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  • 1.
    Bergström, Sven
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Chromosomal β-lactamases in enterobacteria and in vivo evolution of β-lactam resistance1983Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The ß-lactam antibiotics are the most important antibacterial agents in the treatment of infectious diseases. A severe problem in ß-lactam therapy is the emergence of ß-lactam resistant bacteria. Clinical ß-lactam resistance is most often due to the production of ß-lactamases. ß-lactamase genes reside either on plasmids or on the chromosome. The aim of this study was to acquire an understanding of organisation and regulation of chromosomal ß- lactamase genes in different Gram negative species and to elucidate the mechanisms for ampC hyperproduction in the in vivo situation.

    By DNA hybridization with an ampC probe from Escherichia coli K-12 it was shown that other Gram negative bacteria contained an artpC like chromosomal gene, suggesting a common evolutionary origin. Furthermore, the preceding frd operon that overlaps the ampC gene in E. coli K-12 was found to be much more conserved than the ampC gene in the bacterial species investigated.

    The ampC and frd opérons in Shigella sonnei and Citrobacter freundii were cloned and characterized by physical mapping. The respective maps were compared to the ampC and frd region in E. coli K-12. The physical map of Sh. sonnei was almost identical to the E. coli K-12 map, whereas in C. freundii only the frd region exhibited any considerable homology. Moreover, in C. freundii, the anpC and frd regions were separated by 1100 basepairs. It is suggested that this DNA is involved in the induction of ß-lactamase production in this organism. A hypothesis for the evolution of the anpC operon in enterobacteria is presented.

    By isolating and characterizing six ß-lactam resistant clinica], isolates of E. coli hyperproducing the dhrcmosomal ß-lactamase, genetic mechanisms for in vivo evolved resistance was aimed at. These isolates exhibited a 24-48 fold increase in ß-lactamase production. The ß-lactamase produced was found to be biochemically and immunologically identical to the ß-lactamase produced by E. coli K-12. The ampC control region of these six E. coli isolates was DNA-seqenced. The cause of ß-lactamase hyperproduction in five of the clinical E. coli isolates, identical in the DNA segment sequenced, was due to a strong novel ampC promoter displaced 5 bp upstream of the ampC promoter defined in E. coli K-12. The ß-lactamase hyperproduction in the sixth clinical isolate was shown to be caused by two mutations affecting both the promoter and the attenuator in the regulatory region defined by E. coli K- 12. The obtained changes were sufficient to explain the increase in ampC ß- 1 act ama se expression exhibited in these clinical E. coli isolates.

    Sequence analysis of the ampC control region in Sh. sonnei revealed that it was, with one exception, identical to the one found in the five clinical E. coli ß-lactamase hyperproducers. The only difference was in a position that creates the strong novel ampC promoter in the E. coli hyperproducers. By isolating spontaneous Sh. sonnei mutants with a 40-fold increase in ß-lactamase production carrying the same novel ampC promoter as the clinical E. coli isolates it was concluded that this DNA segment has been transferred in vivo frcm Shigella to E. coli across the species barrier.

  • 2.
    Bergström, Sven
    et al.
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Olsén, Björn
    Umeå universitet, Medicinska fakulteten, Mikrobiologi. Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Allmänmedicin.
    Burman, Nils
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Gothefors, Leif
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Pediatrik.
    Jaenson, Thomas G.T.
    University of Uppsala.
    Jonsson, Maria
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Mejlon, Hans A
    University of Uppsala.
    Molecular characterization of Borrelia burgdorferi isolated from Ixodes ricinus in northern Sweden1992Inngår i: Scandinavian Journal of Infectious Diseases, ISSN 0036-5548, E-ISSN 1651-1980, Vol. 24, nr 2, 181-188 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ixodes ricinus ticks, harbouring Borrelia burgdorferi, were found in an area in northern Sweden, not thought to be endemic for Lyme borreliosis. This investigation took place at Norrbyskär, an island situated in the Bothnian Gulf, 63 degrees 33'N/19 degrees 52'E. One of 42 nymphal and 8/43 adult I. ricinus ticks collected carried spirochetes as seen by phase contrast microscopy. Pure bacterial cultures were obtained from 2 of the ticks. Western blot analysis using species-specific monoclonal antibodies showed that the isolated spirochetes were B. burgdorferi. The identity of the isolated spirochetes was confirmed by DNA amplification using B. burgdorferi OspA and flagellin gene specific oligonucleotides as well as partial DNA sequencing of the respective OspA and flagellin genes. The 2 isolated spirochaete populations were different as shown by their protein profiles in sodium dodecyl sulphate polyacrylamide gels. Moreover, the demonstration of Lyme borreliosis in a patient from the island of Norrbyskär indicates the need for clinical consideration of this disease in northern Sweden.

  • 3.
    Burman, Nils
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Antigenic variation in relapsing fever Borrelia1994Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The spirochete Borrelia hermsii avoids the immune response of its mammalian host through multiphasic antigenic variation. Serotype specificity is determined by Variable major proteins (Vmp), in the outer membrane. Through a non reciprocal recombination between linear plasmids, a formerly silent vmp gene replaces another vmp gene at a telomeric expression locus downstream from a common expression site. B. hermsii before and after the switch from serotype 7 to serotype 21, was examined in detail.

    The nucleotide sequence of the vmp7 and vmp21 genes and flanking regions was determined. The vmp7 and vmp21 are 77% identical in their coding sequence, and the deduced translation products are 63% identical. No antigenic cross reactivity is observed between Vmp7 and Vmp21. This suggests a folding of the proteins in which the similar regions are buried, and not exposed when it is presented at the bacterial surface. Vmp7 and Vmp21 have consensus sequences of prokaryotic lipoproteins and are processed as such when expressed in E. coli.

    The 5' regions of silent and expressed vmp7 and vmp21 were compared. Silent and active vmp7 and vmp21 genes shared a block of homologous sequence at their 5' ends. Sequences upstream of silent vmp7 and vmp21 genes lacked a promoter and differed substantially from each other. In this antigenic switch a vmp gene was activated by a recombination event which placed it downstream of a promoter.

    The vmp gene promoter is preceded by a poly(dT dA) ran and three imperfectlyrepeated elements of 2 kb. Each of the 2 kb repeats contains inverted repeats of approximately 0.2 kb at their termini. There is no evidence of the presence of similar elements elsewhere in the genome of B. hermsii. One or more of these elements may stimulate vmp gene switch or expression.

    The African relapsing fever species Borrelia crocidurae and the American species B. hermsii display many similarities. In both species the vmp genes are localised to linear plasmids, and the vmp genes are activated on the transcriptional level. The nucleotide sequence of their expression sites, however, are not related. Still, the possibility that the switch is mechanistically similar in B. crocidurae and B. hermsii, cannot be ruled out.

    The binding of B. crocidurae causes aggregation of erythrocytes around the spirochete. The aggregation is reminiscent of the erythrocyte rosetting seen in malarial infections. The erythrocytes at the B. crocidurae surface may protect them from clearance by the host. Thus, the rosetting may constitute an additional mechanism in B. crocidurae for the evasion of the immune reaction.

  • 4.
    Bölin, Ingrid
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Temperature-inducible and calcium-regulated proteins encoded by the virulence plasmid of Yersinia1987Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The pathogenic members of the genus Yersinia, Y. pseudotuberculosis, Y. pestis and Y. enterocolitica are transmitted from animals to man and may give rise to disease with a variety of symptoms. These bacteria possess related plasmids necessary for virulence. In this study, gene products encoded by the virulence plasmid have been identified and characterized.

    A temperature-inducible outer membrane protein YOP1, is encoded by the virulence plasmid. YOP1 is expressed by Y. pseudotuberculosis and Y. enterocolitica at 37°C. The genetic locale of trie structural gene for YOPl on the virulence plasmid was determined. A mutant that was unable to express this protein, remained fully virulent, showing that YOP1 is not a virulence determinant.

    Several other proteins encoded by the virulence plasmid are induced at 37°C in a medium lacking Ca2+. These proteins are not expressed at 26°C and expression is repressed by Ca2+-concentrations in excess of 2.5 mM. In Ca2+-deficient medium, the induced proteins can be found extracellu- larly as well as in the outer membrane. However, in the presence of Ca at 37°C they are only found in the outer membrane. The released proteins consist of eight polypeptides as revealed by two-dimensional electro­phoresis. These proteins, Y0P2a and 2b, YOP3, Y0P4a and 4b, the V-antigen and a small uncharacterized polypeptide, are expressed by all three pathogenic Yersinia species, both in vivo and in vitro.

    The Ca2+-controlled expression of the YOP proteins is regulated by genes in the Ca2+ -region, which are conserved in the three species. Mutations in this region repress the expression of the Ca2+-regulated YOPs. The genetic loci identified for five of these proteins revealed that only the structural gene of the Y0P4b protein is part of the Ca2+ -region. The other genes were found at separate locations outside this region. The structural genes for YOP4b, YOP3 and the V-antigen, together with the genes for two additional polypeptides, were localized to a common region conserved on the plasmids of the Yersinia species. The structural genes for Y0P2b (yopH) and Y0P5 (yopE) are located in different positions on the plasmid from Y. enterocolitica, compared to the other two species. This plasmid has Been rearranged so that these genes are located close to one another.

    The DNA sequence of the yopH gene shows that it is a singly transcrip­tional unit. Transcription of this gene is regulated by Ca2+-concentra­tion and by temperature. A mutant strain of Y. pseudo tuberculosis, de­leted for the yopH gene on the virulence plasmid, is avirulent In mice. Virulence is restored by trans-complementation with the cloned yopH gene. The mutant strain is also’ unable to inhibit phagocytosis of macrophages as compared to the wild-type strain. The trans-compleroented strain shows inhibition comparable to that of the wild-type. Therefore, the YOP2b protein is considered to be an essential virulence determinant.

  • 5.
    Holmström, Anna
    et al.
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Rosqvist, Roland
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Wolf-Watz, Hans
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Forsberg, Åke
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Virulence plasmid-encoded YopK is essential for Yersinia pseudotuberculosis to cause systemic infection in mice.1995Inngår i: Infection and Immunity, ISSN 0019-9567, E-ISSN 1098-5522, Vol. 63, nr 6, 2269-2276 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The virulence plasmid common to pathogenic Yersinia species encodes a number of secreted proteins denoted Yops (Yersinia outer proteins). Here, we identify and characterize a novel plasmid-encoded virulence determinant of Yersinia pseudotuberculosis, YopK. The yopK gene was found to be conserved among the three pathogenic Yersinia species and to be homologous to the previously described yopQ and yopK genes of Y. enterocolitica and Y. pestis, respectively. Similar to the other Yops, YopK expression and secretion were shown to be regulated by temperature and by the extracellular Ca2+ concentration; thus, yopK is part of the yop regulon. In addition, YopK secretion was mediated by the specific Yop secretion system. In Y. pseudotuberculosis, YopK was shown neither to have a role in this bacterium's ability to resist phagocytosis by macrophages nor to cause cytotoxicity in HeLa cells. YopK was, however, shown to be required for the bacterium to cause a systemic infection in both intraperitoneally and orally infected mice. Characterization of the infection kinetics showed that, similarly to the wild-type strain, the yopK mutant strain colonized and persisted in the Peyer's patches of orally infected mice. A yopE mutant which is impaired in cytotoxicity and in antiphagocytosis was, however, found to be rapidly cleared from these lymphoid organs. Neither the yopK nor the yopE mutant strain could overcome the primary host defense and reach the spleen. This finding implies that YopK acts at a different level during the infections process than the antiphagocytic YopE cytotoxin does.

  • 6.
    Jeppsson, Jan-Olof
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Structural studies on human transferrin1967Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This review is a dissertation and contains a summary of the following publications:

    I. J.-O Jeppsson and J. Sjöquist: Separation of Normal Human Transferrin into Two Fractions. Biochim. Biophys. Actay 78 (1963) 658

    II. J.-O. Jeppsson: Isolation and Partial Characterization of Three Human Transferrin Variants. Biochim. Biophys. Acta, 1967, in press

    III. J.-O. Jeppsson: Subunits of Human Transferrin. Acta Chem. Scand.1967, in press

    IV. J.-O. Jeppsson and J. Sjöquist: Thin-layer Chromatography of PTH Amino Acids. Analyt. Biochem. 18 (1967) 264

    V. J.-O. Jeppsson: Structural Studies of Fragments Resulting from Cyanogen Bromide Degradation of Human Transferrin. Biochim. Biophys. Acta, 1967, in press.

    In addition the dissertation contains some hitherto unpublished results. In the text the above mentioned papers will be referred to by the Roman figures I — V, other references are indicated by Arabic figures.

  • 7.
    Johansson, J
    et al.
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Eriksson, S
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Sondén, B
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Wai, S N
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Uhlin, B E
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Heteromeric interactions among nucleoid-associated bacterial proteins: localization of StpA-stabilizing regions in H-NS of Escherichia coli.2001Inngår i: Journal of Bacteriology, ISSN 0021-9193, E-ISSN 1098-5530, Vol. 183, nr 7, 2343-2347 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The nucleoid-associated proteins H-NS and StpA in Escherichia coli bind DNA as oligomers and are implicated in gene regulatory systems. There is evidence for both homomeric and heteromeric H-NS-StpA complexes. The two proteins show differential turnover, and StpA was previously found to be subject to protease-mediated degradation by the Lon protease. We investigated which regions of the H-NS protein are able to prevent degradation of StpA. A set of truncated H-NS derivatives was tested for their ability to mediate StpA stability and to form heteromers in vitro. The data indicate that H-NS interacts with StpA at two regions and that the presence of at least one of the H-NS regions is necessary for StpA stability. Our results also suggest that a proteolytically stable form of StpA, StpA(F21C), forms dimers, whereas wild-type StpA in the absence of H-NS predominantly forms tetramers or oligomers, which are more susceptible to proteolysis.

  • 8.
    Jonsson, Maria
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Contribution of the outer surface proteins of Borrelia burgdorferi s.l. to the pathogenesis of Lyme disease1994Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Borrelia burgdorferi s. l. is a spirochete which causes the multisystemic disorder Lyme disease. As the borreliae lack toxin production, the pathogenicity is thought to involve, at least in part, molecules from the outer surface. Most Lyme disease Borrelia strains express two major outer surface lipoproteins, OspA (31 kD) and OspB (34 kD), on their surface. However, some strains lack the expression of OspA and OspB, but express a smaller 21 to 25 kD OspC protein instead. This thesis focuses on the importance of these proteins in the pathogenesis of Lyme disease.

    Biochemical and immunochemical studies of the OspA and OspB proteins from strains of various geographic origins show considerable differences in the apparent molecular weights and in their reactivities to monoclonal antibodies. The cloning and sequencing of the ospAB opérons from strains of different origins has demonstrated that the heterogeneity is found also at the DNA level Comparison of the ospAB sequences allows the classification of the strains into three types, which coincide with the recent species designations, B. burgdorferi sensu stricto, B. afzelii and B. garinii The genes are located on a linear plasmid about 50 kb in size, and are cotranscribed as a single message.

    The expression of the osp operon in different strains was studied by Western blot and Northern blot analysis. The ospAB operon of strains expressing varying amounts of the Osp proteins was cloned and sequenced. The DNA sequence was found to be >99% identical. The regulation appears to be primarily at the transcriptional level.

    In patients who have received incomplete treatment, B. burgdorferi have been isolated several years after the onset of the disease. As mentioned above, the ospAB loci of different strains show considerable heterogeneity, and it has been speculated that the spirochetes evade the host’s immune system by antigenic variation of the Osp proteins. In a mouse model system it was shown that no variation of the osp genes occurs over the course of an infection, and that other escape mechanisms must be used.

    The OspB proteins in particular have been shown to be very heterogeneous in different isolates. The MAb 84C recognizes a wide variety of B. burgdorferi strains, and the binding epitope was mapped to a conserved region in the carboxyl terminus of the OspB protein with putative structural and/or functional importance.

    It is well known that antibodies can kill bacteria in the presence of complement and phagocytes. Some antibodies seem to have a bactericidal effect by themselves. H6831 is a monoclonal antibody recognizing the OspB protein of some B. burgdorferi strains. The bactericidal action of univalent FAb fragments from H6831 was further characterized, and the binding epitope was mapped to a very heterogeneous region of the carboxyl end of the OspB protein.

  • 9.
    Jonsson, Maria
    et al.
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Bergström, Sven
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Transcriptional and translational regulation of the expression of the major outer surface proteins in Lyme disease Borrelia strains1995Inngår i: Microbiology, ISSN 1350-0872, E-ISSN 1465-2080, Vol. 141, nr 6, 1321-1329 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The major outer surface proteins of Lyme disease spirochaetes are differentially expressed in different isolates. Borrelia afzelii strain F1 expresses none, or very low amounts, of the OspA and OspB proteins. To elucidate the mechanisms that control the expression of these abundant surface proteins the ospAB operon of B. afzelii F1 was cloned, sequenced and compared to the previously sequenced ospAB operon of B. afzelii ACAI and Borrelia burgdorferi B31. The two B. afzelii strains showed almost 100% identity at the DNA level, although Coomassie-stained gels and Western blot analyses showed significant variation in the Osp protein content. Transcriptional analysis revealed that the amount of ospAB mRNA produced in B. afzelii F1 varies more than the amount of protein, suggesting that the expression of OspA and OspB proteins is regulated at both the transcriptional and the translational level. Furthermore, the inverse relationship between the transcription of ospC and the ospAB operon could indicate coregulation of these separately encoded operons.

  • 10.
    Jonsson, Maria
    et al.
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Elmros, Teodor
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Bergström, Sven
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Subcutaneous implanted chambers in different mouse strains as an animal model to study genetic stability during infection with Lyme disease Borrelia1995Inngår i: Microbial Pathogenesis, ISSN 0882-4010, E-ISSN 1096-1208, Vol. 18, nr 2, 109-14 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Tissue metal net cages were implanted subcutaneously in BALB/cJ and C3H/Tif mice as an experimental model of Borrelia burgdorferi infection. B. burgdorferi sensu stricto strain Sh2-82 could be isolated up to 14 weeks after the inoculation. However, a significant difference in infectivity between the two mice strains was observed. C3H/Tif mice were more susceptible to developing chronic B. burgdorferi s.s. infections than BALB/cJ mice. Although a B. burgdorferi infection was established, no rearrangements in the ospA and ospB genes were observed in any of the infected mice.

  • 11.
    Norlander, Lena
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Genome organisation and genetic exchange mechanisms in Neisseria gonorrhoeae: possible implications for cell surface lability and pathogenicity1980Doktoravhandling, med artikler (Annet vitenskapelig)
  • 12.
    Olsen, Björn
    Umeå universitet, Medicinska fakulteten, Mikrobiologi. Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi, Infektionssjukdomar.
    Birds and Borrelia1995Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The Lyme disease causing spirochaete Borrelia burgdorferi sensu lato is transmitted by ticks within the genus Ixodes. These ticks are liberal host seekers and parasitise mammals, birds and reptiles.

    Prior to this study, the distribution of I. ricinus ticks and Lyme disease was thought to be restricted to the southern half of Sweden. On the island Norrbyskär, located in the Bothnian Gulf, there were reports of a high incidence of tick infestation on humans. To investigate the occurrence of B. burgdorferi s.l. in these ticks and to characterise presumptive isolates at the molecular level we sampled a number of I. ricinus ticks. Three different isolates were obtained from two different ticks, NBS16 from a nymph and NBS23a and NBS23b from an adult female tick.

    The seabird associated tick I. uriae is circumpolar distributed in both hemispheres. On the island Bonden, which house one of the largest seabird colonies in the Baltic Sea, I. uriae were collected and surveyed for spirochaetes. One isolate of B. burgdorferi s.l. was obtained. This B. burgdorferi s.l. isolate is identical to the Lyme disease Borrelia strain NBS16 isolated from Norrbyskär.

    To investigate the role of seabirds in the epidemiology of B. burgdorferi s.l., I. uriae were collected from seabird colonies in the southern and northern hemispheres. Borrelia DNA was extracted from the ticks and from cultured spirochaetes. Sequence analysis of the flagellin gene revealed that the DNA obtained was from B. garinii, regardless of the geographical origin of the sample. Identical fla gene fragments in ticks collected in both hemispheres indicate a transhemispheric exchange of B. garinii. A marine ecological niche and epidemiological route for Lyme disease Borrelia are proposed.

    The prevalence of B. burgdorferi s.l. infected ticks on migrating passerine birds was studied. A total of 22, 998 birds were caught and examined for ticks. The presence of spirochaetes in the 967 collected ticks was determined by DNA amplification by PCR on all ticks. To determine which B. burgdorferi s.l. species were present, classification was performed by DNA amplification using species-specific 16S rDNA primers and by DNA sequencing. Flagellin gene sequences of all species of B. burgdorferi s.l. previously recorded in Europe were found. B. garinii was the most prevalent. These data support the notion that passerine birds are at least partly responsible for the distribution of Lyme disease Borrelia spirochaetes in Europe.

    To elucidate the distribution of B. burgdorferi s.l. in subarctic regions, strains isolated from I. ricinus and I. uriae ticks found on islands in the northern Atlantic and Baltic Sea were characterised molecularly. All isolates were verified as B. garinii by 16S-rRNA gene analysis and immunoblotting using monoclonal antibodies specific for the outer surface proteins A and C. Three ribotypes (RT's) of B. garinii were found. The I. ricinus associated RT1 is phenotypically the most heterogeneous. RT2 is restricted to the islands in the northern Baltic Sea, whereas RT3 was also recovered from ticks found on islands in the North Atlantic. The heterogeneity of the B. garinii population in the Baltic Sea might be influenced by two geographically opposite directions, North Atlantic (RT3) and Euroasia (RT1).

  • 13.
    Palmgren, Helena
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi, Infektionssjukdomar.
    Aspán, A.
    Department of Bacteriology, National Veterinary Institute, SE-750 07 Uppsala, Sweden.
    Bengtsson, K.
    Broman, Tina
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi, Infektionssjukdomar. Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi, Klinisk bakteriologi.
    Blomquist, L.
    Bergström, Sven
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Sellin, Mats
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi, Klinisk bakteriologi.
    Wollin, R.
    Department of Bacteriology, Swedish Institute for Infectious Disease Control, Solna, Sweden.
    Olsen, Björn
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi, Infektionssjukdomar.
    Salmonella carriage in European Black headed gulls (Larus ridibundus) in SwedenManuskript (preprint) (Annet vitenskapelig)
  • 14.
    Palmgren, Helena
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi, Infektionssjukdomar.
    McCafferty, D.
    British Antarctic SurŠey, National EnŠironment Research Council, Cambridge, UK.
    Aspán, A.
    Department of Bacteriology, National Veterinary Institute, Uppsala, Sweden.
    Broman, Tina
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi, Infektionssjukdomar. Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi, Klinisk bakteriologi.
    Sellin, Mats
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi, Klinisk bakteriologi.
    Wollin, R.
    Department of Bacteriology, Swedish Institute for Infectious Disease Control, Solna, Sweden.
    Bergström, Sven
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Olsen, Björn
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi, Infektionssjukdomar. Department of Infectious Diseases, Kalmar County Hospital, S-381 95 Kalmar, Sweden.
    Salmonella in sub-Antarctica: low heterogeneity in salmonella serotypes in South Georgian seals and birds2000Inngår i: Epidemiology and Infection, ISSN 0950-2688, E-ISSN 1469-4409, Vol. 125, nr 2, 257-262 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The number of human visitors to Antarctica is increasing rapidly, and with it a risk of introducing infectious organisms to native animals. To study the occurrence of salmonella serotypes in sub- Antarctic wildlife, faecal samples were collected from gentoo penguins, macaroni penguins, gray-headed albatrosses, black-browed albatrosses and Antarctic fur seals on Bird Island in the South Georgian archipelago during the austral summer of 1996 and 1998. In 1996, S. havana, S. typhimurium and S. enteritidis were isolated from 7% of gentoo penguins and 4% of fur seals. In 1998, however, 22% of fur seals were found to be infected with S. havana, S. enteritidis and S. newport. All isolates, except one, showed identical pulsed-field gel electrophoresis-patterns within each serotype, irrespective of sampling year and animal reservoir. No significant antibiotic resistance was found. The very low heterogeneity in the salmonella isolates found could either indicate a high genetic adaptation of the bacteria to the environment or a recent introduction of salmonella into the area.

  • 15.
    Palmgren, Helena
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi, Infektionssjukdomar.
    Sellin, Mats
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi, Klinisk bakteriologi.
    Bergström, Sven
    Umeå universitet, Medicinska fakulteten, Mikrobiologi.
    Olsen, Björn
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi, Infektionssjukdomar.
    Enteropathogenic Bacteria in Migrating Birds Arriving in Sweden1997Inngår i: Scandinavian Journal of Infectious Diseases, ISSN 0036-5548, E-ISSN 1651-1980, Vol. 29, nr 6, 565-568 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Birds have been thought to play a role in transmitting infectious agents like influenza, Borrelia and Salmonella. To investigate the role of migrating birds in the dispersal of enteropathogenic bacteria, stool samples from 151 wild birds (50 gulls and 101 passerines) just entering Sweden from their winter grounds were analysed for Salmonella spp., Campylobacter spp. and EHEC O157:H7. The thermophilic isolated enteropathogens found were further analysed by antibiograms. Among the 50 gulls examined, we found 2 isolates of Salmonella typhimurium with multiple antibiotic resistance. Three isolates of C. jejuni were found in the 101 stool samples from passerines. We did not isolate EHEC O157:H7 in any of the bird stools examined.

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