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David J Hampson - One of the best experts on this subject based on the ideXlab platform.
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First identification and characterisation of Brachyspira hyodysenteriae in pigs in Hong Kong
Porcine Health Management, 2019Co-Authors: Kittitat Lugsomya, Friederike Zeeh, Nyree Phillips, David J HampsonAbstract:Swine dysentery (SD) is an important endemic disease of pigs throughout the world. The most common aetiological agent is the anaerobic intestinal spirochaete Brachyspira hyodysenteriae. The related spirochaete Brachyspira pilosicoli causes a milder form of colitis. We report the first isolation of B. hyodysenteriae and B. pilosicoli from a pig farm in Hong Kong. Faecal samples containing mucus or fresh blood were collected from the ground where finisher pigs had just been loaded into a truck for transport to the abattoir. The samples were subjected to selective anaerobic culture and PCR for B. hyodysenteriae and B. pilosicoli , and two isolates of both species were obtained. The B. hyodysenteriae isolates showed clinical resistance to tylosin and lincomycin, whilst the B. pilosicoli isolates were resistant to tylosin and showed intermediate susceptibility to lincomycin. The B. hyodysenteriae isolates were subjected to multilocus sequence typing and a single previously undescribed sequence type (ST250) was identified. Disease was not recorded in other pigs on the farm, but it may have been masked by the use of antimicrobials. Further work is required to examine the distribution of these two pathogens in this and other farms in Hong Kong and in adjoining mainland China.
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Absence of a set of plasmid-encoded genes is predictive of reduced pathogenic potential in Brachyspira hyodysenteriae
Veterinary Research, 2014Co-Authors: Nyree D. Phillips, Jill R Thomson, David J HampsonAbstract:AbstractThe gene content of 14 strains of the intestinal spirochaete Brachyspira hyodysenteriae was compared using a DNA microarray. A consistent difference occurred in a block of four genes on the ~36 Kb plasmid, with these being present in six virulent strains and absent in eight strains with reduced pathogenic potential. These genes encoded a predicted radical S-adenosylmethionine domain protein, a glycosyl transferase group 1-like protein, an NAD dependant epimerase and a dTDP-4-dehydrorhamnose 2–5 epimerase: they may be involved in rhamnose biosynthesis and glycosylation. The absence of these plasmid genes in B. hyodysenteriae isolates is predictive of reduced pathogenic potential.
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The use of ELISAs for monitoring exposure of pig herds to Brachyspira hyodysenteriae
BMC Veterinary Research, 2012Co-Authors: Yong Song, Barbara Frey, David J HampsonAbstract:Background Swine dysentery (SD), a mucohaemorrhagic diarrhoeal disease of pigs, results from infection of the large intestine with the spirochaete Brachyspira hyodysenteriae . ELISA systems using whole spirochaete cells (WC) and the B. hyodysenteriae outer membrane lipoprotein Bhlp29.7 previously have been established as potential diagnostic tools for SD. However, their true value in identifying infected herds remains unclear. The present study aimed to compare the performance of whole-cell and Bhlp29.7 based ELISAs in detecting specific immunoglobulin class IgG and IgM to B. hyodysenteriae in growing pigs, and additionally evaluated whether meat juice could serve as a source of specific antibodies. Results Levels of circulating IgG and IgM reacting with WC spirochaete preparations and recombinant Bhlp29.7 peaked 4-6 weeks post-infection in the experimentally challenged pigs, and remained elevated in the present study. In a cohort of pigs on an infected farm levels of antibody directed against both antigens showed a progressive increase with time. However, other than for the level of IgG against WC antigen, a significant increase in antibody levels also was observed in a cohort of pigs on a non-infected farm. In addition, assays using meat juice had 100% specificity and equivalent sensitivity to those based on serum, and likewise the best performance was achieved using the WC IgG ELISA. Conclusions IgG ELISAs using either WC or Bhlp29.7 as plate-coating antigens were shown to be useful for monitoring the dynamics of B. hyodysenteriae infection in grower pigs. Of the two antigens, the WC preparation tended to give better discrimination between pigs from infected and non-infected farms. Testing of meat juice was shown to have potential for identifying infected herds.
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The use of ELISAs for monitoring exposure of pig herds to Brachyspira hyodysenteriae
BMC veterinary research, 2012Co-Authors: Yong Song, Barbara Frey, David J HampsonAbstract:Background Swine dysentery (SD), a mucohaemorrhagic diarrhoeal disease of pigs, results from infection of the large intestine with the spirochaete Brachyspira hyodysenteriae. ELISA systems using whole spirochaete cells (WC) and the B. hyodysenteriae outer membrane lipoprotein Bhlp29.7 previously have been established as potential diagnostic tools for SD. However, their true value in identifying infected herds remains unclear. The present study aimed to compare the performance of whole-cell and Bhlp29.7 based ELISAs in detecting specific immunoglobulin class IgG and IgM to B. hyodysenteriae in growing pigs, and additionally evaluated whether meat juice could serve as a source of specific antibodies.
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Evidence that the 36 kb plasmid of Brachyspira hyodysenteriae contributes to virulence.
Veterinary microbiology, 2011Co-Authors: Nyree D. Phillips, Matthew I. Bellgard, Phatthanaphong Wanchanthuek, Amanda J O'hara, David J HampsonAbstract:Swine dysentery (SD) results from infection of the porcine large intestine with the anaerobic intestinal spirochaete Brachyspira hyodysenteriae. Recently the genome of virulent Australian B. hyodysenteriae strain WA1 was sequenced, and a 36 kilobase (kb) circular plasmid was identified. The plasmid contained 31 genes including six rfb genes that were predicted to be involved with rhamnose biosynthesis, and others associated with glycosylation. In the current study a set of PCRs was developed to amplify portions of nine of the plasmid genes. When used with DNA extracted from virulent strain B204, PCR products were generated, but no products were generated with DNA from avirulent strain A1. Analysis of the DNA using pulsed field gel electrophoresis (PFGE) identified a plasmid band in strains WA1 and B204, but not in strain A1. These results demonstrate that strain A1 does not contain the plasmid, and suggests that lack of the plasmid may explain why this strain is avirulent. To determine how commonly strains lacking plasmids occur, DNA was extracted from 264 Australian field isolates of B. hyodysenteriae and subjected to PCRs for three of the plasmid genes. Only one isolate (WA400) that lacked the plasmid was identified, and this absence was confirmed by PFGE analysis of DNA from the isolate and further PCR testing. To assess its virulence, 24 pigs were experimentally challenged with cultures of WA400, and 12 control pigs were challenged with virulent strain WA1 under the same conditions. Significantly fewer (P=0.03) of the pigs challenged with WA400 became colonised and developed SD (13/24; 54%) compared to the pigs infected with WA1 (11/12; 92%). Gross lesions in the pigs colonised with WA400 tended to be less extensive than those in pigs colonised with WA1, although there were no obvious differences at the microscopic level. The results support the likelihood that plasmid-encoded genes of B. hyodysenteriae are involved in colonisation and/or disease expression.
Kristian Møller - One of the best experts on this subject based on the ideXlab platform.
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Survival of Brachyspira hyodysenteriae and B. pilosicoli in terrestrial microcosms
Veterinary microbiology, 2001Co-Authors: Mette Boye, Suraj B Baloda, Thomas D. Leser, Kristian MøllerAbstract:The survival of Brachyspira hyodysenteriae and Brachyspira pilosicoli was investigated at 10 degrees C in laboratory microcosms consisting of soil, porcine faeces, and in soil mixed with 10% porcine faeces, respectively. By plate spreading, survival of B. hyodysenteriae was found to be 10, 78 and 112 days in soil, soil mixed with 10% faeces, and in porcine faeces, respectively. The identities of the colonies on the plates were confirmed using PCR targeting 23S rDNA for specific detection of B. hyodysenteriae. A positive PCR signal could be obtained up to 112 days in all microcosms by direct extraction of DNA from microcosms followed by PCR. The survival time for B. pilosicoli was 119 days in pure soil and 210 days in soil mixed with 10% porcine faeces and in pure faeces, respectively, as determined by plate spreading followed by PCR. On the other hand, by direct extraction of DNA followed by specific detection by PCR. B. pilosicoli could be detected up to 330 days in all microcosms.Dot blot hybridisation with digoxigenin-labelled specific oligonucleotide probe targeting rDNA could not be used for direct detection of Brachyspira spp. from microcosms due to low sensitivity. However, it was used for confirmation of the identity of colonies and proved to be a useful technique. These results show that the two Brachyspira species may survive in outdoor environment for the times shown in these investigations using laboratory microcosms.
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survival of Brachyspira hyodysenteriae and b pilosicoli in terrestrial microcosms
Veterinary Microbiology, 2001Co-Authors: Mette Boye, Suraj B Baloda, Thomas D. Leser, Kristian MøllerAbstract:Abstract The survival of Brachyspira hyodysenteriae and Brachyspira pilosicoli was investigated at 10°C in laboratory microcosms consisting of soil, porcine faeces, and in soil mixed with 10% porcine faeces, respectively. By plate spreading, survival of B. hyodysenteriae was found to be 10, 78 and 112 days in soil, soil mixed with 10% faeces, and in porcine faeces, respectively. The identities of the colonies on the plates were confirmed using PCR targeting 23S rDNA for specific detection of B. hyodysenteriae. A positive PCR signal could be obtained up to 112 days in all microcosms by direct extraction of DNA from microcosms followed by PCR. The survival time for B. pilosicoli was 119 days in pure soil and 210 days in soil mixed with 10% porcine faeces and in pure faeces, respectively, as determined by plate spreading followed by PCR. On the other hand, by direct extraction of DNA followed by specific detection by PCR. B. pilosicoli could be detected up to 330 days in all microcosms. Dot blot hybridisation with digoxigenin-labelled specific oligonucleotide probe targeting rDNA could not be used for direct detection of Brachyspira spp. from microcosms due to low sensitivity. However, it was used for confirmation of the identity of colonies and proved to be a useful technique. These results show that the two Brachyspira species may survive in outdoor environment for the times shown in these investigations using laboratory microcosms.
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Changes in Bacterial Community Structure in the Colon of Pigs Fed Different Experimental Diets and after Infection with Brachyspira hyodysenteriae
Applied and environmental microbiology, 2000Co-Authors: Thomas D. Leser, R. H. Lindecrona, Tim Kåre Jensen, Bent Borg Jensen, Kristian MøllerAbstract:Bacterial communities in the large intestines of pigs were compared using terminal restriction fragment length polymorphism (T-RFLP) analysis targeting the 16S ribosomal DNA. The pigs were fed different experimental diets based on either modified standard feed or cooked rice supplemented with dietary fibers. After feeding of the animals with the experimental diets for 2 weeks, differences in the bacterial community structure in the spiral colon were detected in the form of different profiles of terminal restriction fragments (T-RFs). Some of the T-RFs were universally distributed, i.e., they were found in all samples, while others varied in distribution and were related to specific diets. The reproducibility of the T-RFLP profiles between individual animals within the diet groups was high. In the control group, the profiles remained unchanged throughout the experiment and were similar between two independent but identical experiments. When the animals were experimentally infected with Brachyspira hyodysenteriae, causing swine dysentery, many of the T-RFs fluctuated, suggesting a destabilization of the microbial community.
Thaddeus B. Stanton - One of the best experts on this subject based on the ideXlab platform.
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Identification of a Divided Genome for VSH-1, the Prophage-Like Gene Transfer Agent of Brachyspira hyodysenteriae
Journal of bacteriology, 2008Co-Authors: Thaddeus B. Stanton, Samuel B. Humphrey, Darrell O. Bayles, Richard L. ZuernerAbstract:The Brachyspira hyodysenteriae B204 genome sequence revealed three VSH-1 tail genes, hvp31, hvp60, and hvp37, in a 3.6-kb cluster. The location and transcription direction of these genes relative to those of the previously described VSH-1 16.3-kb gene operon indicate that the gene transfer agent VSH-1 has a noncontiguous, divided genome.
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Induction and transcription of VSH-1, a prophage-like gene transfer agent of Brachyspira hyodysenteriae.
Anaerobe, 2007Co-Authors: Eric G. Matson, Richard L. Zuerner, Thaddeus B. StantonAbstract:Abstract The anaerobic spirochete Brachyspira hyodysenteriae is host to a bacteriophage-like agent known as VSH-1. VSH-1 is a novel gene transfer mechanism which does not self-propagate and transfers random 7.5 kb fragments of host DNA between B. hyodysenteriae cells. In these investigations early events during VSH-1 induction by mitomycin C were examined. Quantitative PCR analysis revealed that VSH-1 hvp38 and hvp53 genes did not detectably increase in copy numbers during induction. Based on Northern blot hybridization assays, transcription of VSH-1 genes hvp38, hvp53, hvp45, hvp101, and lys increased fivefold to tenfold between 2 and 4 h after induction whereas mRNA levels for B. hyodysenteriae flaA1 declined over the same time period. Chloramphenicol prevented the mitomycin C-induced increases in VSH-1 gene transcription. Hydrogen peroxide (300 μM) substituted for mitomycin C as an inducer of VSH-1 gene transcription and is a possible ‘natural’ inducer of VSH-1 production in vivo. Northern blot hybridization, RT PCR, and primer extension analyses showed that VSH-1 genes are co-transcribed at an initiation site upstream of the VSH-1 gene operon. Two direct heptanucleotide repeats (ACTTATA) were identified between the putative −35 and −10 positions of the VSH-1 gene operon and are likely to represent a binding site for transcription proteins. These findings indicate VSH-1 virion production does not require genome replication, consistent with the inability of VSH-1 to self-propagate. Early events in VSH-1 induction include de novo synthesis of protein(s) essential for transcription of VSH-1 genes as polycistronic mRNA initiating upstream of the hvp45 gene.
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Identification of Genes of VSH-1, a Prophage-Like Gene Transfer Agent of Brachyspira hyodysenteriae
Journal of bacteriology, 2005Co-Authors: Eric G. Matson, Richard L. Zuerner, Samuel B. Humphrey, M. Greg Thompson, Thaddeus B. StantonAbstract:VSH-1 is a mitomycin C-inducible prophage of the anaerobic spirochete Brachyspira hyodysenteriae. Purified VSH-1 virions are noninfectious, contain random 7.5-kb fragments of the bacterial genome, and mediate generalized transduction of B. hyodysenteriae cells. In order to identify and sequence genes of this novel gene transfer agent (GTA), proteins associated either with VSH-1 capsids or with tails were purified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The N-terminal amino acid sequences of 11 proteins were determined. Degenerate PCR primers were designed from the amino acid sequences and used to amplify several VSH-1 genes from B. hyodysenteriae strain B204 DNA. A lambda clone library of B. hyodysenteriae B204 DNA was subsequently screened by Southern hybridization methods and used to identify and sequence overlapping DNA inserts containing additional VSH-1 genes. VSH-1 genes spanned 16.3 kb of the B. hyodysenteriae chromosome and were flanked by bacterial genes. VSH-1 identified genes and unidentified, intervening open reading frames were consecutively organized in head (seven genes), tail (seven genes), and lysis (four genes) clusters in the same transcriptional direction. Putative lysis genes encoding endolysin (Lys) and holin proteins were identified from sequence and structural similarities of their translated protein products with GenBank bacteriophage proteins. Recombinant Lys protein hydrolyzed peptidoglycan purified from B. hyodysenteriae cells. The identified VSH-1 genes exceed the DNA capacity of VSH-1 virions and do not encode traditional bacteriophage early functions involved in DNA replication. These genome properties explain the noninfectious nature of VSH-1 virions and further confirm its resemblance to known prophage-like, GTAs of other bacterial species, such as the GTA from Rhodobacter capsulatus. The identification of VSH-1 genes will enable analysis of the regulation of this GTA and should facilitate investigations of VSH-1-like prophages from other Brachyspira species.
Ana Carvajal - One of the best experts on this subject based on the ideXlab platform.
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In vitro susceptibility of Brachyspira hyodysenteriae to a commercial citrus fruit extract.
Research in veterinary science, 2017Co-Authors: Pedro J. G. De Nova, Ana Carvajal, Miguel Prieto, Pedro RubioAbstract:Abstract Brachyspira hyodysenteriae is the main etiological agent of swine dysentery (SD). Nowadays, treatment and control of SD is increasingly difficult due to the emergence of antimicrobial resistance together with the restrictions on the use of antibiotics in veterinary practice. The aim of this study was to evaluate, as an alternative in the control of this disease, the antimicrobial activity and the main mechanism of action of BIOCITRO, a citrus extract commercialized as raw material and used as feed additive, against B. hyodysenteriae. Ten isolates of B. hyodysenteriae were used to assess the minimum inhibitory and minimum bactericidal concentrations (MIC and MBC) of BIOCITRO by broth microdilution method. Moreover, stationary phase cultures of two B. hyodysenteriae strains were subjected for 90 min to four different concentrations of BIOCITRO and compared with the untreated controls by flow cytometry (FC), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The results showed that BIOCITRO has a relevant bacteriostatic and bactericidal effect against B. hyodysenteriae with MIC and MBC values ranging from 32 to 128 parts per million (ppm). It induces damage in at least 35% and 76% of the bacterial cells when exposed to 128 and 256 ppm of BIOCITRO respectively as revealed by the intake of propidium iodide by FC. Relevant changes in the structure of the bacterial cells were observed by SEM and confirmed by FTIR. According to these results, BIOCITRO seems to be a satisfactory alternative to the use of antibiotics in the control of SD.
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Evaluation of the in vitro activity of flumequine against field isolates of Brachyspira hyodysenteriae.
Research in Veterinary Science, 2015Co-Authors: Luis Miguel Aller-morán, Francisco Javier Martínez-lobo, Pedro Rubio, Ana CarvajalAbstract:Flumequine is a quinolone derivative used in veterinary medicine to treat enteric infections, mainly those caused by Gram negative bacteria and also some Gram positive. Some recent reports by field practitioners have suggested that its use in swine dysentery outbreaks can minimize the impact of this disease. This study aims to evaluate the in vitro anti-Brachyspira hyodysenteriae activity of flumequine. Forty eight field isolates of the bacterium were evaluated using a microdilution test. The lack of colon bioavailability studies of flumequine in pigs makes it difficult to establish the true efficacy of this antibiotic for swine dysentery control. Nonetheless, the relatively high values of MIC50 (50 μg/mL) and MBC50 (50 μg/mL) obtained suggest poor activity against B. hyodysenteriae. Flumequine activity in swine dysentery outbreaks could be related to its activity against other bacteria, different from B. hyodysenteriae, engaged in swine dysentery pathogenesis.
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Multiple-Locus Variable-Number Tandem-Repeat Analysis of the Swine Dysentery Pathogen, Brachyspira hyodysenteriae
Journal of clinical microbiology, 2010Co-Authors: Álvaro Hidalgo, Pedro Rubio, Ana Carvajal, Nyree D. Phillips, Germán Naharro, David J HampsonAbstract:The spirochete Brachyspira hyodysenteriae is the causative agent of swine dysentery, a severe colonic infection of pigs that has a considerable economic impact in many swine-producing countries. In spite of its importance, knowledge about the global epidemiology and population structure of B. hyodysenteriae is limited. Progress in this area has been hampered by the lack of a low-cost, portable, and discriminatory method for strain typing. The aim of the current study was to develop and test a multiple-locus variable-number tandem-repeat analysis (MLVA) method that could be used in basic veterinary diagnostic microbiology laboratories equipped with PCR technology or in more advanced laboratories with access to capillary electrophoresis. Based on eight loci, and when performed on isolates from different farms in different countries, as well as type and reference strains, the MLVA technique developed was highly discriminatory (Hunter and Gaston discriminatory index, 0.938 [95% confidence interval, 0.9175 to 0.9584]) while retaining a high phylogenetic value. Using the technique, the species was shown to be diverse (44 MLVA types from 172 isolates and strains), although isolates were stable in herds over time. The population structure appeared to be clonal. The finding of B. hyodysenteriae MLVA type 3 in piggeries in three European countries, as well as other, related, strains in different countries, suggests that spreading of the pathogen via carrier pigs is likely. MLVA overcame drawbacks associated with previous typing techniques for B. hyodysenteriae and was a powerful method for epidemiologic and population structure studies on this important pathogenic spirochete.
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Characterization and epidemiological relationships of Spanish Brachyspira hyodysenteriae field isolates.
Epidemiology and infection, 2009Co-Authors: Álvaro Hidalgo, Pedro Rubio, Ana Carvajal, Marit Pringle, C. FellströmAbstract:This research aimed to describe the genetic and phenotypic diversity of 74 Spanish Brachyspira hyodysenteriae field isolates, to establish epidemiological relationships between the isolates and to confirm the presence of tiamulin-resistant isolates in Spain. For these purposes, we performed biochemical tests in combination with diagnostic PCR analysis for the identification of Brachyspira spp. and for detection of the smpA/smpB gene. We also used antimicrobial susceptibility tests, random amplified polymorphic DNA (RAPD) and a new pulsed-field gel electrophoresis (PFGE) protocol. The combination of RAPD and PFGE allowed the study of epidemiological relationships. Both indole-negative and tiamulin-resistant isolates of B. hyodysenteriae are reported in Spain for the first time. The genetic analyses indicated a relationship between these Spanish isolates and indole-negative isolates previously obtained from Germany and Belgium.
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Antimicrobial susceptibility testing of Spanish field isolates of Brachyspira hyodysenteriae.
Research in veterinary science, 2008Co-Authors: Álvaro Hidalgo, Ana Carvajal, C. García-feliz, J. Osorio, Pedro RubioAbstract:This study is the first conducted in Spain to evaluate antimicrobial susceptibility of field isolates of Brachyspira hyodysenteriae. One hundred and eight isolates of the bacterium, recovered from different Spanish swine farms between 2000 and 2007, were investigated. The minimum inhibitory concentrations (MIC) of erythromycin, tylosin, tiamulin, valnemulin, clindamycin and lincomycin were determined using a broth microdilution technique. Most of the isolates showed poor susceptibility to erythromycin (MIC(90)>256 microg/ml), tylosin (MIC(90)>256 microg/ml), clindamycin (MIC(90)>4 microg/ml) and lincomycin (MIC(90)=128 microg/ml). Reduced susceptibility to tiamulin and valnemulin was observed with a MIC>2 microg/ml in 17.6% and 7.41% of the B. hyodysenteriae isolates, respectively. Moreover, a survival analysis permitted the detection of an increasing trend in the MIC values for almost all the antimicrobials used in the treatment of swine dysentery when comparing recent isolates (from 2006 to 2007) with those recovered in earlier years (between 2000 and 2004).
Pedro Rubio - One of the best experts on this subject based on the ideXlab platform.
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In vitro susceptibility of Brachyspira hyodysenteriae to a commercial citrus fruit extract.
Research in veterinary science, 2017Co-Authors: Pedro J. G. De Nova, Ana Carvajal, Miguel Prieto, Pedro RubioAbstract:Abstract Brachyspira hyodysenteriae is the main etiological agent of swine dysentery (SD). Nowadays, treatment and control of SD is increasingly difficult due to the emergence of antimicrobial resistance together with the restrictions on the use of antibiotics in veterinary practice. The aim of this study was to evaluate, as an alternative in the control of this disease, the antimicrobial activity and the main mechanism of action of BIOCITRO, a citrus extract commercialized as raw material and used as feed additive, against B. hyodysenteriae. Ten isolates of B. hyodysenteriae were used to assess the minimum inhibitory and minimum bactericidal concentrations (MIC and MBC) of BIOCITRO by broth microdilution method. Moreover, stationary phase cultures of two B. hyodysenteriae strains were subjected for 90 min to four different concentrations of BIOCITRO and compared with the untreated controls by flow cytometry (FC), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The results showed that BIOCITRO has a relevant bacteriostatic and bactericidal effect against B. hyodysenteriae with MIC and MBC values ranging from 32 to 128 parts per million (ppm). It induces damage in at least 35% and 76% of the bacterial cells when exposed to 128 and 256 ppm of BIOCITRO respectively as revealed by the intake of propidium iodide by FC. Relevant changes in the structure of the bacterial cells were observed by SEM and confirmed by FTIR. According to these results, BIOCITRO seems to be a satisfactory alternative to the use of antibiotics in the control of SD.
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Evaluation of the in vitro activity of flumequine against field isolates of Brachyspira hyodysenteriae.
Research in Veterinary Science, 2015Co-Authors: Luis Miguel Aller-morán, Francisco Javier Martínez-lobo, Pedro Rubio, Ana CarvajalAbstract:Flumequine is a quinolone derivative used in veterinary medicine to treat enteric infections, mainly those caused by Gram negative bacteria and also some Gram positive. Some recent reports by field practitioners have suggested that its use in swine dysentery outbreaks can minimize the impact of this disease. This study aims to evaluate the in vitro anti-Brachyspira hyodysenteriae activity of flumequine. Forty eight field isolates of the bacterium were evaluated using a microdilution test. The lack of colon bioavailability studies of flumequine in pigs makes it difficult to establish the true efficacy of this antibiotic for swine dysentery control. Nonetheless, the relatively high values of MIC50 (50 μg/mL) and MBC50 (50 μg/mL) obtained suggest poor activity against B. hyodysenteriae. Flumequine activity in swine dysentery outbreaks could be related to its activity against other bacteria, different from B. hyodysenteriae, engaged in swine dysentery pathogenesis.
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Multiple-Locus Variable-Number Tandem-Repeat Analysis of the Swine Dysentery Pathogen, Brachyspira hyodysenteriae
Journal of clinical microbiology, 2010Co-Authors: Álvaro Hidalgo, Pedro Rubio, Ana Carvajal, Nyree D. Phillips, Germán Naharro, David J HampsonAbstract:The spirochete Brachyspira hyodysenteriae is the causative agent of swine dysentery, a severe colonic infection of pigs that has a considerable economic impact in many swine-producing countries. In spite of its importance, knowledge about the global epidemiology and population structure of B. hyodysenteriae is limited. Progress in this area has been hampered by the lack of a low-cost, portable, and discriminatory method for strain typing. The aim of the current study was to develop and test a multiple-locus variable-number tandem-repeat analysis (MLVA) method that could be used in basic veterinary diagnostic microbiology laboratories equipped with PCR technology or in more advanced laboratories with access to capillary electrophoresis. Based on eight loci, and when performed on isolates from different farms in different countries, as well as type and reference strains, the MLVA technique developed was highly discriminatory (Hunter and Gaston discriminatory index, 0.938 [95% confidence interval, 0.9175 to 0.9584]) while retaining a high phylogenetic value. Using the technique, the species was shown to be diverse (44 MLVA types from 172 isolates and strains), although isolates were stable in herds over time. The population structure appeared to be clonal. The finding of B. hyodysenteriae MLVA type 3 in piggeries in three European countries, as well as other, related, strains in different countries, suggests that spreading of the pathogen via carrier pigs is likely. MLVA overcame drawbacks associated with previous typing techniques for B. hyodysenteriae and was a powerful method for epidemiologic and population structure studies on this important pathogenic spirochete.
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Characterization and epidemiological relationships of Spanish Brachyspira hyodysenteriae field isolates.
Epidemiology and infection, 2009Co-Authors: Álvaro Hidalgo, Pedro Rubio, Ana Carvajal, Marit Pringle, C. FellströmAbstract:This research aimed to describe the genetic and phenotypic diversity of 74 Spanish Brachyspira hyodysenteriae field isolates, to establish epidemiological relationships between the isolates and to confirm the presence of tiamulin-resistant isolates in Spain. For these purposes, we performed biochemical tests in combination with diagnostic PCR analysis for the identification of Brachyspira spp. and for detection of the smpA/smpB gene. We also used antimicrobial susceptibility tests, random amplified polymorphic DNA (RAPD) and a new pulsed-field gel electrophoresis (PFGE) protocol. The combination of RAPD and PFGE allowed the study of epidemiological relationships. Both indole-negative and tiamulin-resistant isolates of B. hyodysenteriae are reported in Spain for the first time. The genetic analyses indicated a relationship between these Spanish isolates and indole-negative isolates previously obtained from Germany and Belgium.
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Antimicrobial susceptibility testing of Spanish field isolates of Brachyspira hyodysenteriae.
Research in veterinary science, 2008Co-Authors: Álvaro Hidalgo, Ana Carvajal, C. García-feliz, J. Osorio, Pedro RubioAbstract:This study is the first conducted in Spain to evaluate antimicrobial susceptibility of field isolates of Brachyspira hyodysenteriae. One hundred and eight isolates of the bacterium, recovered from different Spanish swine farms between 2000 and 2007, were investigated. The minimum inhibitory concentrations (MIC) of erythromycin, tylosin, tiamulin, valnemulin, clindamycin and lincomycin were determined using a broth microdilution technique. Most of the isolates showed poor susceptibility to erythromycin (MIC(90)>256 microg/ml), tylosin (MIC(90)>256 microg/ml), clindamycin (MIC(90)>4 microg/ml) and lincomycin (MIC(90)=128 microg/ml). Reduced susceptibility to tiamulin and valnemulin was observed with a MIC>2 microg/ml in 17.6% and 7.41% of the B. hyodysenteriae isolates, respectively. Moreover, a survival analysis permitted the detection of an increasing trend in the MIC values for almost all the antimicrobials used in the treatment of swine dysentery when comparing recent isolates (from 2006 to 2007) with those recovered in earlier years (between 2000 and 2004).