PubMed Health⌕ Search

Biomedical subjects

D J Hampson

Publications and source records attributed to D J Hampson.

At least 91 records · Page 5Linked to original sources
PubMed1995

Polymerase chain reaction for identification of human and porcine spirochaetes recovered from cases of intestinal spirochaetosis.

A polymerase chain reaction (PCR) amplification of 16S rDNA was developed to identify spirochaetes recovered from cases of intestinal spirochaetosis in humans and pigs; these bacteria belong to a distinct genetic group of spirochaetes, with the proposed name 'Anguillina coli'. The PCR incorporated a universal eubacterial 16S rDNA sequencing primer (1492r), and a 21-base forward primer designed to include a nucleotide sequence specific for 'A. coli'. The PCR was used to correctly identify DNA extracted from 43 isolates of 'A. coli' from humans and pigs, whilst no product was produced from Escherichia coli, or from other intestinal spirochaetes, including 38 isolates of Serpulina spp., and one each of Treponema succinifaciens and Brachyspira aalborgi. The amplification provided a rapid and simple means of identifying DNA from isolates of 'A. coli', and could be used on boiled whole 'A. coli' cells, with a detection limit equivalent to 2.5 x 10(2) cells. The reaction was used to detect and identify these spirochaetes from selective agar plates inoculated with stool specimens from infected pigs.

Animals↗
PubMed1995

Genetic analysis of dermatophilus spp. using multilocus enzyme electrophoresis.

Multilocus enzyme electrophoresis was used to examine a collection of 41 mainly Australian isolates of Dermatophilus congolensis that had been cultured from sheep, cattle, horses, a goat, a marsupial and Chelonids. Allelic variation was examined at 16 enzyme loci. The isolates were divided into eight distinct electrophoretic types (ETs) with a mean genetic diversity per locus of 0.41. The three isolates from Chelonids represented a distinct clone in ET 1 which was separated from the remaining cluster of isolates of D. congolensis by a genetic distance of 0.852. These findings supported a previous proposal that the isolates from Chelonids represent a new species of Dermatophilus. The other 38 D. congolensis isolates were separated into two divisions (I and II) by a genetic distance of 0.560. The divisions were both subdivided into groups that either only contained alpha-hemolytic or beta-hemolytic isolates, but all isolates in each ET had only one hemolytic pattern. Isolates originating from the same animal species, or from the same geographic location, were not all closely related genetically. The allocation of isolates into ETs correlated well with their distribution into DNA restriction endonuclease analysis patterns previously established for the collection. Although relatively few distinct strains of D. congolensis were identified amongst the collection, significant genetic diversity existed within this population.

Actinomycetales↗
PubMed1995

Identification of a new intestinal spirochete with pathogenicity for chickens.

Two intestinal spirochete isolates obtained from chickens with diarrhea were examined by electron microscopy, biochemical tests, rRNA gene restriction pattern analysis, and multilocus enzyme electrophoresis. One isolate (strain 91-1207/C1) was pathogenicity tested in vivo in chickens. The chicken spirochetes were morphologically indistinguishable from Serpulina innocens and Serpulina hyodysenteriae and phenotypically similar to S. innocens. However, the chicken spirochetes could be distinguished from S. innocens, S. hyodysenteriae, and other swine intestinal spirochetes by rRNA gene restriction pattern analysis and multilocus enzyme electrophoresis. In pathogenicity tests in 1-day-old chicks and 14-month-old hens, chicken spirochete 91-1207/C1 produced pale-yellow, watery cecal contents and mild lymphocytic typhlitis. These findings support the conclusion that avian intestinal spirochetes can be pathogenic to commercial poultry and that the microorganisms are different from intestinal spirochetes that infect pigs.

Animals↗
PubMed1995

Pathogenicity of human and porcine intestinal spirochetes in one-day-old specific-pathogen-free chicks: an animal model of intestinal spirochetosis.

One-day-old chicks were infected orally with two strains of weakly hemolytic spirochetes isolated from a human and a pig with intestinal spirochetosis. These spirochetosis both colonized birds, attached end-on to their cecal enterocytes, induced watery diarrhea, and significantly depressed growth rates. Cultures of Serpulina innocens failed to colonize the chicks.

Animals↗
PubMed1994

Clonal analysis and virulence of Australian isolates of Streptococcus suis type 2.

Multilocus enzyme electrophoresis was used to divide 124 Australian isolates of Streptococcus suis type 2 into 17 electrophoretic types (ETs). Isolates in ET 1 were the most frequent cause of disease amongst Western Australian pigs, but isolates of ET 8 were more commonly associated with disease in other Australian states. Multiple isolates from 10 of 19 farms all belonged to the same ET, whilst isolates from the other farms belonged to between 2 and 4 different ETs. Some isolates could be differentiated further by DNA restriction endonuclease analysis, whilst others with the same restriction pattern were located in different, but closely-related ETs. Fourteen isolates were tested for their virulence in mice. Most caused disease if given in high numbers, but isolates in ET 1 were virulent at lower dose rates. This virulent clone also was distinguished by the fact that 80% of isolates produced extracellular factor (EF).

Animals↗
PubMed1994

Genetic characterisation of intestinal spirochaetes and their association with disease.

Multilocus enzyme electrophoresis was used to assess genetic relationships amongst 175 isolates of anaerobic intestinal spirochaetes, including 72 isolates from individuals living in different parts of the world, 102 from pigs and one from a dog. Amongst porcine isolates belonging to the genus Serpulina, a possible new species was identified. All but one of the isolates from man were clustered with the canine isolate and 59 porcine isolates in a distinct group that we have previously called "Anguillina coli". The human and animal spirochaetes in this group had four-to-six axial flagella and most were recovered from individuals with diarrhoea. They included a strain of the so-called "Serpulina jonesii", that was not a true serpulina. These 71 human isolates were distributed into 44 electrophoretic types and had a mean genetic diversity of 0.32. These were further divided into 26 clonal groups. Three of these clones also contained porcine isolates, one of which was strain P43/6/78, the agent of porcine intestinal spirochaetosis. Four of the clones contained human isolates from different sources. One included isolates from Western Australian Aboriginal children and from Italian adults, and the other three contained isolates from Western Australian Aboriginal children and from homosexual males in Sydney, New South Wales. There were no known connections between these human populations. The other spirochaete of human origin was Brachyspira aalborgi, which was distinct from isolates in the genera Serpulina and "Anguillina". Both B. aalborgi and "A. coli" have been associated with human cases of intestinal spirochaetosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Antimicrobial susceptibility testing of Serpulina hyodysenteriae.

The macrobroth dilution technique was used to test the in-vitro effectiveness of 4 commonly used antimicrobial agents against 23 Australian isolates and 7 overseas strains of Serpulina hyodysenteriae. Minimum inhibitory concentrations and minimum bactericidal concentrations were determined. The growth of 90% of isolates was inhibited by dimetridazole at a concentration of 4 micrograms/mL, and by tiamulin at 8 micrograms/mL. Australian isolates resistant to both antimicrobial agents were identified. Lincomycin was less effective than these antimicrobial agents, with 90% of isolates requiring a concentration of 128 micrograms/mL for inhibition of growth, and 54% being susceptible at 64 micrograms/mL. Tylosin did not prevent the growth of the majority of S hyodysenteriae isolates tested, and 90% were resistant to concentrations of > or = 128 micrograms/mL. Resistant isolates came from different geographical areas. Resistance was not related to overall genetic background of the spirochaetes, and was not correlated with the presence of plasmids or the serogroup of the isolates.

Animals↗
PubMed1994

Pathogenicity of porcine intestinal spirochetes in gnotobiotic pigs.

Twelve intestinal spirochete strains of porcine origin were characterized on the basis of their phenotypic properties, by multilocus enzyme electrophoresis, and by pathogenicity testing in gnotobiotic pigs. The spirochetes used included two strains of Serpulina hyodysenteriae (B204 and P18A), two strains of Serpulina innocens (B256 and 4/71), one strain from the proposed new genus and species "Anguillina coli" (P43/6/78), and seven non-S. hyodysenteriae strains recently isolated from United Kingdom pig herds with a history of nonspecific diarrhea and typhlocolitis. By multilocus enzyme electrophoresis, five of these were identified as S. innocens, one was identified as an unspecified Serpulina sp., and one was identified as "A. coli." S. hyodysenteriae B204 and P18A, "A. coli" P43/6/78 and 2/7, and three (22/7, P280/1, and 14/5) of the five S. innocens field isolates induced mucoid feces and typhlocolitis in gnotobiotic pigs. None of the other spirochetes produced clinical signs or large intestinal pathology in this model. The "A. coli" strains induced a more watery diarrhea, with lesions present more proximally in the large intestine, than did the other pathogenic spirochetes. S. innocens 22/7 was also tested for pathogenicity in hysterotomy-derived pigs that had previously been artificially colonized with a spirochete-free intestinal flora and shown to be susceptible to swine dysentery. Despite effective colonization, strain 22/7 did not produce any disease, nor was there any exacerbation of large intestinal pathology or clinical signs when pigs with an experimentally induced existing colitis caused by Yersinia pseudotuberculosis were superinfected with strain 22/7. Certain non-S. hyodysenteriae spirochetes are therefore capable of inducing disease in gnotobiotic pigs, but their role as primary or opportunistic pathogens in conventional pigs remains equivocal.

Animals↗
PubMed1994

Analysis of Erysipelothrix rhusiopathiae and Erysipelothrix tonsillarum by multilocus enzyme electrophoresis.

The genetic diversity of 74 Australian field isolates of Erysipelothrix rhusiopathiae and 22 reference strains for serovars of E. rhusiopathiae or Erysipelothrix tonsillarum was examined by multilocus enzyme electrophoresis. Four serovar reference strains of E. tonsillarum (strains KS 20 A, Wittling, Lengyel-P, and Bano 107 for serovars 25, 3, 10, and 22, respectively) were genetically distinct from E. rhusiopathiae. However, the E. tonsillarum reference strain for serovar 14 (Iszap-4) and the reference strain for serovar 13 (Pecs-56), which has been said to represent a new genomic species, were found to cluster with typical isolates and reference strains of E. rhusiopathiae. Our reference strain for serovar 7 (Rotzunge) was also genetically typical of E. rhusiopathiae, thus indicating that these serotype reactivities cannot be relied upon as a means of identifying isolates as E. tonsillarum. Australian field isolates of E. rhusiopathiae were genetically diverse. Those recovered from sheep or birds were more diverse than those isolated from pigs, and isolates of serovar 1 were more diverse than those of serovar 2. The diversity found among isolates of the same serovar and the presence of isolates of different serovars in the same electrophoretic types (ETs) indicated that serotyping of E. rhusiopathiae was unreliable for use as an epidemiological tool. Some ETs contained isolates recovered from different animal species. ET 41 contained 32.2% of the field isolates and two reference strains, indicating that this clone of E. rhusiopathiae is both widespread and commonly associated with disease in various species of animals.

Animals↗
PubMed1993

Genetic relationships between isolates of Serpulina (Treponema) hyodysenteriae, and comparison of methods for their subspecific differentiation.

Multilocus enzyme electrophoresis (MEE) was used to examine the extent of genetic diversity amongst 98 isolates of Serpulina (Treponema) hyodysenteriae. The species contained four major genetic divisions (A, B, C and D) and 29 electrophoretic types (ETs). Division D was relatively distinct, being separated from the other three divisions by fixed allelic differences at an average of 6.6 of 15 enzyme loci. Electrophoretic differences were compared with results of DNA restriction endonuclease analysis (REA) and serological typing of the isolates. Most isolates with the same or similar REA banding patterns shared the same or similar ETs. This demonstrated that both techniques could be used as sensitive and specific methods of identifying closely related isolates. However, using MEE analysis, some isolates that had quite different REA patterns were found to be genetically closely related. Therefore ET designations had an advantage over REA patterns in that they were readily quantifiable as a means of estimating genetic relatedness between isolates. Most isolates that were genetically similar to each other were of the same serological group, but some antigenic types were widely distributed across the genetic divisions.

Brachyspira hyodysenteriae↗
PubMed1993

The porcine intestinal spirochaetes: identification of new genetic groups.

The weakly beta-haemolytic isolates were divided into 56 electrophoretic types (ETs), contained in three distinct genetic groups (A,B and C). Group A corresponded to the genus Serpulina, and could be divided into three divisions. It contained 17 weakly haemolytic isolates in divisions b and c, as well as all 98 isolates of S. hyodysenteriae, located in division a. All seven weakly beta-haemolytic isolates that produced indole and had alpha-glucosidase but not alpha-galactosidase activity fell into division b. These spirochaetes may represent a distinct species. The other ten weakly beta-haemolytic spirochaetes, in division c, fitted the description of S. innocens. Group B contained 17 of the weakly beta-haemolytic isolates (18.9%) in ten ETs. Isolates in this group differed from typical S. innocens in that they lacked alpha-galactosidase activity. Group B represented a distinct group of weekly beta-haemolytic spirochaetes, which may constitute a new genus. Group C contained 56 of the weakly beta-haemolytic isolates (62.2%) located in 29 ETs. The original isolate from "spirochaetal diarrhoea" (P43/6/78-Taylor et al., 1980) was located in this group, together with Australian isolates from a similar condition. Spirochaetes in group C were morphologically distinct from those in groups A and B in that they possessed only four, five or occasionally six, subterminal axial filaments, were more slender, and had more pointed ends to their cells. We consider that group C represents a new genus of spirochaetes, members of which may be associated with spirochaetal diarrhoea.

Alleles↗
PubMed1993

Genetic analysis of Actinobacillus pleuropneumoniae, and comparison with Haemophilus spp. Taxon "minor group" and Taxon C.

The genetic diversity among 52 field isolates, mainly from Australia, and 15 reference strains of Actinobacillus pleuropneumoniae was examined using multilocus enzyme electrophoresis. Thirty three electrophoretic types (ETs) were recognised, with a mean genetic diversity per locus of 0.312. Australian strains of serovars 1, 2, 5 and 7 belonged to the same clonal lines as strains of these serovars in other countries, but distinct clones of serovars 3, 7, 11 and 12 were also identified. The type strains of serovars 1, 9 and 11 were placed in the same ET. Strains of A. pleuropneumoniae biovar 2 were closely related to biovar 1 strains. Twenty three isolates which did not react with the typing sera or could not be assigned to a single serovar were divided into seven clonal groups. Five strains of Haemophilus sp. Taxon "minor group" which were included in the study were distinct from A. pleuropneumoniae, and were diverse, being divided into at least two major genetic groupings. Two strains of Haemophilus sp. Taxon C were placed in another distinct ET.

Actinobacillus pleuropneumoniae↗
PubMed1993

The carriage of Streptococcus suis type 2 by pigs in Papua New Guinea.

An indirect fluorescent antibody test was used to detect the presence of Streptococcus suis type 2 in nasal and pharyngeal swabs taken from pigs in Papua New Guinea. The rate of carriage for the two sites in domesticated indigenous village pigs was 0.5 and 2.5% respectively, compared to 39 and 43% for intensively reared pigs. These findings were supported by the results of a serological survey, using an enzyme linked immunosorbent assay, in which 87% of intensively reared pigs but only 8% of village pigs were seropositive to S. suis type 2. It is proposed that in intensive piggeries S. suis type 2 is continually cycled between pigs. In village pigs, the low population density and harsh environmental conditions prevents this cycle of infection.

Animals↗
PubMed1993

Genetic analysis of Escherichia coli from porcine postweaning diarrhoea.

A total of 79 Australian isolates of beta-haemolytic Escherichia coli from cases of porcine postweaning diarrhoea (PWD), and 18 isolates of serotype O 149:K91:K88 (F4) from unweaned pigs from Australia, Indonesia and Denmark, were examined by multilocus enzyme electrophoresis. These were divided into 57 electrophoretic types (ETs), with an overall mean genetic diversity per enzyme locus of 0.466. This value closely resembled that previously recorded for the whole species. Not only was the collection diverse, but there was considerable genetic heterogeneity amongst PWD isolates of the same serogroup. Isolates from serogroups O 8 and O 138 were most varied, whilst many from serogroups O 141 and O 149 were more closely related. In contrast, the isolates from the unweaned pigs all belonged to only one ET.

Animals↗
PubMed1993

Genetic characterisation of isolates of Listeria monocytogenes from man, animals and food.

Multilocus enzyme electrophoresis was used to assess genetic relationships between 95 isolates of Listeria monocytogenes, most of which were isolated in Australia and New Zealand from man, animals and food. The isolates were separable into two major genetic divisions; the majority of those from human patients and animals were in division I, and the majority from those foods that were not specifically associated with human listeriosis were in division II. Isolates in division I were virulent, whereas many isolates from food were probably less virulent and did not pose a large threat to human health. However, isolates from certain foods, particularly paté, were indistinguishable from those causing disease in man, and the consumption of these products represented a clear risk factor for infection. Isolates from infected human patients in Australia and New Zealand belonged to the same clone of serotype 4b that has been responsible for major epidemics in the northern hemisphere. However, a separate clone of serotype 1/2b strains, present in both Australia and New Zealand, was responsible for two major outbreaks that occurred in Western Australia in 1978-80 and 1990-91.

Alleles↗
PubMed1993

Experiences with a vaccine being developed for the control of swine dysentery.

A prototype vaccine that is being developed for the control of swine dysentery (SD) was tested in two groups of experimental pigs. Vaccination induced high circulating antibody titres against the aetiological agent, Serpulina (Treponema) hyodysenteriae. Pigs in the first trial were vaccinated twice before being challenged orally with the bacteria. Five of 6 unvaccinated animals developed dysentery within a fortnight of challenge, but only 1 of 6 vaccinated pigs showed signs of disease at this time. Unexpectedly, 1 mo after challenge, the surviving unvaccinated pig and 2 remaining healthy vaccinated animals succumbed to the disease. The reason for the development of this late-onset form of dysentery was not clear. In the second trial, 8 pigs were vaccinated 3 times. Only 2 of these animals (25%) developed severe dysentery after being mixed with infected pigs, whereas 7 of 8 (88%) unvaccinated control pigs in the same pen became diseased. The late-onset form of dysentery was not observed. The prototype vaccine for SD provided a useful level of protection, and could be used in programs to control the disease in Australia.

Animals↗