The frequency of tail damage amongst cows from a sample of New Zealand dairy farms participating in an animal welfare programme.

AIM: To explore factors associated with the frequency of tail damage in dairy cows on 29 New Zealand farms participating in an animal welfare monitoring programme. MATERIALS AND METHODS: Herd-level tail score data were collected at the cow level and then summarised at the herd level as counts for each lactation over the period 1 June 2014 to 31 May 2018. A cow's tail was considered damaged if there was evidence of any injury that deformed the anatomical structure involving either bone or soft tissue and could include loss of use. There were four categories for tail scoring. Fracture or dislocation of tail bones was considered as a deviation (score 1). When the tail had been docked above the top of the cow's udder, this was considered as docked short tail (score 2). When there was evidence of soft tissue trauma (score 3) or bone damage but no fracture (score 4), this was recorded as damaged (other). Tails were scored for each whole dairy herd. Tail scoring was performed by trained veterinarians or veterinary technicians. The primary outcome variable was counts of deviated tails (DT). Other outcome variables were docked short, damaged (other), and total tail injuries (TTI) which was a summation of all tail injuries. The potential predictor variables were area, season, farm, region, replacement rate, and herd size. A mixed-effects negative binomial or Poisson regression was fitted to the count data. RESULTS: A total of 29 farms contributed data for tail scoring, with 54,831 cows individually scored. The unadjusted regional prevalence of TTI ranged from 3.5% (64/1,835) in Taranaki in 2014-2015 to 28.7% (1,434/4,988) in Southland/Otago in 2017-2018. The unadjusted regional herd prevalence of DT ranged from 2.1% (280/6,862) in Taranaki (2014-2015) to 13.2% (4,627/30,165) in Southland/South Otago (2017-2018). The incident rate ratio (IRR) of DT in 2015-2016 was 1.74 (95% CI = 1.20-2.53; p = 0.003) times the incident rate for the reference group (2014-2015). The IRR for TTI in 2015-2016 was 1.70 (95% CI = 1.60-1.81; p = 0.001) times the incident rate for the reference group (2014-2015). CONCLUSIONS AND CLINICAL RELEVANCE: This is the first quantitative study of the frequency of tail damage within New Zealand dairy farms and whilst variable between regions, it indicates that the frequency is increasing. Opportunities exist to better understand the causes of tail injuries and to improve animal welfare.

Testing the efficacy of kitasamycin for use in the control and treatment of swine dysentery in experimentally infected pigs.

BACKGROUND: Swine dysentery (SD) caused by Brachyspira hyodysenteriae is an important disease in Australia. AIM: The aim of this study is to evaluate the macrolide antibiotic kitasamycin for use in SD control. METHODS: The minimum inhibitory concentrations (MICs) of kitasamycin, tylosin and lincomycin for 32 Australian isolates of B. hyodysenteriae were evaluated. Mutations in the 23S rRNA gene were examined. Isolate '13' with a low kitasamycin MIC was used to challenge weaner pigs. Sixty pigs were housed in 20 pens each containing three pigs: pigs in four pens received 2 kg/tonne of a product containing kitasamycin (3.1% active) prophylactically in their food starting 4 days before B. hyodysenteriae challenge (group 1); pigs in four pens were challenged and received the same dose therapeutically once one pig in a pen showed diarrhoea (group 2); four pens were challenged and received 4 kg/tonne of the product therapeutically (group 3); four pens were challenged but not medicated (group 4); two pens were unmedicated and unchallenged (group 5) and two pens received 2 kg/tonne and were unchallenged (group 6). Pigs were monitored for B. hyodysenteriae excretion and disease. RESULTS: Macrolide resistance was widespread, and mutations in the 23S rRNA gene were identified in 23 isolates. Four isolates with kitasamycin MICs < 5 µg/mL were considered susceptible. Following experimental challenge, 10 of 12 unmedicated pigs developed SD. No pigs receiving kitasamycin prophylactical or therapeutically developed SD. Medicated pigs shed low numbers of B. hyodysenteriae in their faeces. CONCLUSIONS: Kitasamycin can help control SD in pigs infected with susceptible isolates of B. hyodysenteriae.

Sequence types and pleuromutilin susceptibility of Brachyspira hyodysenteriae isolates from Italian pigs with swine dysentery: 2003-2012.

Swine dysentery is a mucohaemorrhagic colitis of pigs caused by infection with Brachyspira hyodysenteriae. The disease can be controlled by treatment with antimicrobial agents, with the pleuromutilins tiamulin and valnemulin being widely used. In recent years, the occurrence of B. hyodysenteriae with reduced susceptibility to these drugs has been increasing. The aim of this study was to determine temporal changes in genetic groups and pleuromutilin susceptibility amongst B. hyodysenteriae isolates from Italy. Multilocus sequence typing (MLST) was performed on 108 isolates recovered from 87 farms in different regions of Italy from 2003 to 2012, and their minimum inhibitory concentrations (MICs) for tiamulin and valnemulin were determined. Logistic regression was performed to assess associations between susceptibility to the two antimicrobial agents and genetic group, year and region of isolation. The isolates were allocated to 23 sequence types (STs), with five clonal clusters (Ccs) and seven singletons. More than 50% of isolates were resistant to both pleuromutilins (MIC >2.0 µg/mL for tiamulin and >1.0 µg/mL for valnemulin). All 10 isolates in ST 83 were resistant; these were first isolated in 2011 and came from nine farms, suggesting recent widespread dissemination of a resistant strain. Significant associations were found between the proportion of pleuromutilin susceptible isolates and the genetic group and year of isolation. Although resistant isolates were found in all Ccs, isolates in Ccs 2 and 7 were over five times more likely to be susceptible than those in the other Ccs. A significant trend in the reduction of susceptibility over time also was observed.

Strains of the intestinal spirochaete Brachyspira pilosicoli attach to and aggregate erythrocytes.

UNLABELLED: The anaerobic intestinal spirochaete Brachyspira pilosicoli colonizes the large intestine of various species of mammals and birds, where it may induce colitis. Strains of the spirochaete have also been isolated from the bloodstream of immunocompromised human patients and have been seen in liver sections, and a similar systemic spread was recently observed in experimentally infected chickens. Some other spirochaete species that may be present in blood attach to and aggregate erythrocytes, and this is believed to contribute to disease severity. The aim of the current study was to determine whether B. pilosicoli strains have the capacity to attach to and aggregate erythrocytes. Initially, four strains of B. pilosicoli were incubated with erythrocytes from sheep, cows, pigs, dogs, humans, chickens and geese, and were observed by phase-contrast microscopy. Only strain WesB attached, and this was only with erythrocytes from chickens and geese. Subsequently, six other strains of B. pilosicoli were tested just with goose erythrocytes, and five attached to and caused aggregation of the erythrocytes. Scanning and transmission electron microscopy demonstrated that spirochaetes abutted and apparently firmly attached to the erythrocyte membranes. Aggregation of erythrocytes by B. pilosicoli may contribute to disease severity in species that develop a spirochaetaemia. SIGNIFICANCE AND IMPACT OF THE STUDY: The intestinal spirochaete Brachyspira pilosicoli has been isolated from the bloodstream of immunocompromised human patients, and spread to the liver has been reported in humans and in experimentally infected chickens. In this study, B. pilosicoli was shown to undergo attachment by one cell end to chicken and goose erythrocytes in vitro and to aggregate them. This activity has the potential to contribute to disease severity in avian and possibly other species that develop a spirochaetaemia and systemic spread. Avian erythrocytes may be useful for studying the mechanisms by which B. pilosicoli attaches to cells.

Identification of weakly haemolytic Brachyspira isolates recovered from pigs with diarrhoea in Spain and Portugal and comparison with results from other countries.

Weakly haemolytic anaerobic intestinal spirochaetes of the genus Brachyspira are commonly identified based on species-specific gene sequences. Apart from the pathogenic Brachyspira pilosicoli, the distribution and disease associations of the other weakly haemolytic Brachyspira species in pigs have not been comprehensively investigated. In this study weakly haemolytic Brachyspira isolates (n=67) from Spanish and Portuguese pigs with diarrhoea, negative in a routine diagnostic PCR for B. pilosicoli, were identified by sequencing their NADH oxidase genes (nox). Nearly half the isolates were identified as Brachyspira murdochii (n=31; 46.3%). The others were Brachyspira innocens (n=26; 38.8%), Brachyspira intermedia (n=7; 10.4%), "Brachyspira pulli" (n=1; 1.5%) and a potentially novel Brachyspira species (n=2; 3%). Multilocus sequence typing (MLST) on a subset of 18 isolates confirmed their species designations, including the potential new species, and identified similarities to strains from other countries.

Gastrointestinal health and function in weaned pigs: a review of feeding strategies to control post-weaning diarrhoea without using in-feed antimicrobial compounds.

For the last several decades, antimicrobial compounds have been used to promote piglet growth at weaning through the prevention of subclinical and clinical disease. There are, however, increasing concerns in relation to the development of antibiotic-resistant bacterial strains and the potential of these and associated resistance genes to impact on human health. As a consequence, European Union (EU) banned the use of antibiotics as growth promoters in swine and livestock production on 1 January 2006. Furthermore, minerals such as zinc (Zn) and copper (Cu) are not feasible alternatives/replacements to antibiotics because their excretion is a possible threat to the environment. Consequently, there is a need to develop feeding programs to serve as a means for controlling problems associated with the weaning transition without using antimicrobial compounds. This review, therefore, is focused on some of nutritional strategies that are known to improve structure and function of gastrointestinal tract and (or) promote post-weaning growth with special emphasis on probiotics, prebiotics, organic acids, trace minerals and dietary protein source and level.

Development of a modified selective medium to enhance the recovery rate of Brachyspira hyodysenteriae and other porcine intestinal spirochaetes from faeces.

AIMS: The aim of this study was to develop a modified selective medium to improve the recovery rate of Brachyspira hyodysenteriae and other clinically significant intestinal spirochaetes from porcine faeces. METHODS AND RESULTS: The susceptibility of five Brachyspira spp. type strains and five Thai field isolates of B. hyodysenteriae to the antimicrobials halquinol and flavomycin was determined by in vitro susceptibility tests in the agar dilution method, and optimal incorporation rates were confirmed by broth dilution. All the spirochaetes were susceptible to halquinol at ≤ 1 µg ml(-1), while 16 µg ml(-1) of flavomycin (F) allowed their growth, and therefore, only the latter was selected for further use. F and different combinations of colistin (C), spectinomycin (S) and rifampacin (R) were incorporated into pre-enrichment broths and/or agar plates, and growth of the spirochaetes from seeded faeces was determined. Two solid media were selected for further testing using faeces from 90 finishing pigs on 10 farms. A previously recommended method of pre-enrichment did not increase the recovery rate. The use of blood agar modified medium (BAM) containing F (16 µg ml(-1)), S (400 µg ml(-1)), R (30 µg ml(-1)) and colistin (C, 100 U ml(-1)) (assigning as BAM-CSRF) reduced the growth of contaminating intestinal microbiota and resulted in a significantly higher rate of spirochaete recovery than the previous recommended medium. CONCLUSION: BAM-CSRF is a useful new selective medium for the isolation of B. hyodysenteriae and other intestinal spirochaetes from pig faeces. SIGNIFICANCE AND IMPACT OF THE STUDY: The new selective medium for isolating B. hyodysenteriae and other Brachyspira spp. from pig faeces will improve their recovery and subsequent disease diagnosis.

An increased ratio of dietary tryptophan to lysine improves feed efficiency and elevates plasma tryptophan and kynurenine in the absence of antimicrobials and regardless of infection with enterotoxigenic Escherichia coli in weaned pigs.

This experiment examined if a higher ratio of dietary Trp:Lys in the absence of antimicrobials improves production indices and modulates diarrhea in weaned pigs infected with enterotoxigenic Escherichia coli (ETEC). Effects of the Trp:Lys ratio on plasma levels of Trp and its metabolite kynurenine (Kyn) were also examined. Individually housed mixed-sex pigs (n = 72) weaned at 21 d of age (Landrace × Large White; initial BW of 6.3 ± 0.32 kg) were stratified into 1 of 6 treatments (n = 12) according to a 2 × 3 factorial arrangement of (i) infection or without infection with ETEC and (ii) 3 dietary standardized ileal digestible (SID) Trp:Lys ratios of 0.17, 0.21, or 0.26 in a randomized complete block design. Pigs were fed diets (10.4 MJ NE; 1.24% SID Lys; 19.5% CP) ad libitum for 3 wk after weaning. Pigs were infected with ETEC (O149:K98:K88) at 72, 96, and 120 h after weaning and then bled on day 11. A Trp:Lys ratio of 0.26 improved (P = 0.021) G:F over the study period compared to other ratios, without an infection effect (P > 0.05). Treatments did not affect ADG or ADFI (P > 0.05). Infection increased (P = 0.039) the diarrhea index and increased fecal consistency scores (P = 0.010). Plasma Trp and Kyn were lower (P < 0.001) in pigs fed 0.17 Trp:Lys than those fed ratios of 0.21 and 0.26 and were not affected (P > 0.05) by infection. In conclusion, in the absence of antimicrobials, increasing the dietary Trp:Lys ratio to 0.26 improved G:F after weaning and increased plasma levels of Trp and Kyn.

Diets containing inulin but not lupins help to prevent swine dysentery in experimentally challenged pigs.

Swine dysentery is a contagious mucohemorrhagic diarrheal disease caused by the intestinal spirochete Brachyspira hyodysenteriae that colonizes and induces inflammation of the cecum and colon. It has been reported that a diet containing chicory root and sweet lupin can prevent swine dysentery. This experiment was conducted to test the hypothesis that inulin in the chicory root rather than galactans in lupins was responsible for protective effects. An experiment with a 2 × 2 factorial arrangement of treatments was undertaken using pigs fed barley- and triticale-based diets, with the main effects being protein source [185 g/kg of canola meal (decreased galactans) or 220 g/kg of lupins (greater galactans)] and inulin supplementation (0 or 80 g/kg). Forty Large White × Landrace pigs weighing 21 ± 3 kg, with 10 pigs per diet, were allowed to adapt to the diets for 2 wk, and then each pig was challenged orally 4 times with a broth culture containing B. hyodysenteriae on consecutive days. Pigs were killed when they showed clinical signs of dysentery or 6 wk postchallenge. Pigs fed diets without inulin had 8.3 times greater risk (P = 0.017) of developing swine dysentery and were 16 times more likely (P = 0.004) to have colon contents that were culture-positive for B. hyodysenteriae, compared with the pigs fed a diet with 80 g/kg of inulin. Diets containing lupins did not prevent pigs from developing clinical swine dysentery; however, inclusion of lupins or inulin or both in the diets delayed the onset of disease compared with the diet based mainly on canola meal (P < 0.05). Diet did not influence the total concentration of organic acids in the ileum, cecum, or upper and lower colon; however, the molar proportions of the organic acids were influenced (P < 0.05). Consequently the pH values in the cecum, and upper and lower colon were not influenced (P > 0.05) by diet. However the pH values of the ileal digesta were decreased in pigs fed the diet with both lupins and inulin compared with the diet containing only lupins (P < 0.05). In conclusion, this study shows that diets supplemented with highly fermentable carbohydrates from inulin protected pigs against developing swine dysentery.

Understanding the molecular epidemiology of the footrot pathogen Dichelobacter nodosus to support control and eradication programs.

The Gram-negative anaerobe Dichelobacter nodosus is the primary etiologic agent of ovine footrot. Few studies of the genetic diversity and epidemiology of D. nodosus have been done, despite the economic cost and welfare implications of the disease. This study examined a large collection of Australian isolates; 735 isolates from footrot-infected sheep from 247 farms in Western Australia (WA) were tested by pulsed-field gel electrophoresis (PFGE), and a subset of 616 isolates was tested by infrequent restriction site PCR (IRS-PCR). The genetic diversity of WA isolates was compared to that of 61 isolates from three other Australian states. WA isolates were genetically diverse, with 181 molecular types resolved by PFGE, resulting in a simple diversity ratio (SDR) of 1:4 and a Simpson's index of discrimination value (D) of 0.98. IRS-PCR resolved 77 molecular types (SDR = 1:8 and D = 0.95). The isolates were grouped into 67 clonal groups by PFGE (SDR = 1:11, D = 0.90) and 36 clonal groups by IRS-PCR (SDR = 1:17, D = 0.87). Despite the high genetic diversity, three common clonal groups predominated in WA and were found in other Australian states. On some farms, molecular type was stable over a number of years, whereas on other farms genetically diverse isolates occurred within a flock of sheep or within a hoof. This study provides a large database from which to appropriately interpret molecular types found in epidemiological investigations and to identify common and unknown types that may compromise footrot eradication or control programs.

Feeding a diet with decreased protein content reduces indices of protein fermentation and the incidence of postweaning diarrhea in weaned pigs challenged with an enterotoxigenic strain of Escherichia coli.

This study evaluated the effect of feeding low protein (LP) diets for 7 or 14 d after weaning or a high protein (HP) diet for 14 d after weaning on postweaning diarrhea (PWD), indices of protein fermentation, and production in pigs infected or not infected per os with an enterotoxigenic strain of Escherichia coli. A total of 72 female pigs weaned at aged 21 d with initial BW of 5.9 +/- 0.12 kg were used in a 3 x 2 factorial arrangement of treatments. The factors were 3 feeding regimens associated with different combinations of feeding duration and diet CP level: (i) HP diet (256 g of CP/kg) fed for 14 d after weaning, (ii) LP diet (175 g of CP/kg) fed for 7 d after weaning, and (iii) LP diet fed for 14 d after weaning; and infection or noninfection with an enterotoxigenic strain of E. coli (10(7) cfu/mL, serotype O149:K91:K88) at 72, 96, and 120 h after weaning. The LP diets were fortified with crystalline Ile and Val to achieve an ideal AA pattern. A second-stage diet (213 g of CP/kg) was fed to pigs at the conclusion of each feeding regimen, and the study finished 4 wk after weaning. None of the diets contained antimicrobials. Feeding the LP diets decreased (P < 0.001) plasma urea nitrogen, fecal ammonia nitrogen concentrations, and the incidence of PWD, but increased (P = 0.001) fecal DM content compared with pigs fed HP in the 2-wk period after weaning. Infection increased shedding of beta-hemolytic E. coli (P < 0.001), the incidence of PWD (P < 0.001), and fecal ammonia nitrogen concentrations (P < 0.01), but did not interact with feeding regimen, after weaning. Pigs challenged with E. coli grew more slowly (P < 0.001) and had decreased G:F (P < 0.01) compared with nonchallenged pigs in the 4-wk period after weaning. Feeding an LP diet for 7 or 14 d after weaning markedly reduced the incidence of PWD after infection with beta-hemolytic E. coli. Infection was associated with decreased indices of protein fermentation in the distal gastrointestinal tract but did not compromise the growth of weaner pigs in the 4-wk period after weaning.

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.

Development of a multilocus sequence typing scheme for intestinal spirochaetes within the genus Brachyspira.

The purpose of this study was to evaluate a multilocus sequence typing (MLST) scheme for intestinal spirochaetes of the genus Brachyspira. Eight loci mainly coding for enzymes previously used in multilocus enzyme electrophoresis analysis of Brachyspira species were examined in 66 Brachyspira field isolates and type/reference strains. The isolates and strains were recovered from pigs, birds, dogs and a mouse and originated from seven European countries, the USA and Canada. Forty-six isolates represented recognized Brachyspira species and 20 represented provisionally designated species or isolates that have not been classified. Only two loci gave PCR products for all 66 strains and isolates, but amplicons for seven loci were obtained for 44 of the isolates. Sequences for each locus had a DNA allelic variation of 30-47 and an amino acid allelic variation of 14-47 that gave rise to the same number of sequence and amino acid types (58) for the strains and isolates studied. A population snapshot based on sequence and amino acid types showed a close phylogenetic relationship amongst the porcine isolates from the same geographical regions, and indicated a close evolutionary relationship between isolates recovered from pigs and mallards. A general concordance was obtained between the MLST groupings and classifications based on culture and biochemical tests, 16S rDNA sequence analysis and random amplified polymorphic DNA analysis. This is a first step towards establishing an MLST system for use in identifying Brachyspira species and determining relationships between individual strains and species in the genus.

Comparison of prevalence and risk factors for faecal carriage of the intestinal spirochaetes Brachyspira aalborgi and Brachyspira pilosicoli in four Australian populations.

This study examined the prevalence of the intestinal spirochaetes Brachyspira aalborgi and Brachyspira pilosicoli in different Western Australian (WA) populations. Faecal samples included 287 from rural patients with gastrointestinal symptoms, comprising 142 from non-Aboriginal and 145 from Aboriginal people; 227 from recent healthy migrants to WA from developing countries; and 90 from healthy non-Aboriginal individuals living in Perth, WA. DNA was extracted from faeces, and subjected to PCR assays for both species. B. pilosicoli-positive individuals were confined to the rural Aboriginal (14.5%) and migrant (15.0%) groups. B. aalborgi was detected at a lower but similar prevalence in all four groups: rural non-Aboriginals, 5.6%; rural Aboriginals, 6.9%; migrants, 7.9%; controls, 5.6%. In migrants and Aborigines, the presence of B. pilosicoli and B. aalborgi was associated (P<0.001), suggesting that colonization by B. pilosicoli may be facilitated by colonization with B. aalborgi. Amongst the Aboriginal patients, logistic regression identified both spirochaete species as being associated with chronic diarrhoea, failure to thrive and being underweight. Both species may have pathogenic potential, but B. aalborgi appears more host-adapted than the opportunistic B. pilosicoli.

Development of a multiplex-PCR for rapid detection of the enteric pathogens Lawsonia intracellularis, Brachyspira hyodysenteriae, and Brachyspira pilosicoli in porcine faeces.

AIMS: To develop an assay to simultaneously detect Lawsonia intracellularis, Brachyspira hyodysenteriae and Brachyspira pilosicoli in pig faeces. METHODS AND RESULTS: A multiplex-polymerase chain reaction (M-PCR) was designed to amplify a 655-base pair (bp) portion of the L. intracellularis 16S rRNA gene, a 354-bp portion of the B. hyodysenteriae NADH oxidase gene, and a 823-bp portion of the B. pilosicoli 16S rRNA gene. Specificity was assessed using 80 strains of Brachyspira spp. and 30 other enteric bacteria. Bacterial DNA was extracted from faeces using the QIAamp DNA Stool Mini Kit. The M-PCR was tested in parallel with culture and/or PCR on 192 faecal samples from eight piggeries. Faeces also were seeded with known cell concentrations of the three pathogenic species, and the limits of detection of the M-PCR tested. The M-PCR was specific, with limits of detection of 10(2)-10(3) cells of the respective species per gram of faeces. CONCLUSIONS: The M-PCR is a rapid, sensitive and specific test for detecting three important enteric bacterial pathogens of pigs. SIGNIFICANCE AND IMPACT OF THE STUDY: The availability of a new diagnostic M-PCR will allow rapid detection and control of three key porcine enteric pathogens.

Antimicrobial susceptibility testing of Brachyspira intermedia and Brachyspira pilosicoli isolates from Australian chickens.

Susceptibilities of predominantly Australian isolates of the pathogenic intestinal spirochaetes Brachyspira intermedia (n = 25) and Brachyspira pilosicoli (n = 17) from chickens were tested in agar dilution against four concentrations each of the antimicrobials tiamulin, lincomycin, tylosin, metronidazole, tetracycline and ampicillin. Based on available minimum inhibitory concentration (MIC) breakpoint values for Brachyspira hyodysenteriae or other Gram-negative enteric veterinary pathogens, isolates of both species generally were susceptible to tiamulin, lincomycin, metronidazole and tetracycline. Although not classed as resistant, four isolates of B. intermedia had an elevated MIC range for tiamulin (1 to 4 mg/l), 11 isolates of B. intermedia and five of B. pilosicoli had an elevated MIC range for lincomycin (10 to 50 mg/l), one isolate of B. pilosicoli had an elevated MIC range for tetracycline (10 to 20 mg/l), and one isolate of B. intermedia and five of B. pilosicoli had an elevated MIC range for ampicillin (10 to 50 mg/l). A clear lack of susceptibility to tylosin (MIC > 4 mg/l) was seen in 11 isolates each of B. intermedia and B. pilosicoli, and to ampicillin (MIC > 32 mg/l) in two isolates of B. pilosicoli. These data suggest that some resistance to common antimicrobials exists among intestinal spirochetes obtained from laying hens and supports the need of MIC data for clinical isolates before any treatment is considered.

The distribution of bmpB, a gene encoding a 29.7 kDa lipoprotein with homology to MetQ, in Brachyspira hyodysenteriae and related species.

The distribution of the bmpB gene encoding BmpB, a 29.7 kDa outer membrane lipoprotein of the intestinal spirochaete Brachyspira hyodysenteriae, was investigated. Using PCR, the gene was detected in all the 48 strains of B. hyodysenteriae examined and in Brachyspira innocens strain B256T, but not in 11 other strains of B. innocens nor in 42 strains of other Brachyspira spp. The gene was sequenced from B. innocens strain B256T and from 11 strains of B. hyodysenteriae. The B. hyodysenteriae genes shared 97.9-100% nucleotide sequence similarity and had 97.5-99.5% similarity with the gene of B. innocens strain B256T. Southern hybridisation indicated that bmpB was present on a 1.9 kb HindIII fragment of the B. hyodysenteriae genome and on a 3.1 kb fragment of the B. innocens B256T genome. The B. innocens lipoprotein did not react in Western blots with monoclonal antibody BJL/SH1 that reacts with the B. hyodysenteriae lipoprotein. The difference in binding with the monoclonal antibody may reside in the replacement of a serine residue with a tyrosine residue at base position 210 in the lipoprotein from B. innocens B256T. Comparison of the BmpB amino acid sequence with sequences in the SWISS-PROT protein database indicated that it has 33.9-39.9% similarity with the d-methionine binding proteins (MetQ) of a number of pathogenic bacterial species. The bmpB gene was confirmed to be the same as a gene of B. hyodysenteriae that was recently designated "blpA".

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.

Effect of diet composition on postweaning colibacillosis in piglets.

The weaning of piglets is often associated with digestive disorders, particularly diarrhea--postweaning colibacillosis (PWC)--which is caused by infection with enterotoxigenic strains of Escherichia coli. It has been shown previously that a diet for newly weaned pigs based on cooked white rice and animal protein decreases the occurrence of PWC, whereas the addition of carboxymethylcellulose (CMC) to this diet enhances PWC. The aims of the current work were to 1) determine whether substitution of animal protein with plant proteins in the cooked-white-rice diet influenced its protective effects on PWC and 2) confirm that an increase in viscosity of the digesta by adding CMC to the diet favors the development of PWC--with (Exp. 1) or without (Exp. 2) experimental infection of piglets with E. coli. The diets were 1) cooked white rice and animal protein sources (RAP), 2) RAP + CMC added at 40 g of CMC/kg (air-dry basis) of diet, 3) cooked white rice and plant protein sources (RPP), and 4) wheat and plant protein sources (WPP). Experiments 1 and 2 were conducted using 32 and 24 piglets (eight and six per treatment), respectively. Piglets were weaned at 21 d (d 1), and fed ad libitum until slaughter on d 9. In Exp. 1, piglets were orally infected with enterotoxigenic E. coli on d 4, 5, 6, and 7. On d 8 of Exp. 1, the E. coli scores in feces of pigs fed RAP + CMC were higher than with RAP (P < 0.01). On d 9 after weaning, feces from pigs fed diet RAP were normal or moist, whereas feces from pigs fed RAP + CMC were wet to diarrheic. On d 7 of Exp. 2, pigs fed diets RAP + CMC and WPP had wetter feces than pigs fed diets RAP or RPP (P < 0.05). On d 8, the E. coli scores in feces were higher (P < 0.01) with pigs fed RAP + CMC than with all other diets. The E. coli scores in the digesta were also higher with pigs fed RAP + CMC, and to a lesser extent with diet WPP, than with pigs fed RAP or RPP (P < 0.01). The large intestine was heavier in pigs fed diets RPP and WPP, and the digesta were more acidic (P < 0.05). This study confirmed that diet RAP was protective against PWC, and that substitution of animal proteins with plant protein in a rice-based diet did not diminish its protective effects. The addition of CMC to cooked white rice increased digesta viscosity and enhanced PWC. Consequently, this diet represents a useful model for studying this condition.