Human intestinal spirochetosis--a review

Decreased expression of DRA (SLC26A3) by a p38-driven IL-1α response contributes to diarrheal disease following in vivo challenge with Brachyspira spp

In this study, we uncovered the novel mechanism of IL-1α-mediated downregulated in adenoma (DRA) (SLC26A3) downregulation in the context of Brachyspira spp.-induced malabsorptive diarrhea. Experimentally infected pigs with Brachyspira spp. had significantly reduced DRA expression in the colon accompanied by IL-1α upregulation. This response was recapitulated in vitro by exposing Caco-2 cells to either Brachyspira lysate or IL-1α. Both p38 and MAPK-activated protein kinase 2 (MAPKAPK-2 also referred as MK-2) showed an increased phosphorylation after exposure to either. SB203580 application, a p38 inhibitor blocked the MK-2 phosphorylation and attenuated the DRA and IL-1α response to both lysate and IL-1α. Exposure to IL-1 receptor antagonist (IL-1RA) produced a similar response. In addition, exposure of cells to either of these blockers without IL-1α or lysate results in increased DRA and decreased IL-1α expression, revealing that DRA needs IL-1α signaling for basal physiological expression. Dual inhibition with both blockers completely inhibited the effect from IL-1α while significantly attenuating the response from Brachyspira lysate, suggesting a minor contribution from another pathway. Together this demonstrates that Brachyspira activates p38 MAPK signaling driving IL-1α expression, which activates IL-1R1 causing DRA downregulation while also driving upregulation of IL-1α through p38 in a positive feedback mechanism. In conclusion, we elucidated a major pathway involved in DRA downregulation and its role in Brachyspira-induced diarrhea. In addition, these observations will aid in our understanding of other inflammatory and infectious diarrhea conditions.NEW & NOTEWORTHY The diarrheal disease caused by the two infectious spirochete spp. B. hyodysenteriae and B. hampsonii reduced the expression of DRA (SLC26A3), a major Cl-/HCO-3 exchanger involved in Cl- absorption. This is attributed to the upregulation of IL-1α driven by p38 MAPK. This work also describes a potential new mechanism in inflammatory diseases while showing the importance of IL-1α in maintaining DRA levels.

A Case Study: Incidental Finding of Human Intestinal Spirochetosis in Screening Colonoscopy

Human intestinal spirochetosis (HIS) is a rare occurrence. We present an interesting case study on an asymptomatic over-60-year-old male who was incidentally discovered to have HIS following a colonoscopy that was conducted for his positive fecal occult blood test (FOBT). Histopathology of the colonic biopsy proved the presence of human intestinal spirochetosis; however, as he was asymptomatic, treatment was not initiated in his case. We discuss here the prevalence, presentation, diagnostic methods, and treatment of colonic HIS.

Intestinal Spirochetosis: To Treat or Not to Treat

Spirochete colonization of the gastrointestinal tract is a poorly understood phenomenon presenting with varying signs and symptoms. Due to the lack of a unified approach and its varying presentations, the management decision for intestinal spirochetosis (IS) has always been challenging. While metronidazole is the commonly preferred antimicrobial treatment, it remains unclear if therapeutic intervention is indicated for everyone, especially asymptomatic patients. We present three patients, diagnosed with IS. They presented with varying demographics, clinical presentations, and past medical histories and underwent different clinical managements. Our decisions for treatment not only included presenting symptoms but also factors like history of pre-existing gastrointestinal diseases, age, and immune status.

Spirochetosis Mimicking Acute Appendicitis: Clinical Report and Review of the Literature

Introduction

Intestinal spirochetosis is sometimes found by chance in histological specimen of routine endoscopies. There are only a few cases described in the literature that spirochetosis of the appendix was mimicking acute appendicitis. We present a case of pseudoappendicitis with the histological finding of spirochetes and review the current literature.

Case Presentation

A 72-year-old woman presented with pain of the lower right abdomen and previous systemic corticoid therapy. In clinical examination, there was a tenderness and pain in the right lower quadrant, and inflammation values were elevated. An abdominal computed tomography scan revealed no obvious inflammation of the appendix. A diagnostic laparoscopy was performed and revealed a macroscopically uninflamed appendix which was removed. Histology revealed spirochetosis of the appendix but no typical signs of appendicitis. The patient was treated with antibiotics for 5 days and was discharged without abdominal pain. In a clinical control 6 weeks later, the abdominal pain had disappeared and the patient was in good clinical condition.

Discussion

Intestinal spirochetosis is randomly found in histological specimen during routine endoscopies, even in asymptomatic patients. There are only a few cases described with spirochetosis of the appendix causing pain and mimicking appendicitis; hence, this entity is an important differential diagnosis of pain in the right lower quadrant of the abdomen.

Identification of intestinal and fecal microbial biomarkers using a porcine social stress model

Understanding the relationships between social stress and the gastrointestinal microbiota, and how they influence host health and performance is expected to have many scientific and commercial implementations in different species, including identification and improvement of challenges to animal welfare and health. In particular, the study of the stress impact on the gastrointestinal microbiota of pigs may be of interest as a model for human health. A porcine stress model based on repeated regrouping and reduced space allowance during the last 4 weeks of the finishing period was developed to identify stress-induced changes in the gut microbiome composition. The application of the porcine stress model resulted in a significant increase in salivary cortisol concentration over the course of the trial and decreased growth performance and appetite. The applied social stress resulted in 32 bacteria being either enriched (13) or depleted (19) in the intestine and feces. Fecal samples showed a greater number of microbial genera influenced by stress than caecum or colon samples. Our trial revealed that the opportunistic pathogens Treponema and Clostridium were enriched in colonic and fecal samples from stressed pigs. Additionally, genera such as Streptococcus, Parabacteroides, Desulfovibrio, Terrisporobacter, Marvinbryantia, and Romboutsia were found to be enriched in response to social stress. In contrast, the genera Prevotella, Faecalibacterium, Butyricicoccus, Dialister, Alloprevotella, Megasphaera, and Mitsuokella were depleted. These depleted bacteria are of great interest because they synthesize metabolites [e.g., short-chain fatty acids (SCFA), in particular, butyrate] showing beneficial health benefits due to inhibitory effects on pathogenic bacteria in different animal species. Of particular interest are Dialister and Faecalibacterium, as their depletion was identified in a human study to be associated with inferior quality of life and depression. We also revealed that some pigs were more susceptible to pathogens as indicated by large enrichments of opportunistic pathogens of Clostridium, Treponema, Streptococcus and Campylobacter. Generally, our results provide further evidence for the microbiota-gut-brain axis as indicated by an increase in cortisol concentration due to social stress regulated by the hypothalamic-pituitary-adrenal axis, and a change in microbiota composition, particularly of bacteria known to be associated with pathogenicity and mental health diseases.

Anal cytology: Diagnosis of intestinal spirochaetosis

OBJECTIVE

A case of intestinal spirochaetosis diagnosed in anal cytology is presented.

METHODS

An anal liquid-based cytology was performed and stained with Papanicolau and Warthin-Starry stains.

RESULTS

An apical filamentous "fringe" was identified in columnar cells groups.

CONCLUSION

Anal cytology is a potential tool for intestinal spirochaetosis diagnosis.

Intestinal Spirochetosis and Chronic Diarrhea: A Case Report and Literature Review

Spirochetosis is a rare condition characterized by the presence of spirochetes in the gastrointestinal tract. It is typically associated with immunodeficiency. We present a case of chronic watery diarrhea in a 48-year-old housewife who had a 12-week history of variable-volume bowel movements without blood or mucus, accompanied by a sense of urgency. Chronic diarrhea led to weight loss and fatigue, significantly impacting her quality of life. Despite the absence of known risk factors, a comprehensive clinical evaluation and exclusion of other potential causes prompted a rectosigmoid biopsy, which revealed distinctive histological findings of spirochetosis. This case underscores the significance of considering spirochetosis as a differential diagnosis in cases of chronic watery diarrhea, even in the absence of immunodeficiency. The utilization of rectosigmoid biopsy and careful histopathological examination played a pivotal role in establishing an accurate diagnosis.

Ulcerative Proctitis: An Unusual Case of Intestinal Spirochetosis

Human intestinal spirochetosis (HIS) is an uncommon disease characterized by the colonization of spirochetes in the colorectal mucosa and is most often found in individuals who are positive for human immunodeficiency virus (HIV) and in homosexual men. Although HIV is known to cause a variety of infectious colitis, the prevalence has significantly declined with antiretroviral therapy. Intestinal spirochetosis, however, remains meaningful as it can be an infectious cause of colonic ulcerations even with well-controlled HIV. Spirochetosis rarely causes macroscopic changes in the colorectal mucosa and reports of an ulcerated rectum are exceedingly scarce. Here, we report a case of a homosexual man with HIV who is compliant with antiretroviral therapy with high CD4 counts who presented with a six-week history of bloody diarrhea and was found to have multiple ulcerations in the rectosigmoid junction and rectum infected with non-treponemal spirochetes as confirmed on biopsy. To our knowledge, there have not been any reports of multiple rectal ulcerations caused by non-treponemal spirochetes. The patient was treated with metronidazole 500 mg four times daily for 10 days with complete resolution of symptoms. This case is notable as it alerts clinicians to consider intestinal spirochetosis as a differential diagnosis in the workup for bloody stool in the presence of colorectal ulcerations.

Pathobiology and dysbiosis of the respiratory and intestinal microbiota in 14 months old Golden Syrian hamsters infected with SARS-CoV-2

The pandemic of severe acute respiratory syndrome coronavirus 2 (SARS2) affected the geriatric population. Among research models, Golden Syrian hamsters (GSH) are one of the most representative to study SARS2 pathogenesis and host responses. However, animal studies that recapitulate the effects of SARS2 in the human geriatric population are lacking. To address this gap, we inoculated 14 months old GSH with a prototypic ancestral strain of SARS2 and studied the effects on virus pathogenesis, virus shedding, and respiratory and gastrointestinal microbiome changes. SARS2 infection led to high vRNA loads in the nasal turbinates (NT), lungs, and trachea as well as higher pulmonary lesions scores later in infection. Dysbiosis throughout SARS2 disease progression was observed in the pulmonary microbial dynamics with the enrichment of opportunistic pathogens (Haemophilus, Fusobacterium, Streptococcus, Campylobacter, and Johnsonella) and microbes associated with inflammation (Prevotella). Changes in the gut microbial community also reflected an increase in multiple genera previously associated with intestinal inflammation and disease (Helicobacter, Mucispirillum, Streptococcus, unclassified Erysipelotrichaceae, and Spirochaetaceae). Influenza A virus (FLUAV) pre-exposure resulted in slightly more pronounced pathology in the NT and lungs early on (3 dpc), and more notable changes in lungs compared to the gut microbiome dynamics. Similarities among aged GSH and the microbiome in critically ill COVID-19 patients, particularly in the lower respiratory tract, suggest that GSHs are a representative model to investigate microbial changes during SARS2 infection. The relationship between the residential microbiome and other confounding factors, such as SARS2 infection, in a widely used animal model, contributes to a better understanding of the complexities associated with the host responses during viral infections.

Intestinal Spirochetes Associated With Asymptomatic COVID-19 Infection

A 60-year-old, human immunodeficiency virus (HIV)-negative, homosexual male presented to our colorectal clinic with abdominal pain for three weeks followed by persistent watery diarrhea refractory to loperamide. He had no history of recent travel, no known infectious contacts, and his last colonoscopy nine years prior was within normal limits. After one episode of hematochezia, computed tomography of the abdomen/pelvis was performed demonstrating colitis and coronavirus disease 2019 (COVID-19)-related changes to the lung bases. Testing confirmed COVID-19 infection which was self-limited. The initial workup for infectious colitis was negative. Colonoscopy revealed no evidence of gross colitis. Histopathology demonstrated microscopic colitis with spirochete colonization of the intestinal epithelium. A course of metronidazole led to the resolution of the patient’s symptoms.

Intestinal spirochetosis has been described as a rare source of colitis caused by the organism Brachyspira pilosicoli in an immunocompromised population (HIV-positive, organ transplant). It is associated with abdominal pain and refractory diarrhea. This report details the unique case of intestinal spirochetosis in an HIV-negative, COVID-19-positive patient with no other risk factors for immunosuppression. Further review is necessary to establish a true association; however, this case suggests that intestinal spirochetosis should be considered during the workup of chronic diarrhea (more than two weeks) in COVID-19-positive patients.

Human Intestinal Spirochetosis: A Rare Case of Intermittent Bloating and Hematochezia

Human intestinal spirochetosis (HIS) is a condition where spirochetes, a group of spiral-shaped bacteria, attach to the apical membrane of the human colorectal epithelium. Although most findings of HIS are simply incidental discoveries found during screening colonoscopies, the ability to mimic the presentation of inflammatory bowel diseases should prompt consideration of this condition as part of a working differential diagnosis. Herein, we present the case of a 57-year-old bisexual, African American male with a medical history of Human Immunodeficiency Virus (HIV) on antiretroviral therapy (ART) with an undetectable viral load that presented for an elective, outpatient colonoscopy after experiencing four months of intermittent bloating and hematochezia. Histologic examination of colonic biopsies confirmed a diagnosis of HIS. The nonspecific clinical presentation in the setting of well-controlled HIV makes HIS a formidable diagnostic challenge that requires increased awareness.

Human Intestinal Spirochetosis Incompatible With Dysplastic Adenomatous Epithelium

Human intestinal spirochetosis (HIS) refers to the colonization of spirochetal bacteria in the human intestinal tract. HIS caused by Brachyspira spp. has been recognized for decades, but their pathological and clinical significance is largely unclear. The coincidence of dysplasia in adenoma or adenocarcinoma and HIS is very rare, and whether spirochetes can colonize on dysplastic epithelium remains controversial. Here, we report a case that showed abrupt abolition of mucosal surface fringe formation on a tubular adenoma (TA) and increased cytoplasmic MUC1 expression in the dysplastic epithelial cells compared with adjacent nondysplastic colonocytes. The findings support the hypothesis that the epithelial colonization of spirochetes is significantly reduced by dysplasia likely due to loss of microvilli, and an increase of epithelial MUC1 expression might contribute to reduced spirochetal colonization in colonic mucosa.

Intestinal Spirochaetosis-A case series from the developing world

Spirochaetes comprise a heterogenous group of gram negative, motile, spiral shaped bacteria. Some of these pathogens are known to cause numerous human diseases such as Lyme disease, relapsing fever, syphilis and leptospirosis. However, intestinal spirochetosis is a rare condition. Patients frequently present with long-term complaints of loose stools, abdominal pain and weight loss and rectal bleeding. Hence to establish a diagnosis an endoscopy with biopsy is required. In this article, we describe four such cases, having different ages and socio- economic background, successfully treated with a short course of metronidazole.

Differential responses of weaned piglets to supplemental porcine or chicken plasma in diets without inclusion of antibiotics and zinc oxide

This study was conducted to investigate the effects of spray-dried porcine plasma protein (SDPP) or spray-dried chicken plasma protein (SDCP) supplementation in diets without the inclusion of antibiotics and zinc oxide (ZnO) on growth performance, fecal score, and fecal microbiota in early-weaned piglets. A total of 192 healthy weaning piglets (Duroc × Landrace × Yorkshire, 21 d old) were blocked by BW (6.53 ± 0.60 kg) and randomly assigned to 4 dietary treatments: negative control (NC, basal diet), positive control (PC), basal diet + ZnO at 2 g/kg and antibiotics at 0.8 g/kg), SDPP (containing 5% SDPP), and SDCP (containing 5% SDCP). The experiment lasted 14 d. The SDPP group had higher (P < 0.05) final BW, average daily gain and average daily feed intake than the NC and SDCP groups. The percentage of piglets with fecal scores at 2 or ≥2 was higher (P < 0.05) in the NC and SDCP groups than in the PC group. A decreased (P < 0.05) bacterial alpha diversity and Bacteroidetes abundance, but increased (P < 0.05) Firmicutes abundance were observed in the PC and SDPP groups when compared to the NC group. The relative abundance of Lactobacillus was higher (P < 0.05) in the SDPP than in the SDCP group, and that of Streptococcus was higher (P < 0.01) in the PC and SDPP groups than in the NC group. The PC group also had higher (P < 0.01) Faecalibacterium abundance than the NC and SDCP groups. Additionally, the SDCP group had higher (P < 0.05) serum urea nitrogen than those fed other diets, and lower (P < 0.10) short-chain fatty acids to branched-chain fatty acids ratio than the PC and SDPP groups. Overall, SDPP was a promising animal protein for piglets in increasing feed intake, modifying gut microbiota profile, reducing gut protein fermentation and alleviating diarrhea frequency, thus promoting growth performance, under the conditions with limited in-feed utilization of antibiotics and ZnO.

An Unusual Case of Subacute Appendicitis and Intestinal Spirochetosis

Intestinal spirochetosis is a gastrointestinal infection with vague and inconsistent symptoms. It similarly presents multiple gastrointestinal diseases such as inflammatory bowel disease and appendicitis. We present a case of a 27-year-old female with intestinal spirochetosis who was later found to have subacute appendicitis. Further understanding of the disease and a set of criteria may have to be created for its management.

Two-Target Quantitative PCR To Predict Library Composition for Shallow Shotgun Sequencing

When determining human microbiota composition, shotgun sequencing is a powerful tool that can generate high-resolution taxonomic and functional information at once. However, the technique is limited by missing information about host-to-microbe ratios observed in different body compartments. This limitation makes it difficult to plan shotgun sequencing assays, especially in the context of high sample multiplexing and limited sequencing output and is of particular importance for studies employing the recently described shallow shotgun sequencing technique. In this study, we evaluated the use of a quantitative PCR (qPCR)-based assay to predict host-to-microbe ratio prior to sequencing. Combining a two-target assay involving the bacterial 16S rRNA gene and the human beta-actin gene, we derived a model to predict human-to-microbe ratios from two sample types, including stool samples and oropharyngeal swabs. We then validated it on two independently collected sample types, including rectal swabs and vaginal secretion samples. This assay enabled accurate prediction in the validation set in a range of sample compositions between 4% and 98% nonhuman reads and observed proportions varied between −18.8% and +19.2% from the expected values. We hope that this easy-to-use assay will help researchers to plan their shotgun sequencing experiments in a more efficient way.

IMPORTANCE When determining human microbiota composition, shotgun sequencing is a powerful tool that can generate large amounts of data. However, in sample compositions with low or variable microbial density, shallowing sequencing can negatively affect microbial community metrics. Here, we show that variable sequencing depth decreases measured alpha diversity at differing rates based on community composition. We then derived a model that can determine sample composition prior to sequencing using quantitative PCR (qPCR) data and validated the model using a separate sample set. We have included a tool that uses this model to be available for researchers to use when gauging shallow sequencing viability of samples.

Intestinal Spirochetosis in an HIV-positive Patient

We present the case of an HIV-positive patient admitted because of costal pain secondary to neoplasia. During investigations, a colonoscopy showed non-specific ulcerations. Histological examination resulted in a diagnosis of intestinal spirochetosis. This infection can be asymptomatic or cause non-specific symptoms such as diarrhoea or abdominal pain. Intestinal spirochetosis should be included in the differential diagnosis of colon lesions in patients with HIV infection.

LEARNING POINTS

Intestinal spirochetosis is associated with chronic diarrhoea and often with normal colonoscopy.This infection should be included in the differential diagnosis of HIV patients with digestive symptomatology in the absence of other more frequent causes.

Association between Brachyspira and irritable bowel syndrome with diarrhoea

OBJECTIVE

The incidence of IBS increases following enteric infections, suggesting a causative role for microbial imbalance. However, analyses of faecal microbiota have not demonstrated consistent alterations. Here, we used metaproteomics to investigate potential associations between mucus-resident microbiota and IBS symptoms.

DESIGN

Mucus samples were prospectively collected from sigmoid colon biopsies from patients with IBS and healthy volunteers, and their microbial protein composition analysed by mass spectrometry. Observations were verified by immunofluorescence, electron microscopy and real-time PCR, further confirmed in a second cohort, and correlated with comprehensive profiling of clinical characteristics and mucosal immune responses.

RESULTS

Metaproteomic analysis of colon mucus samples identified peptides from potentially pathogenic Brachyspira species in a subset of patients with IBS. Using multiple diagnostic methods, mucosal Brachyspira colonisation was detected in a total of 19/62 (31%) patients with IBS from two prospective cohorts, versus 0/31 healthy volunteers (p<0.001). The prevalence of Brachyspira colonisation in IBS with diarrhoea (IBS-D) was 40% in both cohorts (p=0.02 and p=0.006 vs controls). Brachyspira attachment to the colonocyte apical membrane was observed in 20% of patients with IBS and associated with accelerated oro-anal transit, mild mucosal inflammation, mast cell activation and alterations of molecular pathways linked to bacterial uptake and ion-fluid homeostasis. Metronidazole treatment paradoxically promoted Brachyspira relocation into goblet cell secretory granules-possibly representing a novel bacterial strategy to evade antibiotics.

CONCLUSION

Mucosal Brachyspira colonisation was significantly more common in IBS and associated with distinctive clinical, histological and molecular characteristics. Our observations suggest a role for Brachyspira in the pathogenesis of IBS, particularly IBS-D.

A Case of Human Intestinal Spirochetosis Diagnosed During Screening Colonoscopy

Human intestinal spirochetosis (HIS) is a rare disease and mostly encountered incidentally during colorectal cancer screening colonoscopy. Risk factors include homosexuality and immunocompromised states. Patients are usually asymptomatic; however, chronic diarrhea and bloody stools have been reported in some cases. Diagnosis is usually confirmed by histopathology. A watch-and-see approach is usually acceptable, but successful treatment with Metronidazole has been reported in symptomatic cases. Its clinical significance remains questionable given that patients are mostly asymptomatic.

Impairment of electroneutral Na+ transport and associated downregulation of NHE3 contributes to the development of diarrhea following in vivo challenge with Brachyspira spp

The effect of Brachyspira hyodysenteriae and Brachyspira hampsonii spirochetosis on Na⁺ transport was assessed in the colon to determine its contribution to diarrheal disease in pigs following experimental infection. Electrogenic and electroneutral Na⁺ absorption was assessed in Ussing chambers by radiolabeled ²²Na flux and pharmacological inhibitory studies. Basal radiolabeled ²²Na flux experiments revealed that mucosal-to-serosal flux (J_ms) was significantly impaired in B. hyodysenteriae and B. hampsonii-diseased pigs. Inhibition of epithelial sodium channel via amiloride did not significantly reduce electrogenic short-circuit current (I_sc) in the proximal, apex, and distal colonic segments of diseased pigs over control pigs, suggesting that a loss of electroneutral Na⁺ absorption is responsible for diarrheal development. These findings were further supported by significant downregulation of Na⁺/H⁺ exchanger (NHE1, NHE2, and NHE3) mRNA expression in the proximal, apex, and distal colonic segments paired with decreased protein expression of the critical NHE3 isoform. The decrease in NHE3 mRNA expression appears not to be attributed to the host's cytokine response as human IL-1α did not modify NHE3 mRNA expression in Caco-2 cells. However, a whole cell B. hampsonii lysate significantly downregulated NHE3 mRNA expression and significantly increased p38 phosphorylation in Caco-2 cells. Together these findings provide a likely mechanism for the spirochete-induced malabsorptive diarrhea, indicated by a decrease in electroneutral Na⁺ absorption in the porcine colon due to Brachyspira's ability to inhibit NHE3 transcription, resulting in diarrheal disease.NEW & NOTEWORTHY This research demonstrates that diarrheal disease caused by two infectious spirochete spp. is a result of impaired electroneutral Na⁺ absorption via Na⁺/H⁺ exchanger 3 (NHE3) in the porcine colon. Our findings suggest that the decrease in NHE3 mRNA and protein is not likely a result of the host's cytokine response. Rather, it appears that these two Brachyspira spp. directly inhibit the transcription and translation of NHE3, resulting in the development of diarrhea.

Severe Human Intestinal Spirochetosis: An Unusual Cause of Diffuse Colonic Ulcerations in a Patient Living with HIV

We describe a case of a homosexual male with human immunodeficiency virus (HIV) and CD4 count of 246 presenting with acute severe bloody diarrhea. Infectious work up was negative, and colonoscopy revealed severe diffuse colonic ulcerations. Histopathologic analysis and Treponemal pallidum immunostaining confirmed the diagnosis of intestinal spirochetosis. There was no evidence of co-infection with other pathogens. His symptoms completely resolved after a 14-day course of metronidazole. This case is notable as colonic ulceration of any severity in patients living with HIV is rarely identified with intestinal spirochetosis. Hence, it should be considered in the differential diagnosis of colonic ulcerations.

Isolates from Colonic Spirochetosis in Humans Show High Genomic Divergence and Potential Pathogenic Features but Are Not Detected Using Standard Primers for the Human Microbiota

This is the first report of whole-genome analysis of clinical isolates from individuals with colonic spirochetosis. This characterization provides new opportunities in understanding the physiology and potentials of these bacteria that densely colonize the gut in the individuals infected. The observation that standard 16S amplicon primers fail to detect colonic spirochetosis may have major implications for studies searching for associations between members of the microbiota and clinical conditions such as irritable bowel syndrome (IBS) and should be taken into consideration in project design and interpretation of gastrointestinal tract microbiota in population-based and clinical settings.

Colonic spirochetosis, diagnosed based on the striking appearance in histological sections, still has an obscure clinical relevance, and only a few bacterial isolates from this condition have been characterized to date. In a randomized, population-based study in Stockholm, Sweden, 745 healthy individuals underwent colonoscopy with biopsy sampling. Of these individuals, 17 (2.3%) had colonic spirochetosis, which was associated with eosinophilic infiltration and a 3-fold-increased risk for irritable bowel syndrome (IBS). We aimed to culture the bacteria and perform whole-genome sequencing of the isolates from this unique representative population sample. From 14 out of 17 individuals with spirochetosis we successfully isolated, cultured, and performed whole-genome sequencing of in total 17 isolates, including the Brachyspira aalborgi type strain, 513A. Also, 16S analysis of the mucosa-associated microbiota was performed in the cases and nonspirochetosis controls. We found one isolate to be of the species Brachyspira pilosicoli; all remaining isolates were of the species Brachyspira aalborgi. Besides displaying extensive genetic heterogeneity, the isolates harbored several mucin-degrading enzymes and other virulence-associated genes that could confer a pathogenic potential in the human colon. We also showed that 16S amplicon sequencing using standard primers for human microbiota studies failed to detect Brachyspira due to primer incompatibility.

IMPORTANCE This is the first report of whole-genome analysis of clinical isolates from individuals with colonic spirochetosis. This characterization provides new opportunities in understanding the physiology and potentials of these bacteria that densely colonize the gut in the individuals infected. The observation that standard 16S amplicon primers fail to detect colonic spirochetosis may have major implications for studies searching for associations between members of the microbiota and clinical conditions such as irritable bowel syndrome (IBS) and should be taken into consideration in project design and interpretation of gastrointestinal tract microbiota in population-based and clinical settings.

Decreased electrogenic anionic secretory response in the porcine colon following in vivo challenge with Brachyspira spp. supports an altered mucin environment

Brachyspira spp. cause diarrheal disease in multiple animal species by colonization of the colon, resulting in colitis, mucus induction, and disrupted ion transport. Unique to spirochete pathogenesis is the immense production of mucus, resulting in a niche mucin environment likely favoring spirochete colonization. Mucin rheological properties are heavily influenced by anionic secretion, and loss of secretory function has been implicated in diseases such as cystic fibrosis. Here, the effects on the agonist-induced electrogenic anionic secretory response by infectious colonic spirochete bacteria Brachyspira hyodysenteriae and Brachyspira hampsonii were assessed in the proximal, apex, and distal sections of colon in Ussing chambers. Activation of secretion via isoproterenol, carbachol, and forskolin/3-isobutyl-1-methylxanthine demonstrated a significantly decreased change in short-circuit current ( I_sc) in Brachyspira-infected pigs in all sections. Tissue resistances did not account for this difference, rather, it was attributed to a decrease in anionic secretion as indicated by a decrease in bumetanide inhibitable I_sc. Quantitative RT-PCR and Western blot analyses determined that the major anionic channels of the epithelium were downregulated in diarrheic pigs paired with altered mucin gene expression. The investigated cytokines were not responsible for the downregulation of anion channel gene transcripts. Although IL-1α was upregulated in all segments, it did not alter cystic fibrosis transmembrane conductance regulator (CFTR) mRNA expression in Caco-2 monolayers. However, a whole cell Brachyspira hampsonii lysate significantly reduced CFTR mRNA expression in Caco-2 monolayers. Together, these findings indicate that these two Brachyspira spp. may directly cause a decreased anionic secretory response in the porcine colon, supporting an altered mucin environment likely favoring spirochete colonization. NEW & NOTEWORTHY This research demonstrates for the first time that the niche mucin environment produced by two infectious spirochete spp. is supported by a decrease in the electrogenic anionic secretory response throughout the porcine colon. Our findings suggest that the host's cytokine response is not likely responsible for the decrease in anionic secretory function. Rather, it appears that Brachyspira spp. directly impede ion channel transcription and translation, potentially altering colonic mucin rheological properties, which may favor spirochete colonization.

Intestinal Spirochetosis: A Case Series and Review of the Literature

A clinical suspicion of intestinal spirochetosis is required when patients have long lasting complaints of abdominal pain, diarrhea, rectal bleeding, weight loss, and nausea. An endoscopy with biopsies needs to be performed to confirm the diagnosis of intestinal spirochetosis. The diagnosis of intestinal spirochetosis is based on histological appearance. Intestinal spirochetosis can also be associated with other intestinal infections and juvenile polyps (JPs). JPs seem to be more frequent in patients with intestinal spirochetosis than in patients without intestinal spirochetosis. Intestinal spirochetosis in children should be treated with antibiotics. Metronidazole is the preferred option. In this article, we describe 4 cases of intestinal spirochetosis in a pediatric population and provide a review of the literature over the last 20 years. Intestinal spirochetosis is a rare infection that can cause a variety of severe symptom. It is diagnosed based on histological appearance.

Linkages between Epithelial Microbiota and Host Transcriptome in the Ileum during High-Grain Challenges: Implications for Gut Homeostasis in Goats

A high-grain (HG) diet can result in ruminal subacute acidosis, which is detrimental to gut health and can lead to decreased productivity. This study investigated the ileal epithelial microbiota and its relationship with host epithelial function in goats fed a HG diet (concentrate/hay, 90:10) and a control diet (concentrate/hay, 55:45), aiming to elucidate the mechanisms involved in ileal adaptation to subacute acidosis. The HG challenge increased the ileal volatile fatty acid concentration ( p = 0.030) and altered the ileal epithelial microbiota by increasing (FDR < 0.05) relative abundances of active carbohydrate and protein degraders Synergistetes, Prevotella, Fibrobacter, Clostridium, Treponema, and unclassified Ruminococcaceae by 20.1-, 6.3-, 16.8-, 8.5-, 19.9-, and 7.1-fold, respectively. However, the HG diet tended to reduce (FDR < 0.10) the relative abundance of Candidatus Arthromitus (38.8 ± 36.1 versus 2.1 ± 3.1). Microbial functional potentials inferred using PICRUSt indicated that the HG challenge elevated abundances of pathways associated with metabolism of amino acid, glycan, cofactors, and vitamins, whereras it decreased pathways associated with signal transduction, xenobiotic biodegradation, and metabolism. Additionally, in the ileal epithelium of HG goats, transcriptome analysis identified the increment (FDR < 0.10) of candidate genes involved in metabolism of carbohydrates, lipids, proteins, vitamins, and the proinflammatory cytokine pathway, while downregulating genes encoding antimicrobials and complements (FDR < 0.05). Collectively, the HG challenge shifted the structure and functional potentials of the ileal microbial community and affected the host responses in the ileum of goats toward increased metabolic activities of macro- and micronutrients, together with an increased risk of gut inflammation.

Fecal Microbiota Transplantation Is Associated With Reduced Morbidity and Mortality in Porcine Circovirus Associated Disease

Porcine circovirus associated disease (PCVAD) is a term used to describe the multi-factorial disease syndromes caused by porcine circovirus type 2 (PCV-2), which can be reproduced in an experimental setting through the co-infection of pigs with PCV-2 and porcine reproductive and respiratory syndrome virus (PRRSV). The resulting PCVAD-affected pigs represent a subpopulation within the co-infected group. In co-infection studies, the presence of increased microbiome diversity is linked to a reduction in clinical signs. In this study, fecal microbiota transplantation (FMT) was investigated as a means to prevent PCVAD in pigs co-infected with PRRSV and PCV-2d. The sources of the FMT material were high-parity sows with a documented history of high health status and robust litter characteristics. The analysis of the donated FMT material showed the absence of common pathogens along with the presence of diverse microbial phyla and families. One group of pigs (n = 10) was administered the FMT while a control group (n = 10) was administered a sterile mock-transplant. Over the 42-day post-infection period, the FMT group showed fewer PCVAD-affected pigs, as evidenced by a significant reduction in morbidity and mortality in transplanted pigs, along with increased antibody levels. Overall, this study provides evidence that FMT decreases the severity of clinical signs following co-infection with PRRSV and PCV-2 by reducing the prevalence of PCVAD.

Intestinal Spirochetosis: An Obscure Cause of Lower Gastrointestinal Bleeding

Adherence of spirochetes to the apical membrane of the colonic epithelium has been well-described in the literature, but the exact pathogenesis leading to symptomatic clinical manifestations is poorly understood. Most cases are found incidentally on the pathological evaluation of colonic biopsies taken during diagnostic or therapeutic colonoscopies. However, whether the colonization of the intestinal mucosa can be attributed to clinical symptoms is a matter of debate. Here, we present a case of intermittent hematochezia attributed to the overwhelming invasion of the colonic mucosa by intestinal spirochetes.

Intestinal Spirochetosis in an Immunocompetent Patient

Intestinal spirochetosis (IS) is an infestation defined by the presence of spirochetes on the surface of the colonic mucosa. The implicated organisms can be Brachyspiraaalborgior Brachyspirapilosicoli. We present the case of a 66-year-old man with a past medical history of diabetes mellitus, hypertension, morbid obesity, and gastroesophageal reflux. The patient was sent to the gastroenterology clinic for a screening colonoscopy due to a prior history of colonic polyps. The patient was completely asymptomatic as he denies any abdominal pain, diarrhea, melena, or hematochezia. A colonoscopy was done showing colitis in the cecum and at the ileocecal valve, for which random biopsies were taken in the terminal ileum, cecum, and ascending colon. The histopathology result was positive for spirochetosis. Due to this finding, the patient was referred to the infectious diseases clinic, where a rapid plasma reagin (RPR) and human immunodeficiency virus (HIV) tests were found to be negative. Since the patient was immunocompetent and asymptomatic, it was decided to monitor and not initiate antibiotic treatment. Human IS are not related to non-intestinal spirochetes like Treponema pallidum. An infection of T. pallidum leads to a malignant picture called syphilitic proctitis and appears in the setting of an immunocompromised patient. The treatment of IS is based on the clinical presentation, severity of symptoms, and immune status. The purpose of this case is to emphasize the correct antibiotic indication in patients with IS.

Treponema pallidum Immunohistochemistry is positive in human intestinal Spirochetosis

BACKGROUND

Human intestinal spirochetosis (IS) has been recognized for decades, but whether it represents commensalism or a pathogenic process remains controversial. IS is diagnosed on routine stains with confirmation by silver stains but these stains are labor intensive and slow to read. We evaluated the Treponema pallidum immunostain as a diagnostic adjunct for IS.

METHODS

We retrieved biopsies from 33 patients with IS for this study. Each case was tested by Warthin-Starry (WS) and T. pallidum immunohistochemistry (IHC). Species specific genotyping was performed in 3 cases.

RESULTS

Patients with IS ranged from 22 to 82 years without gender predilection. IS involved normal (n = 15), and inflamed (n = 5) mucosa and colonic polyps (n = 13). Warthin-Starry and T. pallidum IHC were positive in all cases including both species of Brachyspira. Six (18%) symptomatic patients were treated for IS, and experienced resolution. In patients diagnosed with incidental IS on cancer screening (n = 5), follow up biopsies, without therapy, were negative for IS. T. pallidum IHC required 75 min less hands-on time than WS for performance and was faster to interpret.

CONCLUSIONS

T. pallidum IHC can be used to confirm the diagnosis of IS and is easier to perform and faster to interpret than WS.

The Spirochete Brachyspira pilosicoli, Enteric Pathogen of Animals and Humans

Brachyspira pilosicoli is a slow-growing anaerobic spirochete that colonizes the large intestine. Colonization occurs commonly in pigs and adult chickens, causing colitis/typhlitis, diarrhea, poor growth rates, and reduced production. Colonization of humans also is common in some populations (individuals living in village and peri-urban settings in developing countries, recent immigrants from developing countries, homosexual males, and HIV-positive patients), but the spirochete rarely is investigated as a potential human enteric pathogen. In part this is due to its slow growth and specialized growth requirements, meaning that it is not detectable in human fecal samples using routine diagnostic methods. Nevertheless, it has been identified histologically attached to the colon and rectum in patients with conditions such as chronic diarrhea, rectal bleeding, and/or nonspecific abdominal discomfort, and one survey of Australian Aboriginal children showed that colonization was significantly associated with failure to thrive. B. pilosicoli has been detected in the bloodstream of elderly patients or individuals with chronic conditions such as alcoholism and malignancies. This review describes the spirochete and associated diseases. It aims to encourage clinicians and clinical microbiologists to consider B. pilosicoli in their differential diagnoses and to develop and use appropriate diagnostic protocols to identify the spirochete in clinical specimens.

Intestinal spirochaetosis mimicking acute appendicitis with review of the literature

Human intestinal spirochaetosis is a well-established micro-organism existing in the colon. It is less commonly seen in the appendix, and rarely presents as acute appendicitis. We present a case of a man presenting with symptoms consistent with acute appendicitis. The literature on spirochaetosis presenting as acute appendicitis is also reviewed.

Brachyspira hyodysenteriae and B. pilosicoli Proteins Recognized by Sera of Challenged Pigs

The spirochetes Brachyspira hyodysenteriae and B. pilosicoli are pig intestinal pathogens that are the causative agents of swine dysentery (SD) and porcine intestinal spirochaetosis (PIS), respectively. Although some inactivated bacterin and recombinant vaccines have been explored as prophylactic treatments against these species, no effective vaccine is yet available. Immunoproteomics approaches hold the potential for the identification of new, suitable candidates for subunit vaccines against SD and PIS. These strategies take into account the gene products actually expressed and present in the cells, and thus susceptible of being targets of immune recognition. In this context, we have analyzed the immunogenic pattern of two B. pilosicoli porcine isolates (the Spanish farm isolate OLA9 and the commercial P43/6/78 strain) and one B. hyodysenteriae isolate (the Spanish farm V1). The proteins from the Brachyspira lysates were fractionated by preparative isoelectric focusing, and the fractions were analyzed by Western blot with hyperimmune sera from challenged pigs. Of the 28 challenge-specific immunoreactive bands detected, 21 were identified as single proteins by MS, while the other 7 were shown to contain several major proteins. None of these proteins were detected in the control immunoreactive bands. The proteins identified included 11 from B. hyodysenteriae and 28 from the two B. pilosicoli strains. Eight proteins were common to the B. pilosicoli strains (i.e., elongation factor G, aspartyl-tRNA synthase, biotin lipoyl, TmpB outer membrane protein, flagellar protein FlaA, enolase, PEPCK, and VspD), and enolase and PEPCK were common to both species. Many of the identified proteins were flagellar proteins or predicted to be located on the cell surface and some of them had been previously described as antigenic or as bacterial virulence factors. Here we report on the identification and semiquantitative data of these immunoreactive proteins which constitute a unique antigen collection from these bacteria.

Intestinal Bacterial Infection Diagnosed by Histological Examination of Endoscopic Biopsy Specimens

Intestinal spirochetosis (IS) in humans is characterized by spirochetal microorganisms attached to the luminal surface of the colonic epithelium. In the present case, attached organisms appeared as 3- to 4 μm-thick (average thickness, 3.4 μm) basophilic fringes or haze in HE-stained endoscopic biopsy specimens. The basophilic fringes were clearly labeled by Treponema pallidum antiserum. Because IS is relatively rare in developed countries, thin basophilic fringes characteristic of IS are readily overlooked. Thus, the recognition of histological characteristics of this disease is important for its diagnosis.

Colonic Spirochetosis in a 60-Year-Old Immunocompetent Patient: Case Report and Review

Spirochetes, a genetically and morphologically distinct group of bacteria, are thin, spiral-shaped, and highly motile. They are known causes of several human diseases such as syphilis, Lyme disease, relapsing fever, and leptospirosis. We report a case of colonic spirochetosis in a healthy patient presenting for surveillance colonoscopy. The diagnosis of intestinal spirochetosis was made accidentally during the histological examination of colonic polyps, which were removed during colonoscopy. We also performed an extensive review on intestinal spirochetosis with a focus on clinical presentation and outcomes of reported cases from the past two decades.

Biogeography of the intestinal mucosal and lumenal microbiome in the rhesus macaque

The gut microbiome is widely studied by fecal sampling, but the extent to which stool reflects the commensal composition at intestinal sites is poorly understood. We investigated this relationship in rhesus macaques by 16S sequencing feces and paired lumenal and mucosal samples from ten sites distal to the jejunum. Stool composition correlated highly with the colonic lumen and mucosa and moderately with the distal small intestine. The mucosal microbiota varied most based on location and was enriched in oxygen-tolerant taxa (e.g., Helicobacter and Treponema), while the lumenal microbiota showed inter-individual variation and obligate anaerobe enrichment (e.g., Firmicutes). This mucosal and lumenal community variability corresponded to functional differences, such as nutrient availability. Additionally, Helicobacter, Faecalibacterium, and Lactobacillus levels in stool were highly predictive of their abundance at most other gut sites. These results quantify the composition and biogeographic relationships between gut microbial communities in macaques and support fecal sampling for translational studies.

Appendiceal spirochaetosis in children

Background

Acute appendicitis is a surgical emergency in which the appendix is surgically removed to prevent peritonitis due to perforation of the appendix. Depending on age and gender, up to 17% of removed appendices do not show the histopathological changes pathognomonic for acute appendicitis and are called ‘pseudo-appendicitis’. Intestinal spirochaetes have been reported in up to 12.3% of these non-inflamed appendices obtained from adults. Although children carry the highest risk for acute appendicitis, not much is known on the prevalence of intestinal spirochaetes in children. The aim of this study was to determine whether there is an association between pseudo-appendicitis and appendiceal spirochaetosis in children.

Methods

Archival appendix specimens from paediatric patients (less than 18 years old) were obtained from two Dutch hospitals (acute appendicitis, n = 63; pseudo-appendicitis, n = 55; control appendices, n = 33) and microscopically analysed by H&E staining and spirochaete-specific immunohistochemistry and Brachyspira species specific real-time PCR.

Results

Five out of 142 appendices were found to be positive, all in male patients: one in the acute appendicitis group, two in the pseudo-appendicitis group and two in the control group.

Conclusion

The results obtained do not provide evidence for a role of Brachyspira species infection in the aetiology of acute appendicitis in children.

Intestinal spirochetosis: an enigmatic disease

INTRODUCTION

Intestinal spirochetosis (IS) is a condition in which colonic and appendiceal epithelial cells are colonized by one of two anaerobic spirochetes, either the Brachyspira aalborgi or Brachyspira pilosicoli. There is much debate in the literature as to whether IS is a pathogen or a commensal inhabitant. A recent case of IS at our institution prompted a retrospective database search and review of the literature.

METHODS

A pathology database search for IS was performed at Carolinas Medical Center from 2003 through 2007. After patient identification, a retrospective review of the endoscopic record and the pathology report was performed. Pathology slides were reviewed for accuracy and special silver stains and/or immunostains were performed if needed. The following data were collected for each patient when available: age, gender, nationality, HIV status, and other co-morbid conditions when noted. We attempted to determine whether patients were treated for spirochetosis and if so, the treatment regimen used as well as the results.

RESULTS

The database search detected 29 patients with biopsies showing IS. Three patients were subsequently removed due to incorrect identification. A total of 26 patients with an average age of 45 years were reviewed. The most common symptoms were abdominal pain, diarrhea, and rectal bleeding. Most patients did not exhibit inflammatory changes despite the presence of spirochetosis. Pathologic examination revealed a relative increase in intra-epithelial lymphocytes in a subset of cases, a non-specific finding. Acute colitis or architectural distortion was not seen in any of the study cases. We were only able to obtain follow-up of two patients after treatment with metronidazole and both responded to therapy.

CONCLUSIONS

To date, our study is the largest case series that includes both endoscopic and pathologic descriptions and confirms the "bland" nature of the condition. In <20 % of our patients inflammation was present microscopically and it did not correlate well with endoscopic appearance. Symptoms reported by our patients were similar to those reported in previous studies, although our lack of endoscopic changes was different from one previous paper. There is no established standard of care for the treatment of IS and our study, reflects the enigmatic nature of IS as a disease process. In the absence of rigorous literature, physicians will need to use a logical and pragmatic approach to the evaluation and treatment of IS.

Intestinal spirochetosis mimicking inflammatory bowel disease in children

Background

Intestinal spirochetosis is an unusual infection in children and its clinical significance in humans is uncertain. The presence of these microorganisms in humans is well-known since the late 1800’s and was first described in 1967 by Harland and Lee by electron microscopy.

Case presentation

This article reports the findings of one pediatric case, review of the current literature, and an overview of therapeutic options.

Conclusion

A high degree of suspicion is required in cases presenting with abdominal pain, chronic diarrhoea and/or hematochezia associated with a normal endoscopic examination, thus emphasizing the importance of multiple biopsies throughout the colon.

Comparative genomics of Brachyspira pilosicoli strains: genome rearrangements, reductions and correlation of genetic compliment with phenotypic diversity

Background

The anaerobic spirochaete Brachyspira pilosicoli causes enteric disease in avian, porcine and human hosts, amongst others. To date, the only available genome sequence of B. pilosicoli is that of strain 95/1000, a porcine isolate. In the first intra-species genome comparison within the Brachyspira genus, we report the whole genome sequence of B. pilosicoli B2904, an avian isolate, the incomplete genome sequence of B. pilosicoli WesB, a human isolate, and the comparisons with B. pilosicoli 95/1000. We also draw on incomplete genome sequences from three other Brachyspira species. Finally we report the first application of the high-throughput Biolog phenotype screening tool on the B. pilosicoli strains for detailed comparisons between genotype and phenotype.

Results

Feature and sequence genome comparisons revealed a high degree of similarity between the three B. pilosicoli strains, although the genomes of B2904 and WesB were larger than that of 95/1000 (~2,765, 2.890 and 2.596 Mb, respectively). Genome rearrangements were observed which correlated largely with the positions of mobile genetic elements. Through comparison of the B2904 and WesB genomes with the 95/1000 genome, features that we propose are non-essential due to their absence from 95/1000 include a peptidase, glycine reductase complex components and transposases. Novel bacteriophages were detected in the newly-sequenced genomes, which appeared to have involvement in intra- and inter-species horizontal gene transfer. Phenotypic differences predicted from genome analysis, such as the lack of genes for glucuronate catabolism in 95/1000, were confirmed by phenotyping.

Conclusions

The availability of multiple B. pilosicoli genome sequences has allowed us to demonstrate the substantial genomic variation that exists between these strains, and provides an insight into genetic events that are shaping the species. In addition, phenotype screening allowed determination of how genotypic differences translated to phenotype. Further application of such comparisons will improve understanding of the metabolic capabilities of Brachyspira species.

Bloodstream infection due to Brachyspira pilosicoli in a patient with multiorgan failure

Brachyspira pilosicoli is an etiological agent of human intestinal spirochetosis. Bloodstream infection due to this microorganism is rare. We report a case of B. pilosicoli bacteremia in a 70-year-old patient who presented with multiorgan failure.

Complete genome sequence of Brachyspira intermedia reveals unique genomic features in Brachyspira species and phage-mediated horizontal gene transfer

Background

Brachyspira spp. colonize the intestines of some mammalian and avian species and show different degrees of enteropathogenicity. Brachyspira intermedia can cause production losses in chickens and strain PWS/A^T now becomes the fourth genome to be completed in the genus Brachyspira.

Results

15 classes of unique and shared genes were analyzed in B. intermedia, B. murdochii, B. hyodysenteriae and B. pilosicoli. The largest number of unique genes was found in B. intermedia and B. murdochii. This indicates the presence of larger pan-genomes. In general, hypothetical protein annotations are overrepresented among the unique genes. A 3.2 kb plasmid was found in B. intermedia strain PWS/A^T. The plasmid was also present in the B. murdochii strain but not in nine other Brachyspira isolates. Within the Brachyspira genomes, genes had been translocated and also frequently switched between leading and lagging strands, a process that can be followed by different AT-skews in the third positions of synonymous codons. We also found evidence that bacteriophages were being remodeled and genes incorporated into them.

Conclusions

The accessory gene pool shapes species-specific traits. It is also influenced by reductive genome evolution and horizontal gene transfer. Gene-transfer events can cross both species and genus boundaries and bacteriophages appear to play an important role in this process. A mechanism for horizontal gene transfer appears to be gene translocations leading to remodeling of bacteriophages in combination with broad tropism.