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

Prevalence and risk factors of Brachyspira spp. in pig herds with a history of diarrhoea in six European countries

Swine dysentery and porcine intestinal spirochaetosis caused by Brachyspira (B.) hyodysenteriae and B. pilosicoli, respectively, are important diseases in swine production worldwide. The aim of this study was to assess the prevalence of both pathogens in farms with a history of diarrhoea within the last 12 months in Denmark, France, Germany, the Netherlands, Spain, and United Kingdom. In addition, risk factors for their prevalence and correlations between presence of different Brachyspira spp. and Lawsonia intracellularis were investigated. Therefore, faecal samples of 6355 nursery to finishing pigs out of 144 herds were sampled in 2017/2018 during a prevalence study on Lawsonia intracellularis, followed by polymerase chain reaction analysis for Brachyspira spp. detection. Herd prevalence differed significantly between countries, from 4.2% to 45.8% for B. hyodysenteriae and 8.3-87.5% for B. pilosicoli, respectively (p < 0.01). For the within-herd prevalence (in positive herds), these values ranged from 2.2% to 27.0% for B. hyodysenteriae and 3.3-50.8% for B. pilosicoli. Mixed infections occurred in 34.1% and 58.7% of B. hyodysenteriae positive samples with Lawsonia intracellularis or B. pilosicoli, respectively. In 43.2% of B. pilosicoli positive samples, Lawsonia intracellularis was detected simultaneously. Overall, nursery pigs were significantly less often positive for one of the pathogens than growing or finishing pigs (p < 0.001). The absence of gastrointestinal problems like diarrhoea, routine use of antimicrobials and well performed biosecurity measures were some of the factors associated with lower detection rate of Brachyspira spp. Surprisingly, deworming of different age categories also showed associations with the detection of Brachyspira spp. which, however, were not always equally directed, and therefore require further investigations. The only risk factor significant for both Brachyspira spp. was the median number of ≥ 30 nursery pigs per pen after weaning, compared to smaller group sizes. Both pathogens were detected with varying frequency between the six European countries. This should be considered in the probability of disease and in case of transnational transport, to prevent spread of pathogens. In addition, the frequent presence of mixed infections in some countries should be taken into account in diagnostics. The most important protective factors against Brachyspira spp. presence on farm are biosecurity measures, while potential new factors such as deworming still require further investigation.

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.

Effect of soy on faecal dry matter content and excretion of Brachyspira hyodysenteriae in pigs

The aim of this study was to investigate the effect of a soy diet on the excretion of Brachyspira hyodysenteriae in five farms with subclinically infected pigs. The effects on general health, faecal consistency and dry matter were analysed. In total, 200 pigs of different ages (group 1 <100 days of age (n=120) and group 2 ≥100 days (n=80)) were randomly assigned to the control (C) and the treatment (T) groups. Group C received the farm's standard diet. In group T half of the daily feed ration was replaced by pure soy on two consecutive days. Faecal scores were used to determine faecal consistency and a microwave method to assess faecal dry matter content (FDMC). In age group 1, soy feeding resulted in a statistically significant decrease of the FDMC of 2.5 per cent compared with group C and in age group 2 in a significant increase of 2.2 per cent compared with group C at day 2. Overall seven (T: 5, C: 2) out of 597 faecal samples tested positive for B hyodysenteriae by PCR.

In conclusion, a high soy diet applied over two days influenced the faecal consistency and the FDMC in growers, finishers and sows under field conditions. Further investigations with more sensitive diagnostic methods are needed to prove a potential influence of a high soy diet on the detection rate of B hyodysenteriae in subclinically infected herds.

Occurrence of Brachyspira hyodysenteriae in multiplier pig herds in Switzerland

OBJECTIVE

This research was aimed to determine the occurrence of Brachyspira (B.) hyodysenteriae in Swiss multiplier pig herds.

MATERIALS AND METHODS

In a pilot study a direct real-time polymerase chain reaction (PCR) method for B. hyodysenteriae was compared to culture followed by PCR on 106 samples from three herds. Subsequently 40 multiplier herds were epidemiologically characterized and analysed for the presence of B. hyodysenteriae using direct PCR on 1412 rectal swabs. For external validation 20 swabs obtained from two positive conventional herds were analysed.

RESULTS

The comparison of direct PCR with culture followed by PCR resulted in a moderate agreement (kappa index: 0.58). In the two conventional herds, 35% of the samples (7/20) tested positive. Samples from 39 multipliers tested negative. In one multiplier herd, 25% (9/36) of the samples tested PCR positive. Risk factors in the multiplier herd may have been rodents or birds, but not pig purchase.

CONCLUSION AND CLINICAL RELEVANCE

B. hyodysenteriae have been detected in a Swiss multiplier herd, which underlines the threat of potential spread by replacement pigs. Consequently, a Brachyspira monitoring programme was established for Swiss multiplier herds.

Development of a microarray for studying porcine cytokine production in blood mononuclear cells and intestinal biopsies

A microarray for demonstration of a limited number of porcine cytokines was initiated. Polymerase chain reaction (PCR) products were synthesized for four house-keeping genes, cyclophilin, beta-actin, hypoxanthine phosphoribosyltransferase (HPRT) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and the following cytokines: interleukin (IL)-1beta, IL-4, IL-6, IL-8, IL-10, IL-12 p35, IL-12 p40, IL-18, interferon (IFN)-alpha, IFN-beta, IFN-gamma, tumour necrosis factor (TNF)-alpha, macrophage inhibition factor (MIF) and granulocyte/macrophage colony-stimulating factor (GM-CSF). Cytokine production was induced by incubation of porcine peripheral blood mononuclear cells (PBMC) with Concanavalin A (ConA) or oligodeoxynucleotide (ODN) 2216. RNA was isolated after 6 or 24 h from stimulated cells or unstimulated control cells and from intestinal biopsies. Cytokine expression was analysed using a 3-DNA Array 350(TM) labelling kit from Genisphere. Data were normalized using external control genes and analysed with the genepix pro 5.0 software. All the cytokines could be induced in PBMC and expressed on the array and the cytokines IL-6 and IFN-alpha were also analysed at protein level. All but one cytokine were expressed in samples from intestinal biopsies. Densitometric analyses of PCR products of the house-keeping genes were performed to validate the results from the microarray. Thus, this microarray will enable analyses of the cytokine profile during local and systemic infections in the pig.

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.

Eradication of endemicBrachyspira pilosicoliinfection from a farrowing herd: a case report

Brachyspira pilosicoliandB. innocenswere isolated repeatedly from a herd of 60 sows which mostly produced feeder pigs but also raised some fattening pigs. Postweaning diarrhea had been a severe problem in this herd for years. TheB. pilosicolieradication plan was based on the general guidelines for elimination ofB. hyodysenteriae, with some modifica-tions. The eradication measures were run in August 1997. In-feed medication with 200p.p.m. tiamulin lasted for 18–30 days, depending on the age group. The piggery unit was emptied, cleaned, disinfected and dried, and all worn surfaces were repaired. The animals were removed to temporary sheds situated 0–100m from the piggery unit. Only the sows and the boar returned to the piggery unit. All other pigs were sold from the sheds within 3 months after the eradication. Immediately after the eradication, the clinical postweaning diarrhea disappeared. The success of the program was monitored four times bacteriologically, and the last control sampling was in December 1999, 7 months after the total withdrawal of antimicrobial feed additives. The primary cultures from the last three samplings were also analysed withB. pilosicoli-specific PCR. All the samples were negative forB. pilosicoli. However,B. innocenscould be isolated from each batch of samples. The analysis ofB. inno-censisolates by pulsed-field gel electrophoresis indicated that at least one genotype persisted in the herd. The clinical and laboratory findings suggest that the eradication ofB. pilosicolihad succeeded in this herd

Neither hippurate-negative Brachyspira pilosicoli nor Brachyspira pilosicoli type strain caused diarrhoea in early-weaned pigs by experimental infection

A hippurate-negative biovariant of Brachyspira pilosicoli (B. pilosicoli^hipp-) is occasionally isolated in diarrhoeic pigs in Finland, often concomitantly with hippurate-positive B. pilosicoli or Lawsonia intracellularis. We studied pathogenicity of B. pilosicoli^hipp- with special attention paid to avoiding co-infection with other enteric pathogens. Pigs were weaned and moved to barrier facilities at the age of 11 days. At 46 days, 8 pigs were inoculated with B. pilosicoli^hipp- strain Br1622, 8 pigs were inoculated with B. pilosicoli type strain P43/6/78 and 7 pigs were sham-inoculated. No signs of spirochaetal diarrhoea were detected; only one pig, inoculated with P43/6/78, had soft faeces from day 9 to 10 post inoculation. The pigs were necropsied between days 7 and 23 after inoculation. Live pigs were culture-negative for Brachyspira spp., but B. pilosicoli^hipp- was reisolated from necropsy samples of two pigs. The lesions on large colons were minor and did not significantly differ between the three trial groups. In silver-stained sections, invasive spirochaetes were detected in colonic mucosae of several pigs in all groups. Fluorescent in situ hybridisation for genus Brachyspira, B. pilosicoli and strain Br1622 was negative. However, in situ detection for members of the genus Leptospira was positive for spirochaete-like bacteria in the colonic epithelium of several pigs in both infected groups as well as in the control group. L. intracellularis, Salmonella spp., Yersinia spp. and intestinal parasites were not detected. The failure of B. pilosicoli strains to cause diarrhoea is discussed with respect to infectivity of the challenge strains, absence of certain intestinal pathogens and feed and management factors.

The Prevalences of Brachyspira spp. and Lawsonia intracellularis in Swedish Piglet Producing Herds and Wild Boar Population

The aim of the present study was to survey the prevalences of the enteric pathogens Brachyspira hyodysenteriae, Brachyspira pilosicoli and Lawsonia intracellularis in Swedish growing pigs and in the Swedish wild boar population and to relate these findings to clinical signs. The study included 105 randomly selected herds, constituting approximately one third of Swedish herds with a herd size of >100 sows. The herds were located all over the country. In these herds, growth promoters were not used and pigs sampled were not subjected to any medication. From each herd, samples were taken from 10 growing pigs aged 8-12 weeks, corresponding to approximately 2.5% of all growing pigs present in the herd at the sampling occasion. If possible, the samples were taken from pigs with diarrhoea. Forty-eight faecal samples and 71 rectal swabs were also taken from free-living wild boars (31 piglets, 19 growers and 21 adult animals) at shooting. The samples were analysed by culture and biochemical tests for the presence of Brachyspira spp. and by nested PCR for the presence of L. intracellularis. Brachyspira hyodysenteriae was not demonstrated in any sample. Brachyspira intermedia was detected in 22 samples originating from 15 herds, Brachyspira innocens/Brachyspira murdochii was detected in 370 samples from 82 herds and B. pilosicoli was detected in 134 samples originating from 34 herds. In 21 herds and in 534 samples, no Brachyspira spp. were detected. Lawsonia intracellularis was demonstrated in 285 samples from 50 herds. Further, 418 samples from conventional herds were negative with respect to L. intracellularis and in 345 samples the PCR had been inhibited. All samples from the wild boars were negative for Brachyspira spp., 12 of 48 samples were negative for L. intracellularis, and in 36 wild boar samples, the PCR was inhibited.

Colonic spirochetosis in animals and humans

Colonic spirochetosis is a disease caused by the gram-negative bacteria Brachyspira aalborgi and Brachyspira pilosicoli. B. pilosicoli induces disease in both humans and animals, whereas B. aalborgi affects only humans and higher primates. Symptoms in humans include diarrhea, rectal bleeding, and abdominal cramps. Colonic spirochetosis is common in third world countries; however, in developed countries, the disease is observed mainly in homosexual males. Terminally ill patients infected with Brachyspira are particularly at risk for developing spirochetemia. Diarrhea, poor growth performance, and decreased feed-to-gain efficiency is seen in pigs with colonic spirochetosis. The disease in chickens is characterized by delayed and/or reduced egg production, diarrhea, poor feed conversion, and retarded growth. Thus, colonic spirochetosis can represent a serious economic loss in the swine and poultry industries. The organisms are transmitted by the fecal-oral route, and several studies have demonstrated that human, primate, pig, dog, or bird strains of B. pilosicoli can be transmitted to pigs, chickens, and mice. B. pilosicoli may be a zoonotic pathogen, and although it has not been demonstrated, there is a possibility that both B. pilosicoli and B. aalborgi can be transferred to humans via contact with the feces of infected animals, meat from infected animals, or food contaminated by food handlers. Neither B. pilosicoli nor B. aalborgi has been well characterized in terms of basic cellular functions, pathogenicity, or genetics. Studies are needed to more thoroughly understand these Brachyspira species and their disease mechanisms.

The effect of antimicrobial growth promoter withdrawal on the health of weaned pigs in Finland

The use of the antimicrobial growth promoters (AGPs) carbadox and olaquindox has been banned in the European Union (EU) since September 1999. We studied the effects of the withdrawal on the health of weaned piglets on two types of piglet-producing farms (farrowing herds and farrow-to-finish herds) from the different regions of Finland. Farms with no major problems with post-weaning diarrhoea were selected for the study to better evaluate the effect of AGPs alone. Data on production, medication and incidence of diarrhoea were collected from 73 farms during 1 year after the withdrawal. On 29 of these farms, the data collection began 4 months before the withdrawal. The health management of the pigs is considered good in Finland, and special attention has been paid to improve the husbandry practices and management of the farms. Eighty-two percent of the farms in the study were free of both Mycoplasma hyopneumoniae and Sarcoptes scabiei infection. Brachyspira hyodysenteriae infection was not detected in any of the farms. The median number of sows in the herds was 56.0 (IQR=43.0; 72.5) in 2000. The level of antimicrobial use in each herd was classified as low, moderate and high when the percentage of weaned pigs treated for diarrhoea during a 4-month period was 0-5%, 6-19% and > or =20%, respectively. Only on four herds (14%), there was an increase in the level of antibiotic use after the AGP withdrawal, when seasonally corresponding 4-month periods were compared. Fourty-one percent of these 29 farms were categorized as low users of antimicrobials, 38% as moderate users and 21% as high users. The level of antimicrobial use for treatment of diarrhoea after weaning (and the incidence of diarrhoea in weaned piglets) did not increase significantly after the withdrawal of AGPs from weaner feeds according to farmers' evaluations. In this study, the Escherichia coli infection was the most-common cause of diarrhoea in weaned pigs. The age at weaning did not change after the withdrawal of AGPs.

Molecular and ultrastructural characterization of porcine hippurate-negative Brachyspira pilosicoli

Brachyspira pilosicoli, the causative agent of porcine intestinal spirochetosis, usually has hippurate-cleaving capacity. We have regularly isolated hippurate-negative B. pilosicoli from cases of porcine diarrhea. In this study, we show that these biochemically atypical B. pilosicoli isolates can be classified as B. pilosicoli. 16S ribosomal DNA was partially sequenced from eight hippurate-negative and two hippurate-positive B. pilosicoli-like isolates from seven herds. The differences in nucleotide sequence with B. pilosicoli P43/6/78 type strain were not associated with hippurate cleavage. In 877 bp, the hippurate-negative isolates had a similarity of 98.63 to 100% to the type strain, with the corresponding figures for the two hippurate-positive isolates being 98.86 and 100%. The nucleotide sequences of hippurate-positive isolates were identical to the respective sequences of hippurate-negative isolates from one herd. The DNA macrorestriction patterns of a total of 20 hippurate-negative and -positive B. pilosicoli isolates were diverse, and no clustering in conjunction with the hippurate reaction was found. In two herds, hippurate-positive and -negative B. pilosicoli isolates had a common macrorestriction pattern. The ultrastructure of hippurate-negative isolates was similar to the type strain. In conclusion, B. pilosicoli can be either hippurate positive or negative and, thus, the scheme for biochemical differentiation of porcine Brachyspira should be revised to include identification of hippurate-negative B. pilosicoli.

Brachyspira pilosicoli isolated from pigs in Japan

Two of four weak beta-hemolytic isolates of intestinal spirochetes isolated from pigs in Japan possessed a unique base alignment of TTTTTT on the 16S ribosomal DNA of Brachyspira pilosicoli and were identified as B. pilosicoli. The other two isolates were not identified by this technique. The identified isolates were 4.2 to 11 microm in length and 0.2 to 0.3 microm in diameter, 4 periplasmic flagella at each end were observed dominantly. The isolates were hippurate positive but indole negative. This is the first report on the isolation of B. pilosicoli from pigs in Japan.

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.