Scanning electron microscopic observations on the surface of the normal and spirochete-infested colonic mucosa of the rhesus monkey

Brachyspira catarrhinii sp. nov., an anaerobic intestinal spirochaete isolated from vervet monkeys may have been misidentified as Brachyspira aalborgi in previous studies

To date nine species of anaerobic intestinal spirochaetes have been validly assigned to the genus Brachyspira. These include both pathogenic and non-pathogenic species. In the current study a genomic analysis of a novel spirochaete isolate was undertaken to determine whether it is a distinct species that previously has been misidentified as Brachyspira aalborgi. The genome of spirochaete strain Z12 isolated from the faeces of a vervet monkey was sequenced and compared to the genomes of the type strains of the nine assigned Brachyspira species. Genome to Genome Distance (GGD) values and Average Nucleotide Identity (ANI) values were determined. Single nucleotide polymorphisms (SNP) were used to create a phylogenetic tree to assess relatedness. The 16S rRNA gene sequences of the strains were aligned and the similarity amongst the Brachyspira species was recorded. Multilocus sequence typing (MLST) using five loci was conducted on Z12 and results compared with those for other Brachyspira isolates. Assembly of the Z12 sequences revealed a 2,629,108 bp genome with an average G + C content of 31.3%. The GGD, ANI, 16S rRNA gene sequence comparisons and the MLST results all indicated that Z12 represents a distinct species within the genus Brachyspira, with its nearest neighbour being B. aalborgi. Spirochaete strain Z12^T was assigned as the type strain of a new species, Brachyspira catarrhinii sp. nov. The diagnostic PCR currently in use to detect B. aalborgi cross-reacts with Z12, but RFLP analysis of PCR product can be used to distinguish the two species. Previous reports of non-human primates being colonised by B. aalborgi based on PCR results may have been incorrect. The development of an improved diagnostic method will allow future studies on the distribution and possible clinical significance of these two anaerobic spirochaete species.

Infection of the Colon of the Rhesus Monkey by Spiral-Shaped Organisms

Intestinal spirochetosis, an infection of the mucosa by spiral-shaped organisms, was studied in clinically normal rhesus monkeys (Macaca mulatta) by histology, transmission and scanning electron microscopy. The incidence of intestinal spirochetosis was 42% in 221 monkeys. Spiral organisms stained with hematoxylin and eosin (HE) appeared as a broad basophilic haze on the colonic surface and were strongly positive by the Warthin-Starry stain.

Spiral-shaped bacteria include two structurally different organisms: spirochetes and flagellated microbes. They intimately populated the brush border of the surface of the epithelium of the large intestine. They were absent in the crypts and in the small intestine. Infection by spirochetes produced no alteration of cytocomponents of the underlying host structures. Spirochetes and flagellates infrequently penetrated beyond the brush border into the epithelial cytoplasm and also into the lamina propria. Even in cases where invasion was documented, no inflammatory response was found.

Colonic spirochetosis of colony-raised rhesus macaques associated with Brachyspira and Helicobacter

Colonic spirochetosis is an inflammatory bowel disease that affects a broad range of hosts, including human and non-human primates. The disease in humans and non-human primates is characterized by intimate attachment of the anaerobic spirochetes Brachyspira aalborgi and B. pilosicoli, and some unclassified flagellated microbes along the apical membrane of colonic enterocytes. Although the presence of spiral-shaped bacteria with single polar flagella and blunted ends in colonic spirochetosis is well established, the identities of many of these organisms is still unknown. Recently, Helicobacter species with a morphology similar to the flagellated bacteria present in colonic spirochetosis have been cultured from intestinal specimens obtained from rhesus macaques, some with idiopathic colitis. The purpose of the present study was to determine whether or not the flagellated bacteria seen in the colons of rhesus macaques with colonic spirochetosis are Helicobacter. The presence of flagellated bacteria alone (n=2) or together with spirochetes (n=1) in formalin-fixed and paraffin-embedded colons of three rhesus macaques with the naturally occurring disease was demonstrated by immunohistochemical staining and ultrastructural examination. Total DNA extracted from affected and control intestinal specimens was amplified by polymerase chain reaction (PCR) using Helicobacter 16S rRNA gene-specific primers. Comparative nucleotide sequence analysis of PCR products cloned from positive reactions indicated that two distinct Helicobacter genomospecies were present either alone or in combination with Brachyspira in the colons of rhesus macaques with microscopic lesions indicative of colonic spirochetosis.

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.

Detection by PCR and isolation assays of the anaerobic intestinal spirochete Brachyspira aalborgi from the feces of captive nonhuman primates

The purpose of this study was to investigate the presence of the anaerobic intestinal spirochetes Brachyspira aalborgi and Brachyspira pilosicoli in the feces of captive nonhuman primates (n = 35) from 19 species housed at the Zoological Gardens, Perth, Western Australia. Both spirochete species are known to infect human beings. DNA was extracted from freshly collected feces with a commercially available QIAamp DNA stool minikit and subjected to PCR protocols amplifying portions of the 16S rRNA genes of the two spirochete species. The feces were also subjected to selective culture for the spirochetes. Subsequently, feces from 62 other captive animals or birds representing 39 species at the zoo were examined by PCR to determine whether they were reservoirs of infection. Six fecal samples from individuals from four primate species (two vervet monkeys, two Tonkean macaques, one Japanese macaque, and one hamadryas baboon) tested positive in the B. aalborgi PCR. B. aalborgi was not detected by PCR in any of the other animal or bird species tested, and B. pilosicoli was not detected in the primates or any of the other animals or birds. B. aalborgi was isolated from both PCR-positive vervet monkeys. This is the first time that B. aalborgi has been isolated from nonhuman primates and the first time that it has been isolated from the feces of any species.

Light microscopic and ultrastructural changes in the ceca of chicks inoculated with human and canine Serpulina pilosicoli

Light microscopic and ultrastructural changes were observed in chicks challenged with North American Serpulina pilosicoli, a weakly beta-hemolytic intestinal spirochete (WBHIS) associated with human and canine intestinal spirochetosis. Chicks in control groups received trypticase soy broth or canine Serpulina innocens. The birds were necropsied at weekly intervals, and the ceca were processed for bacteriologic and pathologic examinations. No WBHIS were isolated from the ceca of chicks in the control groups, but WBHIS with genotypes similar to the parent isolates were isolated from the ceca of chicks inoculated with human and canine S. pilosicoli. Gross examination revealed no significant changes in the ceca of chicks at any time post-inoculation. Light microscopic examination revealed no spirochetal attachment in the ceca of chicks in control groups. In contrast, focal to diffuse thickening of the brush border of the surface epithelium along with dilation of the crypt lumina and mild focal lamina propria heterophil infiltration were present in the ceca of chicks inoculated with human and canine S. pilosicoli. Scanning electron microscopic examination revealed focal to confluent spirochetal attachment mainly in the furrow region at the periphery of the crypt units. Transmission electron microscopic examination revealed spirochetes attached to the brush border of the cecal epithelium, causing effacement of the microvilli and disruption of the terminal web microfilaments. The cecal epithelium of chicks inoculated with the canine S. pilosicoli also had caplike elevations of the apical membrane at the point of attachment of the spirochetes together with large numbers of vesicles in the cytoplasm immediately beneath the terminal web and evidence of spirochetal invasion beyond the mucosal barrier. The changes observed suggested that the mechanism of attachment of human and canine S. pilosicoli to the cecal epithelium of chicks was analogous to but different from that described previously for other attaching and effacing gastroenteric bacterical pathogens of human beings and animals.

Gut microflora of vervet and samango monkeys in relation to diet

The microflora in the gastrointestinal tracts of wild vervet and samango monkeys (Cercopithecus aethiops and C. mitis, respectively) were studied, using fermentation acid analysis, electron microscopy, and culturing methods. The diets of the two species of monkey differ considerably, with that of the samango including a greater proportion of cellulose-rich leaf material, and this is reflected in the microflora. Volatile fatty acid measurements along the gut of both species showed that these end products of bacterial metabolism were concentrated in the cecum and colon. Electron microscopy indicated that morphologically similar bacteria were present in the cecum and colon of both species, but the samango possessed a distinct stomach microflora. Bacteria in the lumina of the four main regions of the gut of the monkeys (stomach, small intestine, cecum, and colon) were plated on a number of anaerobic media (Mann, Rogosa, and Sharp; clostridial basal; and complex media). The cecum and colon were found to contain higher numbers of microbes per gram (wet weight) of gut content than the stomach and small intestine. Microbial isolates were able to catabolize carboxymethyl cellulose and other polymers. This may aid the monkeys, particularly samangos, in the digestion of fibrous dietary components such as leaves.

Rectal spirochaetosis

We report four cases of rectal spirochaetosis, one in an active male homosexual. One of the heterosexual patients was referred to the genitourinary clinic by a general surgeon after spirochaetes had been found on histopathological examination of a rectal biopsy specimen. We doubt that most of our cases represent sexual transmission of spirochaetosis, or that the condition causes disease in most people. Rectal spirochaetosis possibly occurs only when the normal flora of the gut are disturbed for other reasons. Most of our patients became asymptomatic after nonspecific treatment, although metronidazole appears to be specific.

Intestinal spirochaetosis: an electron microscopic study of an unusual case

An unusual case of intestinal spirochaetosis is described. The rectum of a 34-year-old male, suffering from Crohn's disease and ankylosing spondylitis, was heavily infested by spirochaetes. Both absorptive and goblet cells were colonized. Spirochaetes were found not only on the luminal surface of these cells, but also within the cytoplasm, in occasional macrophages within the lamina propria and, even more surprisingly, within the occasional Schwann cell. The significance of these findings is discussed.

The surface topography of the colonic crypt in rabbit and monkey

Scanning electron microscopy (SEM) was used to investigate the epithelial topography of the surface and crypt in rabbit and monkey colon. Crypt openings in monkey colon are arranged in a hexagonal pattern, in sharp contrast to rabbit colon where they are randomly arrayed and frequently hidden by epithelial folds. Crypt lumens were exposed by freezing ethanol-dehydrated tissue in liquid nitrogen and fracturing the tissue with a razor blade. The resulting overview of crypt-cell luminal surfaces showed that as columnar cells mature and migrate up the crypt and onto the colonic surface, their microvilli become progressively more abundant. Goblet cells were readily identified in the cross-fractured crypt epithelium; their luminal surfaces are characterized by short, sparse microvilli. The changing appearance of the luminal surface of goblet cells was visualized by SEM during the exocytosis of single mucous granules from unstimulated crypt goblet cells, and during the compound exocytosis of multiple granules in response to acetylcholine.

Changes of the caecal villi during postnatal development in rats

The villi of the caecal mucosa in postnatal rats were studied using both scanning electron and light microscopy. On the day of birth, numerous villi of various sizes and shapes were present on the caecal mucosa. After the 5th day, the villi decreased very rapidly in length and in number. A strong constriction was observed at the basal region of the caecal villi. During postnatal days 5 approximately 9 the villi probably separated and disappeared from the caecal mucosa. No villi were observed in rats that were over 10 days of age.

Scanning electron microscopy of Crohn's disease and ulcerative colitis of the colon

12 patients with Crohn's disease (CD) and 9 with ulcerative colitis (UC) affecting the colon were studied by scanning electron microscopy (SEM). The macroscopically unaffected mucosa was distorted in both diseases by irregularities in the normal polygonal units. The individual absorptive cells were disorganized, having lost their pentagonal-hexagonal cell borders. In 7 cases of CD an increase of goblet cells was seen. In 4 cases of UC their number was decreased. One case of UC showed an increased number of goblet cells, the case possibly belonging to the sub-category of indeterminate colitis. The microvilli were normal in CD but affected in many cells from cases of UC. Re-epithelization was followed during conservative treatment in 2 UC patients. It is suggested that with simplified SEM techniques the instrument can be a useful aid in the differential diagnosis of inflammatory colonic diseases.

The preservation of surface-associated micro-organisms prepared for scanning electron microscopy

Scanning electron microscopy (SEM) has become a popular means of studying micro-organisms which associate with surfaces. However, as yet no detailed examination has been made of the influence of specimen preparation on the number of organisms finally seen on the SEM screen. In this investigation critical assessment is made of the influence of a wide range or preparative factors on the preservation of filamentous bacteria associated with the epithelial surfaces of rat intestine. Organisms were quantitated using a rigorous counting method (transect line analysis); statistical testing of these counts enabled the comparison of different preparative factors. The composition of the fixative was found to significantly influence the number of organisms preserved; of the fifteen fixatives studied, Karnovsky's fixative with ruthenium red best preserved surface-associated organisms. The influence of other factors on the number and appearance of preserved organisms was also examined. These factors included the washing of specimens prior to fixation, the storage of fixed specimens, and the handling and storage of critical point dried specimens. The results are discussed with reference to the optimal methods for preparing specimens for SEM.

Studies on a canine intestinal spirochete: scanning electron microscopy of canine colonic mucosa

A large homogeneous population of spirochetes was observed attached to the colonic mucosa of clinically normal dogs. Their association with the colonic mucosa and their mode of attachment resembled those of a spirochete reported in primates.

Scanning electron microscopic studies of ileal epithelial cells in suckling rats

The ileal epithelial cells containing the tubulo-vacuolar systems and supranuclear vacuoles in suckling rats were investigated with scanning electron microscopy, using specimens treated with osmium-thiocarbohydrazide-osmium staining methods, and critical point drying and cracking. The cracked surface of the apical cytoplasm is seen as irregular and small hollows and pores of the anastomosing and branching tubulo-vacuolar system. The cracked surface of the supranuclear vacuoles shows the ellipsoidal structures. Numerous pores of various size and irregular shape are present on the apical inner surface of the supranuclear vacuole. These pores are clearly the openings from the tubulo-vacuolar system to the supranuclear vacuole. Some small pores are visible on the inner lateral surface of the supranuclear vacuole, especially near the nucleus. They are probably the pathways of the absorbed materials from the supranuclear vacuole into the lateral cytoplasm. Usually, the inclusions of the supranuclear vacuole reveal the globes or coarse and sponge-like networks.

Intestinal Tyzzer's disease and spirochetosis in a guinea pig

Tyzzer's disease (bacillus pilirformis infection) was diagnosed in young guinea pig killed because of diarrhea and poor condition. There was necrosis and inflammation of the colon, cecum and ileum. Typical B. piliformis were in intestinal epithelial cells. Spirochetes were in large numbers in intestinal crypts and were often adjacent to the intracellular B. piliformis. Extracellular B. piliformis occasionally were surrounded by spirochetes.

Cecal mucosal response to coccidiosis in growing chickens

The cecal mucosal changes of a subclinical coccidial (E. tenella) in chickens was studied by scanning electron microscopy. Oral inoculation was used and the mucosal surface of the ceca was studied. A control group from the same hatch of chickens was sampled simultaneously. The ceca from the infected birds was markedly smaller and contained some hemorrhagic areas. The control birds maintained a relatively smooth continuous epithelium throughout the study. During the infection, early fenestration was seen in the epithelium followed by its disruption. The crypts were easily seen as the disease progressed and in some cases the epithelium became denuded. The infective organism may inhibit replacement of degenerating epithelium.

Absorption of intact protein by colonic epithelial cells of the rat

Colonic absorption of intact protein was examined in adult rats using histological and ultrastructural procedures. Horseradish peroxidase was introduced into ligated colonic loops and retained therein for 5, 10, 20, or 30 minutes prior to excision of the loops, and their processing for microscopy. Morphological evaluation revealed evidence of peroxidase absorption via pinocytosis. Tracer particles were observed adherent to the mucosal border, in apical pinocytotic vesicles, in vesicles adjacent to and fusing with lateral and basal cell membranes, in extracellular spaces throughout the mucosa, in lymphatic channels of the submucosa and occasionally in blood capillaries of mucosal and submucosal regions. The significance of these findings is discussed in light of the frequent presence of dietary and/or microbial macromolecules in the luminal milieu of the large intestine. It is suggested that pinocytotic uptake and subsequent vesicular transport and exocytosis of intact protein may occur in the colon of some species, and that such a phenomenon may be responsible for penetration of the mucosal barrier by macromolecular antigens or toxins.

Characteristics of the absorptive surface of the small intestine of the chicken from 1 day to 14 weeks of age

The epithelial surface of the intertine of chicks 1 day to 14 weeks of age was examined with both scanning and transmission electron microscopes. Most of the intestinal villi were seen to be plate-like structures. During the first week post-hatch, goblet cell orifices were easily seen. Goblet cell pores were not readily apparent in the older birds. During this stage of early development discontinuity was seen among some epithelial cells. The villi of birds one week or older showed a more convoluted mucosal surface than the younger birds. Areas of cell extrusion were observed at the tips of some villi. The three dimensional cylindrical structure of the microvilli was shown with the scanning electron microscope.