Phage typing of cholera vibrios with different sets of phages]

A comparative study was made of two sets of Mukerjee and Drozhevkina-Arutyunova's bacteriophages in typing 514 strains of the El Tor vibrios and 45 strains of clasic biotype. It was shown that the Mukerjee or Drozhevkina-Arutyunova's phages could be used for the typing of cholera vibrios. The phages of the latter set prove to detect more phage types (18 against 11); they determine both the phage type and the biotype at the same time. The typing of cholera vibrios of both biotypes is possible, and the percentage of nontyping strains left is comparatively low (5.2 against 23.5 after Mukerjee). A table of the phage correspondence was made; it permits to obtain comparable data in using any set of the typing phages.     

Superoxide dismutase and catalase levels in halophilic vibrios.

Superoxide dismutase (SOD) and catalase (CAT) levels were determined for several aerobically grown halophilic vibrios and compared with those found in aerobically grown Escherichia coli K-12. The SOD levels ranged from 25 to 103.6 U/mg of protein for the vibrios compared with 44.6 U/mg of protein for E. coli. The CAT levels ranged from 2.1 to 32.1 U/mg of protein. Electrophoretic analysis of cell extracts revealed that the halophilic vibrios tested possessed only one detectable SOD enzyme, except one strain which possessed two distinct enzymes, as compared with the three SOD enzymes in aerobically grown E. coli K-12. A comparison of anaerobically and aerobically grown vibrios revealed a three- to fourfold increase in SOD activity in the aerobic cells, suggesting that oxygen acts as an inducer for SOD in the vibrios as has been reported for E. coli. In one strain, Vibrio parahaemolyticus 27519, both SOD enzymes were observed in low levels in anaerobic and at higher levels in aerobically grown cells as compared with only one SOD enzyme in anaerobically grown E. coli. This suggests that differences in SOD regulation occur between the two genera. Our results indicate that halophilic vibrios possess SOD, which could enhance viruulence by allowing the organisms to survive in oxygenated environments.     

Correlation between medium acidification and pathogenicity in environmental halophilic non-cholera vibrios

AIMS: The metabolic characterization and pathogenicity of vibrios isolated from seafood were studied. METHODS AND RESULTS: Strains of halophilic vibrios, grown in the presence of 0.5% glucose, induced high medium acidification and were non-culturable after 24 h, while moderately acidifying strains were culturable, produced cytotoxins, and remained lethal when inoculated intraperitoneally in mice. Highly acidifying strains failed to elicit pathogenicity in vivo and in vitro. CONCLUSION: The high acidification of the medium and the self-killing activity of NCVs might be considered a significant phenotypic marker of virulence and/or cytotoxicity. SIGNIFICANCE AND IMPACT OF THE STUDY: We suggest the medium acidification test as possible screening method for pathogenic NCVs in food microbiology.     

Vibrio parahaemolyticus and other halophilic vibrios associated with seafood in Hong Kong

The summer prevalence of Vibrio parahaemolyticus and other halophilic vibrios in seafood from Hong Kong markets was investigated. Halophilic vibrios were isolated from all seven types of seafood examined, and comprised 9.1%, 8% and 6.1% of contaminating aerobic heterotrophic bacteria from mussels, clams and oysters respectively. Sucrose-positive vibrios were more common than sucrose-negative varieties. Vibrio alginolyticus was the most frequently isolated species, followed by V. parahaemolyticus, V. harveyi, V. fluvialis, V. vulnificus, V. pelagius, V. campbellii, V. spendidus and V. marinus. Mussels contained the highest concentration of V. parahaemolyticus (4.6 x 10(4)/g); oysters and clams contained 3.4 x 10(4)/g and 6.5 x 10(3)/g respectively. The ubiquity and relatively high concentrations of V. parahaemolyticus and other pathogenic vibrios in shellfish is a potential public health hazard in Hong Kong and other subtropical Asian countries.     

Vibrio parahaemolyticus and other halophilic vibrios associated with seafood in Hong Kong

The summer prevalence of Vibrio parahaemolyticus and other halophilic vibrios in seafood from Hong Kong markets was investigated. Halophilic vibrios were isolated from all seven types of seafood examined, and comprised 9.1%, 8% and 6.1% of contaminating aerobic heterotrophic bacteria from mussels, clams and oysters respectively. Sucrose-positive vibrios were more common than sucrose-negative varieties. Vibrio alginolyticus was the most frequently isolated species, followed by V. parahaemolyticus, V. harveyi, V.fluvialis, V. vulnificus, V. pelagius, V. campbellii, V. spendidus and V. marinus. Mussels contained the highest concentration of V. parahaemolyticus (4.6×10³/g); oysters and clams contained 3.4×10⁴/g and 6.5×10³/g respectively. The ubiquity and relatively high concentrations of V. parahaemolyticus and other pathogenic vibrios in shellfish is a potential public health hazard in Hong Kong and other subtropical Asian countries.     

Occurrence and distribution of halophilic vibrios in subtropical coastal waters of Hong Kong

The summer occurrence and distribution of halophilic vibrios in the subtropical coastal waters of Hong Kong were investigated. The density of vibrios in six sample sites ranged from 90 to 6,700 per ml, which made up 0.41 to 40% of the total bacterial populations of these sample sites. The sucrose-positive vibrios were found to be much more common (88% of total vibrios) than the sucrose-negative ones. A total of 48 strains belonging to six Vibrio species were fully characterized. Among these, Vibrio alginolyticus was the most frequently isolated, followed by V. parahaemolyticus, V. harveyi, V. vulnificus, V. campbellii, and V. fluvialis. The finding that eight of the nine strains of V. harveyi showed a positive Kanagawa reaction warrants further study.     

Pathogenicity of nonagglutinating vibrios]

In studying the pathogenicity of nonagglutinating vibrios it was established that the majority of the strains isolated from the patients suffering from enteritis possessed enteropathogenic properties which were revealed in the trials on nursling rabbits and on the isolated intestinal loop a of an adult rabbit. In difference to the cholera vibryos, these microorganisms produced no typical cholerogenicity syndrome expressing, however, a number of enteropathogenic properties: caused diarrhea, overfilling of the intestine with fluid, etc. Autopsy showed a typical enterocolitis picture, confirmed by histological studies. Nonagglutinating vibrio cultures isolated from the water and from healthy persons possessed no enteropathogenic properties. An isolated intestinal loop of an adult rabbit proved to be the most sensitive experimental model.     

Occurrence and distribution of halophilic vibrios in subtropical coastal waters of Hong Kong.

The summer occurrence and distribution of halophilic vibrios in the subtropical coastal waters of Hong Kong were investigated. The density of vibrios in six sample sites ranged from 90 to 6,700 per ml, which made up 0.41 to 40% of the total bacterial populations of these sample sites. The sucrose-positive vibrios were found to be much more common (88% of total vibrios) than the sucrose-negative ones. A total of 48 strains belonging to six Vibrio species were fully characterized. Among these, Vibrio alginolyticus was the most frequently isolated, followed by V. parahaemolyticus, V. harveyi, V. vulnificus, V. campbellii, and V. fluvialis. The finding that eight of the nine strains of V. harveyi showed a positive Kanagawa reaction warrants further study.     

Potentiality of a new compound for in vitro differentiation between halophilic and non-halophilic vibrios

Sensitivity of 21 halophilic vibrios and 16 clinical isolates of non-halophilic vibrios was determined against a new possible antivibrio agent, a pyrimidine analogue, 4, 6-dimethylpyrimidine -2-thiol (4,6-DMPT). It appeared to be a vibriocidal agent, having a mean MIC and MBC of 32 microg/ml for halophilic strains and 64 microg/ml for non-halophilic strains and an LD50 of 300 mg/Kg body weight of mice. Thus, 4,6-DMPT may help an in vitro distinction between halophilic and non-halophilic vibrios. Sensitivity of these strains was also studied with respect to pteridine, crystal violet and Tween 80 hydrolysis as further markers distinguishing between these 2 groups which could also be differentiated by their growth on TCBS or/and CLED media.     

Recombineering mycobacteria and their phages

Bacteriophages are central components in the development of molecular tools for microbial genetics. Mycobacteriophages have proven to be a rich resource for tuberculosis genetics, and the recent development of a mycobacterial recombineering system based on mycobacteriophage Che9c-encoded proteins offers new approaches to mycobacterial mutagenesis. Expression of the phage exonuclease and recombinase substantially enhances recombination frequencies in both fast- and slow-growing mycobacteria, thereby facilitating construction of both gene knockout and point mutants; it also provides a simple and efficient method for constructing mycobacteriophage mutants. Exploitation of host-specific phages thus provides a general strategy for recombineering and mutagenesis in genetically naive systems.     

Results of typing staphylococci isolated from cows and their milk products using the basic set of phages and local phages]

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.     

Influence of salinity upon the phenotypic expression of antibiotic resistance in nonhalophilic and halophilic vibrios

The purpose of the present work is to demonstrate the influence of different NaCI concentrations included in the Mueller Hinton medium, upon the antibiotic susceptibility of 10 non-halophilic and 28 halophilic Vibrio strains. The highest number of resistance aspects were recorded at 1% NaCl concentration for V. cholerae O1/non O1 strains and at 3% for V. parahaemolyticus, V. algynolyticus, V. vulnificus, V. fisheri, V. anguillarum and V. metschnikovii.     

Cholera phages from open reservoirs of the Lake Issyk-Kul basin and their taxonomy]

In the water of open water bodies in the basin of Lake Issyk-Kul the presence of Vibrio cholerae belonging to group O1 and other groups and V. cholerae phages of known serotypes, as well as phages of a new type having no serological and morphological analogs in the current classification of V. cholerae phages, has been established. On the basis of analysis of inaccuracies appearing in the determination of the specificity of V. cholerae phages their systematization within the adequate unified classification of vibriophages is proposed.     

Studies on halophilic vibrios causing a food poisoning outbreak in the city of Vladivostok

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.     

Makeup of a population El Tor vibrios according to their agglutinability by type-specific sera]

The authors studied population composition of 14 strains of EL Tor vibrios. Of 7 strains of Ogava serological type the population composition was homogeneous in 2, and heterogeneous in 5. All the 7 strains of EL Tor vibrios of Inaba serological type had homogeneous population composition. Changes of the existence conditions of EL Tor vibrios of Ogava serological type, containing in their population 5% cells of Hikoshima serological tupe, led to separation of the cells of Inaba serological type; under the same conditions, in El Tor vibrios of Ogava and Inaba serological type with homogeneous population the latter was stable.     

Clinico-epidemiological characteristics of diseases caused by halophilic vibrios along the coast of the Sea of Azov

The epidemiological and clinical features of alimentary toxinfections caused by halophilic vibrios on the Crimean coast of the Sea of Azov at the period of 1976-1984 were studied. Toxinfections were linked mainly with the use of sea-food subjected to different kinds of culinary treatment and took the course of gastroenteritis. To prevent toxinfections caused by halophilic vibrios, the technology, as well as sanitary and hygienic norms, should be strictly observed in the production of sea-food; besides, special methods of bacteriological diagnosis should be introduced into practice at laboratories of medical institutions and fish-processing plants.