Long-term dynamics and prognosis for tularemia and pseudotuberculosis morbidity in the Iaroslavl region

The trends and main factors influencing the fluctuations of the levels of tularemia and pseudotuberculosis morbidity in the Iaroslavl region were revealed by the methods of mathematical statistics (regress analysis, time-series analysis, etc.). Tularemia morbidity was 0.467 +/- 0.216 cases (1950-1997) and pseudotuberculosis morbidity was 0.979 +/- 0.297 cases (1979-1997) per 100,000 of the population. The multiple regression equations permitting the prognostication of tularemia and pseudotuberculosis morbidity in the Iaroslvl region were derived.     

Yersinia pseudotuberculosis plasmids and their significance in the realization of the epidemic process in pseudotuberculosis

The results obtained in the electrophoretic study of the plasmid spectra of 190 Y. pseudotuberculosis strains, isolated from different sources, in 0.6% agarose gel are presented. 11 types of plasmids differing in their molecular weight have been detected. Plasmids with a molecular weight of 45 MD determine Ca2+ dependence, bacterial virulence for white mice and autoagglutination. The presence of differences in Y. pseudotuberculosis strains of serovars I, III and IV has been established, which is manifested by their differing plasmid spectra. The relationship between the presence of plasmids with a molecular weight of 75 and 45 DM in the strains and the character of pseudotuberculosis morbidity in the population has been demonstrated. The epidemic course of infection correlates with the presence of both these plasmids and the sporadic course of infection, with the presence of the plasmid with a molecular weight of 45 MD only.     

Population structure of the Yersinia pseudotuberculosis complex according to multilocus sequence typing

Multilocus sequence analysis of 417 strains of Yersinia pseudotuberculosis revealed that it is a complex of four populations, three of which have been previously assigned species status [Y.?pseudotuberculosis sensu stricto (s.s.), Yersinia pestis and Yersinia similis] and a fourth population, which we refer to as the Korean group, which may be in the process of speciation. We detected clear signs of recombination within Y.?pseudotuberculosis s.s. as well as imports from Y.?similis and the Korean group. The sources of genetic diversification within Y.?pseudotuberculosis s.s. were approximately equally divided between recombination and mutation, whereas recombination has not yet been demonstrated in Y.?pestis, which is also much more genetically monomorphic than is Y.?pseudotuberculosis s.s. Most Y.?pseudotuberculosis s.s. belong to a diffuse group of sequence types lacking clear population structure, although this species contains a melibiose-negative clade that is present globally in domesticated animals. Yersinia similis corresponds to the previously identified Y.?pseudotuberculosis genetic type G4, which is probably not pathogenic because it lacks the virulence factors that are typical for Y.?pseudotuberculosis s.s. In contrast, Y.?pseudotuberculosis s.s., the Korean group and Y.?pestis can all cause disease in humans.     

Anthropurgic foci of pseudotuberculosis and the mechanisms of their formation in groups of servicemen

At the period of 1982 - 2003, morbidity rate in pseudotuberculosis and the Yersinia pseudotuberculosis culture rates in groups of servicemen (from different abiotic objects, from humans and small rodents) in different geographic zones were studied. The cases of the isolation of Y. pseudotuberculosis were most frequently registered in groups of servicemen in the Far East and the Kola Peninsula. In these regions the highest morbidity rate in pseudotuberculosis was registered among servicemen. The contamination rate of vegetables during the year was always greater than in other objects under study, including small rodents. The study demonstrated that in the Armed Forces could appear, temporary and relatively constant anthropurgic foci of pseudotuberculosis even in non endemic regions. They were formed in the objects of the food supply service due to the supply of contaminated vegetables. Synanthropic rodents played a secondary role, though they too facilitated the formation of new anthropurgic foci. Under definite conditions anthropurgic foci could exist autonomously, independently of natural foci.     

The plasmid composition and pathogenetic characteristics of Yersinia pseudotuberculosis strains isolated from human subjects against a background of epidemic and sporadic morbidity

112 newly isolated clinical cultures of Y. pseudotuberculosis have been studied. The strains have been characterized by the presence of plasmids and pathogenicity signs associated with plasmids. The results of the study have confirmed the decisive role of the plasmid with a molecular weight of 44-48 MD in the virulence of Y. pseudotuberculosis. The plasmid with a molecular weight of 82 MD, previously attributed the role of an epidemic marker, has also been found to be widely spread. Our study has revealed no specific features in the plasmid composition of the strains isolated under the conditions of sporadic and epidemic pseudotuberculosis morbidity. The results of the study of the pathogenicity of isogenic derivatives differing by the presence of pXV indicate that the role of plasmids with molecular weights of 3.8 and 82 MD in this process is not essential in the model systems, traditional for enteroinvasive Yersinia.     

Pathogenetic significance of the psychrophilia of Yersinia pseudotuberculosis

The work presents the data indicating that the temperature of Y. pseudotuberculosis cultivation is very important in regulating the activity of pathogenicity factors, necessary for the initiation of the pathogenic process in the cells of the macroorganism. Low temperature (8-10 degrees C), necessary for the growth of Y. pseudotuberculosis, facilitates the activation of invasive and toxic pathogenicity factors. At a growth temperature of 37 degrees C the inhibition of such necessary attributes of virulence as adhesion and invasion into epithelial cells occurs in Y. pseudotuberculosis, which decreases the capacity of these bacteria for inducing the infectious process. The virulence of Y. pseudotuberculosis population, lost as the result of its cultivation in synthetic culture media at a temperature of 37 degrees C, has been found to be restored at low temperature.     

Variability of the clonal structure of Yersinia pseudotuberculosis population under different conditions

In a series of experiments the dynamics of the clonal structure of Y. pseudotuberculosis population was evaluated by cytopathogenicity in soil extract, as well as in associations with blue-green algae (cyanobacteria) and infusoria, under different temperature conditions. In all variants of experiments made at low environmental temperature (10 degrees C) a considerable part of Y. pseudotuberculosis clones (25-40%) was found to be cytopathogenic, while at 22 degrees C such clones were absent or had low cytopathogenicity. At the same time experiments made under the same temperature conditions (10 degrees C) showed the variability of the clonal structure of the bacterial population in different associations and sterile soil extract, as well as at different periods of the experiments. At low temperatures Y. pseudotuberculosis virulent (cytopathogenic) clones, in contrast to avirulent ones, were characterized by the presence of virulence plasmid p45, as well as high urease and catalase activity. The results of the experiments are discussed from the viewpoint of the clonal concept of bacterial populations and their pathogenicity.     

Yersinia enterocolitica 03 findings on porcine tongues in comparison with yersiniosis incidence in man in Czechoslovakia

Positive isolations of Yersinia obtained in repeated bacteriological examinations of porcine tongues at three slaughter-houses in Prague and a single examination at the slaughter-house at Kladno were compared with notified yersiniosis morbidity. The incidence of illnesses caused by Y. enterocolitica 03 does not exceed values of 4.5/100,000 and 3.5/100,000 population in the Czech and Slovak Socialist Republics, respectively, and is equal to a sixtieth part of the notified shigellosis and salmonellosis morbidity. Cultivation of 334 pooled samples consisting of 1142 porcine tongues yielded 12 strains (1.05%) of Y. enterocolitica 03, five strains (0.44%) of Y. pseudotuberculosis and 55 strains (4.82%) of other Yersinia organisms (indole-positive serotypes). Because of the low isolation rates obtained for the individual Yersinia species, Y. enterocolitica 03 in particular, the isolation efficiency of different cultivation techniques and culture media was statistically evaluated for all Yersinia organisms jointly. Primary cultivation on deoxycholate-citrate medium yielded five of the 12 Y. enterocolitica 03 strains isolated. The other Yersinia strains grew only after preliminary propagation. Yersinia pseudotuberculosis grew almost exclusively (4 out of 5 strains) on McConkey's agar.     

The entry portals and routes of Yersinia pseudotuberculosis penetration into the warm-blooded organism

This work presents data indicating that Y. pseudotuberculosis population, cultivated at lower temperature (6-8 degrees C), has a high potential of cellular and tissue invasiveness. Pseudotuberculosis has been experimentally shown to start as generalized infection due to the rapid (during 10-15 minutes) penetration of the infective agent through the epithelium of the mouth cavity, the small intestine, the urinary bladder, conjunctiva, pulmonary alveoli and vascular walls into the blood and then into internal organs. The data, obtained in this study, on the penetration of Y. pseudotuberculosis through any mucous surfaces in different species of warm-blooded animals are indicative, to a considerable extent, of the fact that this process occurs due to the action of nonspecific mechanisms.     

The complete genome sequence of Yersinia pseudotuberculosis IP31758, the causative agent of Far East scarlet-like fever

The first reported Far East scarlet-like fever (FESLF) epidemic swept the Pacific coastal region of Russia in the late 1950s. Symptoms of the severe infection included erythematous skin rash and desquamation, exanthema, hyperhemic tongue, and a toxic shock syndrome. The term FESLF was coined for the infection because it shares clinical presentations with scarlet fever caused by group A streptococci. The causative agent was later identified as Yersinia pseudotuberculosis, although the range of morbidities was vastly different from classical pseudotuberculosis symptoms. To understand the origin and emergence of the peculiar clinical features of FESLF, we have sequenced the genome of the FESLF-causing strain Y. pseudotuberculosis IP31758 and compared it with that of another Y. pseudotuberculosis strain, IP32953, which causes classical gastrointestinal symptoms. The unique gene pool of Y pseudotuberculosis IP31758 accounts for more than 260 strain-specific genes and introduces individual physiological capabilities and virulence determinants, with a significant proportion horizontally acquired that likely originated from Enterobacteriaceae and other soil-dwelling bacteria that persist in the same ecological niche. The mobile genome pool includes two novel plasmids phylogenetically unrelated to all currently reported Yersinia plasmids. An icm/dot type IVB secretion system, shared only with the intracellular persisting pathogens of the order Legionellales, was found on the larger plasmid and could contribute to scarlatinoid fever symptoms in patients due to the introduction of immunomodulatory and immunosuppressive capabilities. We determined the common and unique traits resulting from genome evolution and speciation within the genus Yersinia and drew a more accurate species border between Y. pseudotuberculosis and Y. pestis. In contrast to the lack of genetic diversity observed in the evolutionary young descending Y. pestis lineage, the population genetics of Y. pseudotuberculosis is more heterogenous. Both Y. pseudotuberculosis strains IP31758 and the previously sequenced Y. pseudotuberculosis strain IP32953 have evolved by the acquisition of specific plasmids and by the horizontal acquisition and incorporation of different genetic information into the chromosome, which all together or independently seems to potentially impact the phenotypic adaptation of these two strains.     

Fermentative mechanisms of the psychrophilicity of Yersinia tuberculosis

The specific activity of urease, nitrogenase, hialuronidase and neuraminidase in Y. pseudotuberculosis grown in different culture media and at different temperature has been studied. These enzymes have been found capable of functioning at both relatively low (2-8 degrees C) and high (37 degrees C) temperatures. The thermoadaptive properties of Y. pseudotuberculosis within a wide range of temperatures are ensured by the constant presence of isoenzymes, functioning only at low temperatures or only at high temperatures, in the microbial cells. Low temperature in combination with a definite culture medium triggers the activity of certain enzymatic systems, which explains, to some extent, the biochemical mechanisms of the psychrophilic properties of Y. pseudotuberculosis.     

The effect of Yersinia pestis EV76 6 MD plasmid on the composition of outer membrane proteins of Yersinia pseudotuberculosis YPIII]

On the basis of Yersinia pseudotuberculosis strain YPIII the isogenic variants containing the different combinations of 47 Md plasmids from Yersinia pestis or Yersinia pseudotuberculosis cells with the 6 Md pYP plasmid from Yersinia pestis EV (intact or having impaired the pla gene determining the synthesis of plasmocoagulase). The degradation of the secreted proteins encoded by the 47 Md plasmids of Yersinia pestis and Yersinia pseudotuberculosis in the cells harbouring the 6Md pYP plasmid has been registered. Yersinia pseudotuberculosis strain YPIII carrying its own 47Md and pYP plasmids also contained no YOP1 protein, in contract to the parent strain. The damage of the pla gene eliminated the destructive effect on the outer membrane proteins. Imposition of the 47Md and 6Md plasmids from Yersinia pestis in Yersinia pseudotuberculosis cells may be used for obtaining and study of the physiological role of low molecular mass proteins resulting from proteolysis of proteins encoded by the 47Md virulence plasmid of Yersinia.     

The biological action of Yersinia pseudotuberculosis endotoxin

Experimental studies on guinea pigs have shown that Y. pseudotuberculosis lipopolysaccharide is capable of inducing endotoxinemia accompanied by the development of the thrombohemorrhagic syndrome. In cases of pseudotuberculosis the importance of the increased synthesis of prostaglandins and cyclic nucleotides with the prevalence of PGF2 alpha and cGMP in the genesis of toxico-allergic manifestations of pathologic processes has been established. The pathomorphological picture of pseudotuberculosis endotoxinemia is characterized by sludge, the vascular thrombosis of the microcirculatory bed, diapedetic hemorrhages, delymphatization of the immunogenetic organs. The moderately pronounced action of indomethacin, a prostaglandin inhibitor, on the manifestations of pseudotuberculosis endotoxinemia has been revealed.     

Analysis of the plasmid composition of Yersinia pseudotuberculosis strains and its use for typing pseudotuberculosis pathogens

Electrophoresis in agarose gel has been used to study the plasmid spectra of 854 Yersinia pseudotuberculosis strains isolated from different sources. The plasmids found in the microbial strains are represented by the elements with molecular masses 82; 57; 45; 5.5; 4.4; 3.5; 2.7; 2.4; 2.3 Md. The variable spectra of plasmids is peculiar only for serovar I of Yersinia pseudotuberculosis. Plasmids p45 and p82 are classified as the main, while other plasmids as auxiliary ones. In accord with the classification all plasmid containing strains are divided into 8 plasmid strains. Using the proposed method for intraspecific typing of Yersinia pseudotuberculosis permits one to perfect the epidemiological analysis of pseudotuberculosis infection and make concrete the direction of prophylactic and antiepidemic measures.     

Action of sodium chloride on Yersinia pseudotuberculosis and Yersinia enterocolitica

The bacteriostatic and bactericidal action of sodium chloride on 60 Y. pseudotuberculosis strains, 75 Y. enterocolitica strains and 158 urine-fermenting strains has been studied. A new specific feature of Y. pseudotuberculosis has been revealed: high sensitivity to sodium chloride. The suitability of the sodium chloride test has been shown for the identification of Yersinia and the differentiation of Y. pseudotuberculosis and Y. enterocolitica.     

Impact of Yersinia pseudotuberculosis on the in vitro production of cytokines by whole blood cells of donors

The impact of two plasmid (47, 82 MD), single plasmid (47 MD) and non plasmid Y. pseudotuberculosis strains, Y. enterocolitica (47 MD) as well as Y. pseudotuberculosis superantigen (YPM) on the production of interleukin-1 (IL-1), interleukin-6 (IL-6), interferon-alpha (IFN = alpha) and tumor necrosis factor alpha (TNF-alpha) by whole blood cells obtained from donors was studied. All Y. pseudotuberculosis and Y. enterocolitica strains stimulated the production of IFN-alpha, IL-1, IL-6 and TNF-alpha by whole blood cells, but considerably less than Y. pseudotuberculosis lipopolysaccharide and YPM. These data are indicative of the pathogenetic role played by 82 MD plasmid in manifestation of Y. pseudotuberculosis immunosuppressive properties. The maximum stimulation of the production of cytokines was observed under the action of YPM, which confirmed an important role played by this superantigen in the pathogenesis of Y. pseudotuberculosis.     

Acute oral toxicity of Yersinia pseudotuberculosis to fleas: implications for the evolution of vector-borne transmission of plague

Yersinia pestis diverged from Yersinia pseudotuberculosis相似文献   

Serotype differences and lack of biofilm formation characterize Yersinia pseudotuberculosis infection of the Xenopsylla cheopis flea vector of Yersinia pestis

Yersinia pestis, the agent of plague, is usually transmitted by fleas. To produce a transmissible infection, Y. pestis colonizes the flea midgut and forms a biofilm in the proventricular valve, which blocks normal blood feeding. The enteropathogen Yersinia pseudotuberculosis, from which Y. pestis recently evolved, is not transmitted by fleas. However, both Y. pestis and Y. pseudotuberculosis form biofilms that adhere to the external mouthparts and block feeding of Caenorhabditis elegans nematodes, which has been proposed as a model of Y. pestis-flea interactions. We compared the ability of Y. pestis and Y. pseudotuberculosis to infect the rat flea Xenopsylla cheopis and to produce biofilms in the flea and in vitro. Five of 18 Y. pseudotuberculosis strains, encompassing seven serotypes, including all three serotype O3 strains tested, were unable to stably colonize the flea midgut. The other strains persisted in the flea midgut for 4 weeks but did not increase in numbers, and none of the 18 strains colonized the proventriculus or produced a biofilm in the flea. Y. pseudotuberculosis strains also varied greatly in their ability to produce biofilms in vitro, but there was no correlation between biofilm phenotype in vitro or on the surface of C. elegans and the ability to colonize or block fleas. Our results support a model in which a genetic change in the Y. pseudotuberculosis progenitor of Y. pestis extended its pre-existing ex vivo biofilm-forming ability to the flea gut environment, thus enabling proventricular blockage and efficient flea-borne transmission.     

Chemotaxis of Yersinia pseudotuberculosis as a mechanism in its search for target tissues of the host organism

Y. pseudotuberculosis cells grown at biologically low temperature have been shown capable of chemotaxis with respect to carbohydrates and amino acids. During cultivation at 36-37 degrees C Y. pseudotuberculosis cells retain this property for 10-15 hours and then lose it. The mechanism of chemotaxis makes it possible for Y. pseudotuberculosis to "find" human and animal tissues and can facilitate the realization of the pathogenicity potential of these bacteria. When administered orally to mice motile bacteria, i. e. those grown at 6-8 degrees C, have been more virulent for the animals than nonmotile ones cultivated at 36-37 degrees C.     

Molecular characterization of Corynebacterium pseudotuberculosis isolated from goats using ERIC-PCR

Corynebacterium pseudotuberculosis, the infectious agent of caseous lymphadenitis (CLA), is responsible for substantial economic losses in goat and sheep production. Molecular characterization of C. pseudotuberculosis isolates by enterobacterial repetitive intergenic consensus (ERIC)-PCR has shown promising results in genotyping strains isolated from sheep with CLA. We evaluated the genetic diversity of C. pseudotuberculosis isolates collected from the Sert?o region of the Pernambuco (PE) State, Brazil, and investigated the potential of ERIC-PCR as a tool for the molecular typing of strains of C. pseudotuberculosis isolated from goats. Thirty-two C. pseudotuberculosis strains isolated from goats in the municipalities of Floresta and Ibimirim, PE, C. pseudotuberculosis type strain ATCC 19410, the 1002 vaccine strain, and a field isolate of Rhodococcus equi were fingerprinted using the primers ERIC-1R and ERIC-2 and the primer pair ERIC- 1R+ERIC-2. Using 100% similarity as the cutoff, 8, 10, and 7 genotypes were obtained with ERIC-1-PCR, ERIC-2-PCR, and ERIC-1+2-PCR, respectively. The Hunter-Gaston discriminatory index calculated for the ERIC-1-PCR was 0.75. The index for the ERIC-2-PCR was 0.88, and the index for the ERIC-1+2-PCR was 0.79. Among goat isolates of C. pseudotuberculosis, three, two and four genotypes (found by ERIC-1-PCR, ERIC-2-PCR, and ERIC-1+2-PCR, respectively) had been previously described among sheep isolates from Minas Gerais State, Brazil. These results showed that ERIC-PCR has good discriminatory power and typeability, making it a useful tool for discrimination among C. pseudotuberculosis isolates from goats.