Opportunistic microorganisms: the causative agents of food toxicoinfections and acute intestinal diseases

The analysis of sporadic morbidity due to acute intestinal infections and toxicoinfections caused by potentially pathogenic microorganisms is presented. The hypothesis stating that different pathogenic agents have different levels of pathogenic potential at a given stage of their evolution is proposed. Microorganisms with a low level of pathogenicity potential are characterized by the prevalence of the syndrome of toxicoinfection and by the rarity or absence of the syndrome of an acute intestinal disease. The prevalence of the latter is characteristic of potentially pathogenic microbes with a high level of pathogenicity potential making them similar to complete parasites.     

Use of the coagglutination reaction of yeast-like Candida maltosa fungi for detecting fimbriae in intestinal bacteria

The capacity of nonpathogenic yeast-like C. maltosa strains to coagglutinate Escherichia coli has been studied. C. maltosa cells have also been shown to coagglutinate E. coli possessing mannose-sensitive adhesins in a wide range of their concentrations (5-140 bacterial cells per C. maltosa cell). Strains belonging to types CFA/I and CFA/II with fimbriae, similarly to their corresponding paired genetically related strains without these adhesins, are practically incapable of agglutinating C. maltosa cells, while strains K88 and B41 react with them. The reaction occurs at a concentration of 9.5-37.0 and 38.0-55.5 bacteria respectively per C. maltosa cell and is not inhibited by 1% d-mannose. The suggestion that C. maltosa cell surface glycoproteins contain not only receptors for E. coli fimbriae, type I, but also components similar in their structure to receptors specific to the mannose-resistant adhesins of strains K88, K99 and 41, has been confirmed by hemagglutination inhibition with C. maltosa surface antigens as inhibiting agents.     

HLA system antigens in persons with differing susceptibility to the causative agents of acute respiratory diseases

The relationship between the susceptibility of the body to infections caused by influenza A and B viruses, parainfluenza viruses, adenoviruses, Mycoplasma pneumoniae and antigens of the HLA system was studied on a group of 400 adolescents placed under clinico-epidemiological surveillance for two years. The relationship between histocompatibility antigens and acute respiratory diseases was manifested in a decrease or increase in the occurrence of recurrent diseases and infections or in the probability of the development of the diseases in infected persons. HLA B40 was associated with resistance to influenza A, B18 and B21 were associated with resistance to parainfluenza, B15 and B35 were associated with resistance to M. pneumoniae infection; susceptibility to influenza B was registered in persons with HLA B12 and to M. pneumoniae infection, in persons with HLA B16 and B18. With respect to different infective agents, the relative risk of infection varied within 1.7 and 5.0.     

Mechanism of the transmission of the causative agents of infectious diseases

Another interpretation, differing from the commonly acknowledged one, of the transfer mechanism is presented. The factors transporting pathogens in the body are the integral part of the transfer mechanism. They ensure the interrelation of the infectious and epidemic processes. In typical contact infections these factors function integrally as the transfer mechanism consisting of two components. This is the sum total of environment and internal factors, specific for a given pathogenic species. These factors ensure the travel of the pathogens from an infected body to a new one. From this viewpoint, the source of infection cannot be an independent element of the infectious process. It is only a transfer factor. The localization of the pathogen, constituting just one of the stages of its travel route in the body, cannot determine the specificity of the transfer mechanism. Its specificity depends on the properties of the pathogen.     

Attempt at detecting the systems of host specificity in the bacterial causative agents of plague

An attempt at revealing the system of host specificity in Y. pestis by the methods of transformation and conjugation has been made. No endonuclease restriction has been detected.     

Identification of the causative agents of glanders and melioidosis by polymerase chain reaction

Burkholderia mallei and B. pseudomallei are causative agents of glanders and melioidosis, respectively, i.e. severe and fatal infection diseases of man and animal. The computer-based analysis of the 23S rRNA gene sites was used for selecting the primers. Two pairs of primers were chosen for the identification of B. mallei and Bpseudomallei. DNAs from 48 B. pseudomallei and 15 strains of B. mallei, unlike from other geterological bacteria, were positively amplified. Therefore, the method of polymerase chain reaction can be used in laboratory diagnosis of glanders and melioidosis.     

Use of the indirect hemagglutination reaction for detecting antibodies to Pseudomonas pyocyanea in acute suppurative destructive pneumonia]

No less than 4-fold increase in the antibody titres to Pseudomonas aeruginosa during the infectious process served as laboratory confirmation of its participation in the infectious process. In 49 of 91 patients hemagglutining titre exceeded the diagnostic one (1:640). In 9 patients (chiefly in infants) hemagglutinin titre remained low, but there was a rise of antibody level to Pseudomonas aeruginosa during the disease. High hemagglutinin titres were noted in 12 patients on admission to the clinic, with reduction of the antibody titres at the late periods of the disease. Antibody titres remained unchanged during the disease in 15 patients. In 3 cases the indirect hemagglutination test was assesed as negative. In the rest of the patients hemagglutinin titres varied within the range of the diagnostic titre. Thus, the indirect hemagglutination test with erythrocytic diagnostic agent permitting to determine antibodies to Pseudomonas aeruginosa could be used at the clinic in combination with bacteriological and other investigations for establishing etiology of the destructive process.     

Etiology of purulent septic diseases and the antibiotic resistance of the isolated causative agents

Among the causative agents of purulent septic diseases in the surgical hospital, 25 microbial species were isolated; of these, the prevailing species were Staphylococcus aureus (19.86 +/- 1.07%), Escherichia coli (16.5 +/- 0.99%) and Pseudomonas aeruginosa (10.06 +/- 0.8%). From environmental objects in the hospital 14 microbial species were isolated, among them bacteria of the genus Enterobacter (27 +/- 1.7%), E. coli (19.07 +/- 1.48%), S. aureus (14.7 +/- 1.31%), Klebsiella pneumoniae (13.73 +/- 1.31%), P. aeruginosa (7.33 +/- 0.98%). During 3 years of observation the isolation rate of K. pneumoniae from different environmental objects was found to increase threefold to 24.7 +/- 2.7%. The results of the study of the microbial picture in surgical hospitals, as well as the antibiotic resistance of circulating causative agents, should be borne in mind while taking epidemic control measures.     

Antibacterial activity of rifampicin against the causative agents of suppurative, septic diseases]

The antibacterial activity of rifampicin was studied in comparison with other antibiotics with respect to clinical strains isolated from cases with various purulent inflammatory processes caused by Staphylococcus, E. coli, Ps. aeruginose, Proteus. The aim of the study was to define the role of rifampicin in the treatment of the above infections. No rifampicin resistant strains were found among staphylococci belonging to the phenotype carrying the determinants of resistance to 2-8 antibiotics. Rifampicin was less active against gramnegative organisms. High heterogeneity of the microbial population of rifampicin was shown with respect to all microbial strains tested. The rate of the spontaneous mutants was high. The average rate of the mutants was 1-7.7-10-8. The studies on the dynamics of the rifampicin resistance increase in the strains of Staphylococci, E. Coli, Ps. aeruginosa and Proteus showed that the resistance increased after 1-2 passages, which means that one-stage mutation was characteristic rifampicin.     

Use of a diploid cell line for detecting the toxic components in medical immunobiological preparations

Besides specific antigens medical immunobiological agents (MIBA) contain chemical compounds (formaldehyde, aluminium hydroxide and mercury salt, merthiolate) in permissible concentrations. Therefore, the investigation of MIBA and their components should involve methods studying the effect of chemical compounds on cells and their structural components. For this purpose WHO recommends to use cell cultures. The results obtained show that cell cultures (constant and diploid lines) allow the differentiation in the degree of toxicity of chemical compounds constituting MIBA. Merthiolate had the strongest irreversible lethal effect. The technique can prove useful for more accurate evaluation of toxicity in inactivated bacterial and viral vaccines as well as in serum preparations. Cell culture can be successfully used for the detection of toxic components in vaccines and serum drugs, with the final safety tested by their injection to animals.     

Use of infusoria Paramecium caudatum for the evaluation of the toxicity of antigens of different causative quarantine agents

The results of the evaluation of the toxicity of bacterial antigens obtained from the causative agents of plaque, glanders, melioidosis, cholera on infusoria of the species P. caudatum, as well as on cell lines L-929, CHO K-1 and peritoneal macrophages of BALB/c mice, are presented. As revealed in this study, the method of toxicity determination on infusoria is similar in its sensitivity to the methods of testing on. CHO K-1 and L-929 cells, but the former is simpler, more available and permits the determination of toxic doses producing disturbances in the vital activity of the infusoria, but not leading to their death.     

Cross-reacting antigens of pathogenic Burkholderia and some dangerous causative agents of infectious diseases

Cross-reacting antigens in B. mallei, B. pseudomallei, B. thailandensis, Francisella tularensis, Yersinia pestis and Mycobacterium tuberculosis were studied with the use of immuno- and electrophoretic techniques. The set of antigens was shown to be almost identical in the causative agents of glanders, melioidosis, as well as in B. thailandensis, though in the latter organism 200-kD glycoprotein was absent. The analysis of immuno- and proteinograms demonstrated the presence of cross-reactions in the representatives of the genus Burkholderia with the causative agents of plague, tularemia and tuberculosis, which served as the basis for making the scheme of their antigenic relationships. The use of immunosorption techniques with subsequent analysis of the preparations by means of the SDS polyacryl gel electrophoresis and immunoblotting made it possible to characterize cross-reacting antigens of the pathogenic microorganisms under study, to establish their molecular weights (81-15 kD) and to show that some detected antigens are analogous to B. pseudomallei outer membrane proteins (34 and 30 kD).     

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.