Etiologic structure of bacterial dysentery in the USSR in 1983-1985

The etiological structure of dysentery in the USSR in 1983-1985 is characterized. Sonne dysentery was found to prevail in the territories with adequate water supply, while dysentery caused by Shigella flexneri prevailed at the territories with unsatisfactory water supply. S. dysenteriae and S. boydii were found to play a limited role in the etiology of dysentery. In the presence of global pandemic, an increase in the isolation rate of S. dysenteriae I in the USSR is observed. The data on the biochemical structure of S. sonnei are presented.     

Shigellosis in the USSR: the etiological role of Shigella dysenteriae

The etiological role of S. dysenteriae in Shigella infections at different territories of the USSR in 1983-1987 is analyzed. The study shows that S. dysenteriae pertain to territories with unfavorable water supply of the population. At some of these territories, in particular the Uzbek SSR, Grigor'ev-Shiga dysentery seems to gain ground and the restoration of the area of its spread occurs. In recent years the penetration of Grigor'ev-Shiga dysentery from abroad became more frequent in the presence of the pandemic of this dysentery in the world, which caused the appearance of the disease in 17 out of 27 basic territories of the All-Union Center of Shigella Infections. The ways for increasing the control of this infection are outlined.     

The importance of Shigella boydii in shigellosis morbidity in the USSR

The etiological role of S. boydii in Shigella infections registered at different territories of the USSR in 1986-1987 was analyzed. As established by this analysis, S. boydii infection occurred mainly at the territories with unsatisfactory water supply of the population; from these territories the infection spread to ther territories of the USSR. The dominating serovars causing S. boydii dysentery, as well as Shigella infections, at different territories of the USSR was shown to be identical, which was indicative of the fact that the immunological factor had no influence on the etiological structure of Shigella infections, determined by the activity of the main routes of the transfer of infection. On the whole, S. boydii serovars 2, 4 and 1 were found to prevail in the USSR.     

The etiological structure of shigellosis in the former USSR--an indicator of the activity of the main routes of infection transmission]

The data on the etiological structure of Shigella infections in the USSR in 1988-1989 are presented. The study showed the dominating role of S. flexneri with S. sonnei also retaining great importance in Shigella infections. The process of the liquidation of S. dysenteriae and S. boydii infections began in some large cities. The domination of dysentery caused by S. flexneri and a high typhoid rate, particularly in Central Asia, were due to poor water supply of the population. The spread of dysentery caused by S. sonnei was completely independent of the water factor. The decisive role in the transmission of S. sonnei in infective doses was explained by decentralized milk supply.     

Etiological structure of dysentery in the republic of Armenia]

In this work materials on the etiological structure of Shigella infections at different territories of Armenia are presented. Four Shigella species have been found to circulate in Armenia. The dominating etiological agent is S. flexneri with S. sonnei also playing an important role. The serological picture of S. flexneri is characterized by the prevalence of subserovar 2a.     

Structure of the causative agents of shigellosis in areas of the USSR 1979-1981

Summarized data on the specific structure of Shigella strains isolated in different territories of the USSR in 1979-1981 are presented. These data indicate that in the intra-specific structure of S. flexneri strains the proportion of serological subvariant 2a increased and that of serological variant 6 and subvariants 16 and 4a decreased during this period. Using one of the base territories of the All-Union Shigellosis Center as an example, the spread of an unusual serological variant of S. flexneri (IV:7,8) in the USSR is shown. The increase of the proportion of S. boydii strains, mainly S. boydii 4, is noted.     

Nature of the epidemic process in Sonne and Flexner dysenteries and the causes of its induction

A comparative study of the epidemic process in Sh. sonnei and Sh. flexneri dysentery in different regions of the USSR revealed that the morbidity level of Sh. sonnei dysentery changed simultaneously in the regions under study at intervals of 2-3 years. Sh. flexneri dysentery showed morbidity rises occurring at intervals 6-8 years, and their occurrence did not coincide with the periods of elevated morbidity in Sh. sonnei dysentery. The data obtained in the cohort analysis and in the study of recurrent morbidity suggest that Sh. flexneri dysentery produces more pronounced postinfection immunity than Sh. sonnei dysentery, and the immunological factor probably affects the dynamics of the epidemic of these Shigella infections.     

Epidemiology of bacillary dysentery in Algeria. I. The epidemiological aspects of dysentery in Algeria

Bacterial dysentery plays an important role among infectious diseases in Algeria. A tendency to the growth of the morbidity rate has been observed. Dysentery is irregularly spread in different zones of the country. The highest morbidity rate is registered in the Sahara zone and in the eastern part of the country. The morbidity rate among the urban population is higher than among the rural population. S. flexneri prevail in the etiological structure of dysentery infection. Of all age groups, the highest morbidity rate is observed among children during the first 2 years of life. In recent years lethality varies between 2.9% and 7.5%. Patients are hospitalized mainly on the basis of clinical symptoms.     

Unusual serovar of the causative agent of Flexner's dysentery. I. Its distribution and biochemical properties

The data on the circulation of some S. flexneri strains in the USSR are presented. The antigenic structure of these strains (type antigen 4 and group antigens 7, 8) is not characteristic of known serological subvariants 4a, 4b or var. X. The time course of changes in their spreading on certain base territories controlled by the All-Union Shigellosis Center in 1980-1983 is shown. The biochemical characteristics of S. flexneri strains IV:7,8 under study, isolated in the USSR and abroad (Czechoslovakia, London) from humans, from a monkey and from the environment, are given. Similarities in the biochemical reactions of these strains with respect to indole, rhamnose, saccharose, maltose, arabinose and raffinose have been revealed. The strains isolated in the USSR have shown differences in the spectra of their resistance to antibiotics, depending on their territorial origin.     

Genetic characteristics and trends in the spread of a new Shigella flexneri subserovar with the antigenic formula IV:7,8

As the result of experiments with the conjugation of S. flexneri strains 4 belonging to an unusual subserovar (IV: 7,8) with Escherichia coli donor strains K12 Hfr C and Hfr H, as well as experiments with converting phages IV and 7,8, this new subserovar of S. flexneri 4, similarly to other S. flexneri subserovars, was proved to be the Y-variant of shigellae rendered lysogenic by the two above phages. The experiments also revealed that 97.9% of all S. flexneri strains 4 (IV: 7,8) under study possessed invasive properties and were capable of inducing specific keratoconjunctivitis in guinea pigs. Observations on the isolation of S. flexneri strains 4 belonging to the new serovar (IV: 7,8), carried out by the All-Union Shigelloses Center on its basal territories in 1980-1984, made it possible to establish the tendency towards a wider circulation of this infective agent in the USSR.     

A bacterial invasin induces macrophage apoptosis by binding directly to ICE.

Shigella, the etiological agent of dysentery, kills macrophages by inducing apoptosis. Deletion mutants in the invasion invasion plasmid antigen B (ipaB) of Shigella flexneri are not cytotoxic. Here, we localized IpaB to the cytoplasm of macrophages infected with S. flexneri. Purified IpaB induced apoptosis when microinjected into macrophages, indicating that IpaB is sufficient to induce apoptosis. Using a GST-IpaB fusion protein as a ligand in affinity purification, we isolated four IpaB binding proteins from macrophages which were identified as the precursor and the mature polypeptides of interleukin-1beta converting enzyme (ICE) or a highly homologous protease. We found that IpaB binds directly to ICE and this enzyme is activated during S. flexneri infection. Furthermore, specific inhibitors of ICE prevented Shigella-induced apoptosis.     

Tendencies in the epidemic process of dysentery in Ryazan

In shigellosis caused by Sh. sonnei and Sh. flexneri the epidemic process was found to have considerable difference in the tendencies and pace of its development. Shigellosis which dominated in the etiological structure at the period following 1966 was dysentery caused by Sh. sonnei; it showed the tendency towards a decrease in morbidity rate. Dysentery caused by Sh. flexneri was second in respect to the frequency of its occurrence after 1966 and showed the tendency towards increase. The simultaneous circulation of Sh. sonnei and Sh. flexneri, the differences in the epidemiology of these types of shigellosis make it imperative that they be studied separately, taking into ccount their etiological selectivity to the main routes of transmitting the infection.     

Effect of a live enteral dysentery vaccine from spontaneous Flexner mutant 2a 516m on the immunoglobulin-producing cell count in the large intestine mucosa in dysentery

The influence of vaccinal therapy with live oral dysentery vaccine prepared from S. flexneri 2a 516M on the content of immunoglobulin-producing cells in the mucous membrane of the large intestine was studied. A considerable increase in the number of IgA- and IgM-synthetizing cells was shown to occur in the course of the infectious process in acute dysentery. In chronic dysentery the content of IgA- and IgM-synthetizing cells in patients was considerably lower than in a smooth course of acute dysentery. The use of the vaccine for the therapy of patients with chronic and especially acute dysentery resulted in a considerable rise in the number of plasma cells synthetizing IgA, IgM and IgG.     

Diagnostic test system for the quantitative determination of Shigella antigens in patient blood by an immunoenzyme analytical method

The diagnostic test system under trial has been shown to permit the detection of S. sonnei and S. flexneri specific antigens with an accuracy of 10(-3) micrograms. Along with high sensitivity, the test system has sufficiently high specificity. Statistically significant differences in the occurrence of specific dysentery antigens and their levels in the blood of dysentery patients and healthy persons have been revealed.     

Characteristics and trends in the development of an epidemic process of Sonne and Flexner dysentery among preschool children

The results of studies indicate that the morbidity rates of dysentery among children attending preschool institutions and children brought up at home converged in recent years. This phenomenon was most pronounced among children of the kindergarten age group. At the same time dysentery caused by Sh. sonnei and Sh. flexnery produced a higher morbidity rate among children attending nursery in comparison with that among children of the same age group brought up at home. Group infections in preschool institutions were caused by Sh. sonnei in 89.1% of cases and by Sh. flexneri in 10.9% of cases. Outbreaks due to the transfer of infection through everyday contacts were observed only in dysentery caused by Sh. sonnei, constituting 71.4% of the total number of dysentery outbreaks.     

Shigella flexneri regulates tight junction-associated proteins in human intestinal epithelial cells

Shigella spp. are a group of Gram-negative enteric bacilli that cause acute dysentery in humans. We demonstrate that Shigella flexneri has evolved the ability to regulate functional components of tight junctions after interaction at the apical and basolateral pole of model intestinal epithelia. In the regulation of tight junctional protein assemblies, S. flexneri can engage serotype-specific mechanisms, which targets not only expression, but also cellular distribution and membrane association of components of tight junctions. Distinct mechanisms resulting in the regulation of tight junction-associated proteins are initiated after either apical or basolateral interactions. S. flexneri serotype 2a has the ability to remove claudin-1 from Triton X-insoluble protein fractions upon apical exposure to T-84 cell monolayers. S. flexneri serotype 2a and 5, but not the non-invasive Escherichia coli strain F-18, share the ability to regulate expression of ZO-1, ZO-2, E-cadherin and to dephosphorylate occludin. The disruption of tight junctions is dependent on direct interaction of living Shigella with intestinal epithelial cells and is supported by heat-stable secreted bacterial products. Intestinal epithelial cells have the ability to compensate in part for S. flexneri induced regulation of tight junction-associated proteins.     

Dynamics of bacterial polysensitization in acute dysentery in children depending on the species of the causative agent

Studies on polysensitization, evaluated by the neutrophil damage index, have been made with the use of dysenterin and the allergens of hemolytic staphylococci, enterococci and Escherichia coli. The studies have revealed that both specific and nonspecific sensitization to hemolytic staphylococci and enterococci is higher in dysentery caused by Shigella flexneri than in dysentery caused by S. sonnei and has the tendency to increase in the course of the disease.     

Identification of functional regions within invasion plasmid antigen C (IpaC) of Shigella flexneri

Shigella flexneri causes bacillary dysentery with symptoms resulting from the inflammation that accompanies bacterial entry into the cells of the colonic epithelium. The effectors of S. flexneri invasion are the Ipa proteins, particularly IpaB and IpaC, which are secreted at the host-pathogen interface following bacterial contact with a host cell. Of the purified Ipa proteins, only IpaC has been shown to possess quantifiable in vitro activities that are related to cellular invasion. In this study, ipaC deletion mutants were generated to identify functional regions within the IpaC protein. From these data, we now know that the N-terminus and an immunogenic central region are not required for IpaC-dependent enhancement of cellular invasion by S. flexneri. However, to restore invasiveness to an ipaC null mutant of S. flexneri, the N-terminus is essential, because IpaC mutants lacking the N-terminus are not secreted by the bacterium. Deletion of the central hydrophobic region eliminates IpaC's ability to interact with phospholipid membranes, and fusion of this region to a modified form of green fluorescent protein converts it into an efficient membrane-associating protein. Meanwhile, deletion of the C-terminus eliminates the mutant protein's ability to establish protein-protein contacts with full-length IpaC. Interestingly, the mutant form of ipaC that restores partial invasiveness to the S. flexneri ipaC null mutant also restores full contact-mediated haemolysis activity to this bacterium. These data support a model in which IpaC possesses a distinct functional organization that is important for bacterial invasion. This information will be important in defining the precise role of IpaC in S. flexneri pathogenesis and in exploring the potential effects of purified IpaC at mucosal surfaces.     

Conditions and factors determining the etiological structure of dysentery and its changes. Report 1. Epidemiological theory of etiological selectivity of the main (primary) pathways of infection and their differences in various nosological forms of dysentery]

The authors present the elaborated and formed epidemiological theory ("conformity theory") according to which the etiological structure of dysentery is determined by the etiological selectivity of the main (primary) waves of transmission of the infection differing in various nosological forms of dysentery. In Grigoriev-Shiga dysentery the domestic way of the spread of infection plays the main role, in Flexner and Newcastle dysentery--the water way, and in Sonne dysentery--the food way (particularly through the milk). Evolution of the etiological structure of dysentery serves as the reflection of evolution of the principal ways of transmission. The complex of prophylactic and antiepidemic measures in individual noslogical forms of dysentery should be differentiated and be directed in epidemiological sense to the neutralization of the corresponding main (primary) way of transmission of the infection.     

Detection of Shigella antigens in the feces of patients with acute intestinal diseases using a coagglutination reaction

A total of 113 patients with acute intestinal diseases have been examined with the use of the coagglutination test. 84.95% of the patients showed the presence of different Shigella antigens. In patients with bacteriologically confirmed dysentery the corresponding Shigella antigens were detected in 96.97% of cases in S. sonnei dysentery, in 90% of cases in S. flexneri dysentery, in 75% of cases in S. newcastle dysentery and in 100% of bases in S. boydii dysentery. In 81.6% of patients with acute intestinal diseases of unknown etiology the coagglutination test revealed the presence of various Shigella antigens.