The porcine intestinal spirochaetes: identification of new genetic groups

Unification of the genera Serpulina and Brachyspira, and proposals of Brachyspira hyodysenteriae Comb. Nov., Brachyspira innocens Comb. Nov. and Brachyspira pilosicoli Comb. Nov

The phylogenetic positions of Serpulina hyodysenteriae, Serpulina innocens, Serpulina pilosicoli and Brachyspira aalborgi were studied. Complete 16S ribosomal DNA sequences of these three species and B. aalborgi revealed that their 16S rDNA sequences were related more than 96.0%. The mol% guanine plus cytosine (G+C) of B. aalborgi DNA was 27.1, and was similar to those of the 3 members of the genus Serpulina. The homologous rates using 31P-labeled B. aalborgi chromosome DNA in DNA-DNA reassociation tests were 22.0% to S. hyodysenteriae, 19.1% to S. innocens and 17.2% to S. pilosicoli. Therefore, we propose to transfer the three species of the genus Serpulina to the genus Brachyspira. Descriptions of Brachyspira hyodysenteriae comb. nov., Brachyspira innocens comb. nov. and Brachyspira pilosicoli comb. nov., and an emended description of B. aalborgi are given. Phenotypic characteristics of the 4 members of the genus Brachyspira were also studied. They fermented fructose, galactose, glucose, lactose, maltose, mannose, raffinose and trehalose; however, B. aalborgi did not ferment raffinose. All of them hydrolyzed esculin but did not produce indole except for B. hyodysenteriae. The protein profile of B. aalborgi was different from those of the four strains of B. hyodysenteriae, B. innocens and B. pilosicoli, but the heavy bands with molecular sizes of 49.4 and 52.3 kDa of B. aalborgi were quite similar to those of B. innocens in the points of quantity and molecular size. In immunoblotting tests, B. aalborgi reacted well with anti-B. innocens and B. pilosicoli sera, but reacted weakly with anti-B. hyodysenteriae serum. Only one heavy band and several faint bands were revealed by the reaction between B. aalborgi and anti-B. hyodysenteriae serum, and the heavy band was common among these strains.

Genetic relatedness amongst intestinal spirochaetes isolated from rats and birds

Multilocus enzyme electrophoresis was used to determine genetic relationships amongst 32 intestinal spirochaetes (Serpulina spp.) isolated from rats (17), rheas (7), chickens, (4), ducks (2), a swan (1) and a flamingo (1). The strains were divided into 20 electrophoretic types (ETs), with a mean genetic diversity per locus of 0.62. The results were compared with those previously published for porcine intestinal spirochaetes. One strain from a healthy rat, and three rhea strains which were recovered from cases of necrotizing typhlitis, were grouped in the same ETs as certain porcine strains of Serpulina hyodysenteriae. The rhea strains could be differentiated from these by pulsed-field gel electrophoresis. Fifteen of the rat strains were genetically and phenotypically closely related. In contrast the avian strains were genetically more heterogeneous, with pathogenic isolates located in three different genetic groups.

Rapid identification of porcine Serpulina species by colony blot assay using a genus-specific monoclonal antibody

An immunoglobulin G monoclonal antibody (mAb C9E8) recognising a genus-specific epitope on the 26 kDa protein of porcine Serpulina species organisms was used in a simple colony blot assay to detect Serpulina in cultures grown directly on blood agar plates from pig faeces and tissues. The mAb detected even a few colonies of the organism in the presence of an abundant growth of non-Serpulina organisms. The whole procedure was completed in less than three hours. A total of 123 strains of S hyodysenteriae and S innocens were correctly identified by the colony blot assay whereas all the 26 non-Serpulina Gram-negative organisms commonly isolated from faecal material or tissues of pigs remained negative. The assay was rapid, highly specific and sufficiently reliable to be used with confidence for identifying porcine Serpulina colonies directly on blood agar plates.

Experimental infection of newly weaned pigs with human and porcine strains of Serpulina pilosicoli

Cultures of Serpulina pilosicoli 95/1000, isolated from a pig with porcine intestinal spirochetosis (PIS), and S. pilosicoli WesB, isolated from an Aboriginal child with diarrhea, were used to infect 5-week-old newly weaned pigs. Four of 12 pigs infected with strain 95/1000 and 2 of 12 pigs infected with strain WesB became colonized and developed watery, mucoid diarrhea within 2 to 11 days postinfection. Affected pigs all had moderate subacute mucosal colitis, with gross and histological changes similar to those previously reported in both natural and experimentally induced cases of PIS. Silver-stained histological sections of the colon and cecum from affected pigs demonstrated spirochetes within dilated intestinal crypts, where they were associated with neutrophilic exocytosis and mucus secretion. Sections from one pig infected with strain 95/1000 showed large numbers of spirochetes attached by one end to the colonic epithelium, a feature consistent with PIS. This study confirms the role of S. pilosicoli in the etiology of PIS and provides evidence that S. pilosicoli strains of human origin have pathogenic potential in an animal model.

Identification of the swine pathogen Serpulina hyodysenteriae in rheas (Rhea americana)

Recently intestinal spirochetes were isolated from rheas in Ohio and Iowa with a necrotizing typhlocolitis. These intestinal spirochetes, strains R1 and NIV-1, were characterized and compared with other intestinal spirochetes, including strains of S. hyodysenteriae. Both rhea spirochetes were indole positive, strongly beta-hemolytic, grew under a 1% O2:99% N2 atmosphere, and were morphologically similar to spirochetes in the genus Serpulina. Analysis of rRNA gene restriction patterns (ribotypes), and immunoblots of whole cell proteins, indicated both spirochetes were similar to Serpulina hyodysenteriae strains from swine. Comparisons of nearly complete sequences (> 1458 bases) of the 16S rRNA gene of the two rhea spirochetes with S. hyodysenteriae strains confirmed that rhea spirochetes R1 and NIV-1 were strains of S. hyodysenteriae. These results indicate that S. hyodysenteriae has a broader host range than previously recognized.

Light microscopic and ultrastructural changes in the ceca of chicks inoculated with human and canine Serpulina pilosicoli

Light microscopic and ultrastructural changes were observed in chicks challenged with North American Serpulina pilosicoli, a weakly beta-hemolytic intestinal spirochete (WBHIS) associated with human and canine intestinal spirochetosis. Chicks in control groups received trypticase soy broth or canine Serpulina innocens. The birds were necropsied at weekly intervals, and the ceca were processed for bacteriologic and pathologic examinations. No WBHIS were isolated from the ceca of chicks in the control groups, but WBHIS with genotypes similar to the parent isolates were isolated from the ceca of chicks inoculated with human and canine S. pilosicoli. Gross examination revealed no significant changes in the ceca of chicks at any time post-inoculation. Light microscopic examination revealed no spirochetal attachment in the ceca of chicks in control groups. In contrast, focal to diffuse thickening of the brush border of the surface epithelium along with dilation of the crypt lumina and mild focal lamina propria heterophil infiltration were present in the ceca of chicks inoculated with human and canine S. pilosicoli. Scanning electron microscopic examination revealed focal to confluent spirochetal attachment mainly in the furrow region at the periphery of the crypt units. Transmission electron microscopic examination revealed spirochetes attached to the brush border of the cecal epithelium, causing effacement of the microvilli and disruption of the terminal web microfilaments. The cecal epithelium of chicks inoculated with the canine S. pilosicoli also had caplike elevations of the apical membrane at the point of attachment of the spirochetes together with large numbers of vesicles in the cytoplasm immediately beneath the terminal web and evidence of spirochetal invasion beyond the mucosal barrier. The changes observed suggested that the mechanism of attachment of human and canine S. pilosicoli to the cecal epithelium of chicks was analogous to but different from that described previously for other attaching and effacing gastroenteric bacterical pathogens of human beings and animals.

Phenotypic characteristics of Serpulina pilosicoli the agent of intestinal spirochaetosis

The phenotypic characteristics of three Serpulina pilosicoli strains isolated from humans with diarrhoea (WesB, Kar, Hrm7) and two porcine S. pilosicoli strains isolated from pigs with intestinal spirochaetosis (1648, 3295), were compared with the type strain of the species P43/6/78T (T = type strain) and other intestinal spirochaetes within the genus Serpulina. All S. pilosicoli strains had a characteristic ultrastructural appearance, displayed similar growth rates, hydrolysed hippurate, lacked beta-glucosidase activity, utilised D-ribose as a growth substrate, and had similar sensitivities to rifampicin and spiramycin. The only consistent phenotypic characteristic that differentiated human strains from porcine strains of S. pilosicoli was that the human strains all utilised the pentose sugar D-xylose. These distinguishing phenotypic traits appear useful for identifying S. pilosicoli.

Pulsed-field gel electrophoresis for sub-specific differentiation of Serpulina pilosicoli (formerly 'Anguillina coli')

Pulsed-field gel electrophoresis (PFGE) was developed for subspecific differentiation of Serpulina pilosicoli, and was applied to 52 isolates recovered from cases of intestinal spirochaetosis (IS) in pigs, dogs, human beings and various avian species. The technique was highly sensitive, differentiating the isolates into 40 groupings. Only six groups contained more than one isolate; in five of these groups isolates with the same banding pattern were either from pigs in the same herds (four groups), or from humans in the same community: the sixth group contained two identical Australian porcine isolates from unrelated herds in different states. Overall S. pilosicoli isolates were genetically diverse, but in some cases isolates cultured from the same or different animal species were closely related. This suggested the likelihood of cross-species transmission, including zoonotic spread. PFGE was a powerful tool for epidemiological studies of S. pilosicoli and also allowed examination of genetic relationships between isolates.

The phylogeny of intestinal porcine spirochetes (Serpulina species) based on sequence analysis of the 16S rRNA gene

Four type or reference strains and twenty-two field strains of intestinal spirochetes isolated from Swedish pig herds were subjected to phylogenetic analysis based on 16S rRNA sequences. Almost complete (>95%) 16S rRNA sequences were obtained by solid-phase DNA sequencing of in vitro-amplified rRNA genes. The genotypic patterns were compared with a previously proposed biochemical classification scheme, comprising beta-hemolysis, indole production, hippurate hydrolysis, and alpha-galactosidase, alpha-glucosidase, and beta-glucosidase activities. Comparison of the small-subunit rRNA sequences showed that the strains of the genus Serpulina were closely related. Phylogenetic trees were constructed, and three clusters were observed. This was also confirmed by signature nucleotide analysis of the serpulinas. The indole-producing strains, including the strains of S. hyodysenteriae and some weakly beta-hemolytic Serpulina strains, formed one cluster. A second cluster comprised weakly beta-hemolytic strains that showed beta-galactosidase activity but lacked indole production and hippurate-hydrolyzing capacity. The second cluster contained two subclusters with similar phenotypic profiles. A third cluster involved strains that possessed a hippurate-hydrolyzing capacity which was distinct from that of the former two clusters, because of 17 unique nucleotide positions of the 16S rRNA gene. Interestingly, the strains of this third cluster were found likely to have a 16S rRNA structure in the V2 region of the molecule different from that of the serpulinas belonging to the other clusters. As a consequence of these findings, we propose that the intestinal spirochetes of this phenotype (i.e., P43/6/78-like strains) should be regarded as a separate Serpulina species. Furthermore, this cluster was found to be by far the most homogeneous one. In conclusion, the biochemical classification of porcine intestinal spirochetes was comparable to that by phylogenetic analysis based on 16S rRNA sequences..

Intestinal spirochetosis and giardiasis in a beagle pup with diarrhea

This report describes the light microscopic and ultrastructural changes in a 3-month-old dog with naturally acquired intestinal spirochetosis and giardiasis. It was concluded that the pathogenetic characteristics of weakly beta-hemolytic spirochetes associated with colitis in this pup were similar to those associated with human and porcine spirochetal diarrhea.

Differentiation of intestinal spirochaetes by multilocus enzyme electrophoresis analysis and 16S rRNA sequence comparisons

Multilocus enzyme electrophoresis (MEE) analysis and comparisons of nearly complete 16S rRNA gene sequences (1416 nucleotide positions) were used to evaluate phylogenetic relationships among Serpulina hyodysenteriae strain B78T, S. innocens strain B256T, Brachyspira aalborgi strain 513AT, and eight uncharacterised strains of swine, avian, and human intestinal spirochaetes. From MEE analysis, nine strains could be assigned to five groups containing other intestinal spirochaetes (genetic distances between groups = 0.6-0.9). Chicken spirochaete strain C1 and B. aalborgi 513AT represented unique electrophoretic types and formed their own MEE groups. Despite MEE differences, the 11 strains had highly similar (96.3-99.9%) 16S rRNA sequences. These findings point out limitations of both MEE analysis and 16S rRNA sequence comparisons when used as solitary techniques for classifying intestinal spirochaetes related to Brachyspira/Serpulina species.

Production and characterisation of a monoclonal antibody to Serpulina hyodysenteriae

A monoclonal antibody (mAb) directed against Serpulina hyodysenteriae, the causative agent of swine dysentery, was produced and characterised. The mAb (BJL/SH1) reacted in Western blots with a protein with a molecular mass of about 30 kDa in outer membrane preparations from a range of S. hyodysenteriae isolates of different serotypes. It did not react with preparations made from a variety of non-S. hyodysenteriae intestinal spirochaetes. Immunogold labelling was used to confirm the location of the reactive epitope on the cell outer membrane. The mAb agglutinated and produced fluorescence only with strains of S. hyodysenteriae, and should prove to be a useful reagent for identification of S. hyodysenteriae.

Characterization of Serpulina hyodysenteriae isolates of serotypes 8 and 9 by random amplification of polymorphic DNA analysis

A PCR-based DNA fingerprinting method termed RAPD (Random Amplification of Polymorphic DNA), or AP-PCR (for Arbitrary Primed PCR) was used to detect sequence diversity among reference strains and isolates of Serpulina hyodysenteriae. RAPD fingerprinting of 20 S. hyodysenteriae isolates of serotypes 8 or 9 from Quebec was generated with 2 different 10-base primers used independently. Reference strains and field isolates belonging to serotypes 8 or 9 revealed polymorphisms in RAPD fingerprints with both primers. Interspecies polymorphisms were observed by RAPD analysis of S. hyodysenteriae representing serotypes 1 to 9, S.innocens, and 5 other weakly beta-hemolytic intestinal spirochetes. A dendrogram based on the analysis of RAPD profiles of the strains tested with one of the primers (#17), permitted the clustering of these strains into 11 divisions. The predominance of particular RAPD profiles among S. hyodysenteriae isolates isolated from cases of swine dysentery in different herds suggested that certain S. hyodysenteriae types could be epidemiologically important. Our results indicate that RAPD could be used as a typing method for S. hyodysenteriae and as an epidemiological method for identifying spirochetes isolated from swine.

Identification and characterization of genus-specific epitopes of Serpulina species using monoclonal antibodies

Four murine monoclonal antibodies (mAbs) designated as C9E8, A10, G12, and G8 which recognized both Serpulina hyodysenteriae and S. innocens were produced and characterized. The mAbs reacted with whole cell antigens in ELISA, indirect immunofluorescence and immunoblot assays. The mAbs did not show any cross reactivity in rapid dot ELISA or immunoblot assay with Leptospira icterohemorrhagiae, Campylobacter jejuni and Escherichia coli. Treatment of whole cell suspension with proteinase K and sodium periodate indicated that the reacting epitopes of the mAbs were protein in nature. The genus-specific antigens were identified as heat-stable proteins with molecular weight in the range of 26 to 45 kDa. Immunofluorescence and immunogold labelling studies showed that the antibody-binding epitopes were exposed on the outer-surface of the spirochaetal cell wall. The mAbs inhibited growth of reference strains of both S. hyodysenteriae and S. innocens in vitro but failed to cause agglutination. The detection of spirochaetal forms directly in fecal smears or paraffin-embeded tissue sections from experimentally infected pigs indicated that such mAbs were potentially useful for the diagnosis of swine spirochaetosis. This is the first report of mAbs identifying and characterizing common antigens of porcine Serpulina.

Swine dysentery: more unknown than known

Swine dysentery (SD) is an economically important disease. It is caused by the spirochete Serpulina hyodysenteriae. In order to minimize the economic damage of SD, several methods to control this disease are recommended. Whereas hygienic measures and use of antimicrobials are actually practised for prevention, detection and exclusion of carriers of S. hyodysenteriae and vaccination against the disease still needs further attention. The last two methods require reliable and sensitive diagnostic tests and understanding of the pathogenesis of and immune development against SD. At present the detection of all individual carriers of S. hyodysenteriae is not yet assured, since the tests for screening individual animals are not satisfactorily evaluated as far as sensitivity and/or specificity are concerned. Studies on the pathogenesis of SD have been performed to develop a vaccine. Besides hemolysin/cytotoxin production, no other virulence factors have been identified with certainty for S. hyodysenteriae. Recently however, further indications for a role of motility in the pathogenesis of SD have been obtained. In this manuscript we summarize the most relevant recent findings.

Production and characterization of monoclonal antibodies against Serpulina hyodysenteriae and S. innocens and their use in serotyping

Murine monoclonal antibodies (MAbs) directed against serotypes 1, 2, 8, and 9 of Serpulina hyodysenteriae and strain B256 of Serpulina innocens were produced and characterized. A serological classification of 96 field strains of S. hyodysenteriae and 28 field strains of S. innocens isolated from pigs showing clinical signs of swine dysentery was performed by rapid dot enzyme-linked immunosorbent assay (ELISA) with the MAbs. The results indicated that the majority of the field strains of S. hyodysenteriae (69%) belonged to serotypes 8, 1, and 9, whereas only 31% of the S. innocens strains were recognized by MAb 9H7, indicating the presence of antigenic heterogeneity among S. innocens isolates. Rapid dot ELISA with type-specific MAbs was found to be specific, sensitive, and easy to perform and thus to be suitable for routine serotyping of S. hyodysenteriae and S. innocens isolates. This is the first report of MAbs being used for serotyping clinical isolates of S. hyodysenteriae and S. innocens.

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.

A monoclonal antibody reacting with the cell envelope of spirochaetes isolated from cases of intestinal spirochaetosis in pigs and humans

A monoclonal antibody (mAb) designed BJL/AC1 was prepared against the cell envelope of an intestinal spirochaete (strain 3295) that was isolated from a pig with intestinal spirochaetosis. The mAb reacted with a band of approximately 29 kDa in cell envelope preparations from 13 porcine and 11 human spirochaetes isolated from cases of intestinal spirochaetosis, but did not react with preparations made from a range of other intestinal spirochaetes. Immunogold labelling demonstrated that the reactive epitope was located on the cell envelope of the strains causing intestinal spirochaetosis. The mAb was used in an indirect immunofluorescence test to detect spirochaetes in the faeces of pigs with experimentally induced intestinal spirochaetosis. The mAb should prove to be a useful reagent for detection and identification of spirochaetes that are specifically associated with intestinal spirochaetosis.

Certain canine weakly beta-hemolytic intestinal spirochetes are phenotypically and genotypically related to spirochetes associated with human and porcine intestinal spirochetosis

Four canine weakly beta-hemolytic intestinal spirochetes associated with intestinal spirochetosis (IS-associated WBHIS) were compared with IS-associated human and porcine WBHIS and the type species for Serpulina hyodysenteriae and S. innocens by using phenotypic and genotypic parameters. The IS-associated canine, human, and porcine WBHIS belonged to a phyletic group distinct from but related to previously described Serpulina type species.

Phylogeny of Serpulina based on sequence analyses of the 16S rRNA gene and comparison with a scheme involving biochemical classification

Twenty-one putative Serpulina strains, representing six proposed biochemical groups, were selected for phylogenetic studies based on 16S rRNA sequencing. The biochemical groups were distinguished by the degree of beta-haemolysis, indole production, hippurate hydrolysis and alpha-galactosidase-, and beta-glucosidase activity. The 16S rRNA sequences of the U2 to U5 region, including three evolutionarily variable regions, from representatives of each biochemical group were determined by automated solid phase DNA sequencing after in vitro amplification by the polymerase chain reaction (PCR). The sequences generated were 532 nucleotides in length. Sequence alignments showed that all the strains were closely related, with six informative positions in the region sequenced. A dendrogram was constructed from these data and compared with the tentative biochemical classification. The results support the proposed biochemical classification and indicate that at least five genetic variants of the genus Serpulina can be identified.

Phenotypical characterisation of intestinal spirochaetes isolated from pigs

A combined evaluation of the phenotypical properties of five Serpulina type or reference strains and 163 Swedish isolates of spirochaetes from pigs and two from birds was made. The porcine isolates were collected from herds with a history of dysentery or severe diarrhoea and from herds chosen at random. On the basis of beta-haemolysis, indole production, hippurate hydrolysis, and alpha-galactosidase, alpha-glucosidase and beta-glucosidase activity, the isolates could be divided into four main groups, I to IV, with three subgroups in group III. Group I included the type strain for Serpulina hyodysenteriae (B78). Group II was differentiated from group I only by weak beta-haemolysis. Group III included the type strain for Serpulina innocens (B256). Group IV included the pathogenic, weakly haemolytic strain P43. Group IV-spirochaetes were characterised by their ability to hydrolyse hippurate and by their lack of beta-glucosidase activity. Group I and II-spirochaetes were isolated only from dysenteric or diarrhoeic pigs. There was a statistical relationship between pigs with diarrhoea and the isolation of group IV spirochaetes but no relationship with group III spirochaetes.

DNA probe and polymerase chain reaction procedure for the specific detection of Serpulina hyodysenteriae

Serpulina (Treponema) hyodysenteriae, a Gram-negative anaerobic spirochete, is the causative agent of swine dysentery, a mucohaemorrhagic diarrheal disease in which lesions are confined to the large intestine of pigs. A DNA probe and polymerase chain reaction (PCR) amplification procedures which are specific, rapid , and sensitive for the detection of S.hyodysenteriae have been developed. Clone pF12 from a plasmid library of S.hyodysenteriae B204 genomic DNA was identified as a clone specific for S.hyodysenteriae but not for S.innocens by differential hybridization screening with S.hyodysenteriae and S.innocens genomic DNA probes. A DNA probe consisting of a 1.3 kb restriction fragment from pF12 was found to be highly specific for S. hyodysenteriae and detected 10(5) bacterial cells. A PCR procedure using primers derived from this fragment yielded a single product which was specifically generated for S.hyodysenteriae template DNA and not for other control cells DNA. PCR provided increased sensitivity with the direct detection of as few as 10 S.hyrodysenteriae cells. The PCR procedure could detect S.hyodysenteriae cells in seeded faecal matter. Moreover the PCR assay was able to detect most S. hyodysenteriae field isolates of serotypes 8 and 9. These tools have diagnostic application in veterinary microbiology.

Expression of the SmpA outer membrane lipoprotein of Serpulina hyodysenteriae strain P18A in vivo

An ELISA has been developed using a monoclonal antibody (F325 AC4) to the SmpA surface lipoprotein of Serpulina hyodysenteriae strain P18A when grown in vitro. The lower level of detection of the ELISA was approximately 5 x 10(6) spirochaetes/ml when spirochaetes were either resuspended in phosphate buffered saline or in pig faeces. When pigs were challenged with S. hyodysenteriae strain P18A the lipoprotein was detected in the faeces of pigs by ELISA when the numbers of spirochaetes excreted was greater than 10(6) per g of faeces. After onset of clinical signs in the pig, expression of SmpA was not detected by ELISA or by Western blotting using either monoclonal antibody F325 AC4 or polyclonal antiserum B50 against the SmpA antigen. However, when the in vivo grown spirochaetes were subsequently cultured in vitro expression of SmpA was detected by Western blotting. In the mouse model of swine dysentery S. hyodysenteriae spirochaetes obtained from mice with gross lesions also did not express SmpA. It was concluded that the apparent lack of expression may have been the result of environmental regulation of gene expression or antigenic variation and was not due to denaturation of the antigen in vivo.

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.

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.

Use of commercial enzyme kits and fatty acid production for the identification of Serpulina hyodysenteriae: a potential misdiagnosis

The accuracy of identification of Serpulina hyodysenteriae strains grown in a complex medium was 90% when 2 commercial test kits were used. Unlike the other S. hyodysenteriae strains, S. hyodysenteriae strain P35/2 was unusual in being indole negative. The nonpathogenic intestinal spirochete PWS/A, which is from a different species, was indole positive and alpha-galactosidase negative. Identification of these spirochetes on the basis of these kits alone would have been incorrect. The analysis of volatile fatty acids by gas chromatography showed that the ratio of acetic to butyric acid was from 11:1 to 44:1 for S. hyodysenteriae strains, which distinguished them from the other spirochetes. The exception was PWS/A (acetic: butyric of 32:1), but this spirochete, unlike the S. hyodysenteriae spirochetes, also produced isobutyric acid. Short chain fatty acid (SCFA) analysis by high-performance liquid chromatography detected different SCFAs in addition to acetic and butyric acids. These additional SCFAs did not contribute to further differentiation of the porcine spirochetes.

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.

Chemotactic response to mucin by Serpulina hyodysenteriae and other porcine spirochetes: potential role in intestinal colonization

Chemotaxis of porcine spirochetes towards a variety of mucins was measured quantitatively by a capillary method. A chemotaxis buffer consisting of 0.01 M potassium phosphate buffer (pH 7.0) and 0.2 mM L-cysteine hydrochloride was necessary for chemotaxis of spirochetes. The optimum incubation time and incubation temperature were 1 h and 40 degrees C, respectively. The mucin concentration also affected the chemotaxis observed, and a concentration of 1% (wt/vol) was near the optimum. Virulent Serpulina hyodysenteriae strains were chemotactic towards 1% (wt/vol) hog gastric mucin and 1% (wt/vol) porcine colonic mucin but not towards 1% (wt/vol) bovine submaxillary mucin. Virulent S. hyodysenteriae strains were significantly more chemotactic than avirulent strains of S. hyodysenteriae (SA3 and VS1), Serpulina intermedius, and Serpulina innocens. Other spirochetes belonging to the proposed group of spirochetes Anguillina coli were also not chemotactic. Pathogenicity of S. hyodysenteriae strains that cause swine dysentery may, in part, be attributed to their attraction to porcine intestinal mucus.

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.