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Biomedical subjects

D J Hampson

Publications and source records attributed to D J Hampson.

At least 19 recordsLinked to original sources

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.

Feces↗

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.

Animals↗

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.

Animals↗

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".

Amino Acid Sequence↗

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.

Age Factors↗

Colonization and risk factors for Brachyspira aalborgi and Brachyspira pilosicoli in humans and dogs on tea estates in Assam, India.

The prevalence of colonization with the anaerobic intestinal spirochaetes Brachyspira aalborgi and Brachyspira pilosicoli was investigated in humans (n = 316) and dogs (n = 101) living on three tea estates in Assam, India. Colonization was detected using PCR on DNA from faeces. Nineteen (6%) human faecal samples contained B. aalborgi DNA, 80 (25.3%) contained B. pilosicoli DNA, and 10 (3.2%) contained DNA from both species. One canine sample contained DNA from B. pilosicoli. Significant factors for B. aalborgi colonization in logistic regression were: infection of family members with B. aalborgi (P < 0.001), being a resident of Balipara (P = 0.03), and use of water treatment (P = 0.03). For B. pilosicoli, significant factors were: other family members being positive for B. pilosicoli (P < 0.001), water obtained from a well (P = 0.006), water treatment (P = 0.03), and not having visited a doctor in the previous 12 months (P = 0.03).

Agricultural Workers' Diseases↗

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.

Animal Feed↗

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.

Animals↗

Growth enhancement in broiler chickens receiving CHEMEQRTM polymeric antimicrobial.

This study investigated the use of CHEMEQRTM polymeric antimicrobial as a means of enhancing health and growth rates in broiler chickens. One-day-old Cobb-500 broilers were reared to 42 days. In trial 1, 100 birds received CHEMEQRTM polymeric antimicrobial via water, and 100 birds were untreated. Treated birds had significantly greater (P<0.0001) average daily gain (ADG), significantly lower (P<0.0016) feed conversion ratios, significantly lower (P<0.05) mortality, and a significantly lower (P<0.0042) viscosity of their ileal contents. In trial 2, three groups of 40 birds received reducing dosages of CHEMEQRTM polymeric antimicrobial, and a fourth group remained untreated. Groups receiving CHEMEQRTM polymeric antimicrobial had significantly greater (P<0.05) ADG, and two groups had significantly lower (P<0.05) feed conversion ratios than the controls. In trial 3, groups of 40 birds received either CHEMEQRTM polymeric antimicrobial, Salinomycin or Lasalocid in-feed, or were untreated. Birds receiving CHEMEQRTM polymeric antimicrobial had significantly greater (P<0.05) ADG than those receiving Salinomycin. CHEMEQRTM polymeric antimicrobial helped to maintain the health and to improve the growth performance of broiler chickens.

Animals↗

In vitro antimicrobial susceptibility of Brachyspira pilosicoli isolates from humans.

The in vitro antimicrobial susceptibility of the anaerobic intestinal spirochete Brachyspira pilosicoli was investigated by an agar dilution method. Human (n = 123) and porcine (n = 16) isolates were susceptible to metronidazole, ceftriaxone, meropenem, tetracycline, moxifloxacin, and chloramphenicol; erythromycin and ciprofloxacin were not active. Resistance to amoxicillin and clindamycin varied. Amoxicillin susceptibility was restored by clavulanic acid.

Animals↗

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.

Animal Feed↗

Risk factors for gastric ulcers in Australian pigs at slaughter.

The stomachs of pigs (n=15,741) originating from 136 herds from the Australian states of Queensland, Western Australia, Victoria and New South Wales were examined at slaughter for the presence of oesophago-gastric ulcers (OGUs). Stomachs were categorised as being normal, hyperkeratotic, eroded, ulcerated, or having strictures. A questionnaire was distributed to piggery owners to identify factors associated with an above-average herd prevalence of OGU. Thirty percent of all pigs examined had OGU (median within-herd prevalence of 17%). The median within-herd prevalence in Victoria (53%) was significantly higher than in Western Australia (30%) or Queensland (7%). The prevalence of OGU in culled breeding animals was significantly higher than in porkers or baconers from the same herds. There was no difference between the prevalence of OGU in male and female pigs sampled from the same Western Australian herds. The relationship between OGU and herd and pig risk factors was assessed by random effects logistic-regression analysis. Herds with a high prevalence of OGU were more likely to feed ad libitum (OR=13.7), use automated feeding systems (OR=7.8), feed a pelleted ration (OR=384) and get water from a dam rather than from a bore or river (OR=3.8). Furthermore, for every change in the ration formulation for finisher pigs, the risk of OGU increased 1.5 times.

Abattoirs↗

Increasing the viscosity of the intestinal contents stimulates proliferation of enterotoxigenic Escherichia coli and Brachyspira pilosicoli in weaner pigs.

The present study was designed to evaluate the effect of increased viscosity of the intestinal digesta on proliferation of enterotoxigenic Escherichia coli and the intestinal spirochaete Brachyspira pilosicoli in weaned pigs. Pigs were fed an experimental diet based on cooked white rice (R), which was supplemented with carboxymethylcellulose (CMC; 40 g/kg diet) to increase digesta viscosity. Thirty-six piglets weaned at 21 d of age were divided into six groups, three of which were fed R and three Addition of CMC increased digesta viscosity in the ileum (P=0.01), caecum (P=0.0007) and colon (P=0.0035), without increasing indices of large intestinal fermentation. Pigs fed developed a natural infection with enterotoxigenic E. coli after weaning and had more (P<0.0001) diarrhoea than pigs fed R. Subsequent experimental infection of two groups of pigs with B. pilosicoli resulted in more (P<0.0001) colonisation in pigs fed than R. At this time, all pigs fed had wetter (P<0.0001) faeces than those fed R, irrespective of whether they were infected with B. pilosicoli, but infected pigs also had an increased (P=0.025) number of days with diarrhoea post-infection irrespective of diet. In pigs fed it was not clear to what extent the increased viscosity associated with CMC, or the concurrent infection with enterotoxigenic E. coli, was responsible for the increased proliferation of B. pilosicoli. In a second experiment, five pigs that were weaned onto an R diet were transferred onto 3 weeks later. These pigs did not develop a natural infection with enterotoxigenic E. coli after the diet change, confirming the particular susceptibility of pigs to enterotoxigenic E. coli proliferation immediately post-weaning.

Analysis of Variance↗

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.

Animal Feed↗

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.

Animal Feed↗

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.

Animals↗

PCR detection of Brachyspira aalborgi and Brachyspira pilosicoli in human faeces.

Previously-developed PCR protocols specific for the 16S rRNA gene of the intestinal spirochaetes Brachyspira aalborgi and Brachyspira pilosicoli were adapted for the detection of these species in human faeces, following DNA extraction and purification using mini-prep columns. The limits of detection in seeded faeces for B. aalborgi and B. pilosicoli respectively were 2x10(2) and 7x10(3) cells per PCR reaction, equivalent to 5x10(4) and 1x10(5) cells per g of faeces. The PCR techniques were applied to faecal samples from two patients with histological evidence of intestinal spirochaetosis. In the first patient, in whom B. aalborgi had been identified by 16S rDNA PCR from colonic biopsies, a positive amplification for B. aalborgi only was obtained from the faeces. The organism could not be isolated from these faeces. In the second patient, both colonic biopsies and faeces were PCR positive for B. pilosicoli only, and B. pilosicoli was isolated from the faeces. These new faecal PCR protocols should be valuable for future studies on the epidemiology of intestinal spirochaete infections in human populations, particularly as it is not currently possible to isolate B. aalborgi from faeces.

Adult↗