Isolations of intestinal spirochaetes from the blood of human 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.

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.

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

The anaerobic intestinal spirochaete Brachyspira pilosicoli colonizes the large intestine of various species of mammals and birds, where it may induce colitis. Strains of the spirochaete have also been isolated from the bloodstream of immunocompromised human patients and have been seen in liver sections, and a similar systemic spread was recently observed in experimentally infected chickens. Some other spirochaete species that may be present in blood attach to and aggregate erythrocytes, and this is believed to contribute to disease severity. The aim of the current study was to determine whether B. pilosicoli strains have the capacity to attach to and aggregate erythrocytes. Initially, four strains of B. pilosicoli were incubated with erythrocytes from sheep, cows, pigs, dogs, humans, chickens and geese, and were observed by phase-contrast microscopy. Only strain WesB attached, and this was only with erythrocytes from chickens and geese. Subsequently, six other strains of B. pilosicoli were tested just with goose erythrocytes, and five attached to and caused aggregation of the erythrocytes. Scanning and transmission electron microscopy demonstrated that spirochaetes abutted and apparently firmly attached to the erythrocyte membranes. Aggregation of erythrocytes by B. pilosicoli may contribute to disease severity in species that develop a spirochaetaemia.

SIGNIFICANCE AND IMPACT OF THE STUDY

The intestinal spirochaete Brachyspira pilosicoli has been isolated from the bloodstream of immunocompromised human patients, and spread to the liver has been reported in humans and in experimentally infected chickens. In this study, B. pilosicoli was shown to undergo attachment by one cell end to chicken and goose erythrocytes in vitro and to aggregate them. This activity has the potential to contribute to disease severity in avian and possibly other species that develop a spirochaetaemia and systemic spread. Avian erythrocytes may be useful for studying the mechanisms by which B. pilosicoli attaches to cells.

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.

Evaluation of recombinant Brachyspira pilosicoli oligopeptide-binding proteins as vaccine candidates in a mouse model of intestinal spirochaetosis

The anaerobic intestinal spirochaete Brachyspira pilosicoli colonizes the large intestine of humans, and various species of animals and birds, in which it may induce a mild colitis and diarrhoea. The aim of the current study was to evaluate the use of putative oligopeptide-binding proteins of B. pilosicoli as vaccine components. A partial genome sequence of B. pilosicoli porcine strain 95/1000 was subjected to bioinformatics analysis, and six genes predicted to encode oligopeptide-binding proteins were selected. Following a PCR-based distribution study of the genes across different strains of the spirochaete, they were amplified from B. pilosicoli human strain WesB and cloned in Escherichia coli. The recombinant histidine-tagged proteins were purified and subjected to in vitro and in vivo immunogenicity analysis. Recombinant products (P-1 and P-3) from two genes that were immunogenic and recognized by sera from pigs that had recovered from B. pilosicoli infections were tested in a mouse model of intestinal spirochaetosis. For each recombinant protein, groups of 12 C3H/HeJ mice were vaccinated subcutaneously with 100 microg protein emulsified in Freund's incomplete adjuvant, twice with a 2 week interval. Two weeks later the vaccinated and non-vaccinated control animals were challenged orally with B. pilosicoli strain WesB. Both proteins induced systemic and local colonic IgG antibody responses, and, following experimental infection, the cumulative number of colonization days was significantly (P<0.001) less in both groups of vaccinated mice compared to the control mice. There were significantly (P=0.012) fewer mice colonized in the group vaccinated with P-1 than in the non-vaccinated control group. The results suggest that oligopeptide-binding proteins may have potential for use as components of vaccines for B. pilosicoli.

Isolation of the anaerobic intestinal spirochaete Brachyspira pilosicoli from long-term residents and Indonesian visitors to Perth, Western Australia

Brachyspira pilosicoli is an anaerobic spirochaete that colonizes the large intestine of humans and various species of animals and birds. The spirochaete is an important enteric pathogen of pigs and poultry, but its pathogenic potential in humans is less clear. In the current study, the occurrence of B. pilosicoli in faecal samples from 766 individuals in two different population groups in Perth, Western Australia, was investigated by selective anaerobic culture. Of 586 individuals who were long-term residents of Perth, including children, elderly patients in care and in hospital and individuals with gastrointestinal disease, only one was culture positive. This person had a history of diverticulitis. In comparison, faeces from 17 of 180 (9.4 %) Indonesians who were short- or medium-term visitors to Perth were positive for B. pilosicoli. The culture-positive individuals had been in the city for between 10 days and 4.5 years (median 5 months). Resampling of subsets of the Indonesians indicated that all negative people remained negative and that some positive individuals remained positive after 5 months. Two individuals had pairs of isolates recovered after 4 and 5 months that had the same PFGE types, whilst another individual had isolates with two different PFGE types that were identified 2 months apart. Individuals who were culture-positive were likely to have been either colonized in Indonesia before arriving in Perth or infected in Perth following contact with other culture-positive Indonesians with whom they socialized. Colonization with B. pilosicoli was not significantly associated with clinical signs at the time the individuals were tested, although faeces with wet-clay consistency were 1.5 times more likely (confidence interval 0.55-4.6) than normal faeces to contain B. pilosicoli.

Penicillin resistance in the intestinal spirochaete Brachyspira pilosicoli associated with OXA-136 and OXA-137, two new variants of the class D beta-lactamase OXA-63

Penicillin resistance mediated by beta-lactamase activity has been reported previously in the anaerobic intestinal spirochaete Brachyspira pilosicoli, and a novel class D beta-lactamase (OXA-63) hydrolysing oxacillin was described recently in a resistant human strain from France. In the current study, 18 B. pilosicoli strains from Australia and Papua New Guinea were tested for ampicillin and oxacillin susceptibility, and investigated for the presence of the class D beta-lactamase gene blaOXA-63 using PCR. PCR products were amplified from seven human and four porcine strains that were penicillin resistant, but not from seven penicillin-sensitive strains. Sequence analysis of the whole gene amplified from seven of the resistant strains from humans and pigs revealed only minor nucleotide differences among them, but there were significant differences compared with blaOXA-63. The predicted amino acid sequence of the enzyme from all seven strains had the same key structural motifs as the previously reported OXA-63, but two variants with 94-95% identity with OXA-63 were identified. OXA-136 had an additional amino acid and 12 other consistent amino acid substitutions compared with OXA-63. OXA-137 had the same differences compared with OXA-63 as OXA-136, but had an additional amino acid substitution at position 16. No structures consistent with integrons or transposons were found in the nucleotide sequences in the vicinity of blaOXA-136 in partially sequenced B. pilosicoli strain 95/1000, and the GC content (25.2 mol%) of the gene was similar to that of the whole genome. The gene encoding OXA-136 from B. pilosicoli strain Cof-10 conferred penicillin resistance on Escherichia coli. This study shows that penicillin resistance in human and porcine B. pilosicoli strains from Australia is associated with the production of two variants of OXA-63, and that susceptible strains lack the genes encoding OXA-63 or the variants.

Brachyspira pilosicoli bloodstream infections: case report and review of the literature

Brachyspira pilosicoli is the etiologic agent of human and animal intestinal spirochetosis and is rarely implicated as a cause of bacteremia. Here, we describe the case of a B. pilosicoli spirochetemia in a 53-year-old male patient suffering from cardiogenic shock. This fastidious bacterium was isolated from blood, likely after translocation from the intestinal tract. Blood cultures were positive after 5 days of incubation (one day after the patient's death), highlighting the problem of the recovery of such type of fastidious bacterium. Identification was achieved by molecular methods (16S rRNA sequencing). A review of the English literature found only 8 cases of bacteremia caused by B. pilosicoli, mostly in immunocompromised or critically ill patients. Finally, difficulties in rapid and accurate diagnosis of B. pilosicoli bloodstream infections, in vitro antimicrobial susceptibility of human clinical isolates, and therapeutic options are discussed.

Human intestinal spirochetosis:Brachyspira aalborgiand/orBrachyspira pilosicoli?

Intestinal spirochetosis in humans (HIS) is a condition defined by the presence of a layer of spirochetes attached by one cell end to the colorectal epithelium. The pathologic significance of HIS is uncertain, but it has been linked to chronic diarrhea and other abdominal complaints. Two anaerobic intestinal spirochete species have been associated with HIS, namelyBrachyspira pilosicoliandBrachyspira aalborgi.Brachyspira pilosicoli, which colonizes many animal species, is common (~30%) in the feces of people from developing countries, including Australian Aborigines, and in HIV+ patients and male homosexuals in Western societies. It is also commonly seen attached to the rectal mucosa of homosexual males. In other groups in Western societies both the presence of B.pilosicoliin feces and histologic HIS are uncommon (~1.5%).Brachyspira aalborgiis an extremely slow growing and fastidious spirochete, which previously had been isolated from an HIS patient in Denmark. Recent studies using polymerase chain reaction amplification of DNA from intestinal biopsies from a series of cases of HIS in the general Western population demonstrated thatB. aalborgi, rather thanB. pilosicoli, was the main spirochete species involved in these patients. This review outlines recent developments in the study of HIS and the two spirochete species, and identifies priorities for future research.

Colonic spirochetosis in animals and humans

Colonic spirochetosis is a disease caused by the gram-negative bacteria Brachyspira aalborgi and Brachyspira pilosicoli. B. pilosicoli induces disease in both humans and animals, whereas B. aalborgi affects only humans and higher primates. Symptoms in humans include diarrhea, rectal bleeding, and abdominal cramps. Colonic spirochetosis is common in third world countries; however, in developed countries, the disease is observed mainly in homosexual males. Terminally ill patients infected with Brachyspira are particularly at risk for developing spirochetemia. Diarrhea, poor growth performance, and decreased feed-to-gain efficiency is seen in pigs with colonic spirochetosis. The disease in chickens is characterized by delayed and/or reduced egg production, diarrhea, poor feed conversion, and retarded growth. Thus, colonic spirochetosis can represent a serious economic loss in the swine and poultry industries. The organisms are transmitted by the fecal-oral route, and several studies have demonstrated that human, primate, pig, dog, or bird strains of B. pilosicoli can be transmitted to pigs, chickens, and mice. B. pilosicoli may be a zoonotic pathogen, and although it has not been demonstrated, there is a possibility that both B. pilosicoli and B. aalborgi can be transferred to humans via contact with the feces of infected animals, meat from infected animals, or food contaminated by food handlers. Neither B. pilosicoli nor B. aalborgi has been well characterized in terms of basic cellular functions, pathogenicity, or genetics. Studies are needed to more thoroughly understand these Brachyspira species and their disease mechanisms.

Prevalence, risk factors and molecular epidemiology of Brachyspira pilosicoli in humans on the island of Bali, Indonesia

The purpose of this study was to investigate the prevalence and epidemiology of the anaerobic intestinal spirochaete Brachyspira pilosicoli amongst Indonesians living in rural and urban settings on the island of Bali. Faecal samples (n = 992) were collected on two occasions, 4 months apart, from people living in four traditional farming villages, one peri-urban location and one urban area. Samples were cultured anaerobically on selective agar and intestinal spirochaete isolates were confirmed to be B. pilosicoli by using a species-specific PCR. Forty-eight of the 121 isolates obtained were typed by using PFGE. A questionnaire was administered to participants and analysed in order to identify potential risk factors for colonization. Overall prevalence of carriage on the two visits was 11.8 and 12.6 %, respectively. Prevalence at different locations varied from 3.3 to 23.4 %, with the highest prevalence occurring in the peri-urban location. Considerable strain diversity was found, with the 48 isolates being divided into 44 PFGE types. There was no significant association between colonization and ownership of animals, contact with animals, farming, age or gender. On the first visit, colonization was significantly more common in people who used well water compared to those who used tap water. On the second visit, colonization was significantly more common in people with wet faeces than in those with normal faeces.

Human intestinal spirochaetosis: any clinical significance?

Spirochaetes are well known causative agents of diarrhoea in veterinary medicine. In human medicine the relationship between presence of spirochaetes in the colon on the one hand, and its clinical significance on the other, is far less clear. In the majority of cases the colonization of the colon with these micro-organisms seems to represent a commensal relationship with the host, and is almost always a coincidental finding with no association with the clinical symptoms of the patient whatsoever. Very infrequently the organism may become invasive. In this article the literature on human intestinal spirochaetosis is reviewed, and key points for daily clinical practice are emphasized.

In vitro antimicrobial susceptibility of Brachyspira pilosicoli isolates from humans

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

Experimental infection of layer hens with a human isolate of Brachyspira pilosicoli

The anaerobic intestinal spirochaete Brachyspira pilosicoli commonly colonizes the large intestine of a number of species, including chickens and human beings. The purpose of the current study was to determine whether an isolate of B. pilosicoli recovered from an HIV-infected patient with diarrhoea could infect and cause disease in adult chickens. Over a 4-week period following experimental infection, a group of eight inoculated chickens showed a persistent and significant increase in faecal water content ( approximately 6-7 %). The faeces of three of the eight birds became culture-positive, and remained so. At post-mortem examination, no specific pathological changes were found, and no spirochaetal attachment to the caecal epithelium was observed. These findings confirm that B. pilosicoli strains can infect across species barriers and cause chronic mild diarrhoea in intact adult chickens.

Intestinal spirochetosis in eight pediatric patients from Southern Sweden

Intestinal spirochetes in humans have been recognized for more than a century, but it is still a matter of debate whether they are just commensal organisms or whether they cause colorectal disease. Most descriptions to date are of adult patients, while reports in the pediatric literature have been scarce. In a retrospective study we found eight children with intestinal spirochetosis. The findings, clinical as well as pathological, with light- and electron microscopy, are presented. In all patients, a 3 microm-thick layer of spirochetes was visualised on the luminal aspect of the epithelial cells covering the enterocytes and part of the gland openings. In five of the eight cases an inflammatory cell reaction was seen by light microscopy and in one patient a picture suggesting intracytoplasmatically located spirochetes was seen by electron microscopy. Despite partial or complete destruction of microvilli, spirochetes were still able to adhere to the enterocyte membranes. In three children there was a clear correlation between treatment and relief of symptoms. In four there was partial improvement and in one child no change in bowel-related symptoms. We believe that intestinal spirochetes may cause colorectal disease in children. Possible pathogenic mechanisms are discussed.

PCR detection of Brachyspira aalborgi and Brachyspira pilosicoli in human faeces

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

Brachyspira aalborgi infection diagnosed by culture and 16S ribosomal DNA sequencing using human colonic biopsy specimens

In this study we report on the isolation and characterization of the intestinal spirochete Brachyspira aalborgi using human mucosal biopsy specimens taken from the colon of a young adult male with intestinal spirochetosis. A selective medium, containing 400 microg of spectinomycin/ml and 5 microg of polymyxin/ml was used for the isolation procedure. A high degree of similarity, in terms of phenotypic properties and 16S ribosomal DNA sequence, was observed between the isolated strain, named W1, and the type strain, 513A, of B. aalborgi. A similarity of 99.7% in the nucleotide sequence was found between W1 and 513A(T), based on the almost-complete gene. A short segment of the 16S rRNA gene was amplified by PCR using genetic material enriched from paraffin-embedded biopsy specimens, which were taken from the patient on two occasions. The products showed 16S rRNA gene sequences virtually identical to that of strain 513A(T) in the actual region. Immunohistochemistry was performed on the colonic biopsy specimens with a polyclonal antibody raised against an intestinal spirochete isolated in a previous case of human intestinal spirochetosis. The antibody reacted strongly with the spirochete on the luminal epithelium. No immune reaction was seen within or below the surface epithelium. Routine histology did not reveal signs of colitis. Electron microscopy showed spirochetes attached end-on to the colonic mucosal surface. The isolate grew poorly on a commonly used selective medium for intestinal spirochetes, which may explain previous failures to isolate B. aalborgi.

PCR amplification from fixed tissue indicates frequent involvement of Brachyspira aalborgi in human intestinal spirochetosis

PCR procedures amplifying portions of the 16S rRNA and NADH oxidase genes of Brachyspira aalborgi and Serpulina pilosicoli were applied to DNA extracted from paraffin-embedded human colonic or rectal tissues from 30 Norwegian, Australian, and U.S. patients, 16 of whom had histologic evidence of intestinal spirochetosis (IS). B. aalborgi-specific sequences were identified by PCR in 10 of the IS patients (62.5%) but none of the others, while S. pilosicoli sequences were not detected in tissues from any patient. Direct sequencing of products from three of the positive samples provided further confirmation of the presence of B. aalborgi. B. aalborgi may be a more common cause of intestinal spirochetosis than has been previously thought.

Sub-specific differentiation of intestinal spirochaete isolates by macrorestriction fragment profiling

Macrorestriction fragment profile analysis by PFGE was used to distinguish intestinal spirochaetes, some of which were isolated from cases of swine dysentery and intestinal spirochaetosis in humans, pigs, mice, chickens and dogs. Macrorestriction fragment profiles using SmaI and SacII restriction enzymes were produced and used in statistical analysis. This permitted the division of the isolates into two major clusters. One cluster contained isolates which were identified as Serpulina pilosicoli and the second cluster contained isolates identified as Serpulina hyodysenteriae by immunoblotting with species-specific mAbs. Both species contained sub-specific groups, although these rarely correlated with the source of the isolates. We conclude that PFGE is capable of sub-specific differentiation of intestinal spirochaetes, but that the current species contain a large variety of genotypes among which cross-species transmission may be feasible.

Identification and characterization of Serpulina pilosicoli isolates recovered from the blood of critically ill patients

The phenotypic and genetic characteristics of spirochetes isolated from the blood of one U.S. and six French patients with severe clinical disease or impaired immunity were examined. All spirochetes were anaerobic, weakly beta-hemolytic, positive for hippurate hydrolysis, and negative for beta-glucosidase activity. Cell lengths ranged from 4 to 8 microm, and each isolate had between 8 and 12 periplasmic flagella per cell. These features were consistent with the spirochetes' being Serpulina pilosicoli, the agent of intestinal spirochetosis. All isolates were positive in a PCR assay amplifying a portion of the S. pilosicoli 16S rRNA gene, and they all grouped with fecal isolates of S. pilosicoli in multilocus enzyme electrophoresis (MLEE). The blood isolates could be differentiated from each other by MLEE, although the U.S. and two French isolates were closely related. Apparently S. pilosicoli may translocate from the large intestine to establish spirochetemia. The clinical significance of this finding remains uncertain and requires further investigation.