Specific detection of Lawsonia intracellularis in porcine proliferative enteropathy inferred from fluorescent rRNA in situ hybridization

Preparation and Characterization of a New Monoclonal Antibody Specific Against Lawsonia intracellularis and Its Application in Indirect Immunofluorescence and Immunocytochemistry Assay

Proliferative enteropathy (PE) is an infectious enteric disease caused by Lawsonia intracellularis (L. intracellularis) and is endemic in pig herds worldwide. However, a L. intracellularis-specific monoclonal antibody plays an important role in the evaluation of L. intracellularis infection in vitro. Therefore, the objective of this study was to produce and identify the characteristics of a new monoclonal antibody against the outer membrane protein (Omp2) of L. intracellularis and apply it in an indirect immunofluorescence assay (IFA) and immunocytochemistry (IHC). The results indicated that three highly specific monoclonal antibodies against the Omp2 protein (4D9, 3G2, and 7G5) of L. intracellularis were obtained by using purified Omp2 as an immunogen, the titers of ascitic fluids of 4D9, 3G2, and 7G5 cells were 1:2,048,000, 1:512,000, and 1:256,000, respectively. IFA analysis showed that the 4D9, 3G2, and 7G5 have no cross-reactivity with other enteric bacteria commonly found in the ilea of pigs or closely related to L. intracellularis, such as Desulfovibrio, Bilophila wadsworthia (B. wadsworthia), Salmonella choleraesuis (S. choleraesuis), Salmonella typhimurium (S. typhimurium), Escherichia coli (E. coli), and Brachyspira hyodysenteriae (B. hyodysenteriae). IFA and IHC results indicated that the monoclonal antibodies can be successfully used as primary antibodies to detect L. intracellularis in infected cells and in the crypt of the ileum from infected tissues of PE. Our findings suggested that the new monoclonal antibody specific against L. intracellularis will be useful for the evaluation of L. intracellularis infection in vivo and in vitro.

Fluorescence in situ hybridization in species-specific diagnosis of ovine Campylobacter abortions

Campylobacter infection is a leading cause of ovine abortion worldwide. Campylobacter fetus and C. jejuni are the major species involved. We report herein on abortion storms in 4 Danish sheep flocks. Initially, no pathogenic bacteria were isolated from placental and fetal tissues on aerobic and selective media despite the presence of severe suppurative and necrotizing placentitis with numerous bacteria located intracellularly in trophoblasts. Fluorescence in situ hybridization (FISH) was then applied on abortion material from 13 cases; species-specific oligonucleotide probes directed against either C. fetus or C. jejuni were used in combination with a general bacterial probe. C. fetus was detected as the only lesion-associated bacterial species in 4 cases from 2 flocks, and C. jejuni in 6 cases from the other 2 flocks, thereby establishing the likely etiology of the abortion storms in all 4 flocks. FISH is a useful detection tool in culture-negative cases with tissue lesions suggestive of bacterial infection. Furthermore, FISH is a fast and economical method to detect and identify the zoonotic agent Campylobacter within ovine abortion material.

Application of Fluorescent In Situ Hybridization for Specific Diagnosis of Pneumocystis carinii Pneumonia in Foals and Pigs

Fluorescent in situ hybridization, immunohistochemistry, and Grocott's methenamine-silver nitrate staining were compared as diagnostic methods for Pneumocystis carinii pneumonia in formalin-fixed lung tissue from foals and pigs. An oligonucleotide probe targeting 18S ribosomal RNA of P. carinii was designed for in situ hybridization, and a commercially available monoclonal antibody was used for immunohistochemistry. Samples from six foals and 10 pigs with P. carinii pneumonia, as verified by Grocott's methenaminesilver nitrate staining, were examined concurrently with samples from seven animals with pneumonia caused by other pathogens. Fluorescent in situ hybridization showed distinctive positive reactions for P. carinii in all test samples. The immunohistochemical procedure, however, only revealed P. carinii in the foals. The number of P. carinii organisms observed by fluorescent in situ hybridization and immunohistochemistry far exceeded the number of organisms stained by Grocott's methenamine-silver nitrate staining. The results show that fluorescent in situ hybridization targeting ribosomal RNA can provide a specific diagnosis of P. carinii pneumonia in foals and pigs.

Biology and Diseases of Swine

Swine are used in biomedical research as models for biomedical research and for teaching. This chapter covers normative biology and behavior along with common and emerging swine diseases. Xenotransplantation is discussed along with similarities and differences of swine immunology.

Early pathogenesis in porcine proliferative enteropathy caused by Lawsonia intracellularis

The intestinal bacterium Lawsonia intracellularis, the cause of proliferative enteropathy (PE) in pigs, is believed to infect mitotically active epithelial cells of the intestinal crypts and then multiply and spread in these cells as they divide. Further spread of infection is thought to occur by shedding of bacteria from infected crypts followed by infection of new crypts. The early stages of the pathogenesis of PE, from 0 to 48 hours post-infection (hpi), have not been studied in vivo. In the present study pigs were inoculated with L. intracellularis and killed from 12 hpi to 5 days post-infection (dpi). The localization of L. intracellularis was determined immunohistochemically and by fluorescence in-situ hybridization. At 12 hpi L. intracellularis was found within epithelial cells at the tips of villi, indicating infection of a range of epithelial cells including mature differentiated enterocytes. Furthermore, early invasion of the intestinal connective tissue was observed; with the presence of single bacteria in the lamina propria 12 hpi, and with a further spread of bacteria in the lamina propria observed at 5 dpi, suggesting an active role for the lamina propria in the course of infection.

Comparative evaluation of diagnostic methods for Lawsonia intracellularis infection in pigs, with emphasis on cases lacking characteristic lesions

In this study the following methods for the diagnosis of Lawsonia intracellularis infection in pigs were compared in relation to a reference method (examination of ileal mucosal scrapings by the polymerase chain reaction [PCR]): Warthin-Starry (WS) staining of tissue sections, immunohistochemistry (IHC), in-situ hybridization (ISH), and PCR examination of faeces and of paraffin wax-embedded samples of ileum. Of 204 pigs examined, 32 were considered on the basis of the PCR to be infected. Gross and histopathological examination, including the use of WS staining, were of limited value. PCR examination of faeces proved to be the most sensitive (sensitivity 70%) of the methods used but, due to the occurrence of false positives, its specificity (95%) was the lowest. IHC (sensitivity 66%, specificity 99%) and ISH (sensitivity 54%, specificity 100%) were clearly superior to examination of WS-stained sections (sensitivity 34%, specificity 100%) for routine diagnosis; although less sensitive than the PCR, they indicated only cases of clinical relevance and, moreover, were capable of distinguishing different stages and levels of infection. Because examination of paraffin wax-embedded tissue by the PCR was shown to be associated with low sensitivity (41%), IHC was regarded as the method of choice for retrospective studies.

In situ hybridization for Lawsonia intracellularis--specific 16s rRNA sequence in paraffin-embedded tissue using a digoxigenin-labeled oligonucleotide probe

An in situ hybridization (ISH) procedure with a digoxigenin-labeled oligonucleotide probe for detection of Lawsonia intracellularis in paraffin-embedded tissue is described. This technique recognized 71% of PCR-positive cases and was thus superior to Warthin-Starry silver stain, which only detected 41%. The presented ISH is of comparable sensitivity to previously published immunohistochemical assays and is recommended for laboratories wishing to diagnose L. intracellularis infections in tissue sections but without access to antibodies.

Application of fluorescent in situ hybridisation for demonstration of Coxiella burnetii in placentas from ruminant abortions

A fluorescent in situ hybridisation (FISH) assay targeting 16S ribosomal RNA was developed for detection of the zoonotic bacterium Coxiella burnetii in formalin-fixed, paraffin-embedded tissue, and applied on placentas from ruminant abortions. The applicability of the FISH assay was compared to immunohistochemistry (IHC) using human positive control serum in 12 cases of C. burnetii-associated placentitis as well as 7 negative control tissue samples. In all 12 cases the bacterium was detected within trophoblasts as well as free in the placental debris by both FISH and IHC. Extensive and significant infection by C. burnetii was revealed in 10 of the cases, whereas a slighter and focal distribution of the bacterium was observed in two cases. 90 aborted placentas from Danish ruminants were investigated by FISH. C. burnetii was detected in one bovine case only, representing the first confirmation of C. burnetii in Danish animals. The study shows that FISH targeting 16S ribosomal RNA is a feasible diagnostic tool for detection of C. burnetii in tissue samples and fully comparable to IHC.

Biocompatibility of an enzyme-based, electrochemical glucose sensor for short-term implantation in the subcutis

BACKGROUND

Continuous glucose measurements provide improved glycemic control and may prevent hypoglycemia and long-term complications of diabetes. One of the most promising techniques is the short-term implantation of electrochemical glucose sensors in subcutis. However, the inflammatory reaction to these sensors may lead to bioinstability of sensor measurements. The purpose of the present investigation was to examine factors contributing to the observed subcutaneous inflammatory reaction to an enzyme-based electrochemical glucose sensor for continuous glucose measurements. The sensor biocompatibility was assessed in vitro and in vivo.

METHODS

A toxicological assessment was performed on sensor materials and leachables, and the endotoxin content of sensors was determined by a Limulus amoebocyte lysate (LAL) test. Moreover, as a consequence of permanent penetration of the skin by the sensor the role of bacterial migration to the tissue was investigated. In vivo biocompatibility was investigated through histological examination of implanted sensor membranes for 3 days in pigs. Additionally, the effect of needle size and type (normal vs. inserter needle) on tissue trauma at sensor insertion was evaluated, and the healing of subcutis was assessed histologically from 3 to 14 days after removal of sensors.

RESULTS

The toxicological assessment and the LAL test showed no concerns in a 3-day implantation scenario, and bacterial migration to the subcutis could not be detected. The histological examination showed that a reduction in needle size reduced the extent of inflammation to very low levels, and that the different sensor membranes showed similar extent and type of inflammation. Additionally, the extent of subcutaneous tissue reaction after removal of sensors declined gradually over time and returned to near-normal levels after 2 weeks.

CONCLUSION

The electrochemical enzyme-based glucose sensor for continuous glucose measurements in subcutis is acceptable from a biocompatibility point of view. Reducing the inserter needle in size reduces the trauma induced at sensor implantation to neglible levels. Furthermore, the tissue reaction to the sensor returns to near-normal 2 weeks after the sensor has been removed following a 3-day implantation period.

Lawsonia intracellularis infection in the large intestines of pigs

In this study we examined the proliferative enteropathy, caused by the obligate intracellular bacterium Lawsonia intracellularis, in colon of naturally infected pigs, using immunohistochemistry, in situ hybridisation and scanning confocal laser microscopy. When 396 pigs submitted for routine laboratory examination were investigated, large intestinal gross lesions were seen in 93, including 74 cases of L. intracellularis colitis (proliferative enteropathy). Fifty-one pigs without recorded colonic gross lesions revealed L. intracellularis colitis microscopically. In four cases, L. intracellularis was only revealed in colon. Fifty-seven pigs were positive for L. intracellularis in the small intestines only. Thus, the overall prevalence of colonic infection in L. intracellularis-positive animals was as high as 69% (125 out of 182). In comparison, the large intestinal pathogens Brachyspira hyodysenteriae and Salmonella enterica were only isolated from 5 and 4 of the 93 cases, respectively. Morphologically, an unforeseen severe involvement of the subepithelial mucosa with multiple L. intracellularis found free and within large macrophages was observed in areas with acute infection. The distribution of whole L. intracellularis organisms was confirmed by in situ hybridisation and scanning confocal laser microscopy. The significance and possible role of subepithelial infection in the proliferative enteropathy is discussed. In conclusion, the study shows that L. intracellularis is a prevalent cause of naturally acquired colitis in pigs.

Naturally acquired Lawsonia intracellularis infection in pigs studied from weaning to slaughter by indirect immunofluorescence antibody test and polymerase chain reaction on faeces

The course of naturally acquired Lawsonia intracellularis infection was studied in 41 pigs by testing blood and faeces samples collected four to seven times from before weaning to slaughter 5 months old. At slaughter, a sample of ileum was taken for histopathology. In the first sampling when the pigs were 2-4 weeks old maternally derived IgG against L. intracellularis was demonstrated by immunofluorescence antibody test in nine pigs whereas the bacterium was detected by PCR in faeces from six pigs. The maternally derived antibodies did not prevent pigs from becoming infected as seven pigs later on shed and/or were seropositive for L. intracellularis. The lowest prevalence of L. intracellularis was observed in 6-13 weeks old pigs and it seemed as though L. intracellularis in early infected pigs only activates a minor antibody response. At slaughter 66% of the pigs were found positive by immunofluorescence antibody test compared to 24% by immunohistochemistry on ileal samples. Thus, applied at the time of slaughter the antibody test appeared to be a highly sensitive ante-mortem diagnostic tool for identifying L. intracellularis exposed pigs with or without current proliferative enteropathy.

Evaluation of a novel enzyme-linked immunosorbent assay for serological diagnosis of porcine proliferative enteropathy

A specific enzyme-linked immunosorbent assay (ELISA) for detection of antibodies to the porcine pathogen Lawsonia intracellularis was developed and evaluated using sera from naïve, naturally infected as well as experimentally infected pigs. On the basis of 37 serum samples collected from experimentally infected pigs and 62 serum samples from naturally infected pigs the sensitivity of the ELISA was calculated to 98.0%. The specificity of the test was 99.3%, calculated on the basis of 273 serum samples collected in six herds free of L. intracellularis after medicated eradication. The novel ELISA was a specific and sensitive method for detecting specific antibodies, and may be a good alternative to the existing serological tests for L. intracellularis. It may be usable for diagnosis of proliferative enteropathy and for determination of a herd's epidemiologic status.

Development, characterization and diagnostic application of a monoclonal antibody specific for a proteinase K resistant Lawsonia intracellularis antigen

Proliferative enteropathy (PE) is one of the most important infections in pigs caused by Lawsonia intracellularis, an obligate intracellular bacterium. The purpose of the present investigation was to develop monoclonal antibodies with specificity to L. intracellularis useful both for diagnostic purposes (by immunohistochemistry) and for bacterial characterization. Several antibody producing hybridomas were established by fusion of mouse myeloma with spleen cells from BALB/c mice immunized with mucosa scrapings of the intestinal mucosa from a L. intracellularis infected pig. A monoclonal antibody (mAb), Law1-DK, isotyped as IgG2b was selected by indirect immunofluorescence antibody test (IFAT). Histological sections of the intestines from pigs affected by proliferative enteropathy and in vitro grown bacteria in cell culture were tested positive for the presence of L. intracellularis with the mAb. A molecule at 21 kDa was recognized by the mAb in a Western blotting analysis when a whole-cell preparation of L. intracellularis was run on a sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). This antigen was released from L. intracellularis by mild heat treatment and was resistant to proteinase K digestion, suggesting it to be non-protein, e.g., lipopolysaccharide (LPS). This suggestion was supported by its presence in the aqueous phase of a phenol-water extract. The inhibitory effect of periodate oxidation on the antigen-antibody binding confirmed the participation of a carbohydrate epitope. The new mAb was tested highly specific for L. intracellularis by applying in situ hybridization with a L. intracellularis specific probe targeting 16S ribosomal RNA simultaneously with the IFAT.

Development and validation of a new in vitro assay for selection of probiotic bacteria that express immune-stimulating properties in chickens in vivo

Oral administration of immunoprobiotic bacteria may support animal health. Species specificity of such microorganisms requires appropriate selection. An in vitro assay for the selection of immunoprobiotic lactic acid bacteria was developed in chicken. The assay allowed testing of large numbers of individual strains. Immune stimulation in vitro correlated well with the in vivo situation in two experiments and no false negative results occurred. Therefore this assay is an appropriate selection tool for immunomodulating properties of lactic acid bacteria in chicken.

Application of a 5' nuclease assay for detection of Lawsonia intracellularis in fecal samples from pigs

A 5' nuclease assay was developed to detect Lawsonia intracellularis in porcine fecal samples. The specific probe and primers were chosen by using the 16S ribosomal DNA gene as a target. The 5' nuclease assay was used with a total of 204 clinical samples, and the results were compared to those of immunohistochemistry (IM) on ileal sections of the same animals. There was 91% agreement between the results of IM and the 5' nuclease assay. In the 5' nuclease assay, 111 (54%) of the pigs tested positive for L. intracellularis infection, with a mean cycle threshold (Ct) value of 27.2, whereas 98 (48%) of the pigs tested positive by IM. On average, the Ct and DeltaRn values for the positive samples were 27.2 (standard deviation [SD], 3.7) and 1.6 (SD, 0.7), respectively. A Ct value of 27.2 corresponds to a fecal excretion of approximately 10(7) L. intracellularis cells per g of feces. Furthermore, a total of 40 fecal samples derived from a herd known to be free from infection with L. intracellularis all tested negative, with a Ct value of 40. By using a Ct value of 36 as the cutoff limit, the detection limit of the assay was 1 L. intracellularis cell per PCR tube. In conclusion, the 5' nuclease assay that has been developed represents an applicable fast method for detection of L. intracellularis in fecal samples, with a sensitivity and specificity comparable to those of IM.

Diagnostic examination of human intestinal spirochetosis by fluorescent in situ hybridization for Brachyspira aalborgi, Brachyspira pilosicoli, and other species of the genus Brachyspira (Serpulina)

Human intestinal spirochetosis, characterized by end-on attachment of densely packed spirochetes to the epithelial surface of the large intestines as a fringe has been associated with the weakly beta-hemolytic spirochetes Brachyspira aalborgi and Brachyspira (Serpulina) pilosicoli. In this study, fluorescent in situ hybridization with oligonucleotide probes targeting 16S or 23S rRNA of B. aalborgi, B. pilosicoli, and the genus Brachyspira was applied to 40 sections of formalin-fixed, paraffin-embedded intestinal biopsy specimens from 23 Danish and 15 Norwegian patients with histologic evidence of intestinal spirochetosis. Five biopsy specimens from patients without intestinal spirochetosis and three samples from pigs with experimental B. pilosicoli colitis were examined as well. In addition, the 16S ribosomal DNAs of two clinical isolates of B. aalborgi were sequenced, and a PCR procedure was developed for the identification of B. aalborgi in cultures. The genotypic characteristics of the two clinical isolates showed very high (99.5%) similarity with two existing isolates, the type strain of B. aalborgi and a Swedish isolate. Hybridization with the Brachyspira genus-specific probe revealed a brightly fluorescing fringe of spirochetes on the epithelia of 39 biopsy specimens, whereas 1 biopsy specimen was hybridization negative. The spirochetes in biopsy specimens from 13 Danish and 8 Norwegian patients (55.3%) were identified as B. aalborgi. The spirochetes in the biopsy specimens from the other 17 patients hybridized only with the Brachyspira probe, possibly demonstrating the involvement of as-yet-uncharacterized Brachyspira spirochetes in human intestinal spirochetosis.

Specific detection of Pasteurella multocida in chickens with fowl cholera and in pig lung tissues using fluorescent rRNA in situ hybridization

A Pasteurella multocida species-specific oligonucleotide probe, pmhyb449, targeting 16S rRNA was designed and evaluated by whole-cell hybridization against 22 selected reference strains in animal tissues. It differentiated P. multocida from other bacterial species of the families Pasteurellaceae and Enterobacteriaceae and also from divergent species of the order Cytophagales (except biovar 2 strains of Pasteurella avium and Pasteurella canis, which have high 16S rRNA similarity to P. multocida). The potential of the probe for specific identification and differentiation of P. multocida was further detected in formalin-fixed paraffin-embedded lung tissues from experimental fowl cholera in chickens and infections in pigs. In chicken lung tissues P. multocida cells were detected singly, in pairs, as microcolonies, and as massive colonies within air capillaries (septa and lumen), parabronchial septa, and blood vessels (wall and lumen). In pig lung, postmortem-injected P. multocida was detected in the alveoli (lumen and wall), and in both animals the bacterial cells were seen in the bronchi. The results showed that with the oligonucleotide probe pmhyb449, fluorescent in situ hybridization is a suitable and fast method for specific detection of P. multocida in histological formalin-fixed tissues. The test was replicable and reproducible and is recommended as a supplementary test for diagnosis and as a tool in pathogenesis studies of fowl cholera and respiratory tract infections in pigs due to P. multocida.

Detection of Streptococcus suis by in situ hybridization, indirect immunofluorescence, and peroxidase-antiperoxidase assays in formalin-fixed, paraffin-embedded tissue sections from pigs

Streptococcus suis is an important pathogen in pigs and is considered a zoonotic agent. To aid diagnosis of infection caused by S. suis, a species-specific probe targeting 16S ribosomal RNA was designed and used for fluorescent in situ hybridization. Two additional immunohistochemical detection methods, an indirect immunofluorescence assay and a peroxidase-antiperoxidase method, using polyclonal antibodies also were developed. The specificity of the oligonucleotide probe was examined by whole-cell and dot-blot hybridization against reference strains of the 35 serotypes of S. suis and other closely related streptococci and other bacteria commonly isolated from pigs. The probe was specific for S. suis serotypes 1-31. The specificity of the polyclonal antibodies, which has previously been evaluated for use in diagnostic bacteriology for typing of serotype 2, was further evaluated in experimentally infected murine tissue with pure culture of different serotypes of S. suis, related streptococci, and other bacteria commonly found in pigs. The polyclonal antibodies against S. suis serotype 2 cross-reacted with serotypes 1 and 1/2 in these assays. The in situ hybridization and the immunohistochemical methods were used for detection of S. suis in formalin-fixed, paraffin-embedded tissue sections of brain, endocardium, and lung from pigs infected with S. suis. The methods developed were able to detect single cells of S. suis in situ in the respective samples, whereas no signal was observed from control tissue sections that contained organisms other than S. suis. These techniques are suitable for determining the in vivo localization of S. suis for research and diagnostic purposes.

Comparative pathology of bacterial enteric diseases of swine

Enteric bacterial infections are among the most common and economically significant diseases affecting swine production worldwide. Clinical signs of these infections include diarrhea, reduced growth rate, weight loss, and death of preweaned, weanling, grower-finisher, young and adult age breeding animals. The most common etiological agents include Escherichia coli, Clostridium perfringens, Lawsonia intracellularis, Salmonella enterica, and Brachyspira (Serpulina) spp. With the exception of Brachyspira (Serpulina) hyodysenteriae, the cause of swine dysentery, and Lawsonia intracellularis, the cause of proliferative enteropathy, the pathological changes seen with these agents closely resemble the diseases occurring in human beings. Histological changes in the intestines of swine with enteric bacterial infections include bacterial colonization without significant damage (e.g., certain enterotoxigenic E. coli and C. perfringens type A), attaching and effacing lesions with enteropathogenic E. coli and Brachyspira pilosicoli, the cause of colonic spirochetosis, inflammation with S. enterica, and necrotizing and hemorrhagic lesions with certain C. perfringens. Extraintestinal spread of bacteria and/or toxins occurs with some serotypes of E. coli and most serotypes of S. enterica. Enteric bacterial diseases of swine have been used as models to study the pathogenesis of similar diseases of human beings. Several of these pathogens are also important causes of food-borne disease in humans.

Improved diagnosis of porcine proliferative enteropathy caused by Lawsonia intracellularis using polymerase chain reaction-enzyme-linked oligosorbent assay (PCR-ELOSA)

Proliferative enteropathy (PE) caused by Lawsonia intracellularis is a major diarrheal disease affecting swine worldwide. Routine laboratory diagnosis of PE is done by amplification of L. intracellularis -specific DNA sequences by PCR followed by agarose gel electrophoresis and staining of PCR products with ethidium bromide. We report the development of an enzyme-linked oligosorbent assay (ELOSA) for specific identification of chromosomal L. intracellularis 328-bp PCR amplified products. The ELOSA involved determination of optical density value at 450 nm (OD(450)) after hybridization of biotin-labelled PCR products with an amine-modified internal oligonucleotide capture probe immobilized in microwell plates, and avidin-biotin-peroxidase complex. A positive ELOSA cut-off value of > or =0.375 was established using the mean OD(450)of negative control specimens plus three times the standard deviation. Using this value, the detection limit of PCR amplified L. intracellularis -specific products by ethidium bromide-stained agarose gel electrophoresis, Southern blot, and ELOSA were estimated to be 6.1 ng, between 0.8 and 3.0 ng, and 0.8 ng of DNA, respectively. Comparison of ethidium bromide-stained agarose gel analysis with ELOSA for detection of L. intracellularis -specific PCR products from 315 clinical specimens revealed 78% sensitivity, 100% specificity and 94% accuracy. The ELOSA produced a spectrophotometric signal that confirmed the authenticity of PCR products without subjective interpretation of ethidium bromide-stained PCR products after agarose gel electrophoresis.

Diarrhea in growing-finishing swine

Regardless of the etiology of an enteric disease in nursery age to finisher swine, making a prompt and accurate diagnosis is crucial. Eliciting a complete history, assessing clinical signs and pathology, and selecting and interpreting laboratory tests are essential components in achieving this. Early detection and diagnosis of enteric disease is particularly critical in the nursery through finisher phase because of economic impacts. Recurrent topics when discussing control and prevention of enteric diseases are reducing stress and improving pig comfort and reducing or eliminating exposure through sanitation and biosecurity. These are not new concepts; in fact, prior to the advent of antimicrobials, they were the mainstay of treatment of enteric diseases. With concern over the use of antimicrobials in food animal production increasing, exploiting disease ecology to control enteric diseases is increasing in importance. New vaccines and bacterins for postweaning swine enteric diseases are needed tools to exploit the pig's immune system. Recent advances in diagnostic capabilities allow an increase in understanding and exploitation of disease ecology.

Quantification of the flavonoid-degrading bacterium Eubacterium ramulus in human fecal samples with a species-specific oligonucleotide hybridization probe

To investigate the occurrence of the flavonoid-degrading bacterium Eubacterium ramulus in the human intestinal tract, an oligonucleotide probe designated S-S-E.ram-0997-a-A-18 was designed and validated, with over 90 bacterial strains representing the dominant described human fecal flora. Application of S-S-E. ram-0997-a-A-18 to fecal samples from 20 subjects indicated the presence of E. ramulus in each individual tested in numbers from 4.4 x 10(7) to 2.0 x 10(9) cells/g of fecal dry mass. Six fecal E. ramulus isolates were recognized by S-S-E.ram-0997-a-A-18 but exhibited different band patterns when analyzed by randomly amplified polymorphic DNA.

Specific detection of the genus Serpulina, S. hyodysenteriae and S. pilosicoliin porcine intestines by fluorescent rRNA in situ hybridization

A fluorescent-labelledin situ hybridization method targeting rRNA was devised to facilitate specific identification and diagnosis of diarrhoea and colitis in pigs caused by the genus Serpulina, as well as to distinguish the species Serpulina hyodysenteriae and Serpulina pilosicoli in formalin-fixed colon tissue sections. A genus-specific oligonucleotide probe SER1410 targeting the five species of porcine Serpulina was thus designed. Furthermore, species specific oligonucleotide probes (Hyo1210, Pilosi209 and Pilosi1405) were also designed to detect, identify and differentiate S. hyodysenteriae and S. pilosicoli. These probes clearly demonstrated and possessed the desired specificity, when evaluated by whole cell hybridization on five reference strains and 20 isolates covering the five species of porcine Serpulina. Furthermore, the oligonucleotide probes were specific when used both, for the detection of Serpulina isolates at genus level as well as for specific detection of S. hyodysenteriae and S. pilosicoli in formalin-fixed colon tissue sections from pigs suffering from swine dysentery and porcine colonic spirochaetosis, respectively. Tissue sections were also used from pigs without any intestinal disorders as controls for estimating the specificity of the probes. The probes developed in this study thus had the potential of specific identification and histological recognition obtained in the formalin-fixed tissue samples.