Vibrio cholerae O139 isolated from humans and the water from open reservoirs: a comparative genotyping

The comparative study of the genomes of V. cholerae O139 isolated from humans and from water of surface reservoirs was carried out with the use of single- and double-primer polymerase chain reaction (PCR). The profiles of polymorphic DNA fragments obtained in this study made it possible to find out differences between groups of strains, as well as the individual features of some of them. The comparison of strains isolated from humans and from water in single-primer PCR revealed that they, in spite of the general similarity of their genomes, essentially differed, which was probably due to changes in the genome of this infective agent. Strains of aqueous origin lacked genes ctx and tcpA, which made them epidemiologically unimportant.     

Genotyping of Yersinia pseudotuberculosis isolated in Siberia and Far East

Genotypic characteristics based three main factors of pathogenicity (presence of resident plasmids [pYV, pVM], gene of toxin-superantigen ypm and nine genes for high pathogenicity island [HPI]) of 212 strains of Y. pseudotuberculosis isolated in Siberia and Far East were studied. It was shown that strains of Y. pseudotuberculosis with one of two variants of plasmids 82:47 MDa and 47 MDa (60.8% and 31.6% respectively) are predominated. Gene ypmA was detected in 96.2% of isolated strains. Eight strains had none of the ymp gene variants. HPI were detected in 96.2% of isolated strains. Obtained characteristics of Y. pseudotuberculosis allowed to determine the dominating genogroup pWYV+, ypmA+, HPI- (95.8% of strains) that cause systemic infection.     

Variable nucleotide tandem repeats (VNTR analysis) in Vibrio cholerae 0139 isolated from humans and from water of surface reservoirs in Russia

The comparative study of variable tandem repeats (VNTR analysis) in genomes of V. cholerae 0139 isolated from humans and from water samples taken from surface reservoirs was carried out. The results of the study of the allele state of 5 loci of tandem repeats in 50 strains of vibrios, carried out in the double-primer polymerase chain reaction (PCR), as well as the earlier comparison of the same isolates in the single-primer PCR, showed essential differences and the absence of clonality in the cultures of the clinical and aqueous origin. The suggestion was made that vibrios with individual VNTR genotypes and having no genes ctx and tcpA, isolated from water samples, were epidemic unimportant representatives of the autochthonous microflora of water reservoirs.     

PCR-detection of markers for epidemiologically-significant strains of Vibrio cholerae 0139, isolated in Siberia]

Fourteen V. cholerae 0139 strains were isolated in 1996-1999 in Siberia from the Ob river (Novosibirsk) and bogs and lakes (Irkutsk). The strains were tested in PCR for the key virulence determinants (ctx AB, tcp, acf). The genomes lacked these elements, and therefore the strains were acknowledged avirulent. The results correlate completely with the data of phenotypical analysis, characterizing the pathogenic characteristics of isolated strains.     

Drug resistance in Vibrio cholerae strains isolated from clinical specimens

Cholera is a serious epidemic and endemic disease caused by the Gram-negative bacterium Vibrio cholerae. SXT is an integrative conjugation element (ICE) that was isolated from a V. cholerae; it encodes resistance to the antibiotics chloramphenicol, streptomycin and sulfamethoxazole/trimethoprim. One hundred seven V. cholerae O1 strains were collected from cholera patients in Iran from 2005 to 2007 in order to study the presence of SXT constin and antibiotic resistance.The study examined 107 Vibrio cholerae strains isolated from cholera prevalent in some Iranian provinces. Bacterial isolation and identification were carried out according to standard bacteriological methods. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) to four antibiotics (chloramphenicol, streptomycin, sulfamethoxazole, and trimethoprim) were determined by broth microdilution method. PCR was employed to evaluate the presence of established antibiotic resistance genes and SXT constin using specific primer sets.The resistance of the clinical isolates to sulfamethoxazole, trimethoprime, chloramphenicol, and streptomycin was 97%, 99%, 99%, and 90%, respectively. The data obtained by PCR assay showed that the genes sulII, dfrA1, floR, strB, and sxt element were present in 95.3%, 95.3%, 81.3%, 95.3%, and 95.3% of the V. cholerae isolates.The Vibrio strains showed the typical multidrug-resistance phenotype of an SXT constin. They were resistant to sulfamethoxazole, trimethoprime, chloramphenicol, and streptomycin. The detected antibiotic resistance genes included dfrA for trimethoprim and floR, strB, sulII and int, respectively, for chloramphenicol, streptomycin, sulfamethoxazole, as well as the SXT element.     

Factors contributing to preservation of Vibrio cholerae in water reservoirs

The summarized data of literature concerning the survival of V. cholerae in the environment and the influence of abiotic and biotic factors on this process are presented. These data make it possible to regard cholera as sapronosis and to form an idea of the role of factors contributing to the survival of V. cholerae in the environment and to its spread among human population.     

Model of Vibrio cholerae biofilm as a mechanism of its survival in surface water reservoirs

Vibrio cholerae eltor strains with different epidemic importance isolated from river water in the city of Vladivostok during a cholera outbreak (1999) and in the city of Irkutsk during a safe cholera period (2005) are used in the experiment. A biofilm structure consisting of a peripheral part, bundles, polysaccharide matrix, canals, and polymorphic vibrios is presented by light and luminescent microscopy. The metachromatic pink coloring of the matrix (crystal violet and toluidine blue) or fluorescent reddish orange color (acridine orange) are evidence of acid mucopolysaccharide (glucosaminoglycans) content. The biofilm of a toxigenic strain as opposed to a nontoxigenic one is formed much later, while the elements comprising its structure are more apparent. The viability of vibrio cells during the experiment (90 days) preserving the initial pathogenic potential testifies to the highly adaptable properties of the Vibrio cholerae eltor, which promotes its survival and existence in surface water reservoirs under favorable ecological conditions (optimal temperature, existence of chitin-containing substratum, etc.).     

Detection of L forms of Vibrio cholerae in the water of open water reservoirs

L-forms of cholera vibrios were isolated from the river water for the first time. The presence of L-forms in water permitted to suppose that such variants served as one of the forms of cholera causative agent preservation in the external medium.     

Antibiotic sensitivity of Vibrio cholerae 01 isolated from environmental objects]

The sensitivity of 252 Vibrio cholerae-O1 strains isolated from environmental objects to antibiotics of various groups was assayed by the method of serial dilutions on solid media. The biological characteristics of the isolates are presented. The Vibrio cholerae isolates with serological variation were the most frequent (36.6 per cent), so are the cultures detected by their sensitivity to the specific phages (87.5 per cent). It was found that changes in some biological properties of the strains did not coincide with the changes in the antibiotic sensitivity. The isolates were highly sensitive to tetracycline, chloramphenicol, gentamicin, erythromycin and rifampicin and less sensitive to novobiocin and the other aminoglycosides. The sensitivity to the beta-lactams was the lowest. The resistance determinants were detected in single strains (6.3 per cent), the kanamycin and novobiocin resistance determinants being detected in 15 out of the 16 strains tested. The study showed that the cultures of Vibrio cholerae-O1 isolated from the environmental objects generally preserved their sensitivity to the diverse group antibiotics.     

Dynamics of the isolation and biological properties of Vibrio cholerae cultures,serogroups 01 and 0139, isolated from water reservoirs and sewage water on the territory of the city of Rostov-on-Don

The dynamics of the isolation of V. cholerae cultures from various water objects on the territory of Rostov-on-Don during the period of 1994-2001 was analyzed and biological properties of 14 such cultures were studied. In the absence of epidemic complications during the above-mentioned period, a growth in the amount of V. cholerae isolates, serogroups 01 and 0139, including toxigenic V. cholerae 01, was registered. The microbiological and epidemiological aspects of the monitoring of surface reservoirs and sewage were considered and the expediency of the profound and systematic study of its results for epidemiological surveillance on cholera was emphasized.     

Characterization of a Vibrio cholerae phage isolated from the coastal water of Peru

A Vibrio cholerae bacteriophage, family Myoviridae, was isolated from seawater collected from the coastal water of Lima, Peru. Genome size was estimated to be 29 kbp. The temperate phage was specific to V. cholerae and infected 12/13 V. cholerae O1 strains and half of the four non-O1/non-O139 strains tested in this study. Vibrio cholerae O139 strains were resistant to infection and highest infection rates were obtained in low nutrient media amended with NaCl or prepared using seawater as diluent.     

Mitochondrial DNA variation in goldfish Carassius auratus gibelio from water reservoirs in the Far East

MtDNA variation of goldfish samples from several water bodies of Southern Primorye was examined by RFLP analysis. High mtDNA polymorphism was found in the river populations but not in the lake ones. Considerable among-haplotype divergence was found within samples, which suggests periodic gene exchange between populations having long histories of independent evolution. The absence of substantial differences between clusters of mtDNA haplotypes indicates recurrent transfer from bisexual to gynogenetic reproduction mode and vice versa.     

The clinico-epidemiological characteristics of Powassan encephalitis in the southern Soviet Far East]

The present communication deals with the analysis of 14 cases of Powassan encephalitis. As shown in this study, the course of this infection may be accompanied by symptoms indicating the presence of cerebral and meningeal lesions (in 7 cases meningoencephalitic forms with one fatal outcome and in 2 cases meningeal forms were registered) or take febrile and inapparent forms (5 cases). Powassan encephalitis was found to give characteristic symptoms of cerebellovestibular lesions, differentiating this disease from tick-borne encephalitis (TBE). The cases of mixed infections caused by TBE virus, Powassan encephalitis virus and tick-born Borrelia were found to be possible.     

Karyological and cytogenetic studies of conifers from West Siberia and Far East

The results summarize many years of karyological and cytogenetic studies of conifers from the boreal zone, done at the Sukachev Forest Institute. The species under study belong to four genera of the family Pinaceae: Larix (larch), Pinus (pine), Picea (spruce), and Abies (fir). Overall, the research covers more than 100 populations and habitats of the species from these genera. The study concerns species growing under both optimal and marginal conditions. The studies of the family Cupressaceae have been initiated. A special attention is given to conifers growing on bogs and in planted forests.     

Identification of virulence factors in Vibrio cholerae isolated from Iraq during the 2007-2009 outbreak

Thousands of people were infected with Vibrio cholerae during the outbreak in Iraq in 2007-2009. Vibrio cholerae was shown to be variable in its content of virulence determinants and in its antibiotic sensitivity. This study was designed to isolate and characterize clinical and environmental V.?cholerae isolates and to determine antibiotic sensitivity, enzyme and toxin production, and the presence of virulence genes. Eighty clinical and five environmental bacterial isolates were collected and diagnosed by subjecting them to microscopic, biochemical, serological, and molecular analysis. The results revealed that 55% of clinical isolates belonged to the Inaba serotype, 32.5% to the Ogawa serotypes, and 12.5% to the Non-O1 serotype. All environmental V.?cholerae isolates belonged to the Non-O1 serotype. All environmental isolates were sensitive to all examined antimicrobial agents, while all clinical isolates showed a high sensitivity (100%) to ampicillin, gentamicin, cephalothin, tetracycline, erythromycin, and ciprofloxacin, and a high resistance (97.5%) to co-trimoxazole, nalidixic acid, and chloramphenicol. It was found that all V.?cholerae (O1) isolates were resistant to the Vibrio static O129 and all Non-O1 V.?cholerae isolates were sensitive to the Vibrio static O129. All clinical and environmental isolates produced hemolysin (100%) and lecithinase (100%), while they showed various production rates of protease (90% of clinical and 60% of environmental) and lipase (50% of clinical and 20% of environmental). The ompW gene was amplified in all the clinical and environmental V.?cholerae isolates, but not in other related and nonrelated bacteria. Multiplex PCR analysis showed that the toxR gene was amplified in all clinical and environmental isolates, while ctxA, ctxB, tcpA genes were amplified only in clinical (O1) isolates. This study indicates the differences in the production of some enzymes and toxins and in the content of virulence genes between clinical and environmental isolates in Iraq during the outbreak (2007-2009).     

Serovars of NAG vibrios isolated from the water of open reservoirs]

Composition of serological types of NAG-vibrios isolated from the river water contaminated by effluents was found to be more varied than in uncontaminated water body. Vibrios of serological types 6, 8, 39, 41, 50, 53, 55 revealed frequently and in great amounts apparently inhabit the mentioned water bodies for prolonged periods.     

Problems of epidemiology and diagnostics of leptospiroses in Siberia and Far East

Multi-year literature data as well as materials of the Reference centre of monitoring of natural foci infections of Irkutsk Research Institute of Plague Control of Siberia and the Far East regarding epidemiology, epizootology and laboratory diagnostics of leptospiroses in Siberia and the Far East are analyzed and summarized in the review. Situation on leptospiroses in the region has changed significantly. In 50 - 70s of the 20th century diseases were registered ubiquitously in the form of outbreaks, group and single cases. Currently a low level of sporadic morbidity is noted in separate subjects of the Russian Federation. The contemporary state of the problem remains insufficiently clear, this demands the expansion of studies, creation of modern databases, as well as introduction into the practice of highly sensitive methods of express diagnostics in a complex with bacteriologic and serologic methods.