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M Bisgaard

Publications and source records attributed to M Bisgaard.

At least 55 records · Page 3Linked to original sources
PubMed1998

Evaluation and application of ribotyping for epidemiological studies of Actinobacillus pleuropneumoniae in Denmark.

The aim of the present study was to evaluate ribotyping as an epidemiological tool for Actinobacillus pleuropneumoniae and apply the method in studies of A. pleuropneumoniae infections in Danish pig herds. The evaluation of ribotyping was based on the 13 international reference strains and 106 epidemiologically unrelated Danish field strains representing the nine serotypes of biotype 1 (1, 2, 5A/B, 6, 7, 8, 10, 12, and K2:O7) and one serotype 14 of biotype 2. Enzymes CfoI and HindIII were chosen for generation of ribotype patterns. Ribotyping of the reference strains resulted in 10 CfoI types and 11 HindIII types. Ribotyping of the Danish strains resulted in 17 different CfoI ribotypes and 24 different HindIII ribotypes. Combining HindIII- and CfoI-ribotyping divided the Danish strains into 26 different types. The stability, reproducibility and typability of ribotype patterns were good, and the discriminatory power was between 0.85-0.89. The relatively low discriminatory power was caused by four predominant types, containing 61% of the isolates. The typing system was applied in studies of routes of infection of specific pathogen-free (SPF) pig herds and included 112 strains of A. pleuropneumoniae. Airborne transmission from neighboring conventional pig farms was investigated in 12 cases of infected SPF herds. Transmission via vehicles transporting pigs between SPF herds was investigated in nine cases while transmission by trading of pigs between SPF herds was investigated in two cases. Serotype 2 was isolated from all SPF herds included in this study, except one, emphasizing the high prevalence of this serotype in Denmark. By ribotyping, airborne transmission was indicated in five of 12 cases, transmission via pig transporting vehicle was indicated in six of nine cases, and transmission via trading was indicated in one of two cases. In many cases findings of predominant ribotypes made interpretations of suspected routes of transmission difficult. The relationship of strains based on ribotypes was calculated using Dices coefficient and clustered by UPGMA. HindIII ribotypes of serotype 2 strains were closely related, though only showing 43% similarity to HindIII ribotypes of remaining serotypes.

Actinobacillus Infections↗
PubMed1998

Phenotypic and genotypic diversity of organisms previously classified as maltose positive Pasteurella multocida.

Fifteen isolates tentatively classified as maltose positive Pasteurella multocida have been characterized in 79 biochemical tests and by ribotyping using HindIII and HpaII for digestion of DNA. Phenotypic and genotypic results were analysed using the computer programmes NTSYS and GelCompar, respectively. Two strains were classified as maltose positive P. multocida ssp. multocida while six strains were classified as maltose positive P. multocida ssp. septica. The remaining strains clustered with P. volantium and P. gallinarum, but remained unclassified. With the exception of a single isolate correlation was observed between phenotypic and genotypic results. The unclassified isolates which represented three different sources were heterogenous according to both phenotypic and genotypic results. The findings obtained support the 16S rRNA sequencing results indicating that the genus Pasteurella sensu stricto might represent two or more genera.

Animals↗
PubMed1998

Ascaridia galli infections in free-range layers fed on diets with different protein contents.

1. One hundred and twenty 17-week-old Lohman Brown hens were divided into 4 groups. Groups 1 and 3 were given a diet with 180 g protein/kg and groups 2 and 4 were given a diet with 140 g protein/kg. Groups 1 and 2 were orally infected with 500 (+/- 50) embryonated Ascaridia galli eggs. 2. Marked differences in mean weekly weight gain for the 4 groups were observed. 3. Hens given 140 g protein/kg had a significant lower mean worm burden of adult A. galli worms and a significant lower weight gain compared to the group given 18 g protein/kg. 4. There was no significant difference in faecal egg counts between the 2 parasitised groups. 5. The egg production did not differ significantly between any of the groups. 6. The results of this study indicate that the amount of dietary protein in the diet has an effect on the establishment of A. galli infections in the gut of layers kept under free range conditions.

Animal Feed↗
PubMed1998

Diversity among isolates of Actinobacillus equuli and related organisms as revealed by ribotyping.

OBJECTIVE: The objective of this work was to examine the diversity within Australian isolates of Actinobacillus equuli and related organisms by the genotypic method of ribotyping. DESIGN: Ribotyping, performed using the enzyme HaeIII, was used to examine the diversity in 12 field isolates of A equuli (five being capable of fermenting L-arabinose), one field isolate of Pasteurella caballi and two unclassifiable field isolates. Isolates were obtained from Australian horses, except for three isolates of A equuli (one L-arabinose positive and two L-arabinose negative) which were obtained from horses and a pig in Africa. In addition, the type strains for A equuli and P caballi and a reference strain for Bisgaard Taxon 9 were included in the study. RESULTS: The ribotype patterns were analysed by computerised cluster analysis, yielding five clusters (A to E). All five of the L-arabinose positive A equuli were assigned to cluster A, with all the other seven A equuli isolates (all L-arabinose negative) and the type strain being assigned to cluster B. One of the two unclassified isolates formed cluster C along with the reference strain for Bisgaard Taxon 9. The remaining unclassified isolate formed cluster D. Cluster E consisted of the field isolate and reference strain of P caballi. CONCLUSION: The results of this study indicate that A equuli is a diverse species, with L-arabinose positive isolates of A equuli being quite distinct from typical L-arabinose negative isolates. Ribotyping appears to be a useful tool in confirming the identity of A equuli-like organisms from horses.

Actinobacillus↗
PubMed1997

Ascaridia galli populations in chickens following single infections with different dose levels.

In all, 3 groups of 20 Lohman Brown chickens aged 1 day were orally infected with doses of 100, 500, or 2,500 embryonated Ascaridia galli eggs, respectively. After 8 weeks, egg counts (eggs per gram of feces, EPG) were determined for all animals prior to slaughter. The gastrointestinal tracts were examined for the presence of adult and immature stages of A. galli. All groups had roughly similar worm burdens and, hence, significantly different establishment rates of 14.2%, 2.9%, and 0.5%, respectively. A significantly lower mean female worm burden was seen in the high-dose group (P = 0.02), which also showed a significantly lower level of egg excretion (P = 0.01). However, fecundity (EPG per female) did not significantly differ between the groups (P = 0.55). The mean lengths of adult worms as well as the weight of the mean worm burdens were significantly smaller in the high-dose group. This study demonstrated that single infections with varying doses of A. galli eggs influenced the establishment rate, sex ratio, egg excretion, and worm size and weight but not the worm fecundity.

Animals↗
PubMed1997

Further studies of the relationships among strains classified as taxon 15, taxon 18, taxon 20, (Pasteurella) granulomatis or the (Pasteurella) haemolytica-complex in ruminants using quantitative evaluation of phenotypic data.

Ninety-three trehalose-negative (P.) haemolytica-like strains of ruminant, porcine and leprine origin were investigated. A quantitative evaluation of phenotypic tests was used and the results obtained were compared with those from 246 previously investigated ruminant strains. Cluster analysis of the results obtained displayed most of the taxa as distinct groups which could be related to differences in key characters. Although only minor phenotypic differences were observed between the taxa investigated and the taxa were internally heterogeneous for many of the tests, it was possible to identify characters separating most groups. However, in three instances, taxa isolated from different species could not be separated by any of the tests used or by quantitative evaluation of all 79 tests--the only difference being the species of animals from which they had been isolated. Taxa which could not be separated by phenotypic tests included the ruminant biogroup 6 of (P.) haemolytica and the porcine taxon 15/biovar 1, the ruminant biogroup 7 of (P.) haemolytica and the porcine taxon 15/biovar 2, and ruminant biogroup 31 of (P.) haemolytica and the leprine taxon 20/biovar 1.

Animals↗
PubMed1997

Genotypic relationships among strains classified under the (Pasteurella) haemolytica-complex as indicated by ribotyping and multilocus enzyme electrophoresis.

Two-hundred and one strains classified under the (Pasteurella) haemolytica-complex isolated from cattle, sheep, deer, pigs, hares and rabbits were investigated by ribotyping. Fifty-nine of these strains were selected for further studies using multilocus enzyme electrophoresis (MEE). A correlation between the clusters identified by ribotyping and MEE was demonstrated and the results furthermore indicated that a genetic basis exists for most clusters previously outlined by the use of quantitative evaluation of phenotypic data. The taxonomic relevance of ornithine decarboxylase and fermentation of L-arabinose, D-sorbitol and glucosides for taxonomic delineation within the (P.) haemolytica-complex was supported. A taxonomic importance was further indicated for ONPG, ONPX, ONPF, meso-inositol, D-xylose, maltose, dextrine and NPG in relation to some of the taxa. Within the porcine taxon 15, however, differences in ornithine decarboxylase did not correspond to genetic clusters. Six lineages were revealed by MEE. Lineage A contained electrophoretic types (ETs) representing biogroups 1, 3A-3H, 8A and 9, indicating a genetic relationship between these groups--an observation which was supported by ribotyping. Lineage B included biogroup 8D, 3 strains from biogroup 10 and a single strain from biogroup 1 and taxon 18/biovar 1. Lineage C contained strains allocated to biogroup 6 from ruminants and the porcine taxon 15. The similarity between these two groups was accentuated by ribotyping. Lineage D and the single isolate in lineage E contained strains allocated to biogroups 7, 10, 8B and 8C, in addition to single strains from biogroups 6 and 9. The same strains were found in the heterogenous ribotype cluster 17. Lineage F contained strains representing the leprine taxon 20 and the ruminant (P.) granulomatis. Ribotyping indicated that the ruminant biogroup 3J was affiliated with both taxon 20 and (P.) granulomatis.

Alleles↗
PubMed1997

Relationships among strains classified with the ruminant Pasteurella haemolytica-complex using quantitative evaluation of phenotypic data.

The phenotypic relationships among 246 trehalose-negative strains classified under the [Pasteurella] haemolytica-complex in ruminants were investigated by clustering and multidimensional ordinations based upon 79 phenotypic characters. A quantitative evaluation of phenotypic data using a 5-level scoring system is presented permitting a comprehensive utilization of the recorded phenotypic variation among the strains in the analyses. Clustering and ordination analyses display complementary aspects of data which has been clearly demonstrated in this investigation. The main clusters revealed by the numerical techniques could be related to distinctive phenotypic differences and showed an extensive correlation with the recognized biogroups. This classification was based only upon 4 characters (fermentation of L-arabinose, D-sorbitol, glucosides and ornithine decarboxylase). In contrast, there was no obvious interpretation of the clusters formed by using binary scores. Phenotypic subgroups within the recognized biogroups have been described as well as a new, related group of bacteria, tentatively named Bisgaard taxon 36. Quantitative interpretation of phenotypic data seems to represent a promising method for finding relations among affiliated strains of bacteria and to assist in forming hypotheses for subsequent genotypic investigations.

Animals↗
PubMed1997

A cross-sectional study of helminths in rural scavenging poultry in Tanzania in relation to season and climate.

A cross-sectional study on the prevalence of helminths in rural scavenging poultry on six hundred adult chickens selected randomly from six villages in the Morogoro Region, Tanzania during the wet and the dry seasons, was conducted. The trachea and gastrointestinal tract of each bird were examined for the presence of parasites. All chickens were infected with one or several species of helminths, the average being 4.8 +/- 1.7 helminths per chicken during the wet season and 5.1 +/- 1.8 during the dry season. A total of 29 different helminth species were shown in the trachea or the gastrointestinal tract. The following species were identified: Syngamus trachea (0.7% (wet season), 2% (dry season)); Gongylonema ingluvicola (6.3%, 17.7%); Tetrameres americana (54.3%, 60.3%); Dispharynx nasuta (0%, 2.7%); Acuaria hamulosa (8.3%, 19.3%); Ascaridia galli (28.3%, 32.3%); Heterakis gallinarum (74.0%, 78.7%); H. isolonche (18.7%, 5.0%); H. dispar (25.7%, 6.3%); Allodapa suctoria (40.0%, 52.0%); Subulura strongylina (3.3%, 1.0%); Strongyloides avium (0.3%, 3.0%); Capillaria annulata (2.0%, 0.0%); C. contorta (9.0%, 1.0%); C. caudinflata (2.0%, 4.3%); C. obsignata (8.7%, 25.0%); C. anatis (4.0%, 9.0%); C. bursata (1.0%, 2.7%); Raillietina echinobothrida (41.3%, 46.3%); R. tetragona (25.3%, 21. 3%); R. cesticillus (8.7%, 2.7%); Choanotaenia infundibulum (0.0%, 3. 7%); Hymenolepis carioca (9.0%, 18.0%); H. cantaniana (48.0%, 43. 0%); Amoebotaenia cuneata (39.3%, 36.0%); Metroliasthes lucida (1.0%, 0.3%); Davainea proglottina (5.7%, 0.3%) and Polymorphus boschadis (0.3%, 0.0%). No trematodes were found. No correlation was found between season and prevalence, or season and mean worm burdens. Twelve helminths of the species recovered represent new local records.

Animals↗
PubMed1997

Separation of Salmonella typhimurium DT2 and DT135: molecular characterization of isolates of avian origin.

In Denmark, 0.4 and 3.4% of the human Salmonella Typhimurium cases registered between 1988 and 1993 were caused by DT2 and DT135, respectively. Separation of these two phage types was, however, problematic as only minor differences in lysis pattern and lysis strength occurred. Molecular characterization of 23 Danish isolates, 10 German isolates and the two type strains have subsequently been performed. With only minor exceptions, strains examined could be separated by combination of 0.5 agglutination, ribotyping, and PFGE typing into two major groups in conformity with their phage types. The differences between the two groups were, however, very small and it has not been completely clarified whether this grouping is the result of two independent types or of two related lines developing in different environments. It is concluded that the classification of related phage types DT2 and DT135 has to be supported by molecular methods.

Animals↗
PubMed1997

Genomic relationships between selected phage types of Salmonella enterica subsp. enterica serotype typhimurium defined by ribotyping, IS200 typing and PFGE.

The genomic relationship between isolates representing 17 definitive phage types (DTs) of Salmonella enterica subsp. enterica serotype typhimurium (S. typhimurium) were analysed using three different typing methods: IS200 typing using the restriction enzymes EcoRI and PvuII, ribotyping using SmaI and EcoRI, and PFGE using XbaI. These methods were used to study four DTs in greater detail; in all 18 (DT 49), 10 (DT 110), five (DT 120) and seven (DT 135) isolates were studied. The combined data generated two large clusters, which could be divided into five groups. Within the first cluster, a close similarity was indicated between isolates of the following phage types: group A-DTs 44, 49, 135 and 204c, with DT 9 distantly related; group B-DTs 95 and 99; and group C-DTs 104a, 110 and 120. The other large cluster contained group D-DTs 10, 20 and 146, with DT 12 distantly related, and group E-DTs 69, 103 and 153. The same grouping was observed by principal component analysis, but a minimum spanning tree linked DT 12 to group E and not group D in this analysis. Among the typing methods used, IS200 gave the best representation of the overall similarity between the S. typhimurium isolates. Five different IS200 profiles were obtained among isolates belonging to DT 49. Only one profile was observed within each of the phage types DT 110, 120 and 135. All isolates within each of these four phage types were of one ribotype. Isolates of DT 49 showed four PFGE patterns, while one pattern was present within isolates of the three other phage types. Members of these four phage types were found to be clonally related as they formed tight subclusters separated from isolates of other phage types.

Bacterial Typing Techniques↗
PubMed1997

Characterisation of Australian isolates of Actinobacillus capsulatus, Actinobacillus equuli, Pasteurella caballi and Bisgaard Taxa 9 and 11.

OBJECTIVE: The objective of this work was to perform a comprehensive phenotypic characterisation of 16 isolates of bacteria previously identified as Actinobacillus equuli. DESIGN: The 16 isolates that had been obtained from Australian animals--15 from horses and one from a rabbit--were compared with reference strains of A equuli, A capsulatus, Pasteurella caballi and Bisgaard Taxa 9 and 11. RESULTS: The characterisation study demonstrated that only nine of the isolates were A equuli. The other isolates were identified as A capsulatus (the isolate from rabbit), P caballi (one isolate), Bisgaard Taxon 11 (two isolates) and Bisgaard Taxon 9 (one isolate). The final two isolates could not be assigned to any recognised species or taxa. CONCLUSION: This study has highlighted the importance of a complete characterisation of Actinobacillus-like organisms isolated from horses and rabbits. The study represents the first time that A capsulatus, P caballi and Bisgaard Taxa 9 and 11 have been recognised as being present in Australia.

Actinobacillosis↗
PubMed1996

Virulence and genotype stability of Salmonella enterica serovar Berta during a natural outbreak.

Strains of Salmonella enterica serotype Berta, collected over a period of 6 years from a well documented natural outbreak in Denmark, have been characterized in order to assess the stability of chromosomal typing systems and virulence properties. Outbreak strains were identical in Pvu II and PSTI IS200 profiles, all but two strains showed the same Sma I ribotype, and all but one strain showed the same Not I pulsed field gel electrophoretic pattern, indicating that these molecular markers remained almost constant during the outbreak. In general, strains of S. Berta were found to be of moderate to low virulence; log VC10 values were found to vary between 3.0 and 4.4 after i.p. challenge of mice, and maximum CFU in internal organs of day-old chicks varied between 2 and 4 log10 units following oral challenge. The minor differences observed between strains in vivo did not correlate with differences in in vitro invasion into cultured MDCK cells, nor with in vitro growth characteristics. A succession of different plasmid profile types was observed during the outbreak but a hierarchical selection of clones based on differences in virulence was unlikely to have caused the succession of types of S. Berta during this outbreak.

Animals↗
PubMed1996

Genomic lineage of Salmonella enterica serotype Gallinarum.

Forty-eight strains of Salmonella enterica serotype Gallinarum of biotypes Gallinarum and Pullorum were characterised by three chromosomally based typing methods. The patterns obtained were compared with those of strains of eight other serotypes of Salmonella of O serogroup D. The same PvuII and PstI IS200 patterns were commonly observed among strains of both biotypes and the three SmaI ribotypes of serotype Gallinarum strains differed in only one or two bands, supporting the view that members of these two biotypes are closely related. The same IS200 patterns were also commonly observed among strains of serotype Enteritidis, indicating its evolutionary relationship with serotype Gallinarum. NotI pulsed-field gel electrophoresis (PFGE) patterns divided strains into 24 types. Based on a similarity analysis, two clusters were formed. One contained the majority of biotype Gallinarum strains and two atypical strains of Pullorum; the other contained strains of biotype Pullorum and an otherwise typical strain of biotype Gallinarum. Two atypical strains of biotype Pullorum remained unclustered by PFGE analysis. The grouping of strains differed according to the typing method used, but the majority of strains within each of the biotypes Gallinarum and Pullorum were very similar by the chromosomal markers analysed.

Animals↗
PubMed1996

Listeria monocytogenes in poultry and poultry products: epidemiological investigations in seven Danish abattoirs.

Listeria monocytogenes was isolated from 11/236 (4 x 7%) caecal samples from parent flocks, providing broilers to the abattoirs investigated. Caecal samples from 2078 broilers representing 90 randomly selected broiler flocks were negative for L. monocytogenes. A total of 3080 samples from seven abattoirs including poultry processing line samples, and final products were also examined for L. monocytogenes. Listeria monocytogenes was isolated in 0 x 3% to 18 x 7% of the samples collected in the different abattoirs. Epidemiological typing of 247 L. monocytogenes isolates, including serotyping, phage typing, pulsed-field gel electrophoresis and ribotyping revealed 62 different clones. Based upon typability and discriminatory power, DNA typing methods used were found equally suitable as epidemiological markers. Serotyping and phage typing were not found useful as epidemiological markers for poultry isolates of L. monocytogenes since only 120/247 (48 x 6%) isolates were typable by phage typing and 230/247 (93 x 1%) L. monocytogenes belonged to serotype 01 while 6/247 (2 x 4%) belonged to 04. The discovery of a few dominating clones in each abattoir might indicate an endemic occurrence of L. monocytogenes. It is concluded that L. monocytogenes in the broiler production is primarily localized to the abattoirs. The incidence of L. monocytogenes may be reduced by improving the hygiene.

Abattoirs↗