The porcine intestinal spirochaetes: identification of new genetic groups

Brachyspira Species Avidity to Colonic Mucins from Pigs with and without Brachyspira hyodysenteriae Infection Is Species Specific and Varies between Strains

Brachyspira hyodysenteriae is commonly associated with swine dysentery (SD), a disease that has an economic impact on the swine industry. B. hyodysenteriae infection results in changes to the colonic mucus niche with massive mucus induction, which substantially increases the number of B. hyodysenteriae binding sites in the mucus. We previously determined that a B. hyodysenteriae strain binds to colon mucins in a manner that differs between pigs and mucin types. Here, we investigated if adhesion to mucins is a trait observed across a broad set of B. hyodysenteriae strains and isolates and furthermore at a genus level (B. innocens, B. pilosicoli, B. murdochii, B. hampsonii, and B. intermedia strains). Our results show that binding to mucins appears to be specific to B. hyodysenteriae, and within this species, the binding ability to mucins varies between strains/isolates, increases for mucins from pigs with SD, and is associated with sialic acid epitopes on mucins. Infection with B. hyodysenteriae strain 8dII results in mucin glycosylation changes in the colon, including a shift in sialic acid-containing structures. Thus, we demonstrate through hierarchical cluster analysis and orthogonal projections to latent structures discriminant analysis (OPLS-DA) models of the relative abundances of sialic acid-containing glycans that sialic acid-containing structures in the mucin O-glycome are good predictors of B. hyodysenteriae strain 8dII infection in pigs. The results emphasize the role of sialic acids in governing B. hyodysenteriae interactions with its host, which may open perspectives for therapeutic strategies.

Polymerase chain reaction assay targeting nox gene for rapid identification of Brachyspira canis in dogs

Genus Brachyspira, as Gram negative anaerobic bacteria, colonize in dogs intestine. The aim of the current study was to determine the prevalence of Brachyspira spp. for the first time in Iran and rapid identification of Brachyspira spp. in dogs by a new designment of a species-specific primer set for B. canis. One hundred fifty-one fecal samples were obtained from dogs by rectal swab. Twenty dogs suffered from diarrhea and 131 of them were healthy. In 9.27% (14/151) of samples, spirochaetes were detected on primary cultures by weak hemolysis and positive Gram staining and then Brachyspira genus was confirmed by NADH oxidase (nox) gene via polymerase chain reaction. Among 14 isolates, twelve isolates were B. canis, one isolate was B. intermedia and another one was non-typeable. From 12 B. canis, only eight isolates were detected by designed specific primers. Ten Brachyspira spp. were isolated from dogs ≤ 1 year old (10/67, 14.92%) and 4 isolates were from > 1 year old dogs (4/84, 4.76%). The isolation rates from healthy and diarrheic dogs were (12/131, 9.16%) and (2/20, 10.00%), respectively. A statistically significant association was observed between the presence of Brachyspira spp. and the age under one year. Based on our findings, the nox gene in B. canis might have more sequence variability compared to other Brachyspira spp.

Antimicrobial Susceptibility Patterns of Brachyspira Species Isolated in Taiwan

Some members of the Brachyspira genus cause diseases such as swine dysentery (SD) and porcine intestinal (or colonic) spirochetosis. Severe economic losses are caused by decreased feed intake and increased feed conversion ratio, as well as costs associated with treatment and death. A loss of clinical efficacy of some antimicrobial agents authorized for treating SD has been observed in many countries. The aim of this study was to analyze the antimicrobial susceptibility of Brachyspira isolated from Taiwan and to investigate the mechanism of decreased susceptibility to macrolides. A total of 55 Brachyspira isolates obtained from the grower-finisher period were evaluated in this study. These isolates included B. hyodysenteriae (n = 37), B. murdochii (n = 11), B. pilosicoli (n = 5), B. intermedia (n = 1), and B. innocens (n = 1). Antimicrobial susceptibility testing was performed to examine 12 selected antimicrobial agents. The results showed that the 50% and 90% minimum inhibitory concentration (MIC) values of the tested macrolides were all >256 μg/ml. The MIC₅₀ of lincomycin, tiamulin, carbadox, olaquindox, ampicillin, amoxicillin, doxycycline, oxytetracycline, and gentamicin were 32, 1, ≤0.125, ≤0.125, 0.5, 0.25, 2, 2, and 2 μg/ml. The genetic basis of the decreased susceptibility to tylosin and lincomycin in Brachyspira spp. was investigated and the results showed a possible connection to the mutations at position A2058 and G2032 of the 23S rRNA gene. These findings demonstrated that, in Taiwan, there may be a decrease in susceptibility of Brachyspira spp. to antimicrobials commonly used for the treatment of SD.

The Spirochete Brachyspira pilosicoli, Enteric Pathogen of Animals and Humans

Brachyspira pilosicoli is a slow-growing anaerobic spirochete that colonizes the large intestine. Colonization occurs commonly in pigs and adult chickens, causing colitis/typhlitis, diarrhea, poor growth rates, and reduced production. Colonization of humans also is common in some populations (individuals living in village and peri-urban settings in developing countries, recent immigrants from developing countries, homosexual males, and HIV-positive patients), but the spirochete rarely is investigated as a potential human enteric pathogen. In part this is due to its slow growth and specialized growth requirements, meaning that it is not detectable in human fecal samples using routine diagnostic methods. Nevertheless, it has been identified histologically attached to the colon and rectum in patients with conditions such as chronic diarrhea, rectal bleeding, and/or nonspecific abdominal discomfort, and one survey of Australian Aboriginal children showed that colonization was significantly associated with failure to thrive. B. pilosicoli has been detected in the bloodstream of elderly patients or individuals with chronic conditions such as alcoholism and malignancies. This review describes the spirochete and associated diseases. It aims to encourage clinicians and clinical microbiologists to consider B. pilosicoli in their differential diagnoses and to develop and use appropriate diagnostic protocols to identify the spirochete in clinical specimens.

Emergence of Brachyspira species and strains: reinforcing the need for surveillance

This short review discusses the increasing complexity that has developed around the understanding of Brachyspira species that infect pigs, and their ability to cause disease. It describes the recognition of new weakly haemolytic Brachyspira species, and the growing appreciation that Brachyspira pilosicoli and some other weakly haemolytic species may be pathogenic in pigs. It discusses swine dysentery (SD) caused by the strongly haemolytic Brachyspira hyodysenteriae, particularly the cyclical nature of the disease whereby it can largely disappear as a clinical problem from a farm or region, and re-emerge years later. The review then describes the recent emergence of two newly described strongly haemolytic pathogenic species, “Brachyspira suanatina” and “Brachyspira hampsonii” both of which appear to have reservoirs in migratory waterbirds, and which may be transmitted to and between pigs. “B. suanatina” seems to be confined to Scandinavia, whereas “B. hampsonii” has been reported in North America and Europe, causes a disease indistinguishable from SD, and has required the development of new routine diagnostic tests. Besides the emergence of new species, strains of known Brachyspira species have emerged that vary in important biological properties, including antimicrobial susceptibility and virulence. Strains can be tracked locally and at the national and international levels by identifying them using multilocus sequence typing (MLST) and comparing them against sequence data for strains in the PubMLST databases. Using MLST in conjunction with data on antimicrobial susceptibility can form the basis for surveillance programs to track the movement of resistant clones. In addition some strains of B. hyodysenteriae have low virulence potential, and some of these have been found to lack the B. hyodysenteriae 36 kB plasmid or certain genes on the plasmid whose activity may be associated with colonization. Lack of the plasmid or the genes can be identified using PCR testing, and this information can be added to the MLST and resistance data to undertake detailed surveillance. Strains of low virulence are particularly important where they occur in high health status breeding herds without causing obvious disease: potentially they could be transmitted to production herds where they may colonize more effectively and cause disease under stressful commercial conditions.

Biology and Diseases of Swine

Swine are used in biomedical research as models for biomedical research and for teaching. This chapter covers normative biology and behavior along with common and emerging swine diseases. Xenotransplantation is discussed along with similarities and differences of swine immunology.

Brachyspira and its role in avian intestinal spirochaetosis

The fastidious, anaerobic spirochaete Brachyspira is capable of causing enteric disease in avian, porcine and human hosts, amongst others, with a potential for zoonotic transmission. Avian intestinal spirochaetosis (AIS), the resulting disease from colonisation of the caeca and colon of poultry by Brachyspira leads to production losses, with an estimated annual cost of circa £ 18 million to the commercial layer industry in the United Kingdom. Of seven known and several proposed species of Brachyspira, three are currently considered pathogenic to poultry; B. alvinipulli, B. intermedia and B. pilosicoli. Currently, AIS is primarily prevented by strict biosecurity controls and is treated using antimicrobials, including tiamulin. Other treatment strategies have been explored, including vaccination and probiotics, but such developments have been hindered by a limited understanding of the pathobiology of Brachyspira. A lack of knowledge of the metabolic capabilities and little genomic information for Brachyspira has resulted in a limited understanding of the pathobiology. In addition to an emergence of antibiotic resistance amongst Brachyspira, bans on the prophylactic use of antimicrobials in livestock are driving an urgent requirement for alternative treatment strategies for Brachyspira-related diseases, such as AIS. Advances in the molecular biology and genomics of Brachyspira heralds the potential for the development of tools for genetic manipulation to gain an improved understanding of the pathogenesis of Brachyspira.

Complete genome sequence of Brachyspira murdochii type strain (56-150)

Brachyspira murdochii Stanton et al. 1992 is a non-pathogenic, host-associated spirochete of the family Brachyspiraceae. Initially isolated from the intestinal content of a healthy swine, the ‘group B spirochaetes’ were first described as Serpulina murdochii. Members of the family Brachyspiraceae are of great phylogenetic interest because of the extremely isolated location of this family within the phylum ‘Spirochaetes’. Here we describe the features of this organism, together with the complete genome sequence and annotation. This is the first completed genome sequence of a type strain of a member of the family Brachyspiraceae and only the second genome sequence from a member of the genus Brachyspira. The 3,241,804 bp long genome with its 2,893 protein-coding and 40 RNA genes is a part of the Genomic Encyclopedia of Bacteria and Archaea project.

Comparative pathology and pathogenesis of naturally acquired and experimentally induced colonic spirochetosis

Research in the past decade has led to the recognition ofBrachyspira(formerlySerpulina)pilosicolias the primary etiologic agent of colonic spirochetosis (CS), an emerging cause of colitis in humans and animals. Attachment of spirochetes to the epithelial surface of the lower intestine is considered to be the hallmark of CS. However, becauseB. pilosicoli, B. aalborgiand unclassified flagellated bacteria are found singly or together in humans and non-human primates with CS lesions, attachment of spiral-shaped bacteria may not represent the same etiopathogenetic entity in all hosts. Moreover, North American opossums with CS are infected withB. aalborgi-like spirochetes together with flagellated bacteria, whereasB. pilosicoliis found alone in dogs, pigs, chickens and other species of birds with CS. Conversely, guinea-pigs with CS have unidentified spirochetes that may beB. pilosicoli or B. aalborgi.The pig model of CS suggests that attachment ofB. pilosicolito epithelial cells may be transient. By contrast, persistence ofB. pilosicoliin the cecal and colonic crypt lumina, chronic inflammation caused by spirochetal invasion into the subepithelial lamina propria and translocation to extraintestinal sites may be more important than previously thought. This review describes the lesions seen in naturally occurring and experimentally induced CS of animals, and it sets the stage for future research into the pathogenic mechanisms of infection and colitis caused byB. pilosicoli.

Human intestinal spirochetosis:Brachyspira aalborgiand/orBrachyspira pilosicoli?

Intestinal spirochetosis in humans (HIS) is a condition defined by the presence of a layer of spirochetes attached by one cell end to the colorectal epithelium. The pathologic significance of HIS is uncertain, but it has been linked to chronic diarrhea and other abdominal complaints. Two anaerobic intestinal spirochete species have been associated with HIS, namelyBrachyspira pilosicoliandBrachyspira aalborgi.Brachyspira pilosicoli, which colonizes many animal species, is common (~30%) in the feces of people from developing countries, including Australian Aborigines, and in HIV+ patients and male homosexuals in Western societies. It is also commonly seen attached to the rectal mucosa of homosexual males. In other groups in Western societies both the presence of B.pilosicoliin feces and histologic HIS are uncommon (~1.5%).Brachyspira aalborgiis an extremely slow growing and fastidious spirochete, which previously had been isolated from an HIS patient in Denmark. Recent studies using polymerase chain reaction amplification of DNA from intestinal biopsies from a series of cases of HIS in the general Western population demonstrated thatB. aalborgi, rather thanB. pilosicoli, was the main spirochete species involved in these patients. This review outlines recent developments in the study of HIS and the two spirochete species, and identifies priorities for future research.

Intestinal spirochete infections of chickens: a review of disease associations, epidemiology and control

This paper presents an overview of intestinal spirochete infections of chickens. It focuses particularly on studies in Australia, where recent surveys of 136 layer and broiler breeder flocks have revealed a high rate of infection (>40%) with intestinal spirochetes. Infection was not detected in broiler flocks. Approximately 50% of isolates from infected flocks wereBrachyspira(Serpulina)intermediaorB. pilosicoli, with the other isolates beingB. innocens, B. murdochiior the proposed species ‘B. pulli’. No isolates ofB. alvinipulliwere found. Intestinal spirochetes were significantly associated with wet litter problems and/or reduced egg production. Experimental infection of point-of-lay birds with eitherB. intermediaorB. pilosicolicaused reduced egg production, and, withB. intermedia, a significant increase in fecal moisture content. Infection withB. innocenscaused no significant changes. In-water treatment of a flock with a mixed spirochete infection using lincospectin resulted in a slimy diarrhea lasting for 2–3 weeks, followed by absence of spirochetes for 3 months. Birds treated with tiamulin remained healthy, and had a reduced level of infection with intestinal spirochetes (30%) for 3 months. Trials are under way to test the efficacy of antimicrobials in point-of-lay chickens experimentally infected with eitherB. intermediaorB. pilosicoli.

Classification ofBrachyspiraspp. isolated from Swedish dogs

Brachyspira spp.were isolated from 21 of 32 sampled dogs (66%) in a colony of Swedish beagle dogs with a history of diarrhea and from 3 of 17 Swedish pet dogs (17%) with diarrhea. All Swedish isolates were weakly β-hemolytic and gave a negative indole reaction. Eighty-eight percent showed negative α-galactosidase and hippurate reactions, but a positive β-glucosidase reaction. Two isolates were hippurate positive with a negative β-glucosidase reaction. One additional German isolate diverged by showing a positive indole reaction in combination with a positive hippurate reaction. Sequencing of 16S rDNA indicated that the hippurate-positive isolates belonged to the speciesBrachyspira pilosicoli. Four representative isolates were examined using pulsed-field gel electrophoresis (PFGE) and compared with six reference strains and five porcine isolates ofBrachyspiraspp. The canine isolates clustered together in the PFGE analysis. Necropsy examination of a culture-positiveB. pilosicolicolony-raised beagle dog revealed macro- and microscopical lesions of colitis with numerous spiral-shaped bacteria in the lumens of the crypts, in goblet cells and within the colonic epithelium.

Typhlocolitis associated with spirochaetes in goose flocks

The role of Brachyspira bacteria in the aetiology of increased mortality observed in two breeder goose flocks (Flock A consisting of 1,500 and Flock B comprising 4,500 laying geese) at the end of the first egg-laying season, in the period of moulting, was studied. In Flock A 415 geese (28%) died during an 8-week period while in Flock B 834 geese (18%) died during a 12-week period. On gross pathological examination, the geese were found to have haemorrhagic-to-necrotic inflammation of the large intestine (colon and rectum) and fibrinonecrotic typhlitis accompanied by severe degeneration. Often, fibrosis of the kidneys, and in five of the geese secondary visceral urate deposition ("visceral gout") was also observed. Histopathological examination consistently demonstrated spirochaetes in the mucous membrane of the affected large intestine. This was confirmed by the results of immunohistochemical and electron microscopic examination. In addition, Trichomonas stages were also detected from the large intestine of 11 geese. On the basis of their cultural and biochemical properties, and PCR sequencing analysis, eight out of the nine spirochaete strains isolated from the geese by culture on special media under anaerobic conditions were identified as Brachyspira alvinipulli. This is the first report on the isolation of B. alvinipulli from laying geese affected with fibrinonecrotic typhlocolitis.

Reclassification of Serpulina intermedia and Serpulina murdochii in the genus Brachyspira as Brachyspira intermedia comb. nov. and Brachyspira murdochii comb. nov

A reassessment was undertaken of published characteristics of the five species of anaerobic intestinal spirochaetes in the genus Brachyspira (Brachyspira aalborgi, Brachyspira alvinipulli, Brachyspira hyodysenteriae, Brachyspira innocens and Brachyspira pilosicoli) and the two species in the genus Serpulina (Serpulina intermedia and Serpulina murdochii). Comparisons were made of published descriptions, including phenotypic properties, grouping by multilocus enzyme electrophoresis, DNA base composition, DNA-DNA relative reassociation values and 16S rRNA gene sequence similarity. On the basis of extensive similarities between all the species, it is proposed to reclassify Serpulina intermedia Stanton et al. 1997 and Serpulina murdochii Stanton et al. 1997 in the genus Brachyspira, as Brachyspira intermedia comb. nov. (type strain ATCC 51140T) and Brachyspira murdochii comb. nov. (type strain ATCC 51284T).

The 23S rRNA gene PCR-RFLP used for characterization of porcine intestinal spirochete isolates

Using three reference strains of Brachyspira hyodysenteriae (B204, B234, B169), one B. pilosicoli (P43/6/78), one B. murdochii (56-150), one B. intermedia (PWS/A), one B. innocens (B256) and ten Korean isolates, PCR-RFLP analysis of DNA encoding 23S rRNA was performed to establish a rapid and accurate method for characterizing porcine intestinal spirochetes. Consequently, B. hyodysenteriae and B. pilosicoli revealed different restriction patterns; however, the other three species shared the same pattern. These findings are not consistent with a prior report. Differences in 23S rRNA gene sequences, between two B. murdochii strains, 56-150 and 155-20, were observed. These results indicate that 23S rRNA PCR-RFLP could be used as an identification method for pathogenic Brachyspira spp. (B. hyodysenteriae and B. pilosicoli) as well as an epidemiological tool for characterizing spirochetes isolated from swine.

Amplification and sequencing of Brachyspira spp. specific portions of nox using paraffin-embedded tissue samples from clinical colitis in Austrian pigs shows frequent solitary presence of Brachyspira murdochii

Brachyspira infections are significant causes of enterocolitis in pigs. In order to differentiate pathogenic species (Brachyspira (Br.) hyodysenteriae, Brachyspira pilosicoli) from less pathogenic or non-pathogenic species (Brachyspira intermedia, Brachyspira innocens, Brachyspira murdochii) in paraffin-embedded tissue samples a polymerase chain reaction (PCR) protocol allowing identification of Brachyspira at species level in archival material was developed. This approach was complemented by sequencing of the PCR amplification products. All seven cases presented with clinical and morphological Brachyspira-associated enterocolitis. Br. hyodysenteriae was not identified in any of the cases, while Br. pilosicoli was identified in a single case in conjunction with Br. murdochii. One case each was found positive for Br. innocens and Br. intermedia. Interestingly, the majority of cases presented as single or double infections with Br. murdochii. In some of the pigs other pathogens, like porcine circovirus-2 or Lawsonia intracellularis were present. These observations point at the possibility that under certain conditions even Brachyspira species of low pathogenicity can multiplicate extensively and lead to Brachyspira-associated enterocolitis.

Application of nox-restriction fragment length polymorphism for the differentiation of Brachyspira intestinal spirochetes isolated from pigs and poultry in Australia

Sixty-nine intestinal spirochetes isolated from pigs and poultry in eastern Australia were selected to evaluate the effectiveness of a species-specific PCR-based restriction fragment length polymorphism (RFLP) analysis of the Brachyspira nox gene. For comparative purposes, all isolates were subjected to species-specific PCRs for the pathogenic species Brachyspira hyodysenteriae and Brachyspira pilosicoli, and selected isolates were examined further by sequence analysis of the nox and 16S ribosomal RNA genes. Modifications to the original nox-RFLP method included direct inoculation of bacterial cells into the amplification mixture and purification of the PCR product, which further optimized the nox-RFLP for use in a veterinary diagnostic laboratory, producing sufficient product for both species identification and future comparisons. Although some novel profiles that prevented definitive identification were observed, the nox-RFLP method successfully classified 45 of 51 (88%) porcine and 15 of 18 (83%) avian isolates into 5 of the 6 recognized species of Brachyspira. This protocol represents a significant improvement over conventional methods currently used in veterinary diagnostic laboratories for rapid specific identification of Brachyspira spp. isolated from both pigs and poultry.

The use of multilocus enzyme electrophoresis to characterise intestinal spirochaetes (Brachyspira spp.) colonising hens in commercial flocks

Multilocus enzyme electrophoresis (MLEE) was used to identify, examine genetic relationships and look at disease associations of a collection of 53 intestinal spirochaete isolates previously recovered from the faeces of adult hens on 14 farms in Qld, Australia. The MLEE results were compared with those previously obtained using species-specific PCR amplifications. The isolates were divided into five Brachyspira species groups by MLEE: Brachyspira murdochii (n=17), B. intermedia (n=15), B. pilosicoli (n=14), B. innocens (n=2) and "B. pulli" (n=1). Three new MLEE groups each containing single isolates also were identified. The results of the PCR assay for B. pilosicoli were concordant with the MLEE results, but the 23S rDNA-based PCR for B. intermedia had failed to detect 8 of the 15 isolates. The B. innocens/B. murdochii nox-based PCR had correctly identified all the isolates of B. murdochii, but did not identify either of the two B. innocens isolates. Using MLEE, isolates from two farms (14%) were identified as B. murdochii, whilst the pathogenic species B. intermedia and B. pilosicoli were present in hens from eight (57%) and five (36%) farms, respectively, and were identified together in four (29%) farms. All seven of the farms with production problems or wet litter were colonised with B. intermedia and/or B. pilosicoli. Six farms had multiple spirochaete isolates available for examination. Two broiler breeder farms both had five isolates of B. pilosicoli that shared the same MLEE electrophoretic type (ET), whilst one laying hen farm had three isolates of B. intermedia that all belonged to the same ET. Hence on each of these farms a predominant strain of a pathogenic species was present. On the other farms isolates of the same species were more diverse and belonged to different ETs. These results show that the epidemiology of intestinal spirochaetal infections in broiler breeder and laying hen flocks can vary considerably between farms, although the reasons for these differences were not established.

Development of a duplex PCR assay for detection of Brachyspira hyodysenteriae and Brachyspira pilosicoli in pig feces

A duplex PCR (D-PCR) amplifying portions of the Brachyspira hyodysenteriae NADH oxidase gene and the B. pilosicoli 16S rRNA gene was developed and then tested on DNA extracted from 178 porcine fecal samples. The feces also underwent anaerobic culture and species-specific PCRs. Fecal extraction-D-PCR detected seven additional samples containing B. hyodysenteriae and five more containing B. pilosicoli.

Colonisation of pet shop puppies with Brachyspira pilosicoli

Anaerobic intestinal spirochaetes of the genus Brachyspira are known to colonise dogs, but relatively little is known about their prevalence, distribution or pathogenic potential. One species, Brachyspira pilosicoli, is thought to cause diarrhoea in dogs, as well as in other animals and humans. To investigate the prevalence and distribution of infection, faecal samples from 49 puppies from six pet shops in the suburbs of Perth, Western Australia were subjected to selective culture for anaerobic intestinal spirochaetes. Growth from the primary plates was also harvested, the DNA extracted and a polymerase chain reaction (PCR) amplification of a portion of the 16S rRNA gene of B. pilosicoli applied. Weakly beta-haemolytic intestinal spirochaetes (WBHIS) grew on plates from 20 of the dogs (40.8%). Seven plates (14.2%) yielded PCR positive amplification for B. pilosicoli. Seven WBHIS isolates were obtained in pure culture, and two of these were shown to be B. pilosicoli by PCR. Application of multilocus enzyme electrophoresis to the seven isolates confirmed that the two PCR positive isolates were B. pilosicoli, whilst the other five belonged to a group previously designated "Brachyspira canis". All the "B. canis" isolates came from healthy puppies, suggesting that this WBHIS is a commensal. Three of the seven puppies with PCR evidence of B. pilosicoli had diarrhoea, but the sample size was small and the association between colonisation and diarrhoea was not statistically significant. Pet shop puppies are commonly infected with intestinal spirochaetes, and may act as a reservoir of B. pilosicoli for other animals and humans.

Epidemiological studies of Brachyspira pilosicoli in two Australian piggeries

The epidemiology of infection with the intestinal spirochaete Brachyspira pilosicoli within pig herds is incompletely understood. To investigate this further, cross-sectional and cohort studies were undertaken on two piggeries. Faeces were subjected to selective culture, and DNA was extracted from growth on the primary media and amplified by polymerase chain reaction (PCR). On one farm, samples from other animal species and the environment were also examined. Isolates were subjected to multilocus enzyme electrophoresis (MLEE) and pulsed field gel electrophoresis (PFGE). The prevalence on farm A (>2000 sows) was 2.4% (95% confidence interval (CI): 0.3, 4.4%). Infection was largely confined to grower/finisher pigs. The six isolates of B. pilosicoli recovered belonged to a single MLEE electrophoretic type (ET) and a single PFGE type. On piggery B, an 80-sow unit located on a research farm, the prevalence amongst growers and finishers was 12.2% (95% CI: 4.7, 19.6%). There was also evidence that weaners were being infected. Ten isolates obtained were genetically heterogeneous, being divided into six ETs and seven PFGE types. One of four isolates in one ET had an identical PFGE type to those on piggery A, and may have been introduced to piggery B in stock from piggery A. On farm B, B. pilosicoli was also detected by PCR in chickens, effluent pond water and wild ducks on the pond. An isolate from the pond belonged to the same ET as one from a pig, whereas the duck isolates were distinct. This study demonstrates the complex epidemiology of B. pilosicoli infections in piggeries.

Identification of porcine intestinal spirochetes by PCR-restriction fragment length polymorphism analysis of ribosomal DNA encoding 23S rRNA

The Brachyspira (formerly Serpulina) species rrl gene encoding 23S ribosomal RNA (rRNA) was used as a target for amplification of a 517bp DNA fragment by polymerase chain reaction (PCR). The primers for PCR amplification had sequences that were conserved among Brachyspira 23S rRNA gene and were designed from nucleotide sequences of Brachyspira hyodysenteriae, Serpulina intermedia, Brachyspira innocens and Brachyspira pilosicoli available from the GenBank database. Digestion of PCR-generated products from reference and field isolates of swine intestinal spirochetes with restriction enzymes Taq I and Alu I revealed five restriction fragment length polymorphism (RFLP) patterns. Each RFLP pattern corresponded to previously established genetic groups including B. hyodysenteriae (I), S. intermedia/B. innocens (II), Brachyspira murdochii (III), B. pilosicoli (IV) and B. alvinipulli (V). The 23S rRNA PCR/RFLP provided a relatively simple genotypic method for identification of porcine pathogenic B. hyodysenteriae and B. pilosicoli.

Influences of diet and vaccination on colonisation of pigs by the intestinal spirochaete Brachyspira (Serpulina) pilosicoli

The purpose of this study was to determine whether methods used to control swine dysentery (SD), caused by the intestinal spirochaete Brachyspira (Serpulina) hyodysenteriae, would also be effective in controlling porcine intestinal spirochaetosis (PIS) caused by the related spirochaete Brachyspira (Serpulina) pilosicoli. Weaner pigs in Groups I (n=8) and II (n=6) received a standard weaner pig diet based on wheat and lupins, whilst Group III (n=6) received an experimental diet based on cooked white rice and animal protein. Pigs in Group II were vaccinated intramuscularly twice at a 3-week-interval with a formalinised bacterin made from B. pilosicoli porcine strain 95/1000 resuspended in Freund's incomplete adjuvant. Eleven days later pigs in all groups were infected orally with 10(10) cells of strain 95/1000 on three successive days. One control pig in Group I developed acute diarrhoea, and at post-mortem had a severe erosive colitis with end-on attachment of spirochaetes to the colonic epithelium. All other pigs developed transient mild diarrhoea and had moderate patchy colitis at post-mortem 3 weeks later. B. pilosicoli was isolated from the faeces of all pigs, except for one fed rice, and was isolated from the mesenteric nodes of three pigs from Group I and from one vaccinated pig in Group II. Consumption of the rice-based diet, but not vaccination, delayed and significantly (p<0.001) reduced the onset of faecal excretion of B. pilosicoli after experimental challenge. Vaccination induced a primary and secondary serological response to B. pilosicoli, as measured using sonicated whole cells of strain 95/1000 as an ELISA plate coating antigen. Antibody titres in the vaccinated pigs then declined, despite intestinal colonisation by B. pilosicoli. Both groups of unvaccinated animals also failed to develop a post-infection increase in circulating antibody titres.

Prevalence of Brachyspira species isolated from diarrhoeic pigs in Brazil

Pathogenic intestinal spirochaetes of pigs include Brachyspira (formerly Serpulina) hyodysenteriae, the cause of swine dysentery, and Brachyspira pilosicoli, the cause of porcine colonic spirochetosis (PCS). The purpose of this study was to assess the relative importance of Brachyspira species in diarrhoeal disease of growing pigs on farms in southern Brazil. The intensity and pattern of haemolysis, the production of indole and the hydrolysis of hippurate by reference and field porcine intestinal spirochaetes were compared with 16S-ribosomal RNA (mRNA)- and 23S-rRNA-based polymerase chain reaction assays for the identification of B hyodysenteriae and B pilosicoli. Between July and October 1998, 206 rectal swabs were taken from pigs on 17 farms with a history of diarrhoea developing within 30 days after they had been moved from nursery to growing facilities. Of 49 beta-haemolytic spirochaetes that were cultured, 29 (59.2 per cent) were grown in pure culture for phenotypic and genotypic characterisation, leaving 20 untyped. Of the 29 typed isolates, eight isolates obtained from six farms were identified as B hyodysenteriae, and 15 isolates obtained from seven other farms were identified as B pilosicoli; the remaining six isolates were identified as weakly beta-haemolytic commensal spirochaetes. There was complete agreement between the results of the phenotypic and genotypic analyses.

Detectability and prevalence of Brachyspira species in herds rearing health class feeder pigs in Finland

Faeces samples were taken three times at two-week intervals, from the farrowing units of four herds of known Brachyspira (formerly Serpulina) status and one of unknown Brachyspira status. Brachyspira hyodysenteriae, Brachyspira pilosicoli, Brachyspira intermedia and Brachyspira group III were isolated from the faecal samples from the weaners in the herds using either a maximum of 50 ppm of olaquindox or no feed additives. The detection rates were relatively consistent. However, B hyodysenteriae was not detected at one sampling in a known positive herd. The prevalence of Brachyspira species was also studied in feeder pigs originating from LSO 2000 health class farrowing units, comparable with specific pathogen-free herds. These farms were free from swine dysentery, sarcoptic mange, swine enzootic pneumonia and progressive atrophic rhinitis. Fifty of 428 herds were sampled once. B hyodysenteriae was not isolated from any of them, but B intermedia, B pilosicoli and Brachyspira group III were isolated from five, 14 and 37 of the herds, respectively. The detection of Brachyspira species did not relate to the prevalence of diarrhoea in the herds, as judged by the farmers. The herds using carbadox (40 to 50 ppm) had a lower prevalence of Brachyspira species than those using olaquindox (40 to 50 ppm).

Evaluation of a 23S rDNA polymerase chain reaction assay for identification of Serpulina intermedia, and strain typing using pulsed-field gel electrophoresis

A polymerase chain reaction assay, amplifying a 1027 base pair portion of the 23S rDNA gene, was evaluated for identification of the intestinal spirochaete Serpulina intermedia. A total of 34 strains of S. intermedia isolated from pigs and chickens and 195 strains of other related species were tested. The optimised assay correctly identified all the S. intermedia strains, but generated 11 false positive reactions, giving a test sensitivity of 100% and a test specificity of 94.3%. The false positive reactions were generated from strains of four different species of intestinal spirochaetes, and the product was of the original predicted size. This suggests that the primer sites selected on the 23S rRNA gene were not completely specific for S. intermedia. Pulsed-field gel electrophoresis was then developed to investigate diversity amongst the S. intermedia strains. All strains tested had distinct DNA banding patterns using Mlu1, although three isolates from chickens on the same farm appeared closely related. The collection exhibited considerable genetic diversity, and strains from pigs and chickens were distributed in clusters throughout the dendrogram produced. The most closely related porcine and avian strains shared only 62% similarity.

Scanning electron microscopy and fluorescent in situ hybridization of experimental Brachyspira (Serpulina) pilosicoli infection in growing pigs

Two groups of six 8-week-old pigs were challenged with 1x10(9) cfu Brachyspira (Serpulina) pilosicoli or Serpulina intermedia daily for 3 consecutive days to study the pathology of porcine colonic spirochetosis by scanning electron microscopy (SEM) and fluorescent in situ hybridization (FISH) with oligonucleotide probes targeting ribosomal RNA specific for B. pilosicoli and the genus Brachyspira/Serpulina. Six pigs served as noninoculated controls. The animals were euthanatized successively between postinoculation days 14 and 24. B. pilosicoli was reisolated in feces from all of the inoculated pigs; however, only two pigs developed transient watery diarrhea. S. intermedia was reisolated from four of the inoculated pigs, but clinical signs were not observed. Gross examination of the B. pilosicoli-infected pigs revealed dilated large intestines with a hyperemic mucosa, whereas the large intestines of the S. intermedia-inoculated pigs and the control pigs appeared normal. SEM examination of B. pilosicoli-infected pigs revealed degenerated epithelial cells and spirochetal colonization of the colonic mucosa in four pigs. By FISH, B. pilosicoli cells were found colonizing and invading the surface epithelium and the crypts in all the pigs. Spirochetal crypt colonization markedly exceeded the occurrence of spirochetes on the mucosal surface. SEM examination of S. intermedia-inoculated pigs revealed no abnormalities, and Serpulina cells were detected only sporadically in the otherwise normal-appearing mucosa of four pigs by FISH. The results provide further evidence that B. pilosicoli is associated with colitis in pigs, although the gross lesions are mild. The spirochete is capable of colonizing the large intestine, inducing mucosal damage, invasion of the crypt and surface epithelium, and focal infiltration of the lamina propria. In addition, the study shows the applicability of FISH for specific identification of B. pilosicoli in formalin-fixed tissue.

Differentiation of Serpulina species by NADH oxidase gene (nox) sequence comparisons and nox-based polymerase chain reaction tests

The NADH oxidase genes (nox) of 18 strains of intestinal spirochaetes were partially sequenced over 1246 bases. Strains examined included 17 representatives from six species of the genus Serpulina, and the type strain 513A(T) of the human intestinal spirochaete Brachyspira aalborgi. Sequences were aligned and used to investigate phylogenetic relationships between the organisms. Nox sequence identities between strains within the genus Serpulina were within the range 86.3-100%, whilst the nox gene of B. aalborgi shared between 78.8-83.0% sequence identity with the nox sequences of the various Serpulina strains. A phenogram produced based on sequence dissimilarities was in good agreement with the current classification of species in the genus Serpulina, although an atypical strongly beta-haemolytic porcine strain (P280/1), previously thought to be S. innocens, appeared distinct from other members of this species. Primer pairs were developed from the nox sequence alignments for use in polymerase chain reaction (PCR) identification of the pathogenic species S. hyodysenteriae (NOX1), S. intermedia (NOX2), and S. pilosicoli (NOX3), and for the combined non-pathogenic species S. innocens and S. murdochii (NOX4). The PCRs were optimised using 80 strains representing all currently described species in the genus Serpulina, as well as the type strain of B. aalborgi. Tests NOX1 and NOX4 specifically amplified DNA from all members of their respective target species, whilst tests NOX2 and NOX3 were less sensitive. NOX2 amplified DNA from all 10 strains of S. intermedia from pigs but from only 4 of 10 strains from chickens, whilst NOX3 amplified DNA from only 18 of 21 S. pilosicoli strains, even at low stringency. Tests NOX1 and NOX4 should prove useful in veterinary diagnostic laboratories, whilst NOX2 and NOX3 require further refinement.

Canine intestinal spirochetes consist of Serpulina pilosicoli and a newly identified group provisionally designated "Serpulina canis" sp. nov

The spirochetes inhabiting the large intestines of humans and animals consist of a diverse group of related organisms. Intestinal spirochetosis caused by Serpulina pilosicoli is a newly recognized enteric disease of human beings and animals with potential public health significance. The purpose of this study was to determine the species identity of canine intestinal spirochetes by comparing 30 isolates obtained from dogs in Australia (n = 25) and the United States (n = 5) with reference strains representing Serpulina species and Brachyspira aalborgi, by phenotypic and genetically based typing methods. All of the canine isolates were indole negative and produced a weak beta-hemolysis when cultured anaerobically on agar medium containing blood. Four isolates were identified as S. pilosicoli by 16S rRNA-specific PCR assays, rRNA gene restriction fragment length polymorphism or ribotyping, and multilocus enzyme electrophoresis. The remaining 26 isolates formed a cluster related to porcine Serpulina innocens as determined by multilocus enzyme electrophoresis but had a unique ribotype pattern. The data suggested the existence of a novel Serpulina species, provisionally designated "Serpulina canis," colonizing the intestines of dogs.

Identification of porcine Serpulina strains in routine diagnostic bacteriology

Serpulina strains from pigs were identified using simple tests. The large size of S. hyodysenteriae in stainings from colonic contents and faeces was found useful for the presumptive differentiation of this major pathogenic species from the other Serpulinae. However, this morphological characteristic gets lost upon cultivation. The 'ring phenomenon' aided to confirm the strong haemolysis typical for S. hyodysenteriae. The weakly haemolytic species S. innocens, S. pilosicoli, S. intermedia and S. hyodysenteriae could be differentiated with the help of the indole spot test and two or four other simple enzymatic tests. Nearly half of the S. hyodysenteriae strains isolated in Belgium were indole-negative. Such strains have only rarely been reported earlier, and were absent among the strains from other European countries examined.

Evaluation of day-old specific pathogen-free chicks as an experimental model for pathogenicity testing of intestinal spirochaete species

Specific pathogen-free chicks aged 1 day were challenged per os with strains of five different species of intestinal spirochaete originally isolated from pigs or human beings. A virulent strain of Serpulina hyodysenteriae (WA 15) colonized chicks, causing retarded growth rate and histological changes, including caecal atrophy, epithelial and goblet cell hyperplasia, and crypt elongation. A further strain of S. hyodysenteriae (SA3), which was apparently avirulent for pigs, and a strain of Serpulina intermedia (889) colonized fewer chicks, caused less severe lesions and did not significantly depress growth rate. Strains of Serpulina murdochii and Brachyspira aalborgi failed to colonize or cause histological changes. Four strains of Serpulina pilosicoli (Kar, Rosie-2299 and GAP 401, isolated from human beings, and 3295, isolated from a pig) colonized chicks, and large numbers showed polar attachment to the caecal epithelium; all strains, apart from Rosie-2299, caused watery diarrhoea and wet litter, but did not significantly retard growth. Variation both in the degree of spirochaetal attachment and the resulting development of lesions was observed between S. pilosicoli strains as well as between individual chicks infected with the same strain. The study indicated that chicks may be useful in studying the pathogenicity of strains of S. hyodysenteriae, S. intermedia and S. pilosicoli.

Investigations into field cases of porcine colitis with particular reference to infection with Serpulina pilosicoli

Investigations into the possible causes of colitis and typhlocolitis were carried out on 85 pig units in the United Kingdom between 1992 and 1996. Serpulina pilosicoli was identified most commonly, occurring as the suggested primary agent on 21 (25 per cent) of the units but forming part of mixed infections on another 23 (27 per cent) of the units, the main co-infections being Yersinia pseudotuberculosis (eight units), proliferative enteropathy (six units), Salmonella species (four units) or Serpulina hyodysenteriae (two units). 'Atypical' Serpulina species, S hyodysenteriae, Salmonella typhimurium, Y pseudotuberculosis and Lawsonia intracellularis (proliferative enteropathy) were the suggested primary agents on seven, six, four, four and three units, respectively. Various combinations of mixed infections involving the latter organisms and other possibly incidental agents were recorded on another 10 units. Investigations on a further six units failed to detect any recognised pathogens. On units where S pilosicoli was the suggested primary agent, pigs ranging between 20 to 40 kg (eight to 16 weeks of age), but occasionally up to 50 kg, had diarrhoea and grew poorly over a period of two to three weeks. The prevalence was estimated to be between 5 and 15 per cent in affected batches, with a mortality of approximately 1 per cent. The clinical signs usually developed seven to 14 days after the moving and mixing of pigs. At postmortem examination, affected pigs had liquid contents in their colon, which contained accumulations of mucus in some chronic cases. Gross and histological lesions of colitis were prominent in the mid-spiral region of the colon. In mixed infections with Y pseudotuberculosis, Salmonella typhimurium or S hyodysenteriae, lesions were more extensive and affected the caecum as well as the colon. In the colon, lesions of proliferative enteropathy were usually confined to the proximal half of the ascending spiral but mixed infection with S pilosicoli caused more extensive colitis. Mixed infections were reported to prolong the time taken for pigs to recover naturally and to have a more detrimental effect on growth rates than S pilosicoli infection alone. Despite the successful treatment of batches of pigs with tiamulin or lincomycin, S pilosicoli infection persisted as a chronic problem on many units, with diarrhoea and colitis in successive batches of pigs unless prophylactic medication was used.

Cooperative haemolysis between weakly beta-haemolytic human intestinal spirochaetes and Staphylococcus aureus

Weakly beta-haemolytic spirochaetes related to human intestinal spirochaetosis produced a cooperative haemolysis together with S. aureus consisting of an enhanced haemolysis in the zone of the spirochaetal growth which was overlapped by the zone of activity of the staphylococcal beta-haemolysin. The cooperative haemolysis was observed in sheep blood agar media when the concentration of spirochaetes ranged from 1.5 x 10(3) to 1.5 x 10(8) CFU/ml and the concentration of S. aureus from 4 x 10(3) to 4 x 10(8) CFU/ml. With the increase of the distance between the streaks of the spirochaetes and S. aureus from 3 to 10 mm, the period of incubation needed to observe the cooperative haemolysis also increased from 18 to 72 hours. When the spirochaetes and S. aureus were streaked at the same time and when S. aureus was streaked earlier than the spirochaetes, the phenomenon was observed after anaerobic incubation of the plates for 24-72 hours but not after incubation in 10% CO2 under atmospheric conditions. A cooperative haemolysis was also observed between S. aureus and spirochaetes related to the porcine and avian intestinal spirochaetosis and the spirochaete causing swine dysentery when the same experimental conditions were used which allowed an observation of the phenomenon involving human spirochaetes and S. aureus.

Restriction fragment length polymorphism of the periplasmic flagellar flaA1 gene of Serpulina species

Forty-one reference and field isolates of intestinal spirochetes representing Serpulina hyodysenteriae, Serpulina innocens, Serpulina pilosicoli, Brachyspira aalborgi, and nonclassified weakly beta-hemolytic intestinal spirochetes were compared by restriction fragment length polymorphism (RFLP) of the periplasmic flagellar (PF) flaA1 gene. Six genetically distinct groups (I through VI), each with a unique RFLP fingerprint pattern, were identified by Southern blotting analysis of EcoRV chromosomal DNA digests with a PCR-amplified digoxigenin-labeled 1-kb fragment of the S. hyodysenteriae isolate B78 PF flaA1 gene. The RFLP fingerprint patterns corresponded to known DNA homology differences between Serpulina species and to provisionally designated species described previously by using phenotypic and genotypic classification schemes. RFLP fingerprinting of the PF flaA1 gene provides a relatively simple genotypic method for identification of intestinal spirochetes without the use of radioisotopes.

Evidence for Serpulina hyodysenteriae being recombinant, with an epidemic population structure

The population structure of Serpulina hyodysenteriae was investigated using multilocus enzyme electrophoresis. A total of 231 isolates were divided into 50 electrophoretic types (ETs), with a mean genetic diversity of 0.29 for the number of ETs and 0.23 for the number of isolates. Subsets of isolates from two Australian states (71 isolates from Victoria and 68 isolates from Queensland) exhibited as much genetic variation as the entire collection. The calculated index of association (IA) for the number of ETs (0.29 +/- 0.17) was not significantly different from zero, and hence provided evidence for the occurrence of significant genetic recombination accounting for the observed variation between strains. In contrast, the IA for the number of isolates (3.93 +/- 0.03) was significantly different from zero, with seven of the 50 ETs (ETs 4, 6, 13, 14, 20, 33 and 35) containing 51% of all the isolates. Even when multiple isolates from the same farm were removed from the analysis, the IA value for the number of isolates remained significantly greater than zero (IA 9.87 +/- 0.04), indicating that it was not biased by their inclusion. The results suggest that S. hyodysenteriae has an epidemic population structure.

Specific detection of Serpulina hyodysenteriae and potentially pathogenic weakly beta-haemolytic porcine intestinal spirochetes by polymerase chain reaction targeting 23S rDNA

A 2470-bp section of the 23S ribosomal DNA from Serpulina hyodysenteriae and five biochemically different groups of weakly beta-haemolytic porcine intestinal Serpulina strains was sequenced. The similarity between the sequenced strains was high (96.85% to 99.84%). A phylogenetic tree was estimated by the maximum likelihood method. The sequenced strains formed three groups. Serpulina hyodysenteriae and biochemical group II ('S. intermedius') formed a cluster, but 20 nucleotide positions were different between the two, suggesting that biochemical group II is a separate species. Another cluster consisted of the closely related biochemical group IIIa ('S. murdochii') and IIIb/c (S. innocens) (99.84% similarity), while biochemical group IV (S. pilosicoli) constituted a separate group with a relatively low similarity (96.85% to 97.01%) to the other groups. Three primer pairs were designed for specific PCR detection of the clinically important S. hyodysenteriae and biochemical group II and IV. PCR amplification was accomplished with DNA extracted from bacterial colonies by a simple boiling procedure, and with DNA extracted directly from porcine stool samples using a bead beating extraction procedure. The level of detection for the direct extraction and amplification method was 5 x 10(5) cells added g-1 normal faeces.

Sub-specific differentiation of intestinal spirochaete isolates by macrorestriction fragment profiling

Macrorestriction fragment profile analysis by PFGE was used to distinguish intestinal spirochaetes, some of which were isolated from cases of swine dysentery and intestinal spirochaetosis in humans, pigs, mice, chickens and dogs. Macrorestriction fragment profiles using SmaI and SacII restriction enzymes were produced and used in statistical analysis. This permitted the division of the isolates into two major clusters. One cluster contained isolates which were identified as Serpulina pilosicoli and the second cluster contained isolates identified as Serpulina hyodysenteriae by immunoblotting with species-specific mAbs. Both species contained sub-specific groups, although these rarely correlated with the source of the isolates. We conclude that PFGE is capable of sub-specific differentiation of intestinal spirochaetes, but that the current species contain a large variety of genotypes among which cross-species transmission may be feasible.

Pathogenicity of three strains of Serpulina pilosicoli in pigs with a naturally acquired intestinal flora

Serpulina pilosicoli is an anaerobic spirochete which has been isolated from the colons of pigs with enteric disease. The clinical and pathologic features of experimental infections of conventional pigs (born by normal farrowing with a naturally acquired intestinal flora) with three strains of S. pilosicoli were determined in order to confirm the enteropathogenicity of this species. Strains were derived from the colons of British pigs with colitis and passaged 8 to 10 times during expansion and purification in vitro. Eighteen ten-week-old Large White-Landrace cross pigs were each inoculated once orally with 0.7 x 10(9) to 1.6 x 10(9) of one of three strains of S. pilosicoli. Six pigs were challenged with each strain. Control pigs were dosed with uninfected broth medium or with 1.8 x 10(7) cells of the nonpathogenic Serpulina innocens. Eight pigs (two to four per S. pilosicoli challenge group) developed soft or diarrheic feces (fecal dry matter < 24%) between 3 and 8 days after challenge, which persisted for 7 to 8 days or until necropsy at 14 days after challenge. Average weight gains in two of the three groups challenged with S. pilosicoli were significantly less than controls. The feed conversion ratios of all the groups challenged with S. pilosicoli were impaired compared to controls. The mean values for daily liveweight gain (and feed conversion ratio) for the three groups challenged with S. pilosicoli were 0.799 (2.13), 0.783 (2.05), and 0.844 kg (2.10), respectively, while that of the uninoculated controls was 0.944 kg (1.70). Gross lesions with slight mucosal thickening, congestion, and multifocal erosions were evident in seven of eight diarrheic pigs. The relative weights of the large intestines of pigs challenged with S. pilosicoli were significantly less than controls. Histologic lesions with an increase in mucosal height, infiltration of the lamina propria with mononuclear cells, mucosal erosion with mixed inflammatory cell infiltration, and goblet cell hyperplasia in colonic glands were evident in 15 of the 18 challenged pigs. S. pilosicoli was recovered on bacterial culture of the colon from all except one of the pigs with these histologic lesions. Serpulina sp. was clearly visible within the colonic glands of these affected pigs in silver-stained sections of the gut. Clinical and pathologic findings in control pigs were unremarkable, with no diarrhea or colonic lesions evident. The results provide further evidence that S. pilosicoli is a specific enteric pathogen for conventional pigs. It is capable of colonizing the large intestine and causing mucosal damage, which although mild is sufficient to result in significant adverse effects on growth.

Laboratory identification and enteropathogenicity testing of Serpulina pilosicoli associated with porcine colonic spirochetosis

Pathogenic intestinal spirochetes of swine include Serpulina hyodysenteriae, a strongly beta-hemolytic spirochete that causes swine dysentery, and S. pilosicoli, a weakly beta-hemolytic intestinal spirochete (WBHIS) that causes porcine colonic spirochetosis. Because of the existence of nonpathogenic WBHIS in the normal swine colon, it is important to develop laboratory procedures for accurate identification of S. pilosicoli. The purpose of the present study was to assess hippurate hydrolysis and polymerase chain reaction (PCR) amplification of specific 16S ribosomal RNA (rRNA) sequences for identification of porcine S. pilosicoli. Additionally, the enteropathogenicity of 8 field isolates of porcine S. pilosicoli was determined by challenge exposure of 1-day-old chicks and sequential histologic examination of the cecal mucosa. The field isolates of porcine S. pilosicoli hydrolyzed hippurate and yielded S. pilosicoli-specific products by PCR amplification of 16S rRNA sequences. Although all of the field isolates of porcine S. pilosicoli attached to the cecal epithelium of challenge-exposed chicks by day 21 postinoculation, some isolates had locally invasive phenotypes. We concluded that identification of porcine S. pilosicoli could be made on the basis of results of hippurate hydrolysis and 16S rRNA PCR amplification. Challenge inoculation of 1-day-old chicks followed by histologic examination of the cecal mucosa demonstrated the enteropathogenicity of porcine S. pilosicoli.

Identification and characterization of Serpulina pilosicoli isolates recovered from the blood of critically ill patients

The phenotypic and genetic characteristics of spirochetes isolated from the blood of one U.S. and six French patients with severe clinical disease or impaired immunity were examined. All spirochetes were anaerobic, weakly beta-hemolytic, positive for hippurate hydrolysis, and negative for beta-glucosidase activity. Cell lengths ranged from 4 to 8 microm, and each isolate had between 8 and 12 periplasmic flagella per cell. These features were consistent with the spirochetes' being Serpulina pilosicoli, the agent of intestinal spirochetosis. All isolates were positive in a PCR assay amplifying a portion of the S. pilosicoli 16S rRNA gene, and they all grouped with fecal isolates of S. pilosicoli in multilocus enzyme electrophoresis (MLEE). The blood isolates could be differentiated from each other by MLEE, although the U.S. and two French isolates were closely related. Apparently S. pilosicoli may translocate from the large intestine to establish spirochetemia. The clinical significance of this finding remains uncertain and requires further investigation.

Genetic and phenotypic characterization of intestinal spirochetes colonizing chickens and allocation of known pathogenic isolates to three distinct genetic groups

Infection with intestinal spirochetes has recently been recognized as a cause of lost production in the poultry industry. Little is known about these organisms, so a collection of 56 isolates originating from chickens in commercial flocks in Australia, the United States, The Netherlands, and the United Kingdom was examined. Strength of beta-hemolysis on blood agar, indole production, API ZYM enzyme profiles, and cellular morphology were determined, and multilocus enzyme electrophoresis was used to analyze the extent of genetic diversity among the isolates. The results were compared with those previously obtained for well-characterized porcine intestinal spirochetes. The chicken isolates were genetically heterogeneous. They were divided into 40 electrophoretic types distributed among six diverse genetic groups (groups b to g), with a mean genetic diversity of 0.587. Strains in two groups (groups d and e) may represent new species of Serpulina, and the groups contained only strains isolated from chickens. Three genetic groups contained isolates previously shown to be pathogenic for chickens. These corresponded to the proposed species "Serpulina intermedius," to an unnamed group (group e), and to Serpulina pilosicoli. Two of the chicken isolates (one "S. intermedius" and one S. pilosicoli isolate) were strongly beta-hemolytic, two (both "S. intermedius") had an intermediate level of beta-hemolysis, and the rest were weakly beta-hemolytic. Fourteen isolates of "S. intermedius" produced indole, as did one isolate from group d. Isolates identified as S. pilosicoli resembled porcine isolates of this species, having four to six periplasmic flagella inserted subterminally in a single row at each end of the cell, and had tapered cell ends. All other spirochetes were morphologically similar, having seven or more periplasmic flagella and blunt cell ends. The identification of three genetic groups containing pathogenic isolates provides an opportunity for more detailed epidemiologic studies with these pathogens and for the development of improved diagnostic tests.

Identification of Serpulina species associated with porcine colitis by biochemical analysis and PCR

A PCR system for the detection and identification of group IV spirochetes (Serpulina pilosicoli) was designed to complement biochemical tests, e.g., the hippurate hydrolysis and beta-glucosidase tests, and to verify the accuracy of a previously proposed biochemical classification system. The PCR assay was based on amplification of a segment of the 16S rRNA gene. Both primers were constructed to selectively amplify the 16S rRNA gene of Serpulina pilosicoli. All analyzed Serpulina strains exhibiting the capacity to hydrolyze hippurate and lacking beta-glucosidase activity, including the type strain for spirochetal diarrhea, P43, were amplified with the PCR system. All other tested strains, including type and field strains of different phenotypes of Serpulina species, as well as Salmonella species, Campylobacter species, and Escherichia coli strains, were negative in the assay. Among the tested strains were 18 Scottish field isolates originating from the mucosae of pigs with colitis. A simple classification scheme, suitable for routine classification of porcine intestinal spirochetes, is also presented. The scheme is based on hemolysis, indole production, and the hippurate hydrolysis test.

Phenotypic and genotypic profiles of human, canine, and porcine spirochetes associated with colonic spirochetosis correlates with in vivo brush border attachment

A group of phenotypically and genotypically distinct weakly beta-hemolytic intestinal spirochetes (WBHIS) have been associated with a diarrheal disease of humans, dogs and swine, designated colonic spirochetosis (CS). Because attachment of spirochetes to the brush border of colonic enterocytes is a consistent feature of CS, it may represent an important virulence mechanism. In this study, pure cultures of WBHIS obtained from humans, dogs, and swine with clinical signs or lesions of CS were compared with Serpulina innocens using biochemical, genotypic and an in vivo brush border attachment assay CS-associated WBHIS did not form genotypic and an in vivo brush border attachment assay CS-associated WBHIS did not form indole, but hydrolyzed hippurate. Analysis of genomic DNA using arbitrarily primed-PCR (AP-PCR) revealed that the CS-associated WBHIS had a closely related pattern which was distinctly different from that of S. innocens. For in vivo brush border attachment assays, one-day old chicks were inoculated by crop gavage with either sterile trypticase soy broth or broth containing either S. innocens or CS-associated WBHIS. On day 7 post-inoculation, the ceca of sham-inoculated control chicks and S. innocens-inoculated chicks had tall columnar enterocytes without spirochetes, and no spirochetes were isolated by culture on selective medium. Focal to segmental attachment of spirochetes to the brush border of superficial enterocytes was present in the ceca of chicks inoculated with WBHIS, and weakly beta-hemolytic spirochetes with effacement of the microvillous brush border of colonic enterocytes. Complete agreement between hippurate hydrolysis, specific- and AP-PCR assays and in vivo brush border attachment studies confirms the enteropathogencity of CS-associated WBHIS.