Disruption of microbiocenosis of the large intestine and the immune and interferon status in children with bacterial complications of acute viral infections of the respiratory tract and their correction by high doses of bifidumbacterin forte]

One hundred and twenty-nine children with acute viral and bacterial infection of the respiratory tract were examined and disturbance of the large intestine microflora was detected. It was characterized by significant reduction of lactobacilli, moderate growth of opportunistic bacteria and higher contents of Candida. Changes in T- and especially B-cellular immunity were observed in 35 per cent of the patients. In patients with decreased avidity of the immunoglobulins G in the peripheral blood the changes were observed in 82-100 per cent of the cases. In the majority of the patients the capacity for interferon genesis was suppressed. A shorten course (5 days) of the bifidumbacterin forte therapy in a dose of not less than 10(9) CFU/ml. normalized the intestinal microflora, improved the indices of the B- and T-cellular immunity (including the subpopulation of the T-helper cells but not the T-suppressor cells), stimulated NK and improved the ability to induce alfa- and gamma-interferons of the peripheral blood leukocytes. The experience with using high doses of bifidumbacterin forte was evident of its good tolerance and possible value in increasing the patient resistance to infection.     

Invasiveness and cytotoxicity as criteria in assessing Yersinia attenuation

The electron microscopic study of cells HEp-2 and the complex microbiological and morphological study of tissues and organs of guinea pigs and mice infected with the isogenic pairs of Yersinia strains (Y. pseudotuberculosis I and Y. enterocolitica 09) differing in the presence of the calcium-dependence plasmid, as well as Y. pseudotuberculosis mutants resistant to rifampicin, nalidixic acid or crystal violet without this plasmid, have revealed that the invasiveness and cytotoxicity of the infective agents are not directly related to the presence of the above-mentioned plasmid in these bacteria. The use of the quantitative characteristics of virulence, such as penetration ability, intracellular multiplication, dissemination and the formation of degenerative changes, has made it possible to find out that the mutants of Y. pseudotuberculosis I, yielding the negative result in the keratoconjunctivitis test and resistant to the above-mentioned antimicrobial substances, can be arranged in the following order according to the degree of attenuation: rifr mutants--nalr mutants--kvlr mutants. In contrast to Y. pseudotuberculosis I, the loss of the calcium-dependence plasmid by Y. enterocolitica 09 is accompanied by an essential decrease in their invasive and cytotoxic properties, but this relationship is indirect and unstable. The proposed criteria intended for use in the evaluation of the degree of the manifestation of the invasive and cytotoxic properties of bacteria can be useful for the selection of optimally attenuated Yersinia strains showing promise as vaccine strains.     

The efficacy of Klebsiella pneumoniae bacteriophage in the therapy of experimental Klebsiella infection

The effectiveness of specific phage therapy was studied on Klebsiella experimental sepsis in noninbred white mice, caused by the intraperitoneal injection of K. pneumoniae highly virulent strain K2 5055 into the animals. For treatment, Klebsiella polyvalent bacteriophage administered on day 2 after the infection of the animals with Klebsiella was used. The study revealed that bacteriophage could be detected in the blood and internal organs of the animals within 24 hours irrespective of the route of its administration: intraperitoneal, intravenous or intranasal. The bacteriophage preparation, introduced intraperitoneally, was shown to be effective in the treatment of generalized Klebsiella infection. One daily intraperitoneal injection of Klebsiella bacteriophage for 15-20 days proved to be the optimum scheme of treatment. In contrast to chemotherapeutic preparations, bacteriophages had no effect on normal microflora and did not aggravate dysbiotic disturbances. For this reason, bacteriophages may become one of alternative antimicrobial remedies, selectively affecting infective agents.     

The modelling of the translocation of the intestinal microflora in conventional animals

To study the mechanisms of the translocation of enteric microflora and to develop the corresponding prophylactic measures, experimental models are necessary. In this connection two methods of simulating translocation are proposed. One of these methods is reproduced in animals resuscitated from the state of apparent death caused by acute venous blood loss and the other method, in animals with acute renal insufficiency induced by the ligation of the middle part of both ureters. During the period from the first hours to two weeks after the state of apparent death enterobacteria penetrate into mesenteric lymph nodes and occasionally into the liver, spleen and blood. On day 3 after the ligation of the ureters enterobacteria can be isolated from the above-mentioned organs and the blood, while the kidneys remain sterile. The models are reproducible, exhibit adequate clinical manifestations of these terminal states, and permit the detailed investigation of the translocation mechanisms.