between effects of C. coli clade 1, 2 and 3 isolates on human cells and suggest that C. coli clade 3 might be more virulent than clade 2 due to the observed cytotoxicity.IMPORTANCECampylobacter coli is a common zoonotic cause of gastroenteritis in humans worldwide. The majority of infections are caused by C. coli clade 1 isolates, whereas infections due to clade 2 and 3 isolates are rare. Whether this depends on a low prevalence of clade 2 and 3 isolates in reservoirs important for human infections or their lower ability to cause human disease is unknown. Here, we studied the effects of C. coli clade 2 and 3 isolates on a human cell line. These isolates adhered to human cells to a higher degree than clinical clade 1 isolates. Furthermore, we could show that C. coli clade 3 isolates rapidly induced cell death suggesting differences in the virulence of C. coli The exact mechanism of cell death remains to be revealed but selected genes showed interesting clade-specific expression patterns.
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| 3. |
- Johansson, Cecilia, et al.
(författare)
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Differences in virulence gene expression between human blood and stool Campylobacter coli clade 1 ST828CC isolates
- 2019
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Ingår i: Gut Pathogens. - : BioMed Central. - 1757-4749. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Campylobacter colonise the gastrointestinal tract of warm-blooded animals and are major enteropathogens in humans. C. coli is less common than C. jejuni and accounts for about 10% of the total number of Campylobacter infections although the two species seem to share many virulence determinants. Campylobacter bacteraemia is rare, estimated to occur in less than 1% of the infections, and the exact mechanisms regulating the progression of the infection from the gastrointestinal tract to the blood stream are unclear. Here, we looked at the contribution of C. coli to Campylobacter infections and further compared various virulence traits in C. coli clade 1 blood and stool isolates. Results: We assessed the numbers of C. jejuni and C. coli among typed isolates in the PubMLST database and found that C. coli accounted for 25.9% of blood isolates, but only 8.9% of the stool isolates. Phylogenetic analysis of 128 C. coli clade 1 whole genome sequences deposited to NCBI revealed no specific clustering of the human blood, stool or animal isolates. Of the six C. coli isolates chosen for phenotypic analyses, stool isolates adhered significantly better to human HT-29 colon cancer cells than the blood isolates, while there was no difference in induced IL-8 levels between the isolates. Furthermore, the stool isolates had two-to fourfold higher RNA expression levels of the flpA, ciaB, iamA and cdt virulence genes than the blood isolates. Finally, we looked at the gene structure of the cdtA, B and C toxin genes and found numerous nucleotide additions and deletions disrupting the open reading frames. In contrast to 58% isolates of animal origin, only 38% and 32% of human blood and stool isolates, respectively, had all three cdt genes intact, a prerequisite to produce functional toxins. Conclusions: This study reveals interesting differences between C. coli clade 1 isolates of human and animal origin on one hand, and also between human blood and stool isolates, on the other. The results suggest that C. coli might downregulate and/or inactivate various virulence determinants as the isolates pass from the animal host to the human gastrointestinal tract and enter the human blood stream.
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| 4. |
- Johansson, Cecilia, et al.
(författare)
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Staphylococcus argenteus and Staphylococcus schweitzeri are cytotoxic to human cells in vitro due to high expression of alpha-hemolysin Hla
- 2019
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Ingår i: Virulence. - : Taylor & Francis. - 2150-5594 .- 2150-5608. ; 10:1, s. 502-510
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Tidskriftsartikel (refereegranskat)abstract
- Staphylococcus argenteus and Staphylococcus schweitzeri are newly identified species of the S. aureus-related complex. S. argenteus, as occurring globally and showing significant prevalence and comparable infection and morbidity rates compared to S. aureus, is becoming clinically important. Whole genome sequencing has revealed the presence of several virulence genes but the molecular mechanisms of S. argenteus infection and virulence are largely unknown. Here, we studied the effect of a previously characterized clinical S. argenteus isolate on human cells in vitro. The clinical isolate, together with the S. argenteus type strain MSHR1132T and the S. schweitzeri type strain FSA084T, had a cytotoxic effect on the cells, which showed necrotic cell death after a few hours of treatment. The protein causing the cytotoxic effect was purified and identified by mass spectrometry as alpha-hemolysin, Hla, which is awell-known pore-forming toxin in S.aureus. The cytotoxic effect could be blocked with an antibody against Hla. S.argenteus showed 12-15 fold higher expression levels of hla at the RNA level and 4-6 fold higher expression levels at the protein level compared to S.aureus. The higher expression levels of hla were supported by higher RNA levels of the regulatory factors sarA and saeR. Also, the RNAIII component of the accessory gene regulator (agr) quorum sensing system was 8,000-10,000 fold higher in the S.argenteus isolates compared to S.aureus. This is the first study on the effect of S.argenteus on ahuman cell line and strengthens the idea of significant virulence of S.argenteus.
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| 5. |
- Kaden, Rene, 1975-, et al.
(författare)
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Which methods are appropriate for the detection of Staphylococcus argenteus and is it worthwhile to distinguish S. argenteus from S. aureus?
- 2018
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Ingår i: Infection and Drug Resistance. - 1178-6973. ; 11, s. 2335-2344
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To further analyze a clinical isolate originally identified as methicillin-resistant Staphylococcus aureus (MRSA) using whole-genome sequencing and comparative genomics.Materials and methods: Classical diagnostic methods such as cultivation, biochemical tests, and PCR were supplemented with whole-genome sequencing and comparative genomics, to identify the isolate.Results: The isolate was phenotypically similar to MRSA. However, the presence of the nuc gene could not be confirmed using PCR, while it was positive for the mecA gene. Whole-genome sequencing correctly identified the isolate as Staphylococcus argenteus. The isolate possessed several resistance genes, such as mecA, blaZ (beta-lactam antibiotics) and dfrG (trimethoprim). The me gene differed from that of MRSA. Six phylogenetic distinct clusters were identified by average nucleotide identity (ANI) analysis of all available S. argenteus whole-genome sequences. Our isolate, RK308, clustered with those isolated in Europe and Asia.Conclusion: Due to the invasive potential, the multi-drug resistance and the similarity to MRSA, S. argenteus should be included in the MRSA screening. Due to the divergent genome compared to MRSA, new PCR approaches have to be developed to avoid an unnoticed spreading of S. argenteus.
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| 6. |
- Kampmann, C., et al.
(författare)
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Composition of human faecal microbiota in resistance to Campylobacter infection
- 2016
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Ingår i: Clinical Microbiology and Infection. - : Elsevier BV. - 1198-743X .- 1469-0691. ; 22:1, s. 1-61
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Tidskriftsartikel (refereegranskat)abstract
- In mice, specific species composition of gut microbiota enhances susceptibility to Campylobacter jejuni but little is known about the specific composition of the human gut microbiota in providing protection from infections caused by enteropathogens. Healthy adult individuals, who travelled in groups from Sweden to destinations with an estimated high risk for acquisition of Campylobacter infection, were enrolled. Faecal samples, collected before travelling and after returning home, were cultured for bacterial enteropathogens, and analysed for Campylobacter by PCR and for the species composition of the microbiota by 16S amplicon massive parallel sequencing. The microbiota compositions were compared between persons who became infected during their travel and those who did not. A total of 63 participants completed the study; 14 became infected with Campylobacter, two with Salmonella and 47 remained negative for the enteropathogens tested. After exclusion of samples taken after antimicrobial treatment, 49 individuals were included in the final analyses. Intra-individual stability of the microbiota was demonstrated for samples taken before travelling. The original diversity of the faecal microbiota was significantly lower among individuals who later became infected compared with those who remained uninfected. The relative abundances of bacteria belonging to the family Lachnospiraceae, and more specifically its two genera Dorea and Coprococcus, were significantly higher among those who remained uninfected. The travel-related infection did not significantly modify the faecal microbiota composition. Species composition of human gut microbiota is important for colonization resistance to Campylobacter infection. Especially individuals with a lower diversity are more susceptible to Campylobacter infection.
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| 7. |
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| 8. |
- Lepuschitz, Sarah, et al.
(författare)
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Multicenter Study of Cronobacter sakazakii Infections in Humans, Europe, 2017
- 2019
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Ingår i: Emerging Infectious Diseases. - : Centers for Disease Control and Prevention (CDC). - 1080-6040 .- 1080-6059. ; 25:3, s. 515-522
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Tidskriftsartikel (refereegranskat)abstract
- Cronobacter sakazakii has been documented as a cause of life-threating infections, predominantly in neonates. We conducted a multicenter study to assess the occurrence of C. sakazakii across Europe and the extent of clonality for outbreak detection. National coordinators representing 24 countries in Europe were requested to submit all human C. sakazakii isolates collected during 2017 to a study center in Austria. Testing at the center included species identification by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, subtyping by whole-genome sequencing (WGS), and determination of antimicrobial resistance. Eleven countries sent 77 isolates, including 36 isolates from 2017 and 41 historical isolates. Fifty-nine isolates were confirmed as C. sakazakii by WGS, highlighting the challenge of correctly identifying Cronobacter spp. WGS-based typing revealed high strain diversity, indicating absence of multi-national outbreaks in 2017, but identified 4 previously unpublished historical outbreaks. WGS is the recommended method for accurate identification, typing, and detection of this pathogen.
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| 9. |
- Nilsson, Anna, 1986-
(författare)
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Characterization of Campylobacter jejuni and Campylobacter coli water isolates
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)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.
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| 10. |
- Nilsson, Anna, et al.
(författare)
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Characterization of Swedish Campylobacter coli clade 2 and clade 3 water isolates
- 2018
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Ingår i: MicrobiologyOpen. - : Wiley. - 2045-8827. ; 7:4
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Tidskriftsartikel (refereegranskat)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.
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