[Dormant state and phenotypic variability of Staphylococcus aureus and Corynebacterium pseudodiphtheriticum].

Ability to produce dormant forms (DF) was demonstrated for non-spore-forming bacteria Staphylococcus aureus (a nonpathogenic strain) and Corynebacterium pseudodiphtheriticum (an organism of the normal oropharyngeal flora). The salient features of the sthaphylococcal and corynebacterial DF were (1) prolonged preservation of viability; (2) resistance to damaging factors (heat treatment); and (3) specific morplology and ultrastructure. The optimal conditions for DF formation were (1) transfer of the stationary-phase cultures into saline solution with CaCl2 (10-300 mM) (for S. aureus); (2) growth in SR1 synthetic medium with fivefold nitrogen limitation (for C. pseudodiphtheriticum); and (3) incubation with (1-5) x 10(-4) M) of C12-AHB, an alkylhydroxybenzene akin to microbial anabiosis autoinducers. Increase of C12-AHB concentration to 7 x 10(-4) -2 x 10(-3) M resulted in "mummification" with irreversible loss of viability without autolytic processes. Germination of the dormant forms was followed by increased phenotypic variability, as seen from (1) diversity of colony types and (2) emergence of antibiotic-resistant clones on selective media. The share of kanamycin-resistant S. aureus variants was most numerous 0.002-0.01% in 4-month DF suspensions in saline with CaCl2. In the C. pseudodiphtheriticum DF produced under the effect of C12-AHB, the share of kanamycin-resistant variants was also found to increase. These data point to association between emergence of antibiotic-resistant variants and their persistence in dormant state mediated by starvation stress and regulated by AHB.

[Sensitivity of corynebacterium diphtheriae strains to antibacterial preparations].

AIM: Study the prevalence and mechanisms of resistance in circulating C. diphtheriae strains. MATERIALS AND METHODS: 664 C. diphtheriae strains isolated in 1987 - 2013 in various regions of Russia and sent to the reference center of Gabrichevsky Moscow Research Institute of Epidemiology and Microbiology were the object of the study. Antibiotic sensitivity of the strains was studied by disk-diffusion and E-test methods using 10 antimicrobial preparations. Nucleotide sequence analysis was carried out by using BLAST program and EMBL/GenBank database. RESULTS: Most of the studied strains turned out to be sensitive to all the antibacterial preparations used. 1.2% of C. diphtheriae strains turned out to be resistant to penicillin and 6.0% had intermediate level of resistance. 0.4 - 0.6% of the strains had intermediate level of resistance to macrolides, and 4.0 - 4.4% were resistant. 2.0% of the strains had multiple resistance. Erm(X)-specific PCR carried out in this study showed that all the C. diphtheriae strains resistant to macrolide antibiotics carry erm(X) gene. CONCLUSION: The results of the study indicate a fairly high level of prevalence for C. diphtheriae strains resistant to antibiotics.

[Genotypic differences between Corynebacterium diphtheriae biovar gravis and mitis strains].

AIM: Study structure ofa genetic determinant of amylase activity (amygene) in Corynebacterium diphtheriae biovar gravis and mitis strains. MATERIALS AND METHODS: 87 C. diphtheriae strains (31 gravis biovar strains and 56 mitis biovar strains) as well as C. diphtheriae PW8 strain were analyzed to detect structural features of C. diphtheriae strains of various biovars. 10 pairs of primers were used in PCR that flank mutually overlapping regions within DIP0357 locus as well as additional primers that flank DIP0353-DIP0354, DIP0357 and DIP0358 loci. RESULTS: All the C. diphtheriae biovar gravis strains were established to contain a full-size DIP0357 locus (amy gene) whereas in all the mitis biovar strains this genome fragment is absent. All the studied C. diphtheriae biovar gravis strains do not have significant changes within DIP0354-DIP0357 loci (amy gene) whereas in genome of 57 studied C. diphtheriae biovar mitis strains the major part of this fragment including the complete nucleotide sequence of amy gene is absent. CONCLUSION: C. diphtheriae biovar gravis strains have a genetically determined ability to produce amylase that can be viewed as an additional pathogenicity factor giving microorganisms wider capabilities to colonize the mucous membrane of oropharynx.

[Polymorphism of tox and dtxR genes in circulating strains of Corynebacterium diphtheriae].

Polymorphism of tox and dtxR genes responsible for diphtheria toxin synthesis was revealed. Seven point mutations in tox gene were detected; study of their combinations allowed to determine 10 allelic variants of the tox gene in C. diphtheriae strains. Majority of mutations did not lead to changes in substitutions in amino acid sequence of diphtheria toxin. In tox gene from 2 strains of mitis biovar, ribotype "Otchakov" isolated in Saint-Petersburg, mutation in position 1252 (G --> C), which corresponds to change of glycine on arginine in amino acid sequence of diphtheria toxin (G393R), was identified. Mutation localizes in R domain of fragment B of diphtheria toxin. In the dtxR gene 16 point mutations were registered; study of their combinations allowed to determine 10 allelic variants of the dtxR gene. Two mutations led to amino acid substitutions in regulatory protein DtxR: in position 640 (C --> A), which corresponds to change of leucine on isoleucine (L2141), and in position 440 (C --> T), which corresponds to change of alanine on valine (A147V). Mutation A147V is characteristic for all strains of epidemic clonal group (strains of biovar gravis, ribotype "Sankt-Peterburg/Rossija", enzyme types of complex 8), dominated in Russia during diphtheria epidemic at 1990s. Strains of this group were characterized by high level of diphtheria toxin production.

Suppression of growth and metastasizing of T-cell lymphoma in mice infected with american trypanosomiasis at different stages of experimental infection.

Antitumor activity of Trypanosoma cruzi CH4 strain isolated in Mexico was studied. This parasite is not tumoritropic, but inhibits the growth and metastasizing of solid L5178Y-R lymphoma transplanted to Balb/C mice. Conditioned medium from cell cultures infected with this strain produced a cytostatic effect. Possible mechanisms of this phenomenon are discussed.

[Corynebacterium diphtheriae nontoxigenic strain carrying the gene of diphtheria toxin]. / Kharakteristika netoksigennykh shtammov Corynebacterium diphtheriae, nesushchikh gen difteriinogo toksina.

Among 828 C. diphtheriae nontoxigenic cultures isolated in different region of Russia in 1994-2002, 114 cultures (13.8%) had the gene of diphtheria toxin (gene tox) and were thus called nontoxigenic tox-carrying (NTTC) strains. All NTTC strains were found to belong to biovar mitis and formed neither normal, nor "defective" diphtheria toxin. The most of NTTC strains (94%) belonged to ribotype "Moskva", not occurring among C. diphtheriae toxigenic strains. The incapacity of NNTC strains of forming diphtheria toxin was caused by mutation: the deletion of one nucleotide which led to the shift of the open reading frame and to the formation of the stop codon. The results of these studies are indicative of the fact that a sufficiently homogeneous and isolated group of C. diphtheriae nontoxigenic strains is spread in Russia. These strains carry the nonexpressing gene of diphtheria toxin and are of no epidemic importance in diphtheria infection.

[Genetic structure of Corynebacterium diphtheriae strains isolated in Russia during epidemics of various intensity]. / Geneticheskaia struktura shtammov Corynebacterium diphtheriae, vydelennykh v Rossii pri raznoi intensivnosti épidemicheskogo protsessa difterii.

The genetic structure of C. dipthteriae toxigenic strains isolated in Russia during the period of more than 50 years was analysed. The use of the method of ribotyping made it possible to register 17 C. diphtheriae ribotypes. The study revealed that the genetic structure of C. diphtheriae population varied in the dynamics of the epidemic process: each epidemic cycle characterized by predominant spread of epidemic strains of definite biovars and ribotypes. Thus, C. diphtheriae strains of biovar gravis, ribotype M11, dominated in the 40-60 years and C. diphtheriae strains of biovar mitis, closely related ribotypes M1 and M1v, dominated in the 80 years. During the last epidemic rise of diphtheriae morbidity in the 90 s C. diphtheriae strains of biovar gravis, closely related ribotypes G1 and G4, dominated among circulating strains. The proportion of these ribotypes began to increase 3 years before the rise of morbidity. The data of microbiological monitoring are recommended for use in the prognostication of the development of the epidemic process of diphtheria infection.

[Clinical characteristics of tick-borne encephalitis complicated by Lyme borreliosis]. / Klinicheskaia kharakteristika kleshchevogo éntsefalita pri ego sochetanii s Laim-borreliozom.

Clinical characteristics of mixed tick borne encephalitis (TBE) + Lyme borrelliosis (LB) infection and monoinfections are compared. Eighty-five patients with TBE + LB mixed infection serologically verified by EIA and 87 with isolated TBE, who fell ill in 1996, were examined. Among patients with mixed infection, cases with blurred TBE predominated; severe forms (meningeal and focal) were almost two times less incident than in TBE monoinfection. Typical clinical symptoms of LB were observed in 63.5% patients, while in the rest 36.5% LB manifested only by circulation of antibodies to B. burgdorferi. Comparative analysis of patients with mixed TBE + LB infection and TBE monoinfection confirmed a more benign course of TBE during the acute period in patients with mixed infection. Mixed infection should be ruled out or confirmed by thorough clinical examinations with obligatory detection of antibodies to agents of both diseases.

[Comparative study of results of serological diagnosis of Lyme borreliosis by indirect immunofluorescence and immunoenzyme analysis]. / Sravnitel'noe izuchenie rezul'tatov serologicheskoi diagnostiki Laim-Borrelioza v reaktsii nepriamoi immunofliuorestsentsii i immunofermentnom analize.

A total of 176 sera from 73 patients with verified Lyme borreliosis at different stages of the disease are examined. Serological diagnosis was carried out by 2 methods: indirect immunofluorescence (IIF) with corpuscular B. burgdorferi antigen and enzyme immunoassay (EIA) with purified flagellar B. burgdorferi antigen (Dako). EIA with Dako antigen is more sensitive for the diagnosis of Lyme borreliosis at any period of the disease than IIF. Analysis of correlations between the results of IIF and EIA showed correlation in the levels of IgG but not IgM antibodies. The findings confirmed a previous hypothesis that inadequate antibacterial therapy before investigation decreases the level of antibodies to Borrelia. In patients with a history of Lyme borreliosis, antibodies to B. burgdorferi are detected less frequently by both IIF and EIA. Patients with persistent levels of antibodies to B. burgdorferi, even without clinical signs of infection, are in need of regular check-ups, because the prognostic significance of antibodies to B. burgdorferi is unknown and relapses may occur after months and years.

[The laboratory diagnosis of spring-summer infections in Yekaterinburg in the epidemic season for tick-borne encephalitis]. / Laboratornaia diagnostika vesenne-letnikh infektsii v Ekaterinburge v épidemicheskii sezon kleshchevogo éntsefalita.

The authors propose a comprehensive approach to laboratory diagnosis of seasonal transmissible infections, based on modern methods permitting etiological deciphering of disease. A universal diagnostic algorithm notably accelerated the laboratory diagnosis due to cutting the period between collection of material from a patient and consecutive screening for antibodies to agents of tick-borne encephalitis, Lyme disease, and California encephalitis.

[The comparative clinico-laboratory characteristics of Lyme arthritis and reactive arthritis]. / Sravnitel'naia kliniko-laboratornaia kharakteristika Laim-artrita i reaktivnogo artrita.

The paper presents comparative clinical and laboratory characteristics of 17 cases of Lyme-arthritis (LA) and 28 cases of reactive arthritis (RA). LA and RA patients differed by age and sex. LA arose after the tick bite followed by erythema migrans or infection symptoms. In RA patients the above symptoms were absent. In LA patients arthritis was associated with typical symptoms of neuroborreliosis. The articular syndrome manifested similarly in LA and RA: arthritis was preceded by arthralgias, low limb joints and periarticular tissues were involved most frequently. The differences were: monoarthritis, elbow and shoulder joints, muscles lesions occurred more frequently in LA; polyarthritis, arthritis of hand and foot joints, talalgia were more common in RA. RA ran more actively, joint syndrome more frequently gave rise to fever. Prevalence of chlamydial infection in LA was close to that in RA. LA may run as RA, is frequently combined with Chlamydia trachomatis infection.

[The characteristics of peripheral nervous system involvement in Lyme borreliosis in an endemic region of Russia]. / Osobennosti porazheniia perifericheskoi nervnoi sistemy pri Laim-borrelioze v éndemichnom raione Rossii.

Clinical and laboratory data are available on affection of the peripheral nervous system (PNS) in 27 patients with Lyme-borreliosis (LB) in the endemic region of Russia. PNS disorders arose early, 88.9% of the patients had them within one month of the disease. 9 (37.5%) patients had meningoradiculoneuropathy (MRN) which emerged in the acute period in 77.8% of the patients. Inflammation in the cerebrospinal fluid was registered only in patients with clinical signs of meningitis. MRN developed more frequently in facial nerve neuritis (FNN) than in radiculopathy (RP)-80.0% and 14.3%, respectively, p = 0.01. Intrathecal synthesis of antibodies to B. burgdorferi in combination with pleocytosis was found only in FNN patients (16.7%). In 6 (37.5%) of 16 patients with neuroborreliosis concentrations of C-reactive protein were elevated. Its high level occurred significantly more frequently in RP (83%) than in FNN (17%) (p = 0.05). 5 out of 14 LB patients exhibited high level of Willebrand factor antigen. No clear clinical relations between this value and PNS lesions in LB were found.

[The potentials for the comprehensive diagnosis of viral encephalitis in Sverdlovsk Province]. / Vozmozhnosti kompleksnoi diagnostiki virusnykh éntsefalitov v Sverdlovskoi oblasti.

The suggested scheme of laboratory tests helped identify the etiology of viral encephalitides in 65.9% of cases. Diagnosis of tick-borne encephalitis was confirmed by laboratory findings in 93.6% of cases. Patients with Californian encephalitis were detected in the Sverdlovsk region for the first time. A rather high rate of detection of antibodies to Tahyna virus was revealed in the examined population: up to 60%. Influenza origin of encephalitis was recognized in 6.2% of cases, Lyme's disease was diagnosed in 9.3%.

[Nutrient media for fermenting Actinomyces]. / Pitatel'nye sredy dlia fermentiruiushchikh aktinomitsetov.

Fitness of various commercial nutrient media, manufactured in the USSR, for isolation and cultivation of fermentation-producing actinomyces was under study. The media were tested in two stages. Reference and newly isolated actinomyces cultures were examined at stage 1, clinical material at stage 2. Hottinger's blood agar was found the best for maintaining the growth of facultative anaerobic actinomyces and possessed the highest differentiating characteristics. This medium maintained sufficiently intensive growth of anaerobic actinomyces but only in the presence of meat extract. A liquid nutrient medium was designed, based on Hottinger's hydrolysate, that may be used for studies of these microorganisms' physiologic parameters.

[The tentative identification of actinomycetes of the oral cavity by a complex of key morphophysiological signs]. / Orientirovochnaia identifikatsiia aktinomitsetov polosti rta po kompleksu kliuchevykh morfofiziologicheskikh priznakov.

In this work the results obtained in the study of the morphology of 208 Actinomyces strains isolated from the oral cavity and a wide spectrum of their enzymatic activity are presented. The identification of these strains was carried out on the basis of chemotaxonomic criteria. Bacteria belonging to the same taxonomic group were found to have considerable similarity in their morphological and physiological features. On the basis of the data obtained in this study a simplified scheme of the tentative identification of fermentative Actinomyces, suitable for use by a wide circle of researchers, is presented.