Imaging of rickettsial, spirochetal, and parasitic infections.

This article is an update and literature review of the clinical and neuroimaging findings of the commonly known rickettsial, spirochetal, and eukaryotic parasitic infections. Being familiar with clinical presentation and imaging findings of these infections is crucial for early diagnosis and treatment especially in patients who live in or have a travel history to endemic regions or are immunocompromised.

Human intestinal spirochetosis accompanied by human immunodeficiency virus infection: a case report.

We present a middle-aged, heterosexual Japanese man with mixed infections including human intestinal spirochetosis, which led us to the detection of human immunodeficiency virus (HIV) infection. The patient had syphilis without related physical or neurological findings. An examination for the serum antibody for HIV performed 9 years previously was negative. In a complete medical checkup at the present time, human intestinal spirochetosis and unspecified entamebic cysts were suggested by histological examination of colonic biopsy material and parasitic examination of the intestinal fluid, respectively. Moreover, a serological test for the antibody for HIV was positive. In specimens obtained by colonoscopy, Brachyspira aalborgi was diagnosed by ultrastructural study and the polymerase chain reaction method for bacterial 16S ribosomal deoxyribonucleic acid. Although HIV infection remains at low prevalence in Japan, we recommend examination for HIV infection in patients with human intestinal spirochetosis, especially when other co-infections are apparent.

Experimental swine dysentery: comparison between infection models.

The aim of the present study was to develop a reproducible porcine infection model with Brachyspira hyodysenteriae. The influence of different factors was evaluated, namely, age, a diet containing large quantities of soybean meal, housing and administration of cortisol or antacids. Furthermore, the synergistic effect of additional bacteria (Escherichia coli O141, Bacteroides vulgatus or a mixture of Bacteroides fragilis, a field isolate of Bacteroides and Fusobacterium necrophorum) was studied. Experimental infection resulted in an increase in the serum concentrations of the acute-phase proteins serum amyloid A and haptoglobin and the percentages of neutrophils and monocytes. These alterations were specifically related to haemorrhagic diarrhoea. Inoculation combined with feeding of large quantities of soybean meal and group-housing induced swine dysentery in all experimental animals. If the pigs were fed soybean meal, kept in single pens and circulated between the pens, five out of nine developed disease.

Brachyspira pilosicoli colonization in experimentally infected mice can be facilitated by dietary manipulation.

The purpose of this study was to determine whether defined dietary manipulations would enhance colonization of mice experimentally challenged with the intestinal spirochaete Brachyspira pilosicoli. Weanling C3H/HeJ mice (n = 48) were fed either a standard balanced mouse diet or a diet supplemented with 50 p.p.m. zinc bacitracin (ZnB), with 50 % (w/w) lactose or with both supplements. Eight mice from each group were challenged orally with a human strain of B. pilosicoli (WesB), whilst four in each group acted as uninfected controls to evaluate the effects of the diets alone. The mice were kept for 40 days following challenge and faeces were collected every 3-4 days and subjected to culture and PCR for B. pilosicoli. Feeding ZnB reduced total volatile fatty acid production in the caecum. Feeding lactose alone doubled the weight of the caecum and its contents compared with control mice, and resulted in a relatively greater production of acetate, but a reduction in propionate and isovalerate production. These effects were negated by the addition of ZnB with the lactose. None of the mice fed the standard diet or receiving ZnB alone became colonized following experimental challenge. One of the mice receiving lactose was culture and PCR positive for B. pilosicoli on one sampling 1 week after inoculation, and one was positive on three samplings taken 20, 25 and 29 days after inoculation. All mice receiving both lactose and ZnB became colonized and remained so, with all samples being positive over the last seven samplings. The colonization was not associated with an end-on attachment of the spirochaete to the epithelial cells of the caecum, but colonized mice developed a specific humoral antibody response to the spirochaete.

Influence of diet on the experimental infection of pigs with Brachyspira pilosicoli.

The effects of five different diets on the experimental infection of pigs with a Danish field isolate of Brachyspira pilosicoli were investigated. The diets tested were a pelleted and a non-pelleted standard diet based on wheat and barley, the standard diet supplemented with 2 per cent lactic acid, a fermented liquid feed and a diet based on cooked rice. Two trials were conducted, each with six groups of six pigs; in each, two of the groups were fed the standard diet. One of these groups and the other four groups were challenged after two weeks on the diets and euthanased four weeks later. The clinical signs of B pilosicoli infection varied from loose stools to watery, mucoid diarrhoea. The group fed the rice diet excreted B pilosicoli in their faeces for a significantly shorter period than the group fed the standard diet (P < 0.01), and fewer of them excreted the organism (P < 0.05). All the pigs fed the pelleted diet excreted B pilosicoli in their faeces, and significantly more of them showed clinical signs of disease than the pigs fed the standard diet (P < 0.05). The fermented liquid feed and the diet containing lactic acid had no significant effect on the excretion of B pilosicoli or on the numbers of pigs showing clinical signs of disease.

Increasing the viscosity of the intestinal contents stimulates proliferation of enterotoxigenic Escherichia coli and Brachyspira pilosicoli in weaner pigs.

The present study was designed to evaluate the effect of increased viscosity of the intestinal digesta on proliferation of enterotoxigenic Escherichia coli and the intestinal spirochaete Brachyspira pilosicoli in weaned pigs. Pigs were fed an experimental diet based on cooked white rice (R), which was supplemented with carboxymethylcellulose (CMC; 40 g/kg diet) to increase digesta viscosity. Thirty-six piglets weaned at 21 d of age were divided into six groups, three of which were fed R and three Addition of CMC increased digesta viscosity in the ileum (P=0.01), caecum (P=0.0007) and colon (P=0.0035), without increasing indices of large intestinal fermentation. Pigs fed developed a natural infection with enterotoxigenic E. coli after weaning and had more (P<0.0001) diarrhoea than pigs fed R. Subsequent experimental infection of two groups of pigs with B. pilosicoli resulted in more (P<0.0001) colonisation in pigs fed than R. At this time, all pigs fed had wetter (P<0.0001) faeces than those fed R, irrespective of whether they were infected with B. pilosicoli, but infected pigs also had an increased (P=0.025) number of days with diarrhoea post-infection irrespective of diet. In pigs fed it was not clear to what extent the increased viscosity associated with CMC, or the concurrent infection with enterotoxigenic E. coli, was responsible for the increased proliferation of B. pilosicoli. In a second experiment, five pigs that were weaned onto an R diet were transferred onto 3 weeks later. These pigs did not develop a natural infection with enterotoxigenic E. coli after the diet change, confirming the particular susceptibility of pigs to enterotoxigenic E. coli proliferation immediately post-weaning.

Porcine enteric spirochete infections in the UK: surveillance data and preliminary investigation of atypical isolates.

Investigations into the possible causes of colitis and typhlocolitis were carried out on 98 pig units in the United Kingdom between 1997 and 1999. Brachyspira pilosicoli was identified most commonly, occurring as the suggested primary agent in 18% of the outbreaks but forming part of mixed infections in another 24% of outbreaks. The equivalent figures for other bacterial pathogens were: B. hyodysenteriae, 13% and 16%; Lawsonia intracellularis, 10% and 15%: Salmonella species, 6% and 12%; and Yersinia species, 4% and 10%. Unclassified Brachyspira species of unknown pathogenicity were identified in 12% of outbreaks. The 24 unclassified isolates divided into three groups on the basis of their phenotypic characteristics. In addition, there were 50 atypical Brachyspira species isolates that showed differences between their phenotypic characteristics and genetic identity based on sequence analysis of a section of the 23S rDNA gene. Four representative atypical isolates were found to be pathogenic as a result of an experimental oral challenge study in pigs.

Serpulina pilosicoli, waterbirds and water: potential sources of infection for humans and other animals.

Serpulina pilosicoli was isolated from 8 of 43 (19%) faecal specimens obtained from feral waterbirds sampled around a small lake at Perth Zoological Gardens, Western Australia, and from 3 of 7 (43%) samples of the lake water. The organism was only isolated from 1 of 204 (0.5%) samples from captive birds and animals in the zoological collection. Multilocus enzyme electrophoresis analysis of the isolates showed that they were genetically diverse, and none had identical electrophoretic profiles as those previously obtained from human beings, dogs, pigs and other avian species. To determine the survival time of S. pilosicoli in water, cells of strain 1648 were seeded into lake and tap water, and incubated at 4, 25 and 37 degrees C. The organism could be recultured from lake water for up to 66 days at 4 degrees C, and for 4 days at 25 degrees C. A healthy human volunteer who drank water seeded with S. pilosicoli strain Wes B became colonized, and developed abdominal discomfort and headaches. Contamination of water by faeces may represent a source of S. pilosicoli infection for both humans and animals.

Pathogenicity of Serpulina hyodysenteriae: in vivo induction of tumor necrosis factor and interleukin-6 by a serpulinal butanol/water extract (endotoxin).

Lipopolysaccharide (LPS) of Gram-negative bacteria is a classic inducer of inflammatory cytokines. In the present experiments, LPS-like (phenol/water extract) or endotoxin-like (butanol/water extract) preparations from Serpulina hyodysenteriae were examined for their ability to induce serum tumor necrosis factor (TNF) or interleukin (IL)-6 bioactivity in mice and swine. Serpulina hyodysenteriae endotoxin (butanol/water extract) elicited increased serum TNF activity in mice, although serpulinal endotoxin was at least 10 times less potent than the LPS preparations of E. coli or S. typhimurium on a weight basis for induction of TNF bioactivity. S. hyodysenteriae LPS induced lower levels of serum TNF in mice than S. hyodysenteriae endotoxin. In contrast, pigs injected with S. hyodysenteriae endotoxin demonstrated no increase in serum TNF activity. However, an induction of IL-6 bioactivity was observed in serum samples from pigs injected with serpulinal endotoxin. In pigs, the serpulinal preparations were five times less potent (on a weight basis) than E. coli or S. typhimurium LPS for induction of IL-6 bioactivity. These data indicate that serpulinal endotoxin, although less bioactive than E. coli or S. typhimurium LPS, is nonetheless capable of inducing the in vivo production of specific pro-inflammatory cytokines.

Dual flaA1 flaB1 mutant of Serpulina hyodysenteriae expressing periplasmic flagella is severely attenuated in a murine model of swine dysentery.

The motility imparted by the periplasmic flagella (PF) of Serpulina hyodysenteriae is thought to play a pivotal role in the enteropathogenicity of this spirochete. The complex PF are composed of multiple class A and class B polypeptides. Isogenic strains containing specifically disrupted flaAl or flaB1 alleles remain capable of expressing PF, although such mutants display aberrant motility in vitro. To further examine the role that these proteins play in the maintenance of periplasmic flagellar structural integrity, motility, and fitness for intestinal colonization, we constructed a novel strain of S. hyodysenteriae which is deficient in both FlaA1 and FlaB1. To facilitate construction of this strain, a chloramphenicol gene cassette, with general application as a selectable marker in prokaryotes, was developed. The cloned flaAl and flaB1 genes were disrupted by replacement of internal fragments with chloramphenicol and kanamycin gene cassettes, respectively. The inactivated flagellar genes were introduced into S. hyodysenteriae, and allelic exchange at the targeted chromosomal flaA1 and flaB1 loci was verified by PCR analysis. Immunoblots or cell lysates with antiserum raised against purified FlaA or FlaB confirmed the absence of the corresponding sheath and core proteins in this dual flagellar mutant. These mutations selectively abolished the expression of the targeted genes without affecting the synthesis of other immunologically related FlaB proteins. The resulting flaA1 flaB1 mutant exhibited altered motility in vitro. Surprisingly, it was capable of assembling periplasmic flagella that were morphologically normal as evidenced by electron microscopy. The virulence of this strain was assessed in a murine model of swine dysentery by determining the incidence of cecal lesions and the persistence of S. hyodysenteriae in the gut. Mice challenged with the wild-type strain or a passage control strain showed a dose-related response to the challenge organism. The dual flagellar mutant was severely attenuated in murine challenge experiments, suggesting that the FlaA1 and FlaB1 proteins are dispensable for flagellar assembly but critical for normal flagellar function and colonization of mucosal surfaces of the gastrointestinal tract. This strain represents the first spirochete engineered to contain specifically defined mutations in more than one genetic locus.

Production of an inducible sucrase activity by Serpulina hyodysenteriae.

Strains of Serpulina hyodysenteriae and Serpulina innocens produced a cell-associated sucrase activity when grown in a medium containing sucrose. S. hyodysenteriae B204 sucrase activity cleaved sucrose and, to a lesser extent, raffinose and had a pH optimum of 5.7 to 6.2. This is the first report of an inducible enzyme produced by either S. hyodysenteriae or S. innocens.

Effect of divalent cations on hemolysin synthesis by Serpulina (Treponema) hyodysenteriae: inhibition induced by zinc and copper.

Serpulina hyodysenteriae produces an oxygen-stable heat-labile hemolysin that may be an important virulence factor in the pathogenesis of swine dysentery. We examined the effect of Ca2+, Co2+, Cu2+, Fe2+, Mg2+, Mn2+, Ni2+, and Zn2+ on the hemolytic activity of cell-free supernatant (CFS) from S. hyodysenteriae, isolate B204. Cells harvested from late logarithmic phase cultures were incubated in phosphate-buffered saline containing glucose and RNA-core (PBS-GR) with or without cations and the hemolytic activity of CFS obtained after successive 30 min incubation and washing cycles was determined. The addition of either ZnSO4 or CuSO4 to the PBS-GR caused complete inhibition of hemolytic activity after 3 cycles; other cations gave results similar to control extracts. Reduction in the concentration of Zn2+ in CFS by 60 to 80% after each incubation cycle and binding of Zn2+ by EDTA indicated that Zn2+ was associated with the cell fraction, and inhibition of hemolysin activity was specifically mediated by Zn2+. When the spirochetes were washed after incubation in the presence of ZnSO4 for 2 cycles and incubated in fresh PBS-GR without Zn2+, inhibition of hemolysin activity remained unchanged, indicating that the inhibitory effect of ZnSO4 was due to a direct action of ZnSO4 on the spirochetes. Since neither the viability of the spirochetes nor the activity of pre-formed hemolysin were affected by the presence of ZnSO4, the inhibitory effect of Zn2+ cations was attributed to reduced biosynthesis by viable S. hyodysenteriae cells rather than interference of Zn2+ cations with lysis of erythrocytes by the hemolysin. Transmission electron microscopic examination of spirochetes after incubation in PBS-GR containing ZnSO4 revealed clumping of ribosomes and clearing of cell cytoplasm.

HIV-associated periodontal disease: new oral spirochete found.

This study examines plaque for the presence of a recently described oral spirochete, tentatively called pathogen-related oral spirochete. This investigation found PROS in plaque of patients with HIV-associated periodontal disease.

The role of hemolysin(s) in the pathogenesis of Serpulina hyodysenteriae.

Serpulina (Treponema) hyodysenteriae, an anaerobic beta hemolytic spirochaete, is the etiologic agent of swine dysentery. Not much is known at present about the virulence factors of S. hyodysenteriae. However, the hemolysin production of this bacterium is generally accepted to be a virulence factor. To study the exact role of hemolysin production in the pathogenesis of swine dysentery, the gene encoding a hemolysin, tly, was cloned and its nucleotide sequence determined. After inactivation of this gene, the virulence of a tly-minus mutant in mice was tested. The mutant had reduced hemolysis indicating that the tly-encoded hemolysin was not the only hemolysin produced by S. hyodysenteriae. Mice infected with the tly-minus mutant had fewer cecal lesions than mice infected with the wild-type S. hyodysenteriae. It was concluded that the tly-encoded hemolysin might be an important virulence factor, but not the only one. Since it was demonstrated that spirochaetes can be transformed through electroporation, this has made a genetic approach to elucidate the pathogenesis of spirochaetal infections possible.

[Intestinal spirochetosis in homosexuals infected with HIV. 3 cases]. / Spirochétose intestinale chez les homosexuels infectés par le virus de l'immunodéficience humaine. Trois observations.

We report 3 cases of intestinal spirochetosis in homosexuals infected with the human immunodeficiency virus (2 group III and 1 group IV C1, according to the Centers for Disease Control classification) presenting with moderate, chronic diarrhea. The diagnosis was made based on the histological examination of colorectal biopsies showing a layer of spirochetes carpeting the epithelium. Electron microscopy evaluation and culturing of the microorganism provided information on the bacterium's morphology. Metronidazole effectively treated the diarrhea. Intestinal spirochetes, whose existence has been recognized for more than a century, constitute a heterogeneous group of bacteria whose pathogenic role in man remains controversial. The systemic search for these organisms in a large series of patients would help to situate their place among the various etiologies of infectious diarrhea in immunodepressed subjects.

Epidemiology and clinical similarities of human spirochetal diseases.

Lyme disease, first identified in 1975, is the most recently recognized of the seven human spirochetal diseases; the evolving clinical picture of Lyme disease indicates it shares many features with the other diseases. These similarities are striking in view of the diverse epidemiology of the seven diseases, which are caused by Treponema species (spread by human-to-human contact) or Leptospira or Borrelia species (zoonoses). These similarities include the following: (1) skin or mucous membrane as portal of entry; (2) spirochetemia early in the course of disease, with wide dissemination through tissue and body fluid; and (3) one or more subsequent stages of disease, often with intervening latent periods. Lyme disease shares with many spirochetal diseases a tropism for skin and neurologic and cardiovascular manifestations, whereas chronic arthritis is unique to Lyme disease. These similarities and dissimilarities offer opportunities to discover which properties unique to the pathogenic spirochetes are responsible for clinical manifestations and suggest that certain clinical features of patients with spirochetal diseases other than Lyme disease may someday be recognized in patients with Lyme disease.

Spirochetal diseases of the CNS.

The neurotropism of the spirochete is evident from the above discussions of syphilis, Lyme disease, leptospirosis, and relapsing fever. In all of these diseases, the organism very likely enters the CNS very early in the course of the disease. The fate of the organism then depends on the virulence of the spirochete, the host defenses, and any antibiotic treatment administered. Why Treponema pallidum lays dormant in the CNS and then somehow reactivates is a mystery; the same mystery occurs in Lyme disease. Leptospirosis and relapsing fever seem to be infections much more limited in time, and are not reported to cause these long-term sequelae. The treatment of these last two infections seems to be fairly straightforward. However, the appropriate treatment for the various stages of the disease in both syphilis and Lyme disease in order to prevent long-term sequelae is not universally accepted. At this time, it seems that high-dose intravenous penicillin is the treatment of choice for each of these infections shown to be active in the nervous system.

Successful cultivation of spirochetes from skin lesions of patients with erythema chronicum migrans Afzelius and acrodermatitis chronica atrophicans.

Spirochetes could be cultivated from 9 out of 13 skin biopsies from patients with erythema chronicum migrans Afzelius (ECMA) and from 2 out of 5 biopsies from patients with acrodermatitis chronica atrophicans (ACA) by using a newly modified serumless Kelly's medium. The different spirochete strains grew best at a low oxygen tension. Attempts to grow spirochetes from blood and cerebrospinal fluid failed. The cultivation of spirochetes from secondary ECMA lesions favours the presumption that a spirochetemia may occur in ECMA. The isolation of spirochetes from an ACA patient who had a disease duration of greater than 10 years proves that the spirochetes may survive in the human body for a considerable time.