Experimental infection of axenic mice by "Yersinia enterocolitica" (author's transl)

Although most of Yersinia enterocolitica strains isolated from man have no pathogenicity for laboratory animals, it has been demonstrated that some strains are pathogenic for conventional mice and that most of the strains are probably pathogenic for Nude mice. The authors report the results of the infection of germ-free mice with a strain of Y. enterocolitica which is non pathogenic for holoxenic mice. It appears that C3H/He mice are sensitive to the infection by gavage or aerogenic and peritoneal routes. They all die within 8 to 12 days after injection of an inoculum of 5.10(5) viable cells. Germ-free NCS mice were also sensitive to the oral and aerogenic infection but not to the peritoneal infection; the difference between C3H/He and NCS sensitivity to this way of infection could be explained by a higher bactericidal activity of the peritoneal phagocytes of the latter. The C3H/He and NCS holoxenic control mice infected with the same inoculum of the same strain, did not show any symptoms and all attempts to isolate Y. enterocolitica failed three months after the challenge. Germ-free mice killed by the infection showed histopathological findings, i.e. abscesses involving intestinal wall. liver and spleen; they were similar to those described in experiments with pathogenic strains for conventional mice (holoxenic) and to those observed in infection of athymic Nude mice with strains non pathogenic for conventional mice. This infectious disease model is discussed in regards to the natural human infection.     

An ectopic parathyroid adenoma revealed by L-thyroxine side effect on bone. Case report

Yersinia was isolated from imported raw meat and fowl products by HeLa cell treatment and conventional KOH-treatment, to obtain information on the origin of pathogenic Yersinia in Japan. Forty-one strains of Yersinia enterocolitica and one strain of Yersinia pseudotuberculosis, serotype 4b were isolated from 38 (3.0%) of 1278 samples of pork, two (0.3%) of 612 samples of beef and two (0.3%) of 615 samples of chicken. Y. enterocolitica isolates belonged to B:4/O:3 (biotype/serotype, 15 strains), B:3/O:3 (two strains) and B:3 variant/O:3 (17 strains) and B:3/O:5.27 (seven strains). The B:4/O:3 which is globally prevalent among humans and animals was isolated from pork samples from Denmark and the US and from beef samples from Australia, the B:3/O:3 from pork samples from Canada, the B:3 variant/O:3 from pork samples from Taiwan and from chicken samples from Thailand, the B:3/O:5.27 from pork samples from the US and Taiwan and Y. pseudotuberculosis, serotype 4b from pork samples from Canada. These findings suggest that pathogenic Y. enterocolitica strains can be introduced into Japan by the import of pork from pig producing countries. The HeLa cell treatment was found to be superior to the conventional method.     

Prevalence of the "high-pathogenicity island" of Yersinia species among Escherichia coli strains that are pathogenic to humans

The fyuA-irp gene cluster contributes to the virulence of highly pathogenic Yersinia (Yersinia pestis, Yersinia pseudotuberculosis, and Yersinia enterocolitica 1B). The cluster encodes an iron uptake system mediated by the siderophore yersiniabactin and reveals features of a pathogenicity island. Two evolutionary lineages of this "high pathogenicity island" (HPI) can be distinguished on the basis of DNA sequence comparison: a Y. pestis group and a Y. enterocolitica group. In this study we demonstrate that the HPI of the Y. pestis evolutionary group is disseminated among species of the family Enterobacteriaceae which are pathogenic to humans. It prevails in enteroaggregative Escherichia coli and in E. coli blood culture isolates (93 and 80%, respectively), but is rarely found in enteropathogenic E. coli, enteroinvasive E. coli, and enterotoxigenic E. coli isolates. In contrast, the HPI was absent from enterohemorrhagic E. coli, Shigella, and Salmonella enterica strains investigated. Polypeptides encoded by the fyuA, irp1, and irp2 genes located on the HPI could be detected in E. coli strains pathogenic to humans. However, these E. coli strains showed a reduced sensitivity to the bacteriocin pesticin, whose uptake is mediated by the FyuA receptor. Escherichia strains do not possess the hms gene locus thought to be a part of the HPI of Y. pestis. Deletions of the juA-irp gene cluster affecting solely the fyuA part of the HPI were identified in 3% of the E. coli strains tested. These results suggest horizontal transfer of the HPI between Y. pestis and some pathogenic E. coli strains.     

Mycobacterial phagosome maturation, rab proteins, and intracellular trafficking

One of the most prominent features of pathogenic mycobacteria, which include the potent human pathogens Mycobacterium tuberculosis and Mycobacterium leprae and their opportunistic relatives Mycobacterium avium and Mycobacterium marinum, is their ability to survive and multiply in phagosomes of mononuclear phagocytic cells. The phagocytosed mycobacteria reside in a vacuolar compartment which is exempted from maturation into the phagolysosome. Recently, the arrest of the maturation of phagosomes containing M. tuberculosis complex organisms (Mycobacterium bovis BCG) has been linked to the accumulation on the phagosomal membrane of the small GTP binding protein rab5, specific for the control of fusion within the early endosomal compartment. Furthermore, M. bovis BCG phagosome is devoid of rab7, a rab protein associated with the late endosome. The selective accumulation of rab5 and exclusion of rab7 defines the check point that has been compromised in mycobacterial phagosome maturation. Here we summarize these observations and relates them to other phenomena in the area of membrane and protein trafficking with the emphasis on phagosomes containing intracellular pathogens.     

Follicular carcinoma

In vitro assays to quantify killing of bacteria by macrophages provide useful insights into host-pathogen relations. In the present study, we used strains of Yersinia enterocolitica and Escherichia coli which varied in their ability to invade mammalian cells to evaluate these assays. The results showed that 30 min and 24 h after incubation with murine bone marrow-derived macrophages, strains of Y. enterocolitica and E. coli which expressed invasin (an outer membrane protein which allows bacteria to penetrate mammalian cells) achieved significantly greater numbers in macrophages than otherwise isogenic bacteria which lacked this protein (P < 0.01). When the 24-h data were corrected for the number of bacteria ingested by macrophages initially, the differences between invasin-positive and -negative bacteria were no longer evident (P> 0.2). This study has shown (1) that invasin-mediated penetration of macrophages by bacteria is not associated with enhanced intracellular survival, and (2) that invasion of macrophages by bacteria may influence the interpretation of assays for bactericidal capacity unless allowance is made for the number of bacteria ingested during the early phase of the assay.     

Virulence and arsenic resistance in Yersiniae

The genus Yersinia contains three pathogenic species: Yersinia pestis, Y. pseudotuberculosis, and Y. enterocolitica. Only a few biotypes and serotypes of Y. enterocolitica are pathogenic, and these form two distinct groups: some are of low virulence, and they are encountered worldwide; others, mainly encountered in North America, are markedly more virulent. All pathogenic yersiniae possess a 70-kb virulence plasmid called pYV which encodes secreted antihost proteins called Yops as well as a type III secretion machinery that is required for Yop secretion. Genes encoding Yop synthesis and secretion are tightly clustered in three quadrants of the pYV plasmid. We show here that in the low-virulence strains of Y. enterocolitica, the fourth quadrant of the plasmid contains a new class II transposon, Tn2502. This transposon encodes a defective transposase, but transposition can be complemented in trans by Tn2501, another class II transposon. Tn2502 was not detected in the pYV plasmids of the more virulent American strains of Y. enterocolitica, of Y. pseudotuberculosis, and of Y. pestis. Tn2502 confers arsenite and arsenate resistance. This resistance involves four genes; three are homologous to the arsRBC genes present on the Escherichia coli chromosome, but no homolog of the fourth one, arsH, has been found. The systematic presence of such a resistance operon on a virulence plasmid is unusual and could be related to the recent spread of low-virulence Y. enterocolitica strains. The presence of this ars operon also constitutes the first significant difference between the pYV plasmids from different Yersinia species.     

Computed tomographic evaluation of comminuted middle phalangeal fractures in the horse

The effect of subinhibitory concentrations of amikacin on Proteus mirabilis motility and adherence to human uroepithelial and to HeLa cells was compared with that of gentamicin. In addition, the effect of both antibiotics on cell surface hydrophobicity was also examined. Exposure of bacterial cells in the logarithmic phase to one fourth of amikacin or gentamicin at one fourth of their respective minimal inhibitory concentrations causes the inhibition of swarming and motility of Proteus strains. Amikacin significantly reduced adhesion of Proteus strains to human uroepithelial cells and gentamicin exerts the same effect to a lesser extent. Such inhibitory concentrations of amikacin or gentamicin had no significant effect on the attachment ability of these strains to HeLa cells compared to the nontreated cells. Treatment of the bacterial cells with amikacin or gentamicin changed significantly the cell surface hydrophobicity towards the hydrophilic state compared to nontreated cells, and it was found to be strain dependent. Since motility and attachment ability are considered as pathogenic traits, these data indicate the impact of amikacin on the virulence factors especially in urinary tract infections with Proteus strains.     

Substance user MMPI-2 profiles: predicting failure in completing treatment

Induced pathogenicity in animals and humans differs considerably. This review is devoted to the relations between Brucella spp. and professional phagocytes, particularly macrophages and macrophagic cell lines in vitro. Although numerous studies have been reported, the type of ingestion by macrophages, the receptor involved, and the molecular mechanisms, are poorly understood. The ability of most Brucella species to actively inhibit their ingestion by neutrophils or macrophages has been proposed as an explanation for the poor rate of in vitro phagocytosis and in vivo alteration of the phagocytic cells. Oxidative burst plays a significant role in the antibacterial processes of phagocytic cells. The effects of whole or fractioned B. abortus on the ability of neutrophils to induce an oxidative burst in response to stimulation with opsonized zymosan particles were examined. Besides oxygen-based killing, the phagocytic cells have developed other types of defence, including hydrolytic enzymes and reactive halides. Inside the cell, the bacteria encounter new environmental conditions. Their survival is conditioned by an adaptation to this new situation. Pathogens that have acquired the ability to multiply within macrophages should synthesize products specifically interacting with the host cell defence system. Survival of intracellular pathogens is closely linked to the mechanisms of evasion from cellular defences. Brucellae stay in membrane bound vacuoles called phagosomes, but the exact nature and the maturation pathway of this compartment have not yet been understood. Macrophages play a central role in the evolution of brucellosis; this first interaction between the pathogens and the cell will determine the course of the disease. There are natural differences between brucellae species regarding macrophage response to the bacteria.     

Infusion therapy with milrinone in the home care setting for patients who have advanced heart failure

The pathogenicity of 14 isolates identified as Prevotella intermedia or Prevotella nigrescens by serogrouping using monoclonal antibodies was compared in a tissue cage model in rabbits. Seven strains from periodontal abscesses, 5 strains from deep periodontal pockets and 2 strains from gingivitis were tested in the animal model comprising 6 Teflon tissue cages implanted on the back each of 34 rabbits. A total of 10(5)-10(8) cells of P. intermedia or P. nigrescens strains were inoculated alone or together with either Actinobacillus actinomycetemcomitans or Streptococcus mitis. Five strains of Porphyromonas gingivalis were used as a reference. The infectivity was recorded as pus formation and log viable count in aspirated material for 3, 7 and 14 days. None of the Prevotella strains inoculated in monoculture survived more than 3 days, and they had no capacity to produce abscess. P. intermedia or P. nigrescens strains in combination with A. actinomycetemcomitans produced abscesses in 33-100% and with S. mitis in 42-100%. No difference in abscess formation or log viable count in samples after 14 days was recorded between serogroup I (P. intermedia) and serogroup II and III (P. nigrescens). The infectivity of P. intermedia or P. nigresceas strains did not differ whether they were isolated from periodontal abscess, periodontal pocket or gingivitis. P. intermedia and P. nigrescens strains produced abscesses in combination with a facultative anaerobic strain and appears to have a similar pathogenicity in the wound chamber model in rabbits.     

Biological properties of three Mexican isolates of Aujeszky's disease virus

Four strains of Aujeszky's Disease virus (ADV) were included in this study; three Mexican field isolates (215,145 and C-8) in conjunction with the Shope reference strain of ADV, which has known pathogenic characteristics. All four strains were included in each treatment, which consisted of heat treatment, trypsin treatment and passed ten times on chicken embryo fibroblasts. Both virus titer and plaque size were determined on the first and tenth passage and on treated and untreated strains. On each of the treatments, the plaque size had significant differences (p = 0.001) which had relation to the two factors studied, namely strain and passage level. There was no significant variation related to the type of treatment between strains. With the strains under study, the authors also made rabbit pathogenicity tests, and it was found that on passage one, the strains caused clear nervous symptoms and death, while on the tenth passage level, the Mexican strains produced slight pruritus, few nervous symptoms and allowed the rabbits to survive. The mouse test revealed an increased median death time after the treatments, as well as a large increase in standard deviations. These data are interpreted as an increased heterogeneity of the strains in all of the treatments to the strains of viruses.     

Selective isolation from HeLa cell lines of Yersinia pseudotuberculosis, pathogenic Y. enterocolitica and enteroinvasive Escherichia coli

Using HeLa cell lines, we obtained an optimal and selective isolation of Yersinia pseudotuberculosis, pathogenic Y. enterocolitica and enteroinvasive Escherichia coli from samples such as pork, feces and river water heavily contaminated with other bacteria.     

Modeling the growth of Yersinia enterocolitica in donated blood

BACKGROUND: Sepsis and death subsequent to the transfusion of blood containing Yersinia enterocolitica is an increasing problem. The organisms probably originate from bacteremia in the donor and can subsequently multiply at low temperature. STUDY DESIGN AND METHODS: Reported here are experiments with a strain of Y. enterocolitica associated with a case of transfusion-associated bacteremia. RESULTS: It was found that the rapid early killing of Y. enterocolitica injected into donated blood does not require viable phagocytes and can be explained by complement-mediated killing. Complement resistance in Y. enterocolitica is known to be plasmid-coded. It is expressed at 37 degrees C, but not at 20 degrees C, and is favored by calcium-deficient culture media. Y. enterocolitica organisms induced to express complement resistance were still killed in donated blood, though the initial rate was slower. Such organisms multiplied in plasma at 37 degrees C, but were killed after 6 hours of incubation at 20 degrees C, presumably because complement resistance genes are switched off at this temperature. CONCLUSION: This experiment is thought to reflect the natural history of Y. enterocolitica contamination of blood, in which complement-resistant organisms in the donor blood encounter lower temperatures after donation. These observations suggest that the practice of plasma depletion may have contributed to the increased incidence of mortality due to Y. enterocolitica contamination of donated blood.     

The construction of the new Kresge Eye Institute

Six strains of Salmonella dublin with distinct antimicrobial susceptibility patterns and/or plasmid profiles were repeatedly isolated from calves in a calf rearing facility. Three of the six strains were isolated from numerous calves during outbreaks of clinical salmonellosis while the other three were not. These strains were compared for their ability to adhere to and internalize in human intestinal epithelial cells (Caco-2) and in bovine alveolar macrophages (BAM), to survive in BAM, and to cause lethal infection in female BALB/c mice. All six strains of S. dublin demonstrated an ability to adhere to and internalize in both Caco-2 cells and in BAM. However, strain differences in the level of adhesion and/or internalization in Caco-2 cells and BAM were demonstrated. Most strains were able to persist but not proliferate in BAM. One outbreak-associated strain which readily attached and internalized in eukaryotic cells in vitro was avirulent to mice at the dose tested. The remaining five strains were virulent to mice. In vitro measures of virulence attributes were not clearly correlated with virulence among S. dublin strains measured either as prevalence in calves during outbreaks of disease or as mouse lethality. Also, there was no association between prevalence of strains in calves during outbreaks of clinical salmonellosis and lethality in mice.     

Pathogenic power of Salmonellae: virulence factors and study models

Salmonellae are potentially pathogenic for humans as well as for numerous animal species. They possess numerous virulence factors, which allow them to adapt to various environmental conditions and to host response at each step of the pathogenic process. Key-steps such as the invasion of epithelial cells or survival within macrophages have been extensively studied. These studies have led to the discovery of an original protein secretion system and have demonstrated the existence of pathogenicity islands. This considerable progress is due to the development of numerous in vitro and in vivo models and of new identification strategies for the implicated genes. Recently, many original and elegant strategies have been recently proposed.     

Duration of carriage and transmission of Yersinia enterocolitica biotype 4, serotype 0:3 in dogs

Human infections with pathogenic strains of Yersinia enterocolitica have been linked to contact with dogs excreting these microorganisms. This study examines the carriage and transmission of Y. enterocolitica biotype 4, serotype 03 in dogs. Fourteen 6-month-old cross-bred dogs were separated into 5 groups, 2 containing 4 dogs (I and II) and the others 2 dogs (III-V). Each of the 4 dogs in Group I and 2 of the dogs in Group II were inoculated orally with the test strain. Bacteriological examination of faecal samples showed that dogs can be readily infected and can carry the organism for up to 23 days. The two in-contact dogs in Group II started to shed the test organism after 5 days. Subsequent transfer of these dogs to Group III and those in Group III to Group IV showed that Y. enterocolitica biotype 4, serotype 03 can be readily transmitted between dogs. At no time did any of the dogs show clinical signs of infection. Group V served as a negative control for the trial. These findings suggest that dogs can carry Y. enterocolitica biotype 4, serotype 03 asymptomatically and hence might act as a potential source of infection for people.     

Direct detection and isolation of plasmid-bearing virulent serotypes of Yersinia enterocolitica from various foods

A procedure was developed for direct detection, isolation, and maintenance of plasmid-bearing virulent serotypes of Yersinia enterocolitica from different food sources. Plasmid-bearing virulent strains of Y. enterocolitica representing five serotypes were simultaneously detected and isolated from enriched swab samples of artificially contaminated pork chops, ground pork, cheese, and zucchini, using Congo red binding and low-calcium-response tests. The method was also effective in isolating plasmid-bearing virulent strains of Y. enterocolitica from naturally contaminated porcine tongues. Virulence of the strains isolated from these foods was confirmed by PCR, the expression of plasmid-associated phenotypes, and mouse pathogenicity.     

Chromosome-mediated resistance of Yersinia enterocolitica serotype O9 to intracellular killing by mouse peritoneal macrophages

The survival of Yersinia enterocolitica serotype O9 within mouse peritoneal macrophages was investigated. To evaluate the role of the virulence plasmid in the resistance to intracellular killing, an isogenic pair of virulent (plasmid-bearing) and avirulent (plasmid-less) O9 strains was used. The virulent strain was able to express plasmid-encoded outer membrane proteins and to colonize the Peyer's patches of orally infected mice. When mice were infected intraperitoneally, both strains were recovered at similar rates and over the same time from the peritoneal cavity. When in vitro assays were performed, both strains showed similar resistance to intracellular killing by monolayers of resident and inflammatory peritoneal macrophages. Previous opsonization of bacteria did not modify their survival within macrophage monolayers. We concluded that serotype O9 strains display a chromosome-mediated resistance to intracellular killing by mouse peritoneal macrophages. Moreover, macrophage resistance does not seem to be of importance for virulence of serotype O9 strains in mice.     

HLA-B27 does not affect invasion of arthritogenic bacteria into human cells

OBJECTIVE: To investigate the effect of HLA-B27 expression on entry of Salmonella typhimurium and Yersinia enterocolitica into human cells. METHODS: We performed standard bacterial invasion assays with S. typhimurium and Y enterocolitica to analyze isogenic pairs of HeLa (epithelial), U937 (promonocyte), C1R (B lymphocyte), and Jurkat (T lymphocyte) human cell lines and their respective HLA-B27 transfectants. Invasion of peripheral blood derived T lymphocytes, monocytes, and B lymphocytes/dendritic cell fraction (corresponding to peripheral blood cells depleted of monocytes and T lymphocytes) from patients with ankylosing spondylitis and healthy donors was also analyzed. The percentage of internalized bacteria was quantified, and the differences between HLA-B27 positive and negative samples were compared. RESULTS: The percentages of intracellular S. typhimurium and Y enterocolitica in HeLa, U937, and C1R with or without B27 were not statistically different (independent t test). We also found that the percentage of internalized bacteria did not differ significantly between HLA-B27 positive and negative samples in the different populations of peripheral blood derived cells. CONCLUSION: The presence of HLA-B27 on the surface of human cells does not alter the degree of bacterial invasion into either cultured human cell lines or peripheral blood derived human cells, and the influence of HLA-B27 expression on bacterial invasion should not be implicated in the pathogenesis of reactive arthritis related to Salmonella and Yersinia.     

Monocytes that have ingested Yersinia enterocolitica serotype O:3 acquire enhanced capacity to bind to nonstimulated vascular endothelial cells via P-selectin

Reactive arthritis is usually a self-limiting polyarthritis which develops after certain gastrointestinal or urogenital infections. Microbial antigens found in the inflamed joints are thought to play a key role in the development of this disease. It is not known how antigens of the pathogenic organisms migrate from the mucosal tissues into the joints. The data presented here show that mononuclear phagocytes which mediate the dissemination of several intracellular pathogens acquire an enhanced capacity to bind to nonstimulated vascular endothelial cells after phagocytosis of Yersinia enterocolitica O:3, one of the causative organisms of reactive arthritis. The increased binding to previously nonstimulated endothelial cells was mediated by P-selectin, whose translocation to the endothelial cell surface was induced by monocytes with intracellular Yersinia bacteria. These results suggest that mononuclear phagocytes may be responsible for the dissemination of bacterial antigens and the initiation of the joint inflammation in reactive arthritis.