Biomedical subjects

K Pedersen

Publications and source records attributed to K Pedersen.

At least 19 recordsLinked to original sources

PubMed2006

Effects of a Campylobacter jejuni infection on the development of the intestinal microflora of broiler chickens.

The effect of a Campylobacter jejuni colonization on the development of the microflora of the cecum and the ileum of broiler chickens was studied using molecular methods. The infection did affect the development and complexity of the microbial communities of the ceca, but we found no permanent effect of a C. jejuni infection on the ileal microflora of the broilers. In addition, denaturant gradient gel electrophoresis (DGGE) profiles generated from cecal and ileal contents revealed several DGGE bands that were present in the control chickens, but not in the chickens colonized with C. jejuni. Some of these DGGE bands could be affiliated with Lactobacillus reuteri, Clostridium perfringens, and the genus Klebsiella.

Animals↗

PubMed2006

Microbial community composition of the ileum and cecum of broiler chickens as revealed by molecular and culture-based techniques.

The microbial communities of the ileum and cecum of broiler chickens from a conventional and an organic farm were investigated using conventional culture techniques as well as cloning and sequencing of 16S rRNA genes. Eighty-five percent of the 557 cloned sequences were <97% related to known cultured species. The chicken ileum was dominated by lactobacilli, whereas the cecum harbored a more diverse microbial community. The cecum was dominated by a large group of bacteria with hitherto no close cultured relatives but most closely related to Faecalibacterium prausnitzii. Approximately 49 and 20% of the cecal clones belonged to this cluster in conventional and organic broiler chickens, respectively. We were, however, able to recover a number of these phylotypes by cultivation, and the isolates were shown to be butyric acid producers. The investigation was a descriptive rather than a comparative study of 2 different rearing systems; however, several differences were observed. For instance, Clostridium perfringens was found in significantly higher numbers in the birds from the organic farm compared with the conventional broilers, probably due to the addition of salinomycin to the conventional feed. In the ileum, the abundance of the different Lactobacillus species differed between the 2 broiler types. The culture-based and culture-independent techniques complemented each other well. Strengths and limitations of the different methods are discussed.

Animal Feed↗

PubMed2005

Pulsed-field gel electrophoresis types of Campylobacter spp. in Danish turkeys before and after slaughter.

In this study, seven Danish turkey flocks were investigated at the farm, on arrival to the slaughterhouse, and during and after slaughter. Flocks were selected based on their Campylobacter spp. status at the farm and three Campylobacter negative and four Campylobacter positive flocks were included in the study. At the slaughterhouse, 70-75 samples were collected at different points from the shackling station to packaging of the final meat cuttings. Samples included cloacal swabs, neckskin, liver, heart, meat and environmental samples. Detection of Campylobacter was carried out by conventional culture and by the EiaFoss system (Foss Electric, Hilleroed, Denmark) for detecting Campylobacter spp. in food, using Preston Broth as enrichment medium. The two methods were compared and sensitivities and specificities were calculated using the conventional culture as gold standard. The three negative flocks were consistently negative from the farm and all through processing. Among the samples from the positive flocks, the frequency of positive samples obtained at the slaughterhouse varied. The frequency of positive samples obtained from the four positive flocks varied and was found to be 4%, 49%, 87% and 96%, respectively. In 31 out of 424 samples, discrepancies were observed between results obtained by the EiaFoss system and the conventional culture technique. The sensitivity for the EiaFoss system was calculated to be 0.94 for meat and neckskin samples. A total of 161 strains were genotyped by pulsed-field gel electrophoresis (PFGE) in order to investigate possible changes in carriage of Campylobacter spp. strains during processing. In three flocks, only one PFGE type was encountered in samples collected at the farm level and, in one flock, two different types were observed. In two flocks, the strain from the farm was also isolated in samples collected at the slaughterhouse. Changes in carriage were observed in two flocks during processing, in particular post chilling.

Abattoirs↗

PubMed2005

Identification of Meiothermus as the dominant genus in a storage system for spent nuclear fuel.

AIMS: To characterize the biofilms in an interim wet storage system (CLAB) for spent nuclear fuel. METHODS AND RESULTS: Planktonic cells and biofilms were analysed with fluorescence microscopy, and scanning and transmission electron microscopy. The organisms in the biofilms were filamentous, consisting of sheaths with series of rod-shaped cells in them. Planktonic cell populations ranged between 1.4 x 10(3) and 5.2 x 10(3) ml(-1), correlated with the system configuration, and was inversely correlated with total organic carbon (TOC) levels. Analysis of 16S rDNA indicated that a potentially novel Meiothermus sp. was dominant in the CLAB biofilms. A Meiothermus-specific probe was designed, and statistical analysis of fluorescence in situ hybridization results confirmed that Meiothermus sp. composed up to 98% of the biofilm. The low TOC levels (2-55 microg l(-1)) in the system combined with elevated water temperatures (ca 36 degrees C) mimic the natural environments of Meiothermus sp. as well as the recommended conditions for isolating Meiothermus sp., thus supporting the results of the 16S rDNA analysis. CONCLUSIONS: A possibly novel Meiothermus sp. is the predominant genus found in the CLAB biofilms. SIGNIFICANCE AND IMPACT OF THE STUDY: TOC levels are often kept low to protect industrial systems from biofouling. However, the present study shows that, rather than protecting industrial systems against biofouling per se, maintaining low TOC levels might still result in biofilms, dominated by new, unknown bacterial species.

Biofilms↗

PubMed2003

Characterisation of yeasts isolated from deep igneous rock aquifers of the Fennoscandian Shield.

The diversity of prokaryotes in the groundwater deep below the surface of the Baltic Sea at the Aspö Hard Rock Laboratory (HRL) in southeast Sweden is well documented. In addition, there is some evidence that eukaryotes, too, are present in the deep groundwater at this site, although their origins are uncertain. To extend the knowledge of eukaryotic life in this environment, five yeast, three yeastlike, and 17 mold strains were isolated from Aspö HRL groundwater between 201 and 444 m below sea level. Phenotypic testing and phylogenetic analysis of 18S rDNA sequences of the five yeast isolates revealed their relationships to Rhodotorula minuta and Cryptococcus spp. Scanning and transmission electron microscopy demonstrated that the strains possessed morphological characteristics typical for yeast, although they were relatively small, with an average length of 3 micro m. Enumeration through direct counting and most probable number methods showed low numbers of fungi, between 0.01 and 1 cells mL(-1), at some sites. Five of the strains were characterized physiologically to determine whether they were adapted to life in the deep biosphere. These studies revealed that the strains grew within a pH range of 4-10, between temperatures of 4 degrees C and 25-30 degrees C, and in NaCl concentrations from 0 to 70 g L(-1). These growth parameters suggest a degree of adaptation to the groundwater at Aspö HRL. Despite the fact that these eukaryotic microorganisms may be transient members of the deep biosphere microbial community, many of the observations of this study suggest that they are capable of growing in this extreme environment.

Adaptation, Physiological↗

PubMed2003

Verrucous endocarditis associated with Streptococcus bovis in mink (Mustela vison).

Between 1998 and 2001, mortalities due to verrucous endocarditis were experienced at several mink farms. Gram-positive cocci were isolated from the endocardium of all the animals examined but not always from other internal organs. Almost all the isolates were identified as Streptococcus bovis and only a few isolates belonged to other Streptococcus species. Typing by pulsed-field gel electrophoresis of a selection of isolates revealed several patterns and several different clones. Attempts to reproduce disease by the injection of cultures of a field isolate into healthy mink failed.

Animals↗

PubMed2003

Analysis by pulsed-field gel electrophoresis of the genetic diversity among Clostridium perfringens isolates from chickens.

The aim of this study was to analyse the genetic diversity among Clostridium perfringens isolates from Danish broiler chickens since both sick and presumably healthy animals were investigated. Isolates (n=279) collected from chickens from 25 farms were analysed by pulsed-field gel electrophoresis (PFGE) with the restriction enzyme SmaI. A high genetic diversity was found. Isolates with different PFGE types were toxin typed by PCR and all were found to be of type A. The results showed that healthy broiler chickens carried several different C. perfringens clones both within a flock and even within individual birds, whereas flocks suffering from necrotic enteritis (NE) or cholangio-hepatitis carried only one or two clones.

Animals↗

PubMed2003

Assessment of the aerobic faecal microflora in mink (Mustela vison Schreiber) with emphasis on Escherichia coli and Staphylococcus intermedius.

The present study was undertaken to investigate the culturable aerobic faecal microflora of mink from newborn until adulthood with emphasis on the potential pathogens Escherichia coli and beta-haemolytic coagulase positive staphylococci. Rectal swabs were taken from 10 healthy dams and their offspring on seven mink farms throughout the production season and a semi-quantitative enumeration of total E. coli and haemolytic E. coli, beta-haemolytic streptococci, beta-haemolytic coagulase positive staphylococci, total lactic acid bacteria, and enterococci was carried out in all samples using selective and non-selective media. Aerobic bacteria were cultured from close to 100% of the samples throughout the survey. Prevalence of E. coli isolates varied between 70 and 90% of the samples throughout the survey with a small decline at the end of the study period. The highest bacterial counts were found among recently weaned kits or kits in the early growth period (P<0.0012). Lactic acid bacteria and enterococci were isolated from more than 90% of all samples, while beta-haemolytic staphylococci were isolated from 20 to 70% of the samples. While beta-haemolytic staphylococci were dominant from birth and during the nursing period, counts of staphylococci gradually decreased during the nursing period and were outnumbered by E. coli during the growth season.

Animals↗

PubMed2003

Distribution of Campylobacter jejuni Penner serotypes in broiler flocks 1998-2000 in a small Danish community with special reference to serotype 4-complex.

During the period January 1998-December 2001, all Danish broiler flocks were monitored bacteriologically for thermophilic campylobacters and isolates were stored at -80 degrees C. Six neighbouring broiler farms in a small community were selected for detailed examination of all Campylobacter jejuni isolated (n = 180) from these farms during 1998-2000 using Penner serotyping and pulsed-field gel electrophoresis (PFGE). The area and the farms were selected according to their prevalence of campylobacter so that both farms with low and high frequencies of campylobacter positive flocks were included in the study. The frequency of campylobacter positive flocks on the six farms ranged from 24.5 to 72.7%. One hundred and eighty of the isolates were C. jejuni (included in this study), 14 isolates were C. coli whereas 7 isolates belonged to other species but were not further identified. By serotyping of all C. jejuni 56 isolates (31.5%) were assigned to the 4-complex, 32 isolates (18.0%) to serotype 2, 12 isolates (6.7%) to serotype 11, and 11 isolates (6.2%) were assigned to serotype 12. In three farms, 4-complex was the most prevalent serotype, in one farm it was the second most frequently isolated serotype, while serotypes 2 and 1,44, respectively, were the most frequently isolated from the two remaining farms. This serotype distribution differed from the overall country-wide distribution where serotypes 2 and 1,44 are the most prevalent. All serotype 4-complex isolates from the six selected farms were compared by PFGE to serotype 4-complex isolates from the rest of the country. The results showed that there was a high level of diversity among isolates from the whole country, whereas isolates from the six farms were very homogeneous and only displayed one or a few different PFGE patterns on each farm. It is suggested that certain campylobacter clones persist in a confined geographical area, probably at the farm, and that the broiler houses may be repeatedly infected with a few C. jejuni clones during succeeding broiler flocks. New clones may be introduced, however, the sources and vehicles are yet unknown.

Animal Husbandry↗

PubMed2003

Resistance to quinolones in Campylobacter jejuni and Campylobacter coli from Danish broilers at farm level.

AIMS: To investigate the prevalence of quinolone resistance among Campylobacter jejuni and Camp. coli isolates from Danish poultry at the farm level, as well as for the whole country. METHODS AND RESULTS: Data and isolates were collected from a national surveillance of Campylobacter in poultry. Quinolone resistance was investigated by determination of minimum inhibitory concentration (MIC) to nalidixic acid and enrofloxacin. Among Camp. jejuni and Camp. coli combined, 7.5% were resistant to nalidixic acid. Quinolone resistance varied considerably from farm to farm, with 0% on some farms and almost 100% on others, but the resistance was evenly distributed geographically. With respect to isolates from farms where resistance was detected, quinolone resistance was higher among Camp. coli (28.7%) than among Camp. jejuni (11.3%). PFGE typing of quinolone-resistant and quinolone-susceptible isolates from four farms indicated that certain resistant isolates belonged to specific clones that were able to persist on the farms during several rotations, even in the absence of selective pressure. Some clones were present and repeatedly isolated in both a quinolone-susceptible and quinolone-resistant variant. CONCLUSIONS: Overall, quinolone resistance among Campylobacter isolates from Danish broilers was 7.5% in 1998 and 1999; it was higher among Camp. coli than Camp. jejuni. Genetic diversity among resistant isolates was lower than among susceptible isolates, and certain clones existed in both a resistant and a susceptible variant. Some resistant clones appeared to persist on the farms and were repeatedly isolated from poultry flocks. SIGNIFICANCE AND IMPACT OF THE STUDY: The study is important for the understanding of persistence and dynamics of Campylobacter in broiler houses. It also highlights the extent, farm-to-farm variation and persistence of quinolone-resistant Campylobacter in broiler houses.

Animals↗

PubMed2003

PCR detection of seven virulence and toxin genes of Campylobacter jejuni and Campylobacter coli isolates from Danish pigs and cattle and cytolethal distending toxin production of the isolates.

AIMS: To study the prevalence of seven virulence and toxin genes, and cytolethal distending toxin (CDT) production of Campylobacter jejuni and C. coli isolates from Danish pigs and cattle. METHODS AND RESULTS: The presence of the cadF, ceuE, virB11, flaA, cdtA, cdtB, cdtC and the cdt gene cluster among 40 C. jejuni and C. coli isolates was detected by polymerase chain reaction. The CDT production of the isolates was determined on Vero, colon 205 and chicken embryo cells. The cadF, flaA, ceuE and cdtB genes were detected from 100% of the isolates. The cdtA and cdtC genes were found in 95.0 and 90.0% of the isolates, respectively. The cdt gene cluster was detected in 82.5% isolates. Only 7.5% of the isolates were positive for virB11. Ninety-five per cent of the isolates produced CDT in Vero and colon 205 cell assays, and 90% of the isolates produced CDT in chicken embryo cell assays. CONCLUSIONS: High prevalence of the cadF, ceuE, flaA and cdtB genes was found. Data of the prevalence of cdt genes was consistent with the CDT titres produced by the isolates. Campylobacter coli from pigs produced high CDT titres. SIGNIFICANCE AND IMPACT OF THE STUDY: The high prevalence of seven virulence and toxin genes demonstrated that these putative pathogenic determinants are widespread among Campylobacter isolates from pigs and cattle. Campylobacter coli isolates from pigs produced much higher CDT titres compared with C. coli isolates from other sources suggesting that C. coli may be particularly adapted to or associated with this species.

Animals↗

PubMed2003

Evaluation of PCR for detection of Campylobacter in a national broiler surveillance programme in Denmark.

AIMS: To develop and evaluate a rapid and sensitive PCR method for detection of Campylobacter spp. directly from chicken faeces. METHODS AND RESULTS: DNA was isolated from faecal swabs using magnetic beads followed by PCR using a prealiquoted PCR mixture, which had been stored in the freezer. The result could be obtained in <6 h. The method was evaluated on 1282 samples from the Danish surveillance programme for Campylobacter in broilers by comparing with conventional culture. The diagnostic specificity was calculated to be 0.99. The detection limits of the PCR method and of the conventional culture were compared using spiked control material. For both methods the detection limit was 36 CFU ml-1. CONCLUSIONS: It was concluded that the PCR proved useful for detection of Campylobacter in pooled cloacal swabs from broilers. SIGNIFICANCE AND IMPACT OF THE STUDY: By taking cloacal samples in the broiler flocks the technique can be used as an important tool for planning and directing the broiler slaughtering process. This will be a great help in minimizing the risk of contaminating Campylobacter-free flocks at the abattoir.

Abattoirs↗

PubMed2003

Identification of campylobacteria isolated from Danish broilers by phenotypic tests and species-specific PCR assays.

AIMS: To validate a phenotypic Campylobacter species identification method employed to identify campylobacters in broilers by comparison with campylobacterial species identification using various species-specific PCR analyses. METHODS AND RESULTS: From a collection of 2733 phenotypically identified campylobacterial cultures, 108 Campylobacter jejuni cultures and 351 campylobacterial cultures other than Camp. jejuni were subjected to various species-specific PCR assays. On the basis of the genotypic tests, it was demonstrated that Camp. jejuni and Camp. coli constituted approx. 99% of all cultures, while other species identified were Helicobacter pullorum, Camp. lari and Camp. upsaliensis. However, 29% of the 309 Camp. coli cultures identified by phenotypic tests were hippurate-variable or negative Camp. jejuni cultures, whereas some Camp. lari cultures and unspeciated campylobacter cultures belonged to H. pullorum. It was also notable that 2-6% of the cultures were, in fact, mixed cultures. CONCLUSIONS: The phenotypic identification scheme employed failed to appropriately differentiate Campylobacter species and particularly to identify the closely related species, H. pullorum. SIGNIFICANCE AND IMPACT OF THE STUDY: Future phenotypic test schemes should be designed to allow a more accurate differentiation of Campylobacter and related species. Preferably, the phenotypic tests should be supplemented with a genotypic strategy to disclose the true campylobacterial species diversity in broilers.

Animals↗

PubMed2003

Pasteurella multocida from outbreaks of avian cholera in wild and captive birds in Denmark.

An outbreak of avian cholera was observed among wild birds in a few localities in Denmark in 2001. The highest mortalities were among breeding eiders (Somateria mollissima) and gulls (Larus spp.). Pulsed-field gel electrophoresis (PFGE) was conducted using ApaI and SmaI as restriction enzymes and restriction enzyme analysis (REA) using HpaII. The Pasteurella multocida subsp. multocida strain isolated from birds in this outbreak was indistinguishable from a strain that caused outbreaks in 1996 and 2003. Most isolates from domestic poultry had other PFGE patterns but some were indistinguishable from the outbreak strain. Among 68 isolates from wild birds, only one PFGE and one REA pattern were demonstrated, whereas among 23 isolates from domestic poultry, 14 different SmaI, 12 different ApaI, and 10 different HpaII patterns were found. The results suggest that a P. multocida strain has survived during several years among wild birds in Denmark.

Animals↗

PubMed2002

Serovars of Salmonella isolated from Danish turkeys between 1995 and 2000 and their antimicrobial resistance.

The prevalence of Salmonella serovars and their antimicrobial resistance patterns were investigated among Danish turkeys between 1995 and 2000, by sampling the flocks approximately 14 days before they were slaughtered. Within the flocks, the prevalence of salmonella varied from 7.1 per cent to 25 per cent, and 24 different serovars were detected. The five most prevalent, which accounted for 58.5 per cent of the isolates were Salmonella Heidelberg (16.2 per cent of the isolates), Salmonella Agona (15.8 per cent), Salmonella Derby (12.4 per cent), Salmonella Muenster (7.3 per cent) and Salmonella Anatum (6.8 per cent). In addition, a few rough isolates and isolates belonging to the antigenically incomplete formulae 6,7:-:- and 4,12:b:- were found. The level of antimicrobial resistance was low; the highest resistance was recorded to ampicillin (13.7 per cent) and streptomycin (9.0 per cent) followed by tetracycline (8.5 per cent), sulphonamides (7.7 per cent) and spectinomycin (4.7 per cent). Resistance to quinolones was very low: four isolates were resistant to nalidixic acid, and only one was resistant to enrofloxacin. No resistance was recorded to colistin, apramycin, ceftiofur, florfenicol, or amoxycillin with clavulanic acid. Only 24 isolates were resistant to two or more compounds in various combinations of up to six compounds; one Salmonella Havana isolate was resistant to six compounds. Six isolates were serovar Typhimurium, but none of them belonged to phage type DT104.

Animals↗

PubMed2002

Rapid PCR using nested primers of the 16S rRNA and the hippuricase (hip O) genes to detect Campylobacter jejuni and Campylobacter coli in environmental samples.

Identification of sources Campylobacter infection in the poultry houses is in general problematic due to the lack of reliable methods to detect campylobacteria in environmental samples. Detection of campylobacteria in environmental samples by conventional culture methods is difficult and of limited sensitivity due to the use of selective media, the low number of bacteria in the samples and possibly also due to the presence of non-culturable or sub-lethally injured stages of the bacteria. The present paper describes a rapid PCR assay using nested primers of the 16S rRNA or the hippuricase (hip O) genes to detect Campylobacter jejuni and Campylobacter coli in environmental samples. The sensitivity of the nested PCR was determined to be 0.01 pg/PCR, corresponding to 2-3 colony forming units (cfu) per ml. The nested PCR assays were applied to detect C. jejuni and C. coli in 269 environmental samples collected from ten broiler farms. The sensitivity, specificity and the usefulness of the PCR assay for detection of C. jejuni and C. coli in environmental samples are presented and discussed.

Amidohydrolases↗

PubMed2002

Thermophilic Campylobacter spp. in turkey samples: evaluation of two automated enzyme immunoassays and conventional microbiological techniques.

AIMS: To determine the sensitivity and specificity of two automated enzyme immunoassays (EIA), EiaFoss and Minividas, and a conventional microbiological culture technique for detecting thermophilic Campylobacter spp. in turkey samples. METHODS AND RESULTS: A total of 286 samples (faecal, meat, neckskin and environmental samples) were collected over a period of 4 months at a turkey slaughterhouse and meat-cutting plant in Denmark. Faecal and environmental samples were tested by the conventional culture method and by the two EIAs, whereas meat and neckskin samples were tested by the two EIAs only. Two enrichment broths were used, Campylobacter Enrichment Broth (CEB) and Preston Broth (PB). Verification of positive test results was carried out by conventional culture on selective solid media. The specificities of all methods were high. The sensitivities of the EIAs were higher than that of the conventional culture technique but varied depending on the type of sample and enrichment broth. For neckskin samples, the Minividas had a significantly higher sensitivity than the EiaFoss and using PB instead of CEB as the enrichment broth significantly improved the sensitivity for both EIAs. CONCLUSIONS: Both EIAs provided more accurate results than the conventional culture technique. Furthermore, neckskin samples enriched in PB resulted in more positive test results and Campylobacter growth than samples enriched in CEB. SIGNIFICANCE AND IMPACT OF THE STUDY: The Eiafoss and Minividas proved to be reliable methods for detecting Campylobacter spp. in various samples. However, the results emphasize the need for the development of specific enrichment protocols for specific samples.

Animals↗

PubMed2002

Three-month neoadjuvant hormonal therapy before radical prostatectomy: a 7-year follow-up of a randomized controlled trial.

OBJECTIVE: To describe the outcome, assessed as the level of prostate specific antigen (PSA), of a mature (more than half the events recorded) prospective randomized study with a median follow-up of 82 months of neoadjuvant hormonal therapy before radical prostatectomy, as this has been suggested to decrease the rate of positive surgical margins (i.e. provide greater potential to completely excise the tumour). PATIENTS AND METHODS: From December 1991 to March 1994, 126 patients with clinically localized prostate cancer were randomized between direct radical prostatectomy or a 3-month course of a gonadotrophin-releasing hormone analogue before surgery. The patients were followed by PSA determinations and a value of > 0.5 ng/mL used to define progression. RESULTS: The incidence of positive surgical margins decreased from 45.5% to 23.6% (P = 0.016) with hormone treatment. Despite this there was no difference in PSA progression-free survival at the last follow-up; it was 51.5% for those undergoing radical prostatectomy only and 49.8% for those who received hormonal pretreatment (P = 0.588). CONCLUSIONS: Three months of neoadjuvant hormonal therapy before radical prostatectomy offers no benefit to the patient and cannot be recommended for routine clinical use.

Aged↗