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Biomedical subjects

D J Hampson

Publications and source records attributed to D J Hampson.

At least 109 records · Page 6Linked to original sources
PubMed1993

Human intestinal spirochetes are distinct from Serpulina hyodysenteriae.

Twenty-nine intestinal spirochetes isolated from Australian aboriginal children and six strains from Italian adults (HRM1, -2, -4, -5, -7, and -14) were genetically examined at 15 enzyme loci by using multilocus enzyme electrophoresis. Results were compared with those previously obtained for 188 porcine intestinal spirochetes. DNA from human strain HRM7 and porcine strain Serpulina hyodysenteriae P18A were also radioactively labeled and hybridized with DNA from 12 other human and porcine intestinal spirochetes. Both the multilocus enzyme electrophoresis and hybridization techniques demonstrated that the human spirochetes were not S. hyodysenteriae. They belonged to another distinct genetic group of spirochetes that included P43/6/78, the bacterium recovered from the first recorded case of porcine intestinal spirochetosis. Bacteria in this distinct group also differed from Serpulina spp. in possessing only four, five, or occasionally six axial filaments, being slightly thinner, and having more pointed ends. These findings add further weight to the possibility that human intestinal spirochetes may act as enteric pathogens.

Adult↗
PubMed1993

Population structure of Australian isolates of Streptococcus suis.

The genetic diversity of 109 isolates of Streptococcus suis, which were recovered mainly from Australian pigs, was examined by multilocus enzyme electrophoresis. The collection was genetically diverse. Sixty-five electrophoretic types (ETs) were recognized, with a mean genetic diversity per enzyme locus of 0.512, or 0.431 when the number of isolates in each ET was considered. Serotype diversity varied, being greatest for isolates of capsular serotype 15 (0.364), and then diminishing in the order of serotypes 9, 1, 4, 1/2, 2, 7, and 3 (0.120). On average, isolates from these eight serotypes represented 4.13 separate clonal groups per serotype. This diversity indicated that serotyping of S. suis for subspecific differentiation is not a reliable technique for identifying specific strains and is not a good predictor of the genetic background of a given isolate. No tendency for isolates recovered from healthy pigs to be genetically distinct from those from diseases animals was found, nor were there consistent differences between isolates recovered from animals with different disease syndromes (meningitis, pneumonia, and septicemia). Danish reference strains of serotypes 1, 2, and 7 each belonged to one of the same clonal groupings of these types found in Australia, but Danish strains of serotypes 3, 4, 6, and 8 and a strain of serotype 1 from the United Kingdom were each genetically distinct from the Australian isolates. Generally, isolates in the same ET belonged to the same serotype, but one ET contained isolates of types 6 and 6/16, and three were made up of isolates of types 2 and 1/2. One isolate of serotype 2, which was recovered from a human with meningitis, belonged to the same ET as two isolates of serotype 2 that were recovered from pigs. The human infection was therefore likely to have been zoonotic.

Animals↗
PubMed1993

Clonal analysis of Escherichia coli of serogroups O9, O20, and O101 isolated from Australian pigs with neonatal diarrhea.

The genetic diversity of 87 isolates of Escherichia coli recovered from Australian pigs with neonatal diarrhea was examined by multilocus enzyme electrophoresis. The isolates were of serogroups O9, O20, and O101, and although most isolates lacked K88(F4), K99(F5), 987P(F6), and F41 fimbriae, they were considered to be involved in the etiology of the diarrhea. The isolates were extremely diverse, considering their origin from a single pathological condition in one country. There were estimated to be 18, 16, and 12 clones of the three respective serogroups in the collection, with serogroup diversities of 0.387, 0.448, and 0.275, respectively. Comparison with the results previously obtained for isolates from piglets with postweaning diarrhea suggested that bacteria from piglets with these two conditions did not come from any particular common genetic background. The overall genetic diversity for the combined collection was the same as that reported by others for representative isolates selected from throughout the species (0.47). The current results indicate that if isolates of these O groups are involved in porcine diarrhea, their pathogenicity is directly linked to their O somatic antigen type and is not simply due to the wide distribution of a small number of virulent clones.

Animals↗
PubMed1992

Typing of Australian isolates of Treponema hyodysenteriae by serology and by DNA restriction endonuclease analysis.

A total of 91 isolates of Treponema hyodysenteriae which were obtained from 62 piggeries located around Australia were typed by serology and by DNA restriction endonuclease analysis (REA). The isolates fell into eight serogroups, of which groups B and D were the most common. Isolates with different REA patterns were recognised within serogroups, whilst a few isolates with the same REA pattern were placed into different serogroups. Some of the latter isolates were either from the same piggery or from farms with epidemiological links, thus indicating the bacteria may have altered their antigenic properties. A total of 31 different REA patterns were recognised amongst the Australian isolates. These comprised eight major patterns, with four of these being subdivided on the basis of minor differences in banding. Where a number of isolates were obtained from individual piggeries these all had the same REA pattern, and in one piggery isolates with the same pattern were recovered over a five year period. Plasmid bands were observed in 70 of the Australian isolates (77%), and in six of the seven overseas isolates included in the study for comparison. These plasmids did not affect the REA pattern. Of the States from which substantial numbers of isolates were examined, the greatest number of different strains (12 amongst 19 piggeries) were found from Victoria, and there were 10 REA patterns in strains from 24 piggeries in Queensland. Despite the large total number of different strains of T. hyodysenteriae in Australia, only three were found in more than one State.

Animals↗
PubMed1992

The serological grouping system for Serpulina (Treponema) hyodysenteriae.

Lipopolysaccharide from serostrains of Serpulina (Treponema) hyodysenteriae for serogroups A to I was characterized using sodium dodecylsulphate polyacrylamide gel electrophoresis and silver staining. All strains had lipopolysaccharide components ranging from 10 to 16 kDa that represented lipid A-core polysaccharide regions, and short O-antigen side chain were also recognized in certain immunoblots. Serological reactions between lipopolysaccharide and antisera against each of these serostrains were examined by Western immunoblotting. There was relatively little antigenic cross-reactivity between LPS from the nine strains, thus confirming their suitability as serostrains. Using cross-absorbed sera, isolates within serogroups A and E were shown to possess unique epitopes on the core lipopolysaccharide, distinct from serogroup reactivities. These isolates were therefore identified as serovars within the serogroups. This study confirmed the usefulness of the serotyping scheme for S. hyodysenteriae, in which the bacteria can be placed into serogroups using unabsorbed sera, and into serovars within these using cross-absorbed sera.

Blotting, Western↗
PubMed1992

A serological survey to determine the prevalence of infection with Treponema hyodysenteriae in Western Australia.

A serological survey to detect antibody titres against Treponema hyodysenteriae was conducted on pigs from 106 herds in Western Australia. Titres indicating a positive result in the tests were determined by examining 400 sera from 4 herds known to be free of swine dysentery, and sera from immunised or experimentally infected pigs. Samples of serum from 40 bacon-weight pigs from each of the 106 herds were then collected at 2 abattoirs. Each serum was tested in enzyme-linked immunosorbent assays (ELISA) against the lipopolysaccharide of T hyodysenteriae of serogroups A, B and E, respectively. To assist in evaluating the test, 19 herds were resampled and retested, and faecal samples from 17 herds were cultured for T hyodysenteriae. Thirty-five of the 106 herds (33%) had serological evidence of infection when only one batch of sera from each herd was tested. The ELISA to detect T hyodysenteriae infection in herds using 40 sera was estimated as having a sensitivity of 77.3% and a specificity of 81.8% based on the owners' opinion of their herds disease status. Prevalence of infection within herds ranged from 2.5% to 47.5%, with a mean of 18%.

Animals↗
PubMed1992

Intestinal spirochaetes colonizing aborigines from communities in the remote north of Western Australia.

Intestinal spirochaetal bacteria were isolated from 59 of 181 (32.6%) faecal samples obtained from Aboriginal children and a few adults living in communities in the Kimberley region in the north of Western Australia. Colonization was more common in young Aborigines between 2 and 18 years of age than it was in adults, or in babies and children less than 2 years of age. Three of 22 Aboriginal children who were sampled on two consecutive years were colonized on both occasions. None of four other children were found to be consistently colonized with the bacteria when sampled on three sequential years, but three were positive on two consecutive visits and the other child was positive on the first and third sampling. Most Aboriginal children had abnormal or watery stools, and both abnormal and watery stool samples were significantly more likely to contain spirochaetes than were normal samples. However, it was not possible to prove that the spirochaetes were the cause of the diarrhoea. In contrast, spirochaetes were only recovered from 8 of 695 (1.2%) faecal samples that were obtained from other mainly non-Aboriginal children and adults in Western Australia or the Northern Territory of Australia, even though most of these individuals were suffering from gastrointestinal disturbances.

Adolescent↗
PubMed1991

Use of a whole chromosomal probe for identification of Treponema hyodysenteriae.

A whole chromosomal DNA probe labelled with photobiotin was used in a dot blot hybridisation to identify DNA from isolates of Treponema hyodysenteriae, the aetiological agent of swine dysentery. The probe was evaluated using DNA from 13 isolates of T hyodysenteriae and 13 isolates of non-T hyodysenteriae spirochaetes recovered from pigs. The initial test had both a sensitivity and specificity of 92.3 per cent, although when it was repeated the specificity fell to 84.6 per cent. The test was helpful in distinguishing between T hyodysenteriae and other morphologically similar treponemes that are part of the normal flora in the large intestine of pigs. The probe could also be used to detect as little as 10 ng of purified DNA from T hyodysenteriae, or DNA from 2 x 10(6) bacterial cells lysed directly onto nitrocellulose.

Animals↗
PubMed1991

A longitudinal study of natural infection of piglets with Streptococcus suis types 1 and 2.

Streptococcus suis types 1 and 2 were detected in nasal swabs taken from five litters of piglets sampled twice weekly from birth. The two types had been detected in all pigs by the time they were 38 and 25 days old respectively with mean ages of first detectable infection being 13.5 and 8.5 days. The prevalence of infection was not affected by housing conditions or the population density of pigs. Piglets originating from a sow with vaginal swabs positive for S. suis type 2 were infected earlier than piglets from non-vaginal carriers. It is concluded that infection of piglets with S. suis type 2 may occur during the birth process.

Animals↗
PubMed1991

Slide-agglutination for rapid serological typing of Treponema hyodysenteriae.

A slide agglutination (SA) test was developed to determine the serogroup of isolates of Treponema hyodysenteriae of serogroups A to F. Rabbit antisera which are normally used for serogrouping T. hyodysenteriae in an agarose gel double-diffusion precipitation test (AGDP) were not suitable for SA because they agglutinated isolates from more than one serogroup. The agglutination reaction was made serogroup-specific by cross-absorbing the typing sera for serogroups A to F with whole treponemes from the other 5 of these 6 serogroups of T. hyodysenteriae. The absorbed sera were reacted in slide agglutination tests with 33 isolates of T. hyodysenteriae and with four non-T. hyodysenteriae intestinal spirochaetes. None of the non-T. hyodysenteriae isolates agglutinated, but 27 of the 33 isolates of T. hyodysenteriae did. The results for 26 of the 27 agglutination reactions agreed with the serogroup as determined in AGDP. One of the 6 isolates of T. hyodysenteriae which failed to react in slide agglutination was of serogroup B, 1 of serogroup D, 1 each were from new serogroups G, H and I, and 1 was untypable in AGDP.

Agglutination Tests↗
PubMed1991

Rotavirus excretion by village pigs in Papua New Guinea.

Cohort studies were conducted on 29 pigs from 3 villages in the Highlands of Papua New Guinea. Animals ranged in age from 9 d to 5 m old. Three hundred and twenty nine faecal samples were collected from individual pigs followed over 3 to 6 w periods, and were examined for group A rotavirus antigen by ELISA, and rotaviral genomic RNA by polyacrylamide gel electrophoresis (PAGE). Electron microscopy was also conducted on selected samples. Group A rotavirus was detected in the faeces of 16 pigs with infected individuals coming from all villages. Non-group A rotavirus resembling group C was found in faeces from pigs from 2 villages. All of the group A rotaviruses examined had the same electrophoretype and this was distinct from that of the common type infecting humans in the area at the time of the study. None of the group A positive samples reacted with monoclonal antisera specific for human group A rotaviruses of serotypes 1, 2, 3, 4, or 8. The non-group A rotaviruses also all had identical electrophoretypes. In contrast to previous findings in intensive piggeries, rotavirus infection did not occur in all young pigs and was not limited to young animals under 2 m of age. Infected pigs varied in age from 12 days to 20 weeks of age. This pattern of infection was attributed to the non-intensive husbandry situations in the villages, with less opportunity for transmission to occur than in intensive piggeries.

Animal Husbandry↗
PubMed1991

The adoption of management and husbandry procedures by Western Australian pig farmers.

A postal survey was conducted to determine the management and husbandry procedures adopted by a sample of 101 Western Australian pig farmers. Seventy seven replies were received and analysed. Over 80% of farmers vaccinated breeding stock against leptospirosis and erysipelas, 35% vaccinated against parvo virus and 15% vaccinated against Escherichia coli. Most farmers used antibiotics: 72% incorporated them into their pig diets and 60% used parenteral antibiotics. Fifty three per cent of farmers reported that they regularly used a veterinarian. Over 59% of piggeries had another piggery located within 10 km, thus increasing the possibility for disease transmission between herds. It is concluded that there is potential for veterinarians to offer advice to pig farmers, particularly on disease control measures and adoption of technological advances.

Animal Husbandry↗
PubMed1990

Multilocus enzyme electrophoresis for identification and typing of Treponema hyodysenteriae and related spirochaetes.

An assessment was made of multilocus enzyme electrophoresis as a means of identifying and typing spirochaetes isolated from pigs. Using five enzyme systems, 36 isolates from Australia, the U.K. and the U.S.A. were divided into 12 electrophoretic types or multilocus genotypes, comprising four major, genetically distinct groups. All 26 isolates of Treponema hyodysenteriae fell into one group, members of which showed relatively little genetic diversity. Ten isolates of non-pathogenic spirochaetes fell into three genetically different groups. Although the technique was capable of typing organisms within the groups, it was not always as discriminatory as DNA-restriction endonuclease analysis. Examination of additional enzyme loci should increase the sensitivity of the method for typing and for overall assessment of genetic relationships between spirochaetes.

Alleles↗
PubMed1990

Serological grouping of Treponema hyodysenteriae.

Two Australian isolates of Treponema hyodysenteriae which did not fit within the current serological grouping system for these bacteria were examined by agarose gel double immunodiffusion tests (AGDP). Isolate Vic1 was serologically unique, and we propose that it becomes the type organism for a new sixth serological group of T. hyodysenteriae (Group F). Isolate Q1 was unusual in that lipopolysaccharide (LPS) extracted from it reacted strongly in AGDP with serum raised against the type organism for serogroup D (A1), and also weakly with serum raised against the type organism for serogroup B (WA1). The nature of this cross-reactivity was examined by using cross-absorbed antisera in AGDP, and by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot analysis. The pattern of serological cross-reactivity between Q1, A1 and WA1 was complex and was not fully defined, but the isolate Q1 apparently shared low molecular weight 'serogroup' LPS antigens with A1, and shared higher molecular weight LPS antigens with WA1. On this basis Q1 was designated as belonging to serogroup D, although it was recommended that this be qualified as D (B) to indicate the presence of weak cross-reactivity with serogroup B. Such serological cross-reactivity may have significance in relation to the development of immunity to T.hyodysenteriae. Isolate Q1 may be a potentially useful organism for vaccine development because of its ability to induce a good serological response to LPS of treponemes from both serogroups D and B.

Animals↗