Experimental infection of laying hens with Serpulina intermedia causes reduced egg production and increased faecal water content

Brachyspira in dogs: risk factors of shedding in central Germany and longitudinal study of an infected kennel

BACKGROUND

Brachyspira (B.) pilosicoli is a zoonotic pathogen, able to infect different animal species such as pigs, poultry, and rodents, causing intestinal spirochetosis. An association of gastrointestinal clinical signs, such as diarrhea, with the isolation of B. pilosicoli from fecal samples or rectal swabs has not been proven in dogs. Other Brachyspira species commonly isolated from dogs, such as "B. canis" and "B. pulli", are considered commensals. This study investigated the occurrence of different Brachyspira species in rectal swabs and fecal samples in an independent canine cohort in central Germany. These included samples from shelter dogs, hunting dogs, and dogs presenting at regional small animal practices with various clinical signs. Data about the dogs, including potential risk factors for Brachyspira isolation, were obtained using a standardized questionnaire. The study also longitudinally investigated a colony of Beagle dogs for Brachyspira over 5 years.

RESULTS

The rate of Brachyspira spp. isolation was 11% and included different Brachyspira species ("B. canis", "B. pulli", and B. pilosicoli). "B. canis" was detected in 18 dogs, whereas B. pilosicoli was only isolated from 1 dog in the independent cohort (not including the Beagle colony). Risk factors for shedding Brachyspira and "B. canis" were being less than 1 year of age and shelter origin. Gastrointestinal signs were not associated with the shedding of Brachyspira. B. pilosicoli and "B. canis" were isolated from several dogs of the same Beagle colony in 2017 and again in 2022, while Brachyspira was not isolated at multiple sampling time points in 2021.

CONCLUSIONS

Shedding of B. pilosicoli in dogs appears to be uncommon in central Germany, suggesting a low risk of zoonotic transmission from dogs. Commensal status of "B. canis" and "B. pulli" is supported by the results of this study. Findings from the longitudinal investigation of the Beagle colony agree with an asymptomatic long-term colonization of dogs with "B. canis" and B. pilosicoli and suggest that introducing new animals in a pack can trigger an increased shedding of B. pilosicoli.

Differentiation of Brachyspira spp. isolated from laying hens using PCR-based methods and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Avian intestinal spirochetosis (AIS), an important but neglected disease in laying hens, is caused by Brachyspira pilosicoli, B. intermedia, and B. alvinipulli. Poultry are also frequently colonized by putatively nonpathogenic species such as B. murdochii and B. innocens. We evaluated the differentiation of Brachyspira species by 3 methods: sequencing of the reduced nicotinamide adenine dinucleotide (NADH) oxidase gene ( nox), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), and a new multiplex (m)PCR targeting genes such as the tryptophanase A gene ( tnaA) and the p-aminobenzoyl-glutamate hydrolase subunit B gene ( abgB). Sequencing of 414 bp of the nox PCR amplification products generated from 41 pure cultures of avian Brachyspira isolates allowed presumptive species identification in 33 isolates with at least 99% identity in basic local alignment search tool analysis, including B. pilosicoli, B. intermedia, B. murdochii, B. innocens, and " B. pulli". MALDI-TOF MS analysis was found to be a reliable tool for differentiation after extension of the manufacturer's database. In the mPCR, all isolates identified as B. pilosicoli and B. intermedia were positive for abgB and tnaA, respectively. The mPCR might be very useful in detecting Brachyspira species in mixed cultures including not only nonpathogenic species, such as B. innocens, but also one of the AIS pathogens. We found that MALDI-TOF MS analysis combined with the mPCR targeting tnaA and abgB was suitable for the identification of avian isolates of B. pilosicoli and B. intermedia, 2 important agents of AIS.

Isolation and antimicrobial susceptibility of Brachy -spira species from feces of layer chickens in Germany

Objective: Anaerobic spirochetes of the genus Brachyspira are important pathogens causing swine dysentery (Brachyspira [B.] hyodysenteriae) and porcine intestinal spirochetosis (B. pilosicoli, PIS). In addition, avian intestinal spirochetosis (AIS) is caused by B. pilosicoli, B. intermedia and B. alvinipulli. Despite the economic impact of AIS, the disease has not received appropriate attention in Germany. This study was aimed at identifying Brachyspira spp. in Germany and determining their antimicrobial susceptibility. Material and methods: From 2009 to 2013, a total of 71 fecal swabs were obtained from clinically healthy layer hens from eight different commercial flocks. Brachyspira spp. culture was performed in trypticase soybean agar added with 5% sheep blood. Species determination was conducted by PCRs targeting the NADH-gen and the 16S rDNA or by nox-gene sequencing. Antimicrobial susceptibility to macrolides, lincosamides and pleuromutilins was tested by a microdilution assay. Results: Brachyspira spp. were isolated from 40 (56.3%) swabs distributed over all eight flocks. In 26 cases, the following species were determined by PCR: B. pilosicoli (n = 16), B. intermedia (2), B. innocens (3), B. murdochii (1), mixtures of B. pilosicoli/B. intermedia (2), B. innocens/B. intermedia (1), B. innocens/B. murdochii (1). Remaining isolates were characterized by noxgene sequencing as B. “pulli” (n = 9), B. alvinipulli (3), B. intermedia (1) and as not identifiable (1). Antimicrobial susceptibility testing of 37 isolates revealed minimal inhibitory concentrations 90 (MIC90) of > 128 mg/l (tylosin), 64 mg/l (lincomycin), 8 mg/l (tiamulin) and 4 mg/l (valnemulin), respectively. Comparing to breakpoints applied to pigs, these values lie within the range of resistance. Conclusion The demonstration of different Brachyspira spp., particularly B. pilosicoli, intermedia and alvinipulli in commercial layers, indicates the need of further research to assess their potential role in causing AIS in German poultry flocks. The increased antimicrobial resistance of Brachyspira spp. isolates to tylosin and pleuromutilins is likely associated with extensive use of these drugs in poultry medicine.

Characterization and Recognition of Brachyspira hampsonii sp. nov., a Novel Intestinal Spirochete That Is Pathogenic to Pigs

Swine dysentery (SD) is a mucohemorrhagic colitis of swine classically caused by infection with the intestinal spirochete Brachyspira hyodysenteriae Since around 2007, cases of SD have occurred in North America associated with a different strongly beta-hemolytic spirochete that has been molecularly and phenotypically characterized and provisionally named "Brachyspira hampsonii." Despite increasing international interest, B. hampsonii is currently not recognized as a valid species. To support its recognition, we sequenced the genomes of strains NSH-16T, NSH-24, and P280/1, representing B. hampsonii genetic groups I, II, and III, respectively, and compared them with genomes of other valid Brachyspira species. The draft genome of strain NSH-16T has a DNA G+C content of 27.4% and an approximate size of 3.2 Mb. Genomic indices, including digital DNA-DNA hybridization (dDDH), average nucleotide identity (ANI), and average amino acid identity (AAI), clearly differentiated B. hampsonii from other recognized Brachyspira species. Although discriminated genotypically, the three genetic groups are phenotypically similar. By electron microscopy, cells of different strains of B. hampsonii measure 5 to 10 μm by 0.28 to 0.34 μm, with one or two flat curves, and have 10 to 14 periplasmic flagella inserted at each cell end. Using a comprehensive evaluation of genotypic (gene comparisons and multilocus sequence typing and analysis), genomic (dDDH, ANI, and AAI) and phenotypic (hemolysis, biochemical profiles, protein spectra, antibiogram, and pathogenicity) properties, we classify Brachyspira hampsonii sp. nov. as a unique species with genetically diverse yet phenotypically similar genomovars (I, II, and III). We designate the type strain NSH-16 (= ATCC BAA-2463 = NCTC 13792).

Drinking water application of Denagard® Tiamulin for control of Brachyspira pilosicoli infection of laying poultry

Avian intestinal spirochaetosis (AIS) caused by Brachyspira spp., and notably Brachyspira pilosicoli, is common in layer flocks and reportedly of increasing incidence in broilers and broiler breeders. Disease manifests as diarrhoea, increased feed consumption, reduced growth rates and occasional mortality in broilers and these signs are shown in layers also associated with a delayed onset of lay, reduced egg weights, faecal staining of eggshells and non-productive ovaries. Treatment with Denagard® Tiamulin has been used to protect against B. pilosicoli colonisation, persistence and clinical presentation of AIS in commercial layers, but to date there has been no definitive study validating efficacy. Here, we used a poultry model of B. pilosicoli infection of layers to compare the impact of three doses of Denagard® Tiamulin. Four groups of thirty 17 week old commercial pre-lay birds were all challenged with B. pilosicoli strain B2904 with three oral doses two days apart. All birds were colonised within 2 days after the final oral challenge and mild onset of clinical signs were observed thereafter. A fifth group that was unchallenged and untreated was also included for comparison as healthy birds. Five days after the final oral Brachypira challenge three groups were given Denagard® Tiamulin in drinking water made up following the manufacturer's recommendations with doses verified as 58.7 ppm, 113 ppm and 225 ppm. Weight gain body condition and the level of diarrhoea of birds infected with B. pilosicoli were improved and shedding of the organism reduced significantly (p=0.001) following treatment with Denagard® Tiamulin irrespective of dose given. The level and duration of colonisation of organs of birds infected with B. pilosicoli was also reduced. Confirming previous findings we showed that the ileum, caeca, colon, and both liver and spleen were colonised and here we demonstrated that treatment with Denagard® Tiamulin resulted in significant reduction in the numbers of Brachyspira found in each of these sites and dramatic reduction in faecal shedding (p<0.001) to approaching zero as assessed by culture of cloacal swabs. Although the number of eggs produced per bird and the level of eggshell staining appeared unaffected, egg weights of treated birds were greater than those of untreated birds for a period of approximately two weeks following treatment. These data conclusively demonstrate the effectiveness of Denagard® Tiamulin in reducing B. pilosicoli infection in laying hens.

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.

Intestinal spirochaetes (Brachyspira spp.) colonizing flocks of layer and breeder chickens in Malaysia

Avian intestinal spirochaetosis causes problems including delayed onset of lay and wet litter in adult chickens, and results from colonization of the caecae/rectum with pathogenic intestinal spirochaetes (genus Brachyspira). Because avian intestinal spirochaetosis has not previously been studied in South East Asia, this investigation was undertaken in Malaysia. Faecal samples were collected from 25 farms and a questionnaire was administered. Brachyspira species were detected by polymerase chain reaction in 198 of 500 (39%) faecal samples from 20 (80%) farms, including 16 (94%) layer and four (50%) breeder farms. Pathogenic Brachyspira pilosicoli was identified in five (29%) layer and two (25%) breeder farms whilst pathogenic Brachyspira intermedia was detected in nine (53%) layer and one (12.5%) of the breeder farms. Twelve (80%) layer farms had egg production problems and 11 (92%) were positive for Brachyspira: three (25%) for B. pilosicoli and six (50%) for B. intermedia. Of three breeder farms with egg production problems, one was colonized with B. pilosicoli. Three of ten layer farms with wet litter were positive for B. pilosicoli and six for B. intermedia. Of four breeder farms with wet litter, one was colonized with B. pilosicoli and one with B. intermedia. No significant associations were found between colonization and reduced egg production or wet litter, perhaps because so many flocks were colonized. A significant association (P = 0.041) occurred between a high prevalence of colonization and faecal staining of eggs. There were significant positive associations between open-sided housing (P = 0.006), and flocks aged >40 weeks (P < 0.001) and colonization by pathogenic species.

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.

Evidence for systemic spread of the potentially zoonotic intestinal spirochaete Brachyspira pilosicoli in experimentally challenged laying chickens

Brachyspira pilosicoli is a potentially zoonotic anaerobic intestinal spirochaete that is one of several species causing avian intestinal spirochaetosis. The aim of this study was to develop a reproducible model of infection in point-of-lay chickens and compare the virulence of two strains of B. pilosicoli in a model using experimentally challenged laying chickens. Seventeen-week-old commercial laying chickens were experimentally challenged by oral gavage with either B. pilosicoli strain B2904 or CPSp1, following an oral dose of 10 % sodium bicarbonate to neutralize acidity in the crop. Approximately 80 % of the chickens became colonized and exhibited increased faecal moisture content, reduced weight gain and delayed onset of lay. Tissues sampled at post-mortem examination were analysed to produce a quantitative output on the number of spirochaetes present and hence, the extent of colonization. The liver and spleen were colonized, and novel histopathology was observed in these tissues. The infection model we report here has potential use in studies to improve our understanding of the mechanisms by which Brachyspira elicit disease in poultry and in testing novel intervention strategies.

Oral treatment of chickens with Lactobacillus reuteri LM1 reduces Brachyspira pilosicoli-induced pathology

Avian intestinal spirochaetosis (AIS) results from the colonization of the caeca and colon of poultry by pathogenic Brachyspira, notably Brachyspira pilosicoli. Following the ban on the use of antibiotic growth promoters in the European Union in 2006, the number of cases of AIS has increased, which, alongside emerging antimicrobial resistance in Brachyspira, has driven renewed interest in alternative intervention strategies. Lactobacillus-based probiotics have been shown to protect against infection with common enteric pathogens in livestock. Our previous studies have shown that Lactobacillus reuteri LM1 antagonizes aspects of the pathobiology of Brachyspira in vitro. Here, we showed that L. reuteri LM1 mitigates the clinical symptoms of AIS in chickens experimentally challenged with B. pilosicoli. Two groups of 15 commercial laying hens were challenged experimentally by oral gavage with B. pilosicoli B2904 at 18 weeks of age; one group received unsupplemented drinking water and the other received L. reuteri LM1 in drinking water from 1 week prior to challenge with Brachyspira and thereafter for the duration of the study. This treatment regime was protective. Specifically, B. pilosicoli was detected by culture in fewer birds, bird weights were higher, faecal moisture contents were significantly lower (P<0.05) and egg production as assessed by egg weight and faecal staining score was improved (P<0.05). Also, at post-mortem examination, significantly fewer B. pilosicoli were recovered from treated birds (P<0.05), with only mild-moderate histopathological changes observed. These data suggest that L. reuteri LM1 may be a useful tool in the control of AIS.

Lactobacilli antagonize the growth, motility, and adherence of Brachyspira pilosicoli: a potential intervention against avian intestinal spirochetosis

Avian intestinal spirochetosis (AIS) results from the colonization of the ceca and colorectum of poultry by pathogenic Brachyspira species. The number of cases of AIS has increased since the 2006 European Union ban on the use of antibiotic growth promoters, which, together with emerging antimicrobial resistance in Brachyspira, has driven renewed interest in alternative intervention strategies. Probiotics have been reported as protecting livestock against infection with common enteric pathogens, and here we investigate which aspects of the biology of Brachyspira they antagonize in order to identify possible interventions against AIS. The cell-free supernatants (CFS) of two Lactobacillus strains, Lactobacillus reuteri LM1 and Lactobacillus salivarius LM2, suppressed the growth of Brachyspira pilosicoli B2904 in a pH-dependent manner. In in vitro adherence and invasion assays with HT29-16E three-dimensional (3D) cells and in a novel avian cecal in vitro organ culture (IVOC) model, the adherence and invasion of B. pilosicoli in epithelial cells were reduced significantly by the presence of lactobacilli (P < 0.001). In addition, live and heat-inactivated lactobacilli inhibited the motility of B. pilosicoli, and electron microscopic observations indicated that contact between the lactobacilli and Brachyspira was crucial in inhibiting both adherence and motility. These data suggest that motility is essential for B. pilosicoli to adhere to and invade the gut epithelium and that any interference of motility may be a useful tool for the development of control strategies.

Vaccination with an autogenous bacterin fails to prevent colonization by Brachyspira intermedia in experimentally infected laying chickens

Avian intestinal spirochaetosis (AIS) is a disease complex affecting adult laying and breeding chickens associated with infection by anaerobic intestinal spirochaetes of the genus Brachyspira. Options for control of AIS are limited, as few effective antimicrobial agents are registered for use in laying chickens. One of the two most commonly encountered pathogenic species in AIS is B. intermedia, and the aim of the current study was to determine whether a B. intermedia bacterin vaccine would help control AIS caused by this species. An autogenous bacterin was prepared from B. intermedia strain HB60 and given twice intramuscularly at a 3-week interval to 12 laying chickens housed in individual cages. Twelve non-vaccinated control chickens were placed in adjacent cages in the same room. Two weeks after the second vaccination all the chickens were experimentally challenged with B. intermedia HB60 by crop tube. Subsequently faeces were cultured for spirochaetes every 2-3 days, faecal water content and chicken weight were measured weekly, and egg numbers and weights were recorded daily. Serum was taken prior to both vaccinations, at the time of challenge and at euthanasia. The chickens were killed 6 weeks post-challenge. The vaccinated chickens showed seroconversion to the vaccine, but antibody levels declined significantly post-infection. In comparison, the non-vaccinated chickens showed seroconversion post-infection. The reason for the reduction in the antibody levels in the vaccinated chickens after infection was not explained. At some point all the chickens excreted spirochaetes in their faeces, and the duration of excretion was not different between vaccinated and non-vaccinated chickens. There were no differences in faecal water content, chicken weights, egg production, or gross and microscopic caecal lesions between vaccinated and non-vaccinated chickens. In conclusion, an autogenous bacterin vaccine did not prevent infection with B. intermedia in laying chickens.

Prevalence, disease associations and risk factors for colonization with intestinal spirochaetes (Brachyspira spp.) in flocks of laying hens in north-eastern Italy

The present study investigated the occurrence of anaerobic intestinal spirochaetes of the genus Brachyspira in laying hen flocks in Treviso province, north-eastern Italy, with respect to prevalence, spirochaete species present, disease associations and risk factors for colonization. A total of 450 faecal samples from 45 sheds on 29 laying hen farms were cultured for intestinal spirochaetes. Nineteen sheds on 12 farms contained chickens with symptoms consistent with avian intestinal spirochaetosis, including reduced egg production, wet litter and/or pasty vents. Spirochaetes were isolated from 157 (34.8%) samples from 21 (72.4%) farms, and from 32 (71.1%) sheds. From these positive samples, 189 spirochaetal isolates were speciated using three polymerase chain reaction assays and a restriction fragment polymorphism analysis of 16S rDNA polymerase chain reaction products. Overall, 52 (27.5%) isolates were identified as pathogenic Brachyspira intermedia, 26 (13.8%) as pathogenic Brachyspira pilosicoli, 93 (49.7%) as non-pathogenic (Brachyspira innocens/Brachyspira murdochii), and 18 (9.6%) were unidentified. Faeces from 14 sheds (31%) on 10 farms (34.5%) contained B. intermedia and/or B. pilosicoli, and disease consistent with avian intestinal spirochaetosis was observed in nine of these sheds on seven farms. There was a significant association (P=0.042) between the presence of spirochaetes and using deep pits rather than conveyor belts for manure disposal. Sheds housing chickens >40 weeks of age were significantly more likely to contain spirochaetes (P=0.048) and pathogenic species (P=007) than sheds housing younger chickens. A significant association (P=0.02) was found between infection with pathogenic spirochaetes and reduced egg production.

Identification of Brachyspira hyodysenteriae and other pathogenic Brachyspira species in chickens from laying flocks with diarrhea or reduced production or both

Cecal samples from laying chickens from 25 farms with a history of decreased egg production, diarrhea, and/or increased feed conversion ratios were examined for anaerobic intestinal spirochetes of the genus Brachyspira. Seventy-three samples positive in an immunofluorescence assay for Brachyspira species were further examined using selective anaerobic culture, followed by phenotypic analysis, species-specific PCRs (for Brachyspira hyodysenteriae, B. intermedia, and B. pilosicoli), and a Brachyspira genus-specific PCR with sequencing of the partial 16S rRNA gene products. Brachyspira cultures were obtained from all samples. Less than half of the isolates could be identified to the species level on the basis of their biochemical phenotypes, while all but four isolates (5.2%) were speciated by using PCR and sequencing of DNA extracted from the bacteria. Different Brachyspira spp. were found within a single flock and also in cultures from single chickens, emphasizing the need to obtain multiple samples when investigating outbreaks of avian intestinal spirochetosis. The most commonly detected spirochetes were the pathogenic species B. intermedia and B. pilosicoli. The presumed nonpathogenic species B. innocens, B. murdochii, and the proposed "B. pulli" also were identified. Pathogenic B. alvinipulli was present in two flocks, and this is the first confirmed report of B. alvinipulli in chickens outside the United States. Brachyspira hyodysenteriae, the agent of swine dysentery, also was identified in samples from three flocks. This is the first confirmed report of natural infection of chickens with B. hyodysenteriae. Experimental infection studies are required to assess the pathogenic potential of these B. hyodysenteriae isolates.

Treatment of a field case of avian intestinal spirochaetosis caused by Brachyspira pilosicoli with tiamulin

There has been much confusion over the significance of spirochaetes found in the caeca of laying hens and the impact they may have on egg production. In recent years, the situation has been made clearer and the presence of such species as Brachyspira pilosicoli have been shown to cause a mild, chronic disease in both layers and breeders and to reduce egg production by reportedly 5%. In the United Kingdom, a multi-age caged laying site with three separate flocks of approximately 12 000 birds each was chronically infected with B. pilosicoli but displayed few clinical signs except for a noticeable reduction in egg production and an increased mortality. The flocks were treated for 3 days in the drinking water with tiamulin at 12.5 mg/kg bodyweight, and a steady improvement in performance was recorded. The production results were compared with a flock that had been untreated with tiamulin previously, as a control, and one that had been treated at 25 and 45 weeks of age. A 9.8% improvement in egg production/hen housed up to 72 weeks of age and 9.7% in total egg weight was recorded, as well as an 8.6% reduction in actual hen mortality, in the tiamulin-treated flock in comparison with the untreated control. After taking into account the difference in breeds used, there was only a 6% reduction in egg production but an 8.84% increase in mortality in the untreated flock compared with the individual breed's standard production data. The cost of the disease was estimated at 14 million pound in the United Kingdom, based on a national laying flock of 30 million or 1.5% of production. Faecal examination for potentially pathogenic spirochaetes should be part of the differential diagnosis of under-performing laying flocks.

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.

Brachyspiraspp. (Serpulinaspp.) in birds: a review and results from a study of Swedish game birds

Only limited data concerning the prevalence of intestinal spirochetes are available in game birds. This paper describes the prevalence and biochemical reactions of spirochetes isolated from 25 common partridges, 7 pheasants and 16 mallards originating from nine Swedish game-bird farms. The birds, which had been submitted for post-mortem examination due to various problems, showed a variety of underlying diseases. Additionally, fecal droppings from 22 common partridges, 20 pheasants and 20 mallards obtained at one of the farms were included in the study. Intestinal spirochetes were isolated from 85.4% of the game birds and from 71% of the fecal droppings. Seven biochemical types were identified. Seventeen per cent of all isolates were classified as Brachyspira pilosicoli and 3% as B. intermedia. One isolate showed strong -hemolysis and a positive indole reaction that is consistent with B. hyodysenteriae. In addition, three previously unknown biochemical types were found. Unclassified spirochetes in presumed mixed cultures were observed in 21% of all samples of fecal droppings. Histologic examination of spirochete-positive birds revealed numerous spirochetes in the lumen and crypts of the cecum, in some cases densely adhered by one end to the luminal surface. The significance of the findings is discussed.

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).

Development of a two-step nested duplex PCR assay for the rapid detection of Brachyspira pilosicoli and Brachyspira intermedia in chicken faeces

Avian intestinal spirochaetosis (AIS) is an infection of the caeca and/or colo-rectum of laying and meat breeder hens caused by anaerobic intestinal spirochaetes of the genus Brachyspira. AIS can result in a variety of symptoms, including delayed and/or reduced egg production, and increased faecal water content. The two most commonly reported Brachyspira species involved in AIS are Brachyspira pilosicoli and Brachyspira intermedia, and their detection and identification can be difficult and time consuming. In the current study a two-step nested duplex PCR (2S-N-D-PCR) was developed for the detection of these two species, using DNA extracted from washed chicken faeces. In the first step, a duplex PCR (D-PCR) amplifying Brachyspira genus-specific portions of the 16S rRNA and NADH oxidase (nox) genes was undertaken on the washed faeces. In the second step, a nested D-PCR was used that amplified species-specific portions of the 16S rRNA gene of B. pilosicoli and the nox gene of B. intermedia from the amplicons produced in the first step. The 2S-N-D-PCR was rapid and specific, and could be used to detect approximately 10(3) cells of each spirochaete species per gram of washed faeces. When tested on 882 chicken faecal samples from infected flocks, it detected 4-5% more positive faecal samples than did the standard method of selective anaerobic culture followed by individual species-specific PCR assays conducted on the growth on the primary plate. The application of this new technique should improve diagnostic capacity, and facilitate further studies on AIS.

The wheat variety used in the diet of laying hens influences colonization with the intestinal spirochaete Brachyspira intermedia

This study investigated whether feeding different wheat varieties to laying hens could influence colonization with the intestinal spirochaete Brachyspira intermedia. Fifty ISA-Brown laying hens were divided into two groups. One group were fed a laying-hen diet formulated with wheat variety Westonia, and one were fed the diet incorporating variety Stilleto. Each group was divided into 15 hens experimentally infected with B. intermedia and 10 uninfected controls. The 30 infected hens were housed in individual cages in one room, and the controls were similarly housed in another room. Following administration of cultures of B. intermedia strain HB60 by crop-tube over 3 days, cloacal swabs were taken for spirochaete culture every 3 to 4 days. The water content of caecal faeces, and egg production and body weight were measured weekly. The hens were killed after 4 weeks, the caeca cultured for spirochaetes and the viscosity of the ileal contents measured. A total of 48/120 (40%) of the excreta samples from infected hens fed Westonia contained B. intermedia, compared with 21/120 (17.5%) for Stiletto (P = 0.0002). The ileal viscosity of hens fed Westonia also was higher (P = 0.048), but viscosity was not clearly related to the non-starch polysaccharide (NSP) content of the wheats. Westonia had a slightly higher total NSP content than Stiletto, but the ratio of soluble to insoluble NSP was lower. Infected hens developed wetter excreta, but neither infection nor diet altered egg production. In conclusion, the wheat variety can influence colonization with B. intermedia, apparently through diet-related alterations in the intestinal microenvironment.

A cross-sectional study to investigate the occurrence and distribution of intestinal spirochaetes (Brachyspira spp.) in three flocks of laying hens

A cross-sectional study was conducted on a commercial egg-producing farm with a history of wet litter. A total of 600 fresh caecal faecal samples were obtained from under cages of laying hens in three sheds each containing flocks of approximately 5400 hens. Samples were cultured for intestinal spirochaetes, and growth on the primary isolation plate was observed under a phase contrast microscope and subjected to PCRs specific for the intestinal spirochaetes Brachyspira intermedia and Brachyspira pilosicoli. Spirochaete isolates obtained in pure culture were assessed for their ability to cause haemolysis on blood agar and to produce indole, and were typed using pulsed field gel electrophoresis (PFGE). A 1250 base pair portion of the 16S rRNA gene of three B. intermedia and five unidentified isolates was sequenced, and the sequences compared with those of other Brachyspira species. Overall, 121 (20.2%) of the faecal samples contained spirochaetes as determined by growth on the plate and microscopy. Using PCR on the primary growth from these positive samples, 43 (7.2% overall) were shown to contain B. intermedia, 8 (1.3%) to contain B. pilosicoli, and 70 (11.7%) were PCR negative. Only 24 isolates of B. intermedia and five isolates of unknown species were obtained in pure culture. Comparative analysis of the 16S rRNA gene sequence identified the non-B. intermedia isolates as belonging to the proposed species "Brachyspira pulli". PFGE analysis of the B. intermedia strains identified them as having four major banding patterns. Individual patterns were found in hens from different flocks, suggesting cross-transmission of strains between flocks. No environmental sources of infection were identified. The youngest flock had a significantly lower level of colonisation with B. intermedia than the flock of intermediate age (P = 0.004), suggesting that following initial infection of individual young hens on this farm there was amplification and transmission of infection amongst members of the flock.

A wheat-based diet enhances colonization with the intestinal spirochaeteBrachyspira intermediain experimentally infected laying hens

This study investigated the influence of feeding diets based on cereals with different non-starch polysaccharide content on colonization with the intestinal spirochaete Brachyspira intermedia in experimentally infected laying hens. The diets were based on wheat, barley, or barley and sorghum, all with or without supplementation with exogenous dietary enzymes. Six groups of 12 individually caged laying hens were fed the respective diets for 2 weeks, and then challenged at 20 weeks of age by crop tube with 10(8) to 10(9) colony forming units of active motile spirochaetes on five successive days. Eggs were collected daily. The birds were weighed weekly, and caecal faeces collected for assessment of water content. Every 3 to 4 days cloacal swabs were collected and subjected to culture and subsequent polymerase chain reaction for B. intermedia. The birds were killed at 27 weeks of age. Caecal contents were cultured for spirochaetes, and the viscosity of the ileal and rectal contents assessed. Dietary soluble non-starch polysaccharide content was not a consistent predictor of viscosity in the ileum, and the addition of enzymes did not significantly reduce the viscosity. A dietary influence on colonization was observed, with birds fed wheat having significantly more colonization than the birds fed the other diets. No significant association was found between either dietary soluble non-starch polysaccharide content or ileal viscosity and colonization with B. intermedia, as assessed by faecal excretion of the spirochaete. Dietary enzymes did not consistently or significantly reduce colonization. It was not established how wheat enhances colonization by B. intermedia, but the results suggest that wheat-based diets should be avoided in flocks infected with B. intermedia.

Survival of intestinal spirochaete strains from chickens in the presence of disinfectants and in faeces held at different temperatures

This study aimed to evaluate the efficacy of some commonly used disinfectants in inactivating the pathogenic avian intestinal spirochaetes Brachyspira intermedia and Brachyspira pilosicoli, and to examine spirochaete survival in chicken caecal faeces held at 4 degrees C, 25 degrees C or 37 degrees C. Six disinfectants were evaluated at their recommended working concentrations: alkaline salts, quaternary ammonium, iodine as an iodophor, chlorine from a chlorine-release agent, glutaraldehyde and hydrogen peroxide. All but alkaline salts inactivated two different concentrations of both spirochaete species in less than 1 min in the presence of organic matter. Both spirochaete species at three different cell concentrations survived in caecal faeces at 37 degrees C for between 2 and 17 h. B. intermedia tended to survive for longer than B. pilosicoli, but the maximum survival time for both species at 4 degrees C was only 72 to 84 h. Hence, avian intestinal spirochaetes are rapidly inactivated by several common disinfectants, and their survival time in chicken caecal faeces is much less than has been reported for porcine intestinal spirochaetes in porcine faeces. It should be relatively easy to break the cycle of infection between batches of laying birds by resting sheds for a few days, and by using disinfectants on any residual faecal matter.

Zinc bacitracin enhances colonization by the intestinal spirochaete Brachyspira pilosicoli in experimentally infected layer hens

Brachyspira pilosicoli strain CPSp1 isolated from a chicken in a broiler breeder flock in Queensland was used to experimentally infect 40 individually caged 22-week-old laying hens. Another 10 birds were sham-inoculated with sterile broth. All chickens received a commercial layer diet, but 10 infected birds had 50 parts/10(6) zinc bacitracin (ZnB) incorporated in their food. Birds were kept for 7 weeks, and faecal moisture, egg numbers, egg weights and body weights were recorded weekly. B. pilosicoli was isolated from the faeces of only three of the 30 inoculated birds receiving the diet without ZnB, whereas seven of the 10 inoculated birds receiving ZnB in their diet were colonized. This difference in colonization rate was highly significant (P = < 0.001). Dietary ZnB at 50 parts/10(6) therefore predisposed to colonization by B. pilosicoli. Despite colonization, no significant production differences were found between the birds in the three groups.

Evaluation of tiamulin and lincomycin for the treatment of broiler breeders experimentally infected with the intestinal spirochaete Brachyspira pilosicoli

Brachyspira pilosicoli strain CPSp1 isolated from a chicken in a broiler breeder flock in Queensland was used to experimentally infect 30 individually caged 22-week-old Cobb 500 broiler breeder hens. Another 10 birds were sham-inoculated with sterile broth. All birds failed to become colonized. At 29 weeks of age, all birds were transferred to a diet containing 50 parts/10(6) zinc bacitracin (ZnB) and were re-challenged with the same B. pilosicoli strain at 32 weeks of age, weekly for 5 weeks. The majority of the inoculated birds then became colonized, confirming previous findings that ZnB can increase susceptibility to colonization with B. pilosicoli. The control group remained uninfected. Infected groups tended to have an increased faecal water content and faecal staining of eggshells. Ten birds were then treated by crop tube with 25 mg/kg body weight tiamulin for 5 days, and 10 birds with 20 mg/kg body weight lincomycin for 5 days. Both treatments removed the infection, while untreated birds remained infected. The results support previous observations that ZnB at 50 parts/10(6) in the diet increases the susceptibility of birds to B. pilosicoli infection, and demonstrated the usefulness of both tiamulin and lincomycin for treatment of infection with B. pilosicoli in adult birds.

Influence of in-feed zinc bacitracin and tiamulin treatment on experimental avian intestinal spirochaetosis caused by Brachyspira intermedia

Thirty individually caged layer hens were inoculated with Brachyspira intermedia, and 20 control birds remained unchallenged. Birds received a diet containing 100 parts/10(6) zinc bacitracin (ZnB), and were monitored for 10 weeks. B. intermedia was recovered sporadically from five of the inoculated birds, and there were no significant effects on body weight, faecal water or egg production. ZnB was presumed to be indirectly inhibiting spirochaete growth, and when removed from the diet, 18 of the 30 inoculated birds rapidly became culture positive. After 4 weeks, 10 of the 30 infected birds were treated with tiamulin at 25 mg/kg for 5 days, and 10 were returned to the diet containing ZnB. Birds receiving tiamulin became spirochaete negative and maintained their egg production, but re-infection occurred. The other 20 infected birds had a significant drop in egg production, but those receiving ZnB showed a reduced colonization by B. intermedia after 3 weeks.

Dietary enzyme and zinc bacitracin reduce colonisation of layer hens by the intestinal spirochaete Brachyspira intermedia

Brachyspira intermedia strain HB60 was used to experimentally infect 40 individually caged 22-week-old laying hens. Another 10 control birds were sham-inoculated with sterile broth. All chickens received an experimental layer diet based on wheat. The infected birds were randomly divided into four groups of 10, with the diet for each group containing either 50 ppm zinc bacitracin (ZnB), 100 ppm ZnB, 256 ppm of dietary enzyme (Avizyme), 1302), or no additive. Birds were kept for 6 weeks after infection, and faecal excretion of B. intermedia, faecal water content, egg numbers, egg weights and body weights were recorded weekly. Control birds remained uninfected throughout the experiment. B. intermedia was isolated significantly less frequently from the groups of experimentally infected birds receiving ZnB at 50 ppm or enzyme than from those receiving 100 ppm ZnB or no treatment. Infected birds had a transient increase in faecal water content in the week following challenge, but no other significant production differences were detected amongst the five groups of birds in subsequent weeks. It was not established how the ZnB at 50 ppm and the dietary enzyme reduced the ability of the spirochaete to colonise, but it may have been by bringing about changes in the intestinal microflora and/or the intestinal microenvironment.

Experimental infection of broiler breeder hens with the intestinal spirochaete Brachyspira (Serpulina) pilosicoli causes reduced egg production

The pathogenic potential of the anaerobic intestinal spirochaetes Brachyspira (Serpulina) pilosicoli and Brachyspira innocens was evaluated in adult chickens. Thirty 17-week-old Cobb broiler breeder hens were individually caged in three groups of 10 birds. Control birds (group A) were sham inoculated with sterile broth medium. Birds in the other two groups (groups B and C) were inoculated, respectively, with an isolate of B. innocens or of B. pilosicoli. Birds were monitored daily, and killed at 41 weeks of age. Infection had no consistent effect on body weight gain, but inoculation with B. pilosicoli resulted in a transient increase in faecal water content. B. innocens infection had no effect on egg production, but B. pilosicoli infection caused a delayed onset of laying, and a highly significant reduction in egg production over the first 11 weeks of lay. This study confirms that B. pilosicoli can cause serious egg production losses in adult chickens, while B. innocens is not obviously pathogenic.

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.