Search

The biological properties of 46 V. cholerae O1 eltor cultures isolated in 2002 from water environment on the territory of Russia are presented. All isolated vibrios proved to be typical in their cultural, morphological, biochemical and serological properties. The atypical character of some of them was mainly linked with their phage resistance. The appearance of vibrios, sensitive to bacteriophage ctx+ and containing gene tcp in the absence gene ctx, was noted. Multilocus VNTR typing made it possible to group the cultures under study in 34 genotypes. The presence of toxin coregulated pili was found to be directly related to locus VcB. The necessity of the systematic study of the pheno- and genotypes of the isolated cultures with the aim of epidemiological surveillance of this infection is emphasized.

In this review the comparative analysis of advantages and disadvantages of the known methods for the immunological diagnostics of streptococcal infections (serotyping, phage typing), as well as the methods of molecular epidemiology (PCR typing with the use of "disseminated" priming, ribotyping, electrophoresis in the pulsing electric field, etc.), is presented. Essentially new approaches, capable of being used in future for the control of epidemically topical clones of group B streptococci, are discussed.

V. parahaemolyticus and V. alginolyticus strains isolated from patients during an outbreak of an acute enteric disease in Vladivostok in 1997 were studied. All strains were found to possess typical taxonomic signs. V. parahaemolyticus isolated from humans had direct heat stable haemolysin exotoxin. The overwhelming majority of these strains belonged to serovar O3K6. Among the cultures under study 7 phage types were determined: phage types 1, 2, 7, 10 in 8 V. parahaemolyticus strains and phage types 2, 4. 5. 7 in 5 V. alginolyticus strains. The diagnostic halophilic phage lyzed vibrios in 30.2% of strains. The cultures under study were found to be highly sensitive to chloramphenicol, cefotaxime, nalidixic acid and cyprofloxacin. The study proved that the outbreak of alimentary toxicoinfection was caused by vibrios of serogroup O3:K6.

Data on the isolation of Listeria spp. cultures on the territory of Ukraine, the frequency of Listeria contamination of alimentary raw materials and foodstuffs, the level of listeriosis morbidity, the clinical forms of the manifestation of this disease, as well as the occurrence of asymptomatic carriership among clinically healthy persons of epidemiologically significant professions, are given. The results of the study of the biological properties of 73 strains of Listeria spp., their sensitivity to antibiotics and Chlorophyllipt are presented.

The data of literature on the pleiotropic variability of the resistance of Y. pestis mutants to diagnostic phage are presented. The conditions of reversion to the initial phenotype are characterized. The mechanisms of the appearance of such variability of Y. pestis, as well as problems arising in connection with this variability and linked with the pathogenic activity of Y. pestis, low effectiveness of the diagnostic methods used in the inspection of the natural foci of plaque, the reservation of microbes in nature during the periods between epidemics, are discussed.

To find out stable and effective producers of major protective antigens intended for use as components of cholera chemical vaccine against V. cholerae strains of serogroups O and O139, the comparative analysis of the production of cholera toxin, toxin-coregulated pili (TCP), antigens O1 and O139, polysaccharide capsule and outer membrane protein OmpU in different V. cholerae strains groups O1 and O139 has been made. V. cholerae strain KM68, serogroup O1, has been found capable of the production of antigen O1, serovar Ogawa, protein OmpU at a sufficiently high level and the hyperproduction of cholera toxin and TCP, and thus suitable for use in the manufacture of cholera bivalent vaccine as the source of these antigens. Specially selected alysogenic noncapsular strain KM137 of serogroup O139, characterized by a high and stable level of the biosynthesis of this somatic antigen when grown in both laboratory and production conditions, may serve as the produces of antigen O139.

On the basis of V. cholerae strain P16064, serogroup O139, spontaneous and transposon mutants with the stable lose of the capacity for producing the polysaccharide capsule, but retaining antigen O139, have been obtained. As revealed in this study, capsular and noncapsular strains differ in their sensitivity to cholera phages 20 and Inaba, as well as in agglutination with O139-antiserum. These data make it possible to use of bacteriophages for the differentiation of capsular and noncapsular strains. The use of noncapsular mutants ensure obtaining rabbit O139-antisera with higher antibody titer.

In 2100 children of different age groups the microbiocenosis of the large intestine was studied. The study revealed that the colonization of the mucous membrane of the large intestine with staphylococci developed in 30% of children with intestinal dysbacteriosis. Young children were mainly affected (91%). The prevailing species among isolated staphylococci was S. aureus (86%), capable of persistence in the intestine (30.9%). In children non typing S. aureus strains mainly circulated (70%), and among phage-typing strains isolates of phage group III prevailed (70.2%). The colonization of the intestine with coagulase-negative staphylococci was possible (14%). Microecological intestinal disturbances in children of different age groups were characterized by different degrees of changes in normal microflora with the prevalence of opportunistic microorganisms in the microbial picture.

7 strains of M.morganii phages and 7 strains of P.rettgeri phages were isolated from lysogenic cultures and the environment. The main biological properties of these phages were studied. The phages under study formed independent taxonomic groups. These phages were found to be highly specific and capable of being used for the identification of bacteria.

The virulent properties of V. cholerae O1 (more than 1000 strains) were studied. For this purpose the following methods were used: the determination of hemolytic activity, the express method based on the determination of the speed of mannite oxidation, complex analysis and polymerase chain reaction (PCR). The comparative analysis of the results of the in vitro determination of virulence revealed that the most frequently occurring strains among the strains isolated from humans were vct+ strains (80.5%), hemolysis-negative strains (83.9%) which were virulent (faintly virulent) as determined by complex analysis (38.2%), cholerogenic as determined by the express method (60.2%). Among the strains isolated from the environment were vct- strains (87.4%), hemolysis-negative strains (63.2%) which were virulent as determined by complex (13.1%), as well as by the express method (74.3%). The data of the determination of the vct gene did not correlate with the results obtained by complex analysis. The use of complex analysis was expedient only in the detection of strains sensitive to eltor phage in the dilution routine test of V. eltor strains. The methods for the determination of virulence, available for practical laboratories, were Grieg's method for the determination of hemolytic activity and express method. PCR proved to reliable in vitro method for the determination of the vct gene.

The study of the biological characteristics used for the identification of the species, biovar and serovar of V.cholerae O1 isolated from environmental objects on the territory of 8 regions of Ukraine for the period of 1974-1993 revealed the tendency towards an increase in the number of altered cultures. Phage sensitivity (60.7%) and capacity for agglutination with cholera species- and type-specific sera (24.6%) proved to be the most variable properties. Resistance to polymyxin (4.8%), the absence of hemagglutination with chick red blood cells (8.7%), the absence of diastatic activity (28.9%) were also detected. The study established that the temporal, ecosystemic and territorial geographical dependence could be observed in the character of variability of V.cholerae O1. The data thus obtained indicate the expediency of monitoring the dynamics of the properties of V.cholerae O1 in order to establish the relationship between its variability and the epidemic process.

As revealed in the realization of the epidemiological surveillance of hospital infections caused by methicillin-resistant S. aureus (MRSA) in different types of hospital, MRSA strains causing purulent inflammatory diseases belong to different clones. The complex marking of MRSA made it possible to determine the presence of the same clone in different hospitals and to detect the outbreaks of hospital infections caused by different clones of MRSA in one hospital. It was found necessary to supplement the commercial international phage-typing set with pages permitting the detection of the specific system of restriction-modification in MRSA.

A high degree of resistance to cholera diagnostic phages and carriership of prophages characteristic of V. cholerae eltor strains vct+ were shown to be the specific features V. cholerae isolated in Daghestan during the period of June-October 1994. Among the strains under study, isolated respectively in 12 and 18 out of 19 regions of Daghestan, a high proportion was found to have resistance to tetracycline (65%) and chloramphenicol (28.6%). Moreover, some strains were found to be resistant to furagin and erythromycin. Out of 242 strains resistant to antibacterial preparations, 163 strains were found to have multiple resistance. Gentamicin, cipropfloxacin and doxicycline were shown to have high in vitro activity with respect to the strains under study.

The morphology and antigenic properties of 34 phages of Vibrio parahaemolyticus and V. alginolyticus strains isolated from Black Sea water, as well as their range of lytic activity and specificity of action, have been studied. Most of these phages have been found to lyze both V. parahaemolyticus and V. alginolyticus strains. In addition, highly specific phages capable of lyzing only V. parahaemolyticus serotype O5:K15, have been detected. The latter fact is a precedent indicating the possibility of search for other typing phages and the development of the scheme for the phage typing of V. parahaemolyticus in future.

Sixteen phages active against bacteria of the genus Serratia have been divided into 4 groups on the basis of the study of their biological properties. As a result, 5 typing phages have been selected, which permitted the typing of 77.3% of S. marcescens cultures under study, divided into 13 phage types.

The range of the lytic activity of 46 phages of parahemolytic vibrios isolated from lysogenic strains, sea water samples, crabs and mussels has been studied. The phages are represented by virions belonging to morphological groups II, IV, V according to the phage classification currently used in Russia and to different serological groups. No relationship between the sensitivity of vibrio strains to the phages under study and the specificity of serotypes O and K has been established. The preparation of diagnostic phage [see text] suitable for the identification of 82% of strains of parahemolytic vibrios has been proposed.

The study of the properties of C. diphtheriae adhesins revealed the absence of their thermostability, which suggested the protein nature of these adhesins. C. diphtheriae also showed pronounced mannose-resistant hemagglutinating activity, as this activity remained unchanged even in the presence of d-mannose. The comparison of the adhesive activity of C. diphtheriae with their phage and corycine sensitivity revealed essential differences between these macroorganisms in the degree of their adhesiveness. The phage lysability and corycine sensitivity of C. diphtheriae strains, determined by the properties of their surface structure, correlated with the degree of their activity.

The lytic activity of plague phage II, serovar 3, with respect to 1,800 bacterial strains has been studied: 760 Yersinia pestis strains, 262 Y. pseudotuberculosis strains, 252 Y. enterocolitica strains, 166 Escherichia coli strains, 90 Shigella strains and 270 strains of other species. The phage has been found to lyse 81.8% of Y. pestis strains, 1 Y. pseudotuberculosis strain and 1 Y. enterocolitica strain. The representatives of other 19 bacterial species have proved to be resistant to the phage. Though having a wide range of action within Y. pestis, the phage does not lyse most of the strains of the causative agent of plague, isolated in certain natural foci. This fact offers promise for using the phage for the differentiation of Y. pestis.

Phage II, isolated from Y. pestis strain 2247 obtained from a desert focus in Central Asia, has been studied. The phage is classified with moderate phages and essentially differs from moderate phages of serovar 2. The sources of isolation, high specificity and the absence of common serological features with presently known Y. pestis phages of serovars 1 and 2 permit the classification of this phage with new serovar 3 of Y. pestis phages.

The biological properties of 106 S. typhi cultures were studied; of these, 59 cultures were isolated from 45 chronic carriers and 47 cultures, from 23 typhoid fever patients. According to the degree of their virulence (CPD50 in the continuous cell-line culture Hep-2), the strains isolated from the patients were more virulent than those isolated from the chronic carriers. The mean value of lg CPD50 was 5.76 +/- 0.04 for the patients and 6.86 +/- 0.03 for the chronic carriers. The strains isolated from the patients showed greater variability in the degree of their virulence. The study of the plasmid spectrum showed that 9.4 +/- 5.6% of the strains contained plasmids. From the patients plasmid-containing strains were isolated more frequently than from the carriers (14.9 +/- 2.5% and 5.1 +/- 2.9%). Multiresistance to antibiotics in combination with the presence of plasmids was detected in 6 strains isolated from the typhoid patients with morbidity having the character of outbreaks.

Materials on the study of four outbreaks of alimentary toxinfections of staphylococcal etiology, carried out by the method of the identification of staphylococci by the spectra of their extracellular proteins, are presented. As the result of this study, the sources and transfer routes of infections have been established. The method of the identification of staphylococci by the exoprotein spectra has made it possible to find out the epidemiological chain with greater accuracy. Such identification may serve as an auxiliary method in epidemiological surveillance.

The differential information content of biological signs in the ecology of different staphylococcal and streptococcal species has been studied by the mathematical method. The method for the intraspecific differentiation of staphylococci, streptococci and gonococci into pathovars with the use of programs for the computerized analysis of the material has been proposed. The mathematical models of strain virulence in different coccal species are described.

The comparative study of 830 hospital and 181 extrahospital S. aureus strains has revealed the existance of the interpopulation (group, geographic) variability of this species. Hospital strains differ from those inhabiting other places by the composition of phago- and resistovars, greater resistance to antibiotics, antiseptic and disinfecting agents, the inhibiting action of antagonist, as well as by pronounced antagonistic activity. The biological characteristics of such strains allow one to classify them with the hospital ecological variants (ecovars) of S. aureus. These properties of hospital strains give them selective advantages in hospitals over extrahospital strains, and the latter are thus ousted from the skin surface, mucous membranes, wound surfaces. The measures taken to prevent hospital infections must be aimed mainly against the hospital ecovars of these bacteria.

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.

In 1,494 pregnant women (on weeks 32-36) staphylococcal carriership was studied. One-third of the women under investigation were found to be carriers, their bacterial discharge increasing in spring and summer. The isolated strains proved to be polyresistant to antibiotics and belonged to epidemic strains. About a half of Staphylococcus aureus strains could not be identified with the use of the international set of phages.

A polyvalent diagnostic bacteriophage for rapid identification (in 6-10 hours) of cholera vibrio of both biotypes has been constructed of virulent E1 Tor phages and recommended for laboratory practice. Polyvalent diagnostic bacteriophage is strictly specific, inactive against the nonagglutinating vibrios, microbes of enteric group and those closely affiliated.

A comparison was made between the results of phage and lysogenic typing of S. aureus strains isolated during several outbreaks of staphylococcal infection and S. aureus cultures isolated from the same carriers at different periods. The study of the groups of strains having the same origin showed that the differences in the number of reactions were more pronounced in lysogenic typing than in phage typing. For this reason lysogenic typing can be recommended only for the identification of those strains which cannot be identified with the use of the phages of the International Basic Set. The results of the experiments with induced phages proliferating in a restriction-defective strain indicated that restriction and modification were mainly responsible for the specificity of lytic reactions.

The basic set of phages recommended for typing staphylococci from cattle and also of local phages were approbated. Staphylococci cultures (950 in all) isolated in various regions of the Soviet Union from milk, milk produce and from cows suffering from mastitis were studied. Percentage of cultures typed by the phages of the basic set proved to be 78.3. Thirty different phage patterns were revealed among staphylococcal cultures lysed by phages. Lytic activity was the greatest in phages of group IV of the basic set. It is suggested that local phage 34k can be used as an additional phage permitting to subdivide the prevailing phage types within group IV into a number of new ones.

The method for differentiating cholera and NAG vibrios by their virulence is proposed. This method is based on the evaluation of the following characteristics: hemolytic activity and sensitivity to phages C and Xdf-5, the vibrios being cultivated in 1% peptone water with 1% of glycerol (for the determination of hemolytic activity) and in 1% peptone water with 1% of barium chloride (for the determination of sensitivity to phages).

The comparative analysis of 133 S. typhi clinical strains isolated from patients and carriers in Dnepropetrovsk Province in 1978-1987 was carried out. As shown by this analysis, 10 Vi phage types were represented in the set of strains under study, phage types A and F1 being the most numerous ones. Phage type F1 occurred less frequently among the strains isolated from carriers. 31.1% of the strains were found to contain plasmids with different molecular weight ranging from 96 to 0.5 MD. The occurrence of plasmid-containing strains remained at the same level during the whole period under study. Low-molecular plasmids occurred more frequently in the strains isolated from carriers. The minimal suppressive concentrations of a number of antibiotics, such as penicillin, ampicillin, monomycin, chloramphenicol, tetracycline, rifampicin and streptomycin, were determined. 7% of the strains were resistant to penicillin, 9% to monomycin, 15%--to tetracycline and 2.6% to chloramphenicol. The correlation between penicillin and monomycin resistance of the strains and the presence of the plasmid with a molecular weight of 60 MD in these strains was established. All strains were shown to be highly variable in the degree of their virulence: from 10(2) to 10(8). The strains isolated from patients possessed greater virulence.

In experimental local staphylococcal infection in white mice, previously immunized with staphylococcal toxoid and the combined preparation (staphylococcal toxoid + protective somatic staphylococcal antigen), the advantage of the latter in protecting the animals against infection with Staphylococcus aureus belonging to different phage groups has been revealed. Immunization with the combined preparation, carried out in 2 injections, has been found to stimulate antimicrobial immunity, simultaneously with antitoxic one, which indicates the expediency of the further study of the combined preparation.

Spontaneous mutants of S. aureus 209 P resistant to proflavine sulphate and possessing cross resistance to acriflavine and acridine yellow were isolated. Sensitivity of these mutants to acridine orange, acridines No. 40 and 56 remained unchanged. The phage type and the indices of potential pathogenicity of proflavine-resistant mutants coincided with the corresponding S. aureus 209 P indices.

The results of the phage typing of 5, 168 Staph. aureus strains isolated in a surgical hospital between 1959 and 1977 are analyzed for each year of this period. The wave of increase in the number of staphylococci belonging to phage group II which began, as discovered in this study, in 1965 and still showed no tendency towards decrease in 1977, as well as the periodicity of rises and falls in the number of staphylococci belonging to phage groups I and III are discussed and compared with the data contained in the literature. The authors come to the conclusion that Staph. aureus is subject to wave-like rises and falls in the number of strains belonging to the main phage groups of the species, and among them the strains belonging to phage groups I and III seem to be inversely related in respect of rises and falls in number, such changes occurring periodically at an interval of 10-12 years, while in the strains belonging to phage group II changes in number occur at a slower rate. The constant account of the percentage of phage groups I, II and III is recommended to ensure rational antibiotic therapy.

This work was aimed at the study of the phage-type pattern of the causative agents of typhoid fever isolated in the Azerbaijan SSR in 1960-1973. As revealed, the following 26 phage-types circulated in Azerbaijan during the period under study: A, B1, B2, B3, C1, C4, C5, D1, D2, D4, D8, E1, E2, E3, E5, F1, F2, I1, M1N, T, 28, 38, 39, 40 and 46. The most widespread were phage-types A (22.86%), E1 (13.96%), F1 (9.74%), F2 (6.70%), and 28 (5.71%) constituting over half of the typed typhoid strains. Sources and ways of transmission of the infection were deciphered with the aid of phage-typing typhoid cultures.

Staphylococci occur in donkeys more frequently than in other animals, and only from donkeys coagulase-negative staphylococci, characteristic of humans (S. hominis, S. capitis, S. cohnii), were isolated. Least frequently staphylococcal carrier state was registered in cats; in these animals only coagulase-negative strains were found to occur. From 30 donkeys coagulase-positive staphylococci belonging to 47 S. aureus strains were isolated. These strains differed from known ecological variants in their biological properties, thus suggesting the existence of S. aureus ecovar specific for donkeys. These strains did not coagulate human, bovine and ovine plasma, but coagulated rabbit plasma in 100% of cases and donkey plasma only in 53% of cases; at the same time they relatively often produced delta hemolysin, rarely phosphatase and hyaluronidase and never fibrinolysin. These strains were typed by KPC phages, mainly 116 and 117.

Altogether 55 S. aureus strains were isolated from the nose and skin of 2 monkey species (Cercopithecus sabaeus and Macaca fascicularis). The strains were studied in 19 biological tests. 45 of these strains were found to differ in their biological properties from the ecological S. aureus variants described in literature. Of these grounds the strains were classified with the new ecovar simiae comprising 2 subvariants. The strains of the ecovar simiae coagulated human plasma, did not coagulate bovine plasma, formed type A/B colonies on a medium containing crystalline violet, required longer time to ferment mannitol (4-5 days), possessed DNase, were sensitive to "human" and resistant to "bovine" phages. The cultures of subvariant 1 produced fibrinolysin and caused type A hemolysis, the strains of subvariant 2 has no fibrinolysin and caused types B and C hemolysis.

A study was made of the sensitivity spectra of various strains of Sh. flexneri and R-mutants of various chemotypes to bacteriophages used for lysotyping of shigellae and to some bacteriophages specific of the R-mutants of salmonellae and E. coli. As a result of study there was selected and characterized a collection of bacteriophages specific of the S-strains and R-mutants of shigellae of different chemotypes, which could be used in genetic and immunochemical investigations.