Intestinal spirochetosis and acquired immunodeficiency syndrome: ultrastructural studies of two cases

Factors and presenting symptoms associated with intestinal spirochaetosis in men who have sex with men: A systematic review

The transmission dynamics and presenting symptoms of intestinal spirochaetosis (Brachyspira pilosicoli, Brachyspira aalborgi) are poorly understood but is seen more frequently in men who have sex with men (MSM) where sexual transmission may occur. We aimed to systemically review the literature to define the factors and presenting symptoms associated with intestinal spirochaetosis in MSM. We systematically searched three bibliographical databases (MEDLINE, EMBASE and Scopus) for manuscripts written in English up to November 2022. The primary author conducted an initial screen and three authors conducted independent reviews to determine the final eligible manuscripts. We only included manuscripts where there were specific data on factors and presenting symptoms associated with intestinal spirochaetosis in MSM. Fifteen manuscripts published between 1981 and 2022 met the inclusion criteria that included 188 MSM. Sexually transmitted intestinal spirochaetosis in MSM was associated with-living with HIV (including having a low CD4 count <200 mm3), having a concomitant sexually transmitted infection, a history of a sexually transmitted infection, co-infection with intestinal parasites; and sexual behaviour including oro-anal sexual contact, oro-genital contact, fisting, condom-less anal sex, receptive anal sex, multiple non-regular sexual partners and increased number of lifetime sexual partners. The presenting symptoms of MSM with intestinal spirochaetosis were diarrhoea, abdominal pain, constitutional symptoms and proctitis, including rectal pain, rectal bleeding rectal discharge, flatulence and tenesmus. We have highlighted some biological and behavioural factors and presenting symptoms associated with intestinal spirochaetosis in MSM which provide insight for clinicians, guidelines and future public health control strategies.

Incidental diagnosis of intestinal spirochetosis in a patient with chronic hepatitis B: A case report

BACKGROUND

Intestinal spirochetosis (IS) is caused by Brachyspira colonization of the gastrointestinal tract. Some patients are asymptomatic, while others present with gastrointestinal complaints such as abdominal pain, diarrhea, or gastrointestinal bleeding. However, the clinical significance of asymptomatic IS is unclear, and guidelines are lacking regarding decision to treat.

CASE SUMMARY

A 73-year-old male with peptic ulcer disease and gastroesophageal reflux was evaluated for elevated liver enzymes. He was diagnosed with chronic hepatitis B virus and prescribed entecavir. Additionally, he was leukopenic and had stage 4 liver fibrosis on transient elastography. After 5 mo, the patient returned for esophagogastroduodenoscopy and screening colonoscopy. He denied any gastrointestinal symptoms at that time. Findings included grade I distal esophageal varices, mild portal hypertensive gastropathy, and patchy nodular gastric antral mucosa. On colonoscopy, several polyps were removed. Hematoxylin and eosin stain of mucosa adjacent to the polyps revealed a “false brush border,” and Steiner stain identified spirochetes adherent to the mucosa. These pathology findings confirmed the diagnosis of IS. He was managed conservatively with careful observation and without antibiotic therapy via a multidisciplinary approach between gastroenterology and infectious disease. He remained asymptomatic at the 7-wk follow-up.

CONCLUSION

This case reports the finding of incidental, asymptomatic IS in a leukopenic patient with hepatitis B virus. Conservative management was appropriate.

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.

Highlighting a Potential Pitfall: Positive Treponema pallidum Immunohistochemical Stain in a Patient Without Syphilis

The Treponema pallidum antibody immunohistochemical (IHC) stain has improved our ability to detect the organism histologically. We present a case of a man with genital condyloma acuminatum with a positive T. pallidum IHC stain but negative T. pallidum serologies and no syphilitic symptoms. It has been shown that the T. pallidum antibody IHC can cross-react, staining other spirochetes, including Borrelia burgdorferi and the Brachyspira family of intestinal spirochetes. Because of the proximity of our patient's lesions to the anus, and the persistently negative T. pallidum serologies, we believe nontreponemal spirochetes colonized the condyloma, giving a false-positive T. pallidum IHC. This cross-reactivity is a potential diagnostic pitfall and is important for the dermatopathologist to recognize, thereby avoiding false diagnosis of syphilis.

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.

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 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.

Morphological Properties of a Human Intestinal Spirochete First Isolated from a Patient with Diarrhea in Japan

A human intestinal spirochete isolated from a rectal biopsy specimen was morphologically characterized. The isolate was comma-shaped, 3-6 microm in length, 0.2 micro m in diameter and had tapered ends. The surface layer, external to the outer envelope, was amorphous. Four string-like periplasmic flagella with a diameter of 20 nm were presented at each end of the SDS-treated cells. Thin sections of the bacterial cell revealed a high-density cytoplasmic membrane and flagella in the periplasmic space between the cytoplasmic membrane and the outer envelope. Three segments of equal length were observed in some of the cells, while other cells were bi-segmented and more frequently observed.

Human intestinal spirochetosis--a review

Human intestinal spirochetosis (IS) is a condition defined histologically by the presence of spirochetal microorganisms attached to the apical cell membrane of the colorectal epithelium. Intestinal spirochetes comprise a heterogeneous group of bacteria. In humans, Brachyspira aalborgi and Brachyspira pilosicoli predominate. Prevalence rates of IS are low where living standards are high, in contrast to poorly developed areas where IS is common. Homosexuals and HIV-infected individuals are at high risk of being colonized. Clinical significance in individual cases has remained unclear up to now. A review of the literature assumes that invasion of spirochetes beyond the surface epithelium may be associated with gastrointestinal symptoms which respond to antibiotic treatment (metronidazole), whereas individuals lacking this feature may be mostly asymptomatic. Of unknown reason, homosexual and HIV-positive men as well as children are more likely to be symptomatic irrespective of invasion. Rare cases of spirochetemia and multiple organ failure have been reported in critically ill patients with IS.

Human intestinal spirochetosis in Japan; its incidence, clinicopathologic features, and genotypic identification

Human intestinal spirochetosis is a common condition in Western countries, but is not well recognized in Japan. To demonstrate the incidence and clinicopathologic findings of human intestinal spirochetosis in Japan, we retrospectively investigated biopsy, and endoscopically or surgically resected specimens of the large intestine. Among a series of 2556 samples, 11 cases of human intestinal spirochetosis were detected (0.4%). Together with additional nine cases sporadically found, 20 cases of human intestinal spirochetosis were subjected to molecular detection of two strains of spirochetes (Brachyspira aalborgi and Brachyspira pilosicoli) by amplifying species-specific portion of 16S ribosomal RNA and NADH oxydase gene by polymerase chain reaction. B. aalborgi was detected in all cases examined, three of which revealed dual infection of both species. Our results suggest that human intestinal spirochetosis infection is relatively rare, and B. aalborgi is the most prevalent species in Japan. Most of human intestinal spirochetosis were asymptomatic, although symptomatic in exceptional cases. In addition, we emphasize a usefulness of immunostaining with anti-Treponema pallidum and anti-Mycobacterium bovis polyclonal antibodies for detecting the spirochetes.

Human intestinal spirochetosis: analysis of the symptoms of 209 patients

OBJECTIVE

Colonization of the colorectal mucosa with spirochetes is very rare. Owing to the small number of cases, it is not clear from the currently available publications whether spirochetes colonizing the colorectal mucosa are harmless commensals or pathogenic organisms. Furthermore, the reported complaints of these patients cannot be pooled to identify a characteristic complex of symptoms. The aim of the present work was to describe the symptoms associated with intestinal spirochetosis in a population of 209 patients, and to elucidate the effect of antibiotic treatment on these symptoms.

MATERIAL AND METHODS

A total of 209 carefully processed questionnaires providing information on the symptoms, treatment and post-treatment symptoms of patients with spirochetosis were evaluated statistically and descriptively with the aid of the SPSS program, and the results were compared with those reported in the currently available literature.

RESULTS

Of the 209 patients 168 (80.4%) were males, and the average age of the entire population at establishment of the diagnosis was 50.75 years. The most common symptoms reported were abdominal pain (46%), diarrhoea (51%) and alternating diarrhoea and constipation (13%). In this population, homosexuality and HIV infection played only a small role (6.5% homosexual patients, 3.8% HIV infected). In 72 of the 84 patients who received treatment (86%), the antibiotic employed was metronidazole, and the symptoms improved in 44 of the 84 patients (5%). Twenty-six of the 84 patients (30.9%) were investigated by colonoscopy/biopsy after receiving medical treatment. Biopsies in 20 of these patients no longer revealed infection with spirochetes, and symptoms were found to have improved in 11 of the 20 patients (55%).

CONCLUSIONS

If intestinal spirochetosis is diagnosed to be the sole intestinal pathology in symptomatic patients, the bacteria should be eradicated with metronidazole and a colonoscopy/biopsy follow-up performed, where indicated, in patients with persisting symptoms. Significant results regarding symptoms and treatment of intestinal spirochetosis can be achieved only in a prospective, placebo-controlled, randomized, crossover study. In view of the low prevalence of this condition, such a study is difficult to implement.

Comparative pathology and pathogenesis of naturally acquired and experimentally induced colonic spirochetosis

Research in the past decade has led to the recognition ofBrachyspira(formerlySerpulina)pilosicolias the primary etiologic agent of colonic spirochetosis (CS), an emerging cause of colitis in humans and animals. Attachment of spirochetes to the epithelial surface of the lower intestine is considered to be the hallmark of CS. However, becauseB. pilosicoli, B. aalborgiand unclassified flagellated bacteria are found singly or together in humans and non-human primates with CS lesions, attachment of spiral-shaped bacteria may not represent the same etiopathogenetic entity in all hosts. Moreover, North American opossums with CS are infected withB. aalborgi-like spirochetes together with flagellated bacteria, whereasB. pilosicoliis found alone in dogs, pigs, chickens and other species of birds with CS. Conversely, guinea-pigs with CS have unidentified spirochetes that may beB. pilosicoli or B. aalborgi.The pig model of CS suggests that attachment ofB. pilosicolito epithelial cells may be transient. By contrast, persistence ofB. pilosicoliin the cecal and colonic crypt lumina, chronic inflammation caused by spirochetal invasion into the subepithelial lamina propria and translocation to extraintestinal sites may be more important than previously thought. This review describes the lesions seen in naturally occurring and experimentally induced CS of animals, and it sets the stage for future research into the pathogenic mechanisms of infection and colitis caused byB. pilosicoli.

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.

Human intestinal spirochetosis diagnosed with colonoscopy and analysis of partial 16S rDNA sequences of involved spirochetes

DNA was extracted from colonic biopsies of 33 patients with and three without evidence of intestinal spirochetosis (IS) in the large bowel. The biopsies were subjected to PCR. A pair of primers, generating a 207 bp fragment, were designed to detect specifically the 16S rDNA gene ofBrachyspira. PCR products of the expected size were obtained from 33 samples with histologic evidence of IS. The PCR amplicons were used for sequencing. The sequences obtained were aligned to the corresponding 16S rRNA sequences of five type strains ofBrachyspira. The sequences of 23 PCR products were 99–100% identical with the correspond-ingB.aalborgitype strain sequence. Two cases showed 99–100% sequence similarity with the type strain ofB.pilosicoliP43/6/78. Six cases could not be referred to any of the known species ofBrachyspira. Two PCR products gave incomplete sequences.

Intestinal spirochetosis and chronic watery diarrhea: clinical and histological response to treatment and long-term follow up

BACKGROUND

The clinical significance of intestinal spirochetosis is uncertain, therefore the aim of the present paper was to assess the prevalence of histological intestinal spirochetosis in patients with and without chronic watery diarrhea and to evaluate its clinical relevance.

METHODS

A prospective diagnostic work-up of intestinal spirochetosis was made on biopsy samples taken from patients with chronic watery diarrhea submitted between 1994 and 2004 (1174 colonoscopies with multiple biopsies). Three other positive cases identified from routine endoscopic biopsies also were reviewed. In addition, samples from 100 asymptomatic control patients and a random sample of another 104 colonic specimens were reviewed for intestinal spirochetosis. The diagnosis was established by light and electron microscopy. Polymerase chain reaction (PCR) amplification of the 16S ribosomal RNA and reduced nicotinamide adenine dinucleotide (NADH) oxidase genes of the intestinal spirochetes Brachyspira aalborgi and Brachyspira pilosicoli was performed on tissue biopsies of the 11 positive patients. After diagnosis, treatment with penicillin benzatine (PB) or metronidazole was offered to all symptomatic patients and they were followed for a mean of 45.4 months (range: 37-113 months).

RESULTS

Eight patients with chronic watery diarrhea were positive for intestinal spirochetosis. Intestinal spirochetosis was not diagnosed in the controls. Histological resolution of the infection paralleled clinical recovery in six patients (following metronidazole treatment in three). Most patients showed mild, non-specific colonic inflammation. Invasion by the spirochetes was not demonstrated by electron microscopy. Brachyspira aalborgi and B. pilosicoli each were identified by PCR in two cases.

CONCLUSIONS

Histological intestinal spirochetosis appears to be relatively uncommon in Catalonia (Spain) compared to previous reports from other countries, but was identified in patients (0.7%) with chronic watery diarrhea. Sustained clinical recovery after spontaneous or drug-induced spirochetal disappearance in these individuals suggests that intestinal spirochetosis may play a pathogenic role in chronic watery diarrhea. Treatment with metronidazole is advisable in patients with persistent symptoms.

Comparison of prevalence and risk factors for faecal carriage of the intestinal spirochaetes Brachyspira aalborgi and Brachyspira pilosicoli in four Australian populations

This study examined the prevalence of the intestinal spirochaetes Brachyspira aalborgi and Brachyspira pilosicoli in different Western Australian (WA) populations. Faecal samples included 287 from rural patients with gastrointestinal symptoms, comprising 142 from non-Aboriginal and 145 from Aboriginal people; 227 from recent healthy migrants to WA from developing countries; and 90 from healthy non-Aboriginal individuals living in Perth, WA. DNA was extracted from faeces, and subjected to PCR assays for both species. B. pilosicoli-positive individuals were confined to the rural Aboriginal (14.5%) and migrant (15.0%) groups. B. aalborgi was detected at a lower but similar prevalence in all four groups: rural non-Aboriginals, 5.6%; rural Aboriginals, 6.9%; migrants, 7.9%; controls, 5.6%. In migrants and Aborigines, the presence of B. pilosicoli and B. aalborgi was associated (P<0.001), suggesting that colonization by B. pilosicoli may be facilitated by colonization with B. aalborgi. Amongst the Aboriginal patients, logistic regression identified both spirochaete species as being associated with chronic diarrhoea, failure to thrive and being underweight. Both species may have pathogenic potential, but B. aalborgi appears more host-adapted than the opportunistic B. pilosicoli.

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.

Espiroquetosis colónica: una causa poco frecuente de diarrea en el adulto

Large intestine infection due to spirochetes was described in 1967 and is mainly related to two pathogens, Serpulina pilosicoli and Brachyspira aalborgi. Clinically, infection presents as diarrhea and/or rectorrhagia and is more frequent among homosexuals. Its prevalence is difficult to estimate but significant differences have been described according to the socioeconomic level of the area studied. We describe three cases of diarrhea due to spirochetes, which are of interest due to the lack of published cases in Spain. Based on these cases, we describe the main characteristics (morphological, therapeutic, etc.) of this infection.

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.

[Human intestinal spirochetosis]

Whenever biopsy material obtained from endoscopically normal colorectal mucosa reveals the blue haematoxyphilic line between the microvilli of the covering epithelium, the rare condition of intestinal spirochetosis is diagnosed. The classification of the bacteria detected with the aid of special stains (e.g. the Warthin Starry silver stain) and in the electron microscope, continues to be something of a problem. A further point of contention is the question whether this spirochetal infection is of pathological significance or not. A point mitigating against pathogenicity is the fact that no histological signs of an inflammatory reaction are to be seen. Also, the symptoms of patients with intestinal spirochetosis are such that they provide no basis for a pronouncement on whether the infection is of a pathological or a pathological nature. On the other hand, however, a number of studies do seem to indicate that the spirochetes might be the cause of such symptoms as diarrhoea, constipation and abdominal pain. A point that would appear to support this view is the fact that such symptoms may disappear after successful treatment with metronidazole. The histological diagnosis is easily established when, faced by an apparently normal histological appearance of the colorectal mucosa, the pathologist considers the possibility of spirochetosis, and undertakes a specific search for the blue haematoxyphilic line in the covering epithelium of the colorectal mucosa.

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.

The histopathology of 103 consecutive colonoscopy biopsies from 82 symptomatic patients with acquired immunodeficiency syndrome: original and look-back diagnoses

OBJECTIVE

To compare the primary diagnoses assigned by general surgical pathologists on a series of 103 consecutive colon biopsies from individuals infected with human immunodeficiency virus (HIV) with diagnoses rendered by a pathologist with extensive experience in gastrointestinal pathology in HIV/acquired immunodeficiency syndrome.

DESIGN

New sections were cut from paraffin blocks of 103 consecutive colon biopsies taken during colonoscopies of 82 different HIV-infected patients; all new sections were stained with hematoxylin-eosin. These individuals either had negative stool studies or had failed to respond to therapy and had chronic large bowel symptoms, such as frequent small volume-type diarrhea, tenesmus, and/or bright red blood per rectum. Immunohistochemistry for cytomegalovirus (CMV) was performed on 18 of 22 specimens originally diagnosed with CMV colitis.

RESULTS

The initial study yielded 70 (68%) negative or nonspecific diagnoses, 22 (21%) cases of CMV colitis, 5 (5%) Cryptosporidium diagnoses, 2 cases each of adenomatous polyps and Kaposi sarcoma, and 1 case each of spirochetosis and squamous cell carcinoma of the anorectum. Review of the recuts yielded 64 (62%) negative or nonspecific diagnoses, 12 (12%) new adenovirus infections (3 combined with CMV), and 11 (11%) lone CMV infections. Three attaching and effacing bacterial infections were diagnosed, 1 with adenovirus coinfection. A total of 4 spirochetosis cases were found on review. Seven (7%) of the biopsies showed at least 1 coinfection. Nine biopsies had features suggestive of inflammatory bowel disease.

CONCLUSIONS

Colonoscopy with biopsy after negative stool studies or failure to respond to therapy yielded a high proportion of negative or nonspecific diagnoses. Adenovirus and enteropathogenic bacterial infections had been totally overlooked on initial examination. It takes particular experience to evaluate gastrointestinal biopsies from HIV-infected patients.

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.

Isolation of Serpulina pilosicoli from rectal biopsy specimens showing evidence of intestinal spirochetosis

Histologic evidence of intestinal spirochetosis (IS) was found in 22 of 41 (53.7%) rectal biopsy specimens from homosexual men attending a sexually transmitted diseases clinic. Serpulina pilosicoli was cultured from 11 of the IS-positive biopsy specimens (50%) and from 2 specimens (10.5%) in which spirochetes were not observed. The association between seeing spirochetes in biopsy specimens and isolating S. pilosicoli was statistically significant, clearly indicating that this spirochete is the agent of IS.

Gastrointestinal pathology in HIV-infected patients

Specific pathologic processes, particularly oral, esophageal, and intestinal infections, are common in the alimentary tract of AIDS patients. Many of these diseases are adequately assessed only by biopsy with histologic examination. Most are rare or unreported in immunocompetent hosts and are easily missed by those not familiar with them. This article describes the gross or endoscopic and histologic appearances and the diagnostic criteria for enteric pathologic processes seen in HIV-infected individuals.

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.

Invasive intestinal spirochetosis: a report of three cases

We here report on three patients with gastrointestinal symptoms in whom spirochetes were found in colonic biopsies. The patients, heterosexual adults, were not immunocompromised. Electron microscopy was performed on colonic biopsies from each of the three patients. Apart from the basophilic band consisting of spirochetes, the mucosa was normal in two patients on light microscopy and showed mild inflammation in the other one. However on electron microscopy there was invasion of the colonic epithelial cells, macrophages, goblet cells and Schwann cells by spirochetes, and stunting of the microvilli. The spirochetes conformed to the morphology of Brachyspira aalborgi, and no other infective etiology or pathology could be identified in these patients to account for their symptoms. Since the clinical significance of intestinal spirochetosis is uncertain, antibiotics were not administered to any of the three patients and all three improved symptomatically with non-specific treatment. Intestinal spirochetosis, previously thought to be non-invasive and non-pathogenic in humans, may be invasive and may be the cause of gastrointestinal symptoms in some patients.

Intestinal spirochetosis: first cases reported in Brazil and the use of immunohistochemistry as an aid in histopathological diagnosis

Colonization of the colon and rectum by intestinal spirochetes is detected for the first time in Brazil in 4 of 282 (1.41%) patients who had undergone sigmoidoscopy and/or colonoscopy with a histopathological diagnosis of chronic non specific-colitis. This frequency is probably underestimated, since surgically obtained specimens were not considered in the present study. Histopathological diagnosis was performed using routine stains like hematoxylin-eosin which showed the typical, of 3-microns thick hematoxyphilic fringe on the brush border of the surface epithelium, and by silver stains like the Warthin-Starry stain. Immunohistochemical procedures using two, polyclonal, primary antibodies, one against Treponema pallidum and the other against Leptospira interrogans serovar copenhageni serogroup Icterohaemorrhagiae cross-reacted with spirochetal antigen/s producing a marked contrast of the fringe over the colonic epithelium, preserving the spiral-shaped morphology of the parasite. In one case with marked diarrhea, immunohistochemistry detected spirochetal antigen/s within a cell in an intestinal crypt, thus demonstrating that the infection can be more widely disseminated than suspected using routine stains. Immunohistochemical procedures, thus, greatly facilitate the histological diagnosis of intestinal spirochetosis and may contribute to a better understanding of the pathogenesis of the disease. Transmission and scanning electron microscopy performed in one case showed that the spirochete closely resembled the species designated as Brachyspira aalborgi.