Henning Sørum

Norwegian University of Life Sciences (UMB), Aas, Akershus county, Norway

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Publications (92)287.22 Total impact

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    ABSTRACT: Aliivibrio wodanis and Moritella viscosa have often been isolated concurrently from fish with winter-ulcer disease. Little is known about the interaction between the two bacterial species and how the presence of one bacterial species affects the behaviour of the other. The impact on bacterial growth in co-culture was investigated in vitro, and the presence of A. wodanis has an inhibitorial effect on M. viscosa. Further, we have sequenced the complete genomes of these two marine Gram-negative species, and have performed transcriptome analysis of the bacterial gene expression levels from in vivo samples. Using bacterial implants in the fish abdomen, we demonstrate that the presence of A. wodanis is altering the gene expression levels of M. viscosa compared to when the bacteria are implanted separately. From expression profiling of the transcriptomes, it is evident that the presence of A. wodanis is altering the global gene expression of M. viscosa. Co-cultivation studies showed that A. wodanis is impeding the growth of M. viscosa, and that the inhibitorial effect is not contact-dependent.
    BMC Genomics 06/2015; 16(1):447. DOI:10.1186/s12864-015-1669-z · 4.04 Impact Factor
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    ABSTRACT: Sequence variation in a region of the virulence array protein gene (vapA; A-layer) was assessed in 333 ('typical' and 'atypical') isolates of the fish pathogenic bacterium Aeromonas salmonicida. Resulting similarity dendrograms revealed extensive heterogeneity, with nearly all isolates belonging to either of 14 distinct clusters or A-layer types. All acknowledged A. salmonicida subspecies (except ssp. pectinolytica, from which no vapA sequence could be obtained) were clearly separated, and notably, all isolates phenotypically identified as ssp. salmonicida formed a distinct and exclusive A-layer type. Additionally, an array of un-subspeciated atypical strains formed several equally prominent clusters, demonstrating that the concept of typical/atypical A. salmonicida is inappropriate for describing the high degree of diversity evidently occurring outside ssp. salmonicida. Most representatives assessed in this study were clinical isolates of spatiotemporally diverse origins, and were derived from a variety of hosts. We observed that from several fish species or families, isolates predominantly belonged to certain A-layer types, possibly indicating a need for host-/A-layer type-specific A. salmonicida vaccines. All in all, A-layer typing shows promise as an inexpensive and rapid means of unambiguously distinguishing clinically relevant A. salmonicida subspecies, as well as presently un-subspeciated atypical strains. © 2015 John Wiley & Sons Ltd.
    Journal of Fish Diseases 04/2015; DOI:10.1111/jfd.12367 · 1.51 Impact Factor
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    ABSTRACT: Antibiotic resistance is a threat to human and animal health worldwide, and key measures are required to reduce the risks posed by antibiotic resistance genes that occur in the environment. These measures include the identification of critical points of control, the development of reliable surveillance and risk assessment procedures, and the implementation of technological solutions that can prevent environmental contamination with antibiotic resistant bacteria and genes. In this Opinion article, we discuss the main knowledge gaps, the future research needs and the policy and management options that should be prioritized to tackle antibiotic resistance in the environment.
    Nature Reviews Microbiology 03/2015; 13(5). DOI:10.1038/nrmicro3439 · 23.32 Impact Factor
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    ABSTRACT: Insertion sequence (IS) elements are short, self-replicating DNA sequences that are capable of efficiently spreading over the host genome. Possessing varied integration specificity IS elements are capable of the irreversible inactivation of genes, which diversifies the pool of intact genetic determinants in host populations. In the current study, we performed a complex analysis of IS elements (Vsa IS) in the previously sequenced genome of Aliivibrio salmonicida LFI1238 and proposed a model of the spread of the Vsa IS elements over the genome of this microorganism. Along with the prediction of the integration sites for Vsa IS elements, the current study provides an overview of the properties of A. salmonicida IS elements, as well as information regarding their occurrence in different bacterial classes. An analysis of individual alleles of the IS elements has allowed us to depict a history of the accumulation of mutations and to describe distinctive microevolution lines for actively transposing Vsa IS elements in the genome of A. salmonicida LFI1238. Our results demonstrate the high importance of the dead end microevolution of actively transposing Vsa IS elements for the inactivation of genes in A. salmonicida LFI1238.
    Gene 01/2015; 554(1). DOI:10.1016/j.gene.2014.10.019 · 2.08 Impact Factor
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    ABSTRACT: A diagnosis of bacterial cystitis commonly relies on a positive microbiological culture demonstrating the presence of a significant number of colony-forming units/ml urine, as urine within the upper urinary tract, bladder and proximal urethra generally is considered sterile. Recent studies from human and veterinary medicine indicate the presence of non-culturable bacteria in culture-negative urine samples. The aim of the present study was to determine the occurrence of bacterial DNA in culture-negative urine samples from cats with signs of feline lower urinary tract disease (FLUTD) and healthy control cats by 16S ribosomal DNA PCR and subsequent sequencing. The study sample included 38 culture-negative urine samples from cats with FLUTD and 43 culture-negative samples from control cats. Eight culture-positive urine samples from cats with FLUTD were included as external positive controls in addition to negative reaction controls. Of possible methodological limitations, degradation of DNA due to storage, the use of non-sedimented urine for DNA isolation and lack of internal positive reaction controls should be mentioned. The positive controls were recognised, but occurrence of bacterial DNA in culture negative urine from cats with or without signs of lower urinary tract disease was not demonstrated. However, considering the possible methodological limitations, the presence of bacterial DNA in the urine of culture-negative FLUTD cats cannot be excluded based on the present results alone. Therefore, a prospective study reducing the possibility of degradation of DNA due to storage in combination with modifications enhancing the chance of detecting even lower levels of bacterial DNA in culture-negative samples seems warranted. © ISFM and AAFP 2014.
    Journal of Feline Medicine & Surgery 12/2014; DOI:10.1177/1098612X14563098 · 1.22 Impact Factor
  • S.Q.A. Shah · H. Sørum
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    ABSTRACT: Pseudomonas fluorescens isolates from Tanzanian tilapia ponds were found to possess a gene encoding a TetR-like transcriptional regulator protein. Phylogenetic analysis revealed close similarity to five previously reported GeneBank sequences which cluster separately from the other 70 members of this family. It is assumed that this TetR-like protein belongs to a new family of TetR-like proteins that has no direct link to the class 1 integron.
    Journal of applied genetics 11/2014; 55(4):1-4. DOI:10.1007/s13353-014-0221-1 · 1.90 Impact Factor
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    ABSTRACT: Moritella viscosa is the aetiological agent of winter-ulcer disease in farmed salmonids in the North Atlantic. Previously, two major (typical and variant) genetic clades have been demonstrated within this bacterial species, one of which is almost solely related to disease in Atlantic salmon (Salmo salar). In the present study infection trials demonstrated that 'typical' M. viscosa isolated from Norwegian Atlantic salmon was highly virulent in this fish species but resulted in lower levels of mortality in rainbow trout. 'Variant' M. viscosa isolated from rainbow trout resulted in modest mortality levels in both Atlantic salmon and rainbow trout. To investigate the possible genetic background for inter-strain virulence differences, 38 M. viscosa isolates of diverse geographical origin and host species and a number of other Moritella spp. were investigated for the presence/absence of putative virulence related homologs. All isolates were positive for DNA sequences coding for; the Type VI secretion ATPase (clpV), hemolysin co-regulated protein (hcp), bacterioferritins (bfrA and bfrB), lectin (hemG), phospholipase D (pld), multifunctional autoprocessing repeats-in-toxin (martxA), aerolysin (aer), invasin (inv), and cytotoxic necrotizing factor (cnf), with the exception of one isolate in which cnf could not be confirmed. The product of an ABC transporter metal-binding lipoprotein (mat) was consistently detected although 11 isolates, all phylogenetically related, appear to produce a truncated version. A putative insecticidal toxin complex (mitABC) was detected almost exclusively in 'typical' Atlantic salmon isolates, and our data indicate that this complex of genes is expressed and co-transcribed. Transmission electron microscopy investigation revealed pili and flagella surface structures on nine M. viscosa representing both typical and variant isolates. Our results provide strong support for the existence of host specificity/high virulence in 'typical' M. viscosa related to Atlantic salmon. The gene distribution also provides further support for the genetic division within M. viscosa, and constitutes a basis for further study of the importance of the mitABC complex in winter-ulcer pathogenesis.
    Microbial Pathogenesis 09/2014; 77. DOI:10.1016/j.micpath.2014.09.014 · 2.00 Impact Factor
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    ABSTRACT: Studies of feline lower urinary tract disease (FLUTD) among Norwegian cats have shown higher prevalences of bacterial cystitis than most previously published reports. The aims of the present study were to identify bacterial isolates obtained from the urine of Norwegian cats with FLUTD and their susceptibility to antimicrobial agents. Eighty-two bacterial isolates from 72 urine cultures obtained from 71 different cats were included. Escherichia coli, Staphylococcus species, Enterococcus species and Streptococcus species were the most frequently detected. The percentages of isolates susceptible to the included antimicrobial agents were as follows: enrofloxacin - 92%; trimethoprim/sulfonamide - 91%; nitrofurantoin - 89%; tetracycline - 78%; ampicillin - 73%; amoxicillin/clavulanic acid - 72%; trimethoprim - 68%; amoxicillin - 58%; cephalexin - 51%; spiramycin - 39%; penicillin - 34%; fucidic acid - 34%; lincomycin - 27%. Although several tendencies towards increasing antimicrobial resistance were detected among the isolates included, the species of bacteria isolated and their patterns of antimicrobial resistance were, in general, in concurrence with the existing literature. Thus, the results do not fully explain the higher prevalence of bacterial cystitis found in Norwegian cats. Moreover, additional explanatory factors beside the inclusion of primary accession cases rather than referred cases were not found.
    Journal of Feline Medicine & Surgery 09/2014; 17(6). DOI:10.1177/1098612X14550171 · 1.22 Impact Factor
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    ABSTRACT: Two species of bacteria are repeatedly isolated from farmed fish with winter-ulcer disease. Moritella viscosa is the aetiological agent of the disease; the significance of Aliivibrio wodanis is uncertain but has not been related to the primary pathogenesis. A cell culture infection model showed that A. wodanis adhered to, but did not invade the fish cells. Exposure to culture supernatant of A. wodanis caused the fish cells to vacoulate, retract, round up and detach from the surface, and rearrange the actin filaments of the cytoskeleton. These observations suggest that the bacterium secretes toxins into the extracellular environment. Any pathologic effect of A. wodanis and the effect of co-culturing with M. viscosa was studied in Atlantic salmon (Salmo salar) bath challenged with; only M. viscosa or only A. wodanis or both bacteria together. Both M. viscosa and A. wodanis were re-isolated from external surfaces and internal organs from live and deceased co-infected fish. It is further hypothesized that A. wodanis colonization might influence the progression of a M. viscosa infection. This is to our knowledge the first study that reproduces field observations where both bacteria infect Atlantic salmon.
    Veterinary Microbiology 06/2014; 171(1-2). DOI:10.1016/j.vetmic.2014.03.011 · 2.73 Impact Factor
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    ABSTRACT: Antimicrobial resistance (AR) detected by disk diffusion and antimicrobial resistance genes (ARG) detected by DNA hybridization and PCR with amplicon sequencing were studied in 124 marine bacteria isolates from a Chilean salmon aquaculture site and 76 from a site without aquaculture 8 km distant. Resistance to one or more antimicrobials was present in 81% of the isolates regardless of site. Resistance to tetracycline was most commonly encoded by tetA and tetG; to trimethoprim, by dfrA1, dfrA5 and dfrA12; to sulfamethizole, by sul1 and sul2; to amoxicillin, by blaTEM ; and to streptomycin, by strA-strB. Integron integrase intl1 was detected in 14 sul1-positive isolates, associated with aad9 gene cassettes in two from the aquaculture site. intl2 integrase was only detected in three dfrA1-positive isolates from the aquaculture site and was not associated with gene cassettes in any. Of nine isolates tested for conjugation, two from the aquaculture site transferred AR determinants to Escherichia coli. High levels of AR in marine sediments from aquaculture and non-aquaculture sites suggest that dispersion of the large amounts of antimicrobials used in Chilean salmon aquaculture has created selective pressure in areas of the marine environment far removed from the initial site of use of these agents.
    Environmental Microbiology 02/2014; 16(5). DOI:10.1111/1462-2920.12421 · 6.24 Impact Factor
  • Alexander Kashulin · Henning Sørum
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    ABSTRACT: Cold-Water Vibriosis (CWV) is a well-known disease which significantly influences the aquaculture industry of the North Atlantic coasts (Egidius et al., 1981). Due to wide implementation of apparently effective vaccines in all farmed Atlantic salmon (Salmo salar) the phenomenon of CWV was not a research focus for nearly two decades (Lillehaug, 1990, 1991). Although prevented by vaccination since the 1980s, CWV was again reported in farmed, vaccinated Atlantic salmon in 2012 (Johansen, 2012). Since CWV emerged as a recognized infection in the early 1980s (Egidius et al., 1981; Sørum et al., 1990), several attempts have been undertaken to identify the initial steps of the pathogenesis of CWV. However, no final explanation to how Aliivibrio (Vibrio) salmonicida enters the host has been reported. In this study, we present a novel and simple model for analyzing the initial steps of CWV. Our results demonstrate that initiation of CWV is more complex than was previously thought. In particular, A. (V.) salmonicida enters the host much faster than was anticipated. To identify the initial pathogenic steps in CWV, Atlantic salmon fry were differentially immersed in a suspension of A. (V.) salmonicida and the number of bacteria entering the host was measured. The putative roles of the gills, skin, rectal and oral routes as well as the role of the fin blood vessels as portals of infection were investigated. Bacterial counts were obtained from freshly collected blood samples, thus representing immediate snapshots of the early stages of host invasion. The results clearly indicated that skin was a major route of infection. The experimental design reported in this study provides a new, rapid and cost-effective model for studying CWV.
    Aquaculture 01/2014; s 420–421:112–118. DOI:10.1016/j.aquaculture.2013.10.025 · 1.83 Impact Factor
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    ABSTRACT: The Gram-negative bacterium Vibrio salmonicida is the causative agent of cold-water vibriosis (CV), a hemorrhagic septicemia that primarily affects farmed Atlantic salmon (Salmo salar L.). The mechanisms of disease development, host specificity and adaptation, as well as the immunogenic properties of V. salmonicida are largely unknown. Therefore, to gain more knowledge on the pathogenesis of CV, 90 Atlantic salmon parr were injected intraperitoneally with 6 × 10(6) CFU of V. salmonicida LFI1238. Samples from blood and spleen tissue were taken at different time points throughout the challenge for gene expression analysis by two-step reverse transcription (RT) quantitative real-time polymerase chain reaction. Out of a panel of six housekeeping genes, accD, gapA, and 16S rDNA were found to be the most suitable references for expression analysis in Vibrio salmonicida. The bacterial proliferation during challenge was monitored based on the expression of the 16S rRNA encoding gene. Before day 4, the concentrations of V. salmonicida in blood and spleen tissue demonstrated a lag phase. From day 4, the bacterial proliferation was exponential. The expression profiles of eight genes encoding potential virulence factors of V. salmonicida were studied. Surprisingly, all tested virulence genes were generally highest expressed in broth cultures compared to the in vivo samples. We hypothesize that this general muting of gene expression in vivo may be a strategy for V. salmonicida to hide from the host immune system. To further investigate this hypothesis, the expression profiles of eight genes encoding innate immune factors were analyzed. The results demonstrated a strong and rapid, but short-lasting innate immune response against V. salmonicida. These results suggest that the bacterium possesses mechanisms that inhibit and/or resist the salmon innate immune system until the host becomes exhausted of fighting the on-going and eventually overwhelming infection.
    Frontiers in Microbiology 12/2013; 4:401. DOI:10.3389/fmicb.2013.00401 · 3.94 Impact Factor
  • T Abayneh · D J Colquhoun · D Austin · H Sørum
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    ABSTRACT: This study describes a novel multilocus variable number tandem repeat analysis (MLVA) based on six variable number of tandem repeat (VNTR) loci for genotyping of 37 Edwardsiella piscicida (previously Edwardsiella tarda) isolates from multiple sources. The number of alleles identified for each of the six VNTR loci ranged from 3 to 5 with VNTR loci 1 (DI = 0.632) and 3 (DI = 0.644), displaying the highest degrees of polymorphism. MLVA typing of the 37 E. piscicida isolates resulted in the identification of five major clusters consistent with their geographical origins, and were designated as MLVA types I, II, III, IV and V. Types III and V were resolved further into subtypes largely consistent with outbreak source. An MLVA profile comprising a string of integers representing the number of tandem repeats for each allele provided a unique identification for each MLVA type and/or strain. The MLVA protocol described in the current study is robust, relatively simple, has a higher power of resolution than multilocus sequence analysis (MLSA) and is capable of discriminating closely related isolates.
    Journal of Fish Diseases 10/2013; 37(11). DOI:10.1111/jfd.12190 · 1.51 Impact Factor
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    ABSTRACT: In spite of yearly vaccination, outbreaks of canine infectious respiratory disease are periodically seen amongst domestic dogs. These infections compromise host defense mechanisms, and, when combined with other stressful events, allow opportunistic pathogens like Streptococcus equi subsp. zooepidemicus to create serious disease. Early recognition and treatment are tremendously important for a successful outcome in these cases. A polyvalent vaccine was given to 22 racing dogs three days after a competition, followed by two days of rest, and then the dogs were returned to regular training. Coughing was noticed among the dogs four days after immunisation. Three days after this outbreak one of the dogs was unusually silent and was found dead the next morning. Simultaneously two other dogs developed haemorrhagic expectorate, depression and dyspnea and were brought in to the veterinary hospital. Streptococcus equi subsp. zooepidemicus was isolated in pure culture from all three cases. They were treated and rehabilitated successfully, and won a sledge race three months later. This paper discusses the necropsy results, treatment regime, rehabilitation and the chronology of vaccination, stressful events and disease.
    Acta Veterinaria Scandinavica 09/2013; 55(1):67. DOI:10.1186/1751-0147-55-67 · 1.00 Impact Factor
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    ABSTRACT: The discovery and introduction of antimicrobial agents to clinical medicine was one of the greatest medical triumphs of the 20th century that revolutionized the treatment of bacterial infections. However, the gradual emergence of populations of antimicrobial-resistant pathogenic bacteria resulting from use, misuse, and abuse of antimicrobials has today become a major global health concern. Antimicrobial resistance (AMR) genes have been suggested to originate from environmental bacteria, as clinically relevant resistance genes have been detected on the chromosome of environmental bacteria. As only a few new antimicrobials have been developed in the last decade, the further evolution of resistance poses a serious threat to public health. Urgent measures are required not only to minimize the use of antimicrobials for prophylactic and therapeutic purposes but also to look for alternative strategies for the control of bacterial infections. This review examines the global picture of antimicrobial resistance, factors that favor its spread, strategies, and limitations for its control and the need for continuous training of all stake-holders i.e., medical, veterinary, public health, and other relevant professionals as well as human consumers, in the appropriate use of antimicrobial drugs.
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    ABSTRACT: The discovery and introduction of antimicrobial agents to clinical medicine was one of the greatest medical triumphs of the 20th century that revolutionized the treatment of bacterial infections. However, the gradual emergence of populations of antimicrobial-resistant pathogenic bacteria resulting from use, misuse, and abuse of antimicrobials has today become a major global health concern. Antimicrobial resistance (AMR) genes have been suggested to originate from environmental bacteria, as clinically relevant resistance genes have been detected on the chromosome of environmental bacteria. As only a few new antimicrobials have been developed in the last decade, the further evolution of resistance poses a serious threat to public health. Urgent measures are required not only to minimize the use of antimicrobials for prophylactic and therapeutic purposes but also to look for alternative strategies for the control of bacterial infections. This review examines the global picture of antimicrobial resistance, factors that favor its spread, strategies, and limitations for its control and the need for continuous training of all stake-holders i.e., medical, veterinary, public health, and other relevant professionals as well as human consumers, in the appropriate use of antimicrobial drugs.
    Frontiers in Microbiology 05/2013; 4:96. DOI:10.3389/fmicb.2013.00096 · 3.94 Impact Factor
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    ABSTRACT: Atpresent,verylittleisknownaboutthefateandpersistenceofmultiresistantbacteria(MRB)andtheirresistancegenesinnaturalaquaticenvironments.Treated,butpartlyalsountreatedsewageofthecityofLausanne,SwitzerlandisdischargedintoVidyBay(LakeGeneva)resultinginhighlevelsofcontaminationinthispartofthelake.InthepresentworkwehavestudiedtheprevalenceofMRBandresistancegenesinthewastewaterstreamofLausanne.Samplesfromhospitalandmunicipalrawsewage,treatedeffluentfromLausanne’swastewatertreatmentplant(WTP)aswellaslakewaterandsedimentsamplesobtainedclosetotheWTPoutletpipeandaremotesiteclosetoadrinkingwaterpumpwereevaluatedfortheprevalenceofMRB.Selectedisolateswereidentified(16SrRNAgenefragmentsequencing)andcharacterizedwithregardstofurtherresistances,resistancegenes,andplasmids.Mostly,studiesinvestigatingthisissuehavereliedoncultivation-basedapproaches.However,thelimitationsofthesetoolsarewellknown,inparticularforenvironmentalmicrobialcommunities,andcultivation-independentmol-eculartoolsshouldbeappliedinparallelinordertotakenon-culturableorganismsintoaccount.Herewedirectlyquantifiedthesulfonamideresistancegenessul1andsul2fromenvironmentalDNAextractsusingTaqManreal-timequantitativePCR.HospitalsewagecontainedthehighestloadofMRBandantibioticresistancegenes(ARGs).Wastewatertreatmentreducedthetotalbacterialloadupto78%butevidenceforselectionofextremelymultiresistantstrainsandaccumulationofresistancegeneswasobserved.OurdataclearlyindicatedpollutionofsedimentswithARGsinthevicinityoftheWTPoutlet.ThepotentialoflakesasreservoirsofMRBandpotentialrisksarediscussed.
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    ABSTRACT: The present study was performed to address putative links between the immune and pigmentary systems. A pigment-producing leukocyte-like cell-line (SHK-1 cells) of Atlantic salmon (Salmo salar L.) was exposed to different temperatures, poly I:C, bacterin or infected with virus (infectious pancreatic necrosis virus or infectious salmon anaemia virus). The effect of this stimulation regarding the transcription-pattern of the tyrosinase gene family (melanin genes) and the immune-related genes MHC class II and IFN-1 was analysed using real-time RT-qPCR. At 10°C cultivation, tyrosinase and dopachrome tautomerase remained unregulated. At 15°C, a moderate up-regulation was induced, while at 20°C, these genes were up-regulated in an exponential manner over time. Temperature did not affect the transcription of the immune-related genes. Virus infections, poly I:C or bacterin had no influence on the transcription of the melanogenesis-related genes, but triggered the immune-related genes. Our findings revealed no connections between the pigmentary and immune systems, but demonstrated a hereto undiscovered temperature-effect on the tyrosinase gene family.
    Developmental and comparative immunology 04/2013; 41(1). DOI:10.1016/j.dci.2013.03.019 · 3.71 Impact Factor
  • T Abayneh · D J Colquhoun · H Sørum
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    ABSTRACT: This study describes a novel species within the genus Edwardsiella based on phenotypic and genetic characterization of fish pathogenic Edwardsiella isolates previously identified as E. tarda. Phenotypic characterization, DNA-DNA hybridization and phylogenetic analysis of representative Edwardsiella isolates from fish previously identified as E. tarda were conducted and compared with E. tarda type strain (ATCC 15947T). Phenotypically, strains from fish grow with pin-point colonies producing slight β-haemolysis under the colony. In contrast to the E. tarda type strain, fish strains did not grow at 42°C or degrade β-methyl-d-glucoside (with the exception of NCIMB 2034), citric acid and l-proline. With the exception of strain ETK01, all fish strains were highly pathogenic to zebra fish, while ATCC 15947T and NCIMB 2034 were nonpathogenic. DNA-DNA hybridization (DDH) levels between representative fish isolates and the E. tarda type strain ranged from 15 to 43·6%, while NCIMB 2034 hybridised with the type strain at the level of 63·2%. DDH values between the various fish isolates ranged from 68·2 to 93·9% defining a new and separate DNA hybridization group differing from the E. tarda type strain consistent with the findings of phylogenetic analysis, in which the fish isolates comprised a separate clade. Phenotypical and genetic characterizations demonstrated that Edwardsiella isolates from fish described in this study do not belong to the species E. tarda or any of the previously established taxa within the genus Edwardsiella. The fish related strains studied here (excluding NCIMB 2034) represent, therefore, a novel species within the genus Edwardsiella for which we propose the name Edwardsiella piscicida sp. nov, with strain ET883T (NCIMB 14824T = CCUG 62929) as the type strain. The current finding will improve the diagnosis, understanding of the epidemiology and in establishment of effective control measures against this serious fish pathogen.
    Journal of Applied Microbiology 11/2012; 114(3). DOI:10.1111/jam.12080 · 2.39 Impact Factor
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    M Saleh · H Soliman · H Sørum · A K Fauske · M El-Matbouli
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    ABSTRACT: European foulbrood (EFB) is a severe bacterial brood disease of honey bees (Apis mellifera) caused by Melissococcus plutonius. Diagnosis of EFB in the field is based on visual inspection of brood-combs and detection of diseased larvae. However, symptoms of EFB may be easily obscured by other diseases or abnormalities in the brood, making definitive diagnosis difficult. Hence, confirmatory laboratory assays, such as PCR and real-time PCR, are used to verify the presence of M plutonius in suspected colonies. While these methods are accurate and specific, they are time consuming and labour intensive. Herein, we report development of a label-free colorimetric nanodiagnostic method for direct detection of unamplified M plutonius DNA using unmodified gold nanoparticles. Under appropriate conditions, the DNA probes hybridised with their complementary target sequences in the sample DNA, which resulted in aggregation of the gold nanoparticles and a concomitant red to blue colour change, which was observed visually. The assay could detect as few as 25 copies of the M plutonius cell wall-associated protease gene within 20 minutes. The assay results were in 100 per cent concordance with real-time PCR-positive and PCR-negative samples. Our study demonstrated that the gold nanoparticles-based assay is a specific and sensitive tool for rapid detection of M plutonius.
    09/2012; 171(16):400. DOI:10.1136/vr.101040

Publication Stats

2k Citations
287.22 Total Impact Points

Institutions

  • 2014–2015
    • Norwegian University of Life Sciences (UMB)
      Aas, Akershus county, Norway
  • 1999–2014
    • Norwegian School of Veterinary Science
      • • Department of Food Safety and Infection Biology
      • • Department of Pharmacology, Microbiology, and Food Hygiene
      Kristiania (historical), Oslo County, Norway
  • 2012
    • Universitetet i Tromsø
      • Department of Chemistry
      Tromsø, Troms, Norway
  • 2007
    • University of Wisconsin, Madison
      • Department of Medical Microbiology and Immunology
      Mississippi, United States
  • 1990
    • University of Bergen
      Bergen, Hordaland, Norway
  • 1989
    • University of Oslo (UiO)
      • Department of Microbiology (MIC)
      Oslo, Oslo, Norway