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R Sakazaki

Publications and source records attributed to R Sakazaki.

At least 19 recordsLinked to original sources
PubMed2001

Mitomycin-supplemented washed blood agar for the isolation of Shiga toxin-producing Escherichia coli other than O157:H7.

AIMS: Isolation and recognition of the prominent Shiga toxin (Stx)-producing strains of Escherichia coli (STEC) serovar O157:H7 can be confirmed easily by their late fermentation of sorbitol and lack of beta-glucuronidase activity, but there has been no culture method of choice for detecting non-O157 STEC strains because of their biochemical diversity. Apart from Stx, many STEC strains produce enterohaemolysin (Ehly) regardless of their serovars. METHODS AND RESULTS: Although washed blood agar media, with or without the addition of antibiotics (vancomycin, cefixime, and cefsulodin) (WBA and WBVCCA), have been used to detect Ehly, a proportion of STEC strains consistently failed to produce haemolysin on these media. Washed blood agar medium was therefore studied further in order to increase the yield of strains producing Ehly. CONCLUSION: It was found that the addition of 0.5 microg ml(-1) of mitomycin C to the agar medium (WBMA) markedly increased the number of such strains. Thus, of 185 STEC strains comprising 95 O157 and 90 non-O157 STEC consisting of 34 serovars. Ninety-seven per cent of these strains produced haemolysis on WBMA, compared with only 76% and 83%, respectively, on WBA and WBVCCA. SIGNIFICANCE AND IMPACT OF THE STUDY: The appearance of the Ehly zone of haemolysis that was easily distinguishable from that of alpha-haemolysin was enhanced by the incorporation of mitimycin C into washed-blood medium.

Blood↗
PubMed2000

Enterobacter cowaniisp. nov., a new species of the family Enterobacteriaceae.

The name Enterobacter cowanii sp. nov. is proposed for a group of organisms referred to as NIH Group 42. Members of this species are Gram-negative, motile rods conforming to the definition of the family Enterobacteriaceae. The DNA relatedness of nine strains of NIH Group 42 to the proposed type strain of this species averaged 85% at 70 degrees C, whereas the relatedness to other species within the family Enterobacteriaceae was less than 38%. Because the DNA relatedness (5-38%) is closer to species of the genus Enterobacter than to other species of the family, the members of NIH Group 42 were placed in the genus Enterobacter. The majority of strains of E. cowanii were isolated from clinical specimens. A culture of the type strain (888-76) has been deposited in the Japan Collection of Microorganisms as JCM 10956.

Bacterial Typing Techniques↗
PubMed1999

[Antagonistic interaction between Clostridium butyricum and enterohemorrhagic Escherichia coli O157:H7].

Antagonistic interaction between Clostridium butyricum strain MIYAIRI 588 and enterohemorrhagic Esherichia coli (EHEC) strain O157:H7 006 was examined using streptomycin-treated SPF mice and germ free mice. All SPF mice pretreated with streptomycin were colonized with EHEC O157:H7. On the other hand, only 20% of the SPF mice pretreated with streptomycin and C. butyricum were colonized with EHEC O157:H7. In addition, germ free mice died within 4-7 days after infection with EHEC O157:H7. In contrast, all gnotobiotic mice mono-associated with C. butyricum survived after the challenge with EHEC O157:H7. Both the number of EHEC and the amounts of shiga-like cytotoxin (SLT, type 1 and type 2) in fecal contents of gnotobiotic mice treated with C. butyricum were less than those of mice infected with only EHEC O157:H7. In conclusion, the probiotic bacterium, C. butyricum strain MIYAIRI 588, has a preventive effect against EHEC O157:H7 infection.

Animals↗
PubMed1996

Enterobacter kobei sp. nov., a new species of the family Enterobacteriaceae resembling Enterobacter cloacae.

The name Enterobacter kobei sp. nov. is proposed for a group of organisms referred to as NIH Group 21 at the National Institute of Health, Tokyo. The members of this species are Gram-negative, motile rods conforming to the definition of the family Enterobacteriaceae. The DNA relatedness of 23 strains of NIH Group 21 to the representative proposed as the type strain of this species averaged 82% at 70 degrees C, whereas the relatedness to other species within the family Enterobacteriaceae was less than 42%. Because the phenotypic resemblance to Enterobacter cloacae is very close and the DNA relatedness (12-42%) is closer to species of the genus Enterobacter than to other species of the family, the members of NIH Group 21 were placed in the genus Enterobacter. Close phenotypic and genetic relationships were also found between NIH Group 21 and a member of a group of organisms referred to as Enteric Group 69 at the Centers for Disease Control and Prevention (CDC), Atlanta, Georgia, USA. It is suggested that the latter could be regarded as a subspecific rank of E. kobei, though this is subject to study of further strains. The majority of strains of E. kobei were isolated from clinical specimens. A culture of the type strain (NIH 1485-79) has been deposited in the Japan Collection of Microorganisms as JCM 8580.

Bacteriological Techniques↗
PubMed1996

Serotyping and categorisation of Escherichia coli strains isolated between 1958 and 1992 from diarrhoeal diseases in Asia.

A total of 3065 strains of Escherichia coli isolated between 1958 and 1992 from patients with diarrhoea in different countries were examined for virulence factors by hybridisation with biotinylated DNA probes for genes that coded for production of heat-labile and heat-stable enterotoxins, enteroinvasiveness, production of verotoxins and attaching-and-effacing factor and were serotyped. Of the 3065 strains, 1998 were placed into one of four pathogenic categories by their virulence factors: 1057 enterotoxigenic E. coli (ETEC) comprising 30 O-groups, 73 serovars and 137 untypable strains; 132 enteroinvasive E. coli (EIEC) comprising 11 O-groups and 13 serovars; 64 verotoxin-producing E. coli (VTEC) comprising 11 O-groups, 17 serovars and 13 untypable strains; and 745 enteropathogenic E. coli (EPEC) comprising 34 O-groups, 92 serovars and 91 untypable strains. The remaining 1067 strains did not hybridise with any of the DNA probes used. About half the number of O-groups recognised were not restricted to a single pathogenic category, although the combinations of O- and H-antigens were different in each category.

Asia↗
PubMed1996

Re-speciation of the original reference strains of serovars in the Citrobacter freundii (Bethesda-Ballerup group) antigenic scheme of West and edwards.

The antigenic scheme for the Bethesda-Ballerup group of bacteria established by West and Edwards in 1954 has continued to be applied as a serotyping scheme for Citrobacter freundii. In 1993, however, the classification of the Citrobacter was drastically revised and the species C. freundii redefined by Brenner et al. Accordingly, to judge the propriety to continuously use a single antigenic scheme for the C. freundii complex, the 90 reference strains listed in the antigenic scheme for C. freundii by West and Edwards were characterized phenotypically and specified based on the revised classification. Of these 90 strains, two strains of Hafnia alvei and one of Escherichia coli were found. Among the remaining 87 reference strains, Citrobacter youngae was the predominant species (40 strains), followed by Citrobacter braakii (25 strains), Citrobacter werkmanii (13 strains), and the unnamed Citrobacter genospecies 10 of Brenner et al (six strains). Citrobacter freundii, as redefined, accounted for only three strains and ranked behind the other four species. No overlapping with most of the 42 O-groups and 82 H-antigens was recognized between species with few exceptions. O-groups 1-9 inclusive, which were estimated to represent more than 90% of the former C.freundii strains, occurred in strains of C. youngae and C. braakii; and all nine strains of O-group 29, formerly known as the Ballerup group, were identified as C. braakii. These findings suggest that further study of the serotyping system is needed for all H2S-producing Citrobacter species.

Antigens, Bacterial↗
PubMed1996

Evaluation of L-pyrrolidonyl peptidase paper strip test for differentiation of members of the family Enterobacteriaceae, particularly Salmonella spp.

The L-pyrrolidonyl peptidase activities of 1,033 strains of the family Enterobacteriaceae were investigated by the paper strip method to evaluate their usefulness for screening those organisms, especially Salmonella cultures. We also evaluated the usefulness of indole and tryptophan deaminase paper strip tests as supplements to the L-pyrrolidonyl peptidase test for the rapid identification of Salmonella cultures. The paper strip tests are simple, and the results are obtainable within 10 min.

Amino Acid Oxidoreductases↗
PubMed1995

Isolation and biological activity of thielocins: novel phospholipase A2 inhibitors produced by Thielavia terricola RF-143.

Thielocins A2 alpha, A2 beta, A3, B1, B2 and B3 were isolated as a novel family of phospholipase A2 inhibitors from the fermentation broth of Thielavia terricola RF-143 together with thielavins and thielocins A1 alpha and A1 beta. The most potent inhibitory activity (IC50 = 0.0033 microM) against rat group II phospholipase A2 was shown by thielocin A1 beta. Against human group II phospholipase A2, thielocin B3 (IC50 = 0.076 microM) was the most potent.

Animals↗
PubMed1992

[Typing of methicillin-resistant Staphylococcus aureus by antibiotic resistance phenotypes as an epidemiological marker in nosocomial infections].

A total of 129 clinical isolates of methicillin-resistant Staphylococcus aureus was tested for the susceptibility to 28 antibiotics, antiseptics and heavy metal salts, according to the method of Gillespie et al. The strains showed resistance ranging from 20% to 80%, to 10 agents, such as amikacin, chloramphenicol, clindamycin, gentamicin, neomycin, streptomycin, tobramycin, acriflavine, cadmium nitrate, ethidium bromide. These agents were finally chosen for typing in this study. Strains resistant to 10 agents were distributed into 55 phenotypes. Most strains isolated from one ward belonged to the specified phenotype, whereas strains isolated from other wards were divided into a variety of phenotypes. It seemed to be the occurrence of nosocomial infection in this hospital. This typing method gives the merit to be easy, economical, rapid and reproducible for the epidemiological investigations in the clinical bacteriological laboratory.

Anti-Bacterial Agents↗
PubMed1991

Biochemical and genetic characterization of autoagglutinating phenotypes of Aeromonas species associated with invasive and noninvasive disease.

The genetic characteristics and biochemical and structural properties of a number of autoagglutinating (AA) strains of Aeromonas associated with invasive and noninvasive disease in humans and infections in animals and from environmental sources were investigated. Of 27 strains analyzed by multilocus enzyme typing and DNA hybridization studies, 25 (93%) were confirmed to belong to either hybridization group 1 (phenospecies and genospecies Aeromonas hydrophila) or 8 (phenospecies Aeromonas sobria; genospecies Aeromonas veronii). Further analysis of 19 of these strains indicated that four major groups could be identified on the basis of serologic and surface characteristics, protein and lipopolysaccharide composition, and virulence properties; these groupings held true regardless of the site of isolation or disease process involved. The major AA+ group identified was serogroup O:11, whose strains possessed an S layer, were resistant to the bactericidal activity of normal serum, and were pathogenic in mice. The results suggest a set of useful phenotypic and structural markers for identification of specific subsets of mesophilic Aeromonas involved in a wide range of infections in the animal kingdom.

Aeromonas↗
PubMed1990

[Identification of acinetobacter species isolated from human infections based on a new classification by Bouvet and Grimont].

The genus Acinetobacter was recently re-classified by Bouvet and Grimont who described four new species, A. baumannii, A. haemolyticus, A. johnsonii and A. junii, and five unnamed genospecies, with a re-definition of A. calcoaceticus and A. lwoffii which appeared in the Approved Lists of Bacterial Names, 1980. One hundred and twenty-eight clinical isolates previously identified as Acinetobacter were retrieved from storage and re-characterized by using a system based on the grouping reactions described by Bouvet and Grimont. Of these 86.7%, 2.3%, and 1.6% were identified as A. baumannii, A. junii and Acinetobacter genospecies 11, respectively, and the remaining 9.4% of the cultures were unidentified. None of the cultures identified as A. calcoaceticus and A. lwoffii was included in the 128 cultures.

Acinetobacter↗
PubMed1990

Nationwide surveillance program to identify diarrhea-causing Escherichia coli in children in Thailand.

Escherichia coli strains isolated from children with diarrhea were collected from 16 hospitals in different districts in Thailand during 1985 and 1986 and submitted to the National Reference Laboratory. Isolates were identified by serogrouping or as enterotoxigenic E. coli (ETEC), enteroinvasive E. coli (EIEC), enteropathogenic E. coli (EPEC) adhesin factor (EAF) E. coli, or Shiga-like-toxin (SLT)-producing E. coli by DNA hybridization. EPEC strains of known serogroups were isolated from 10%, ETEC strains were isolated from 6%, EAF E. coli strains were isolated from 4%, EIEC strains were isolated from less than 1%, and SLT-producing E. coli strains were isolated from none of 393 children with diarrhea. Among 278 children whose ages were recorded, the highest rate of isolation of EAF E. coli was 11% (9 of 85) from children less than 6 months old. ETEC was isolated from 5% (4 of 85) of children less than 6 months old, from 10% (12 of 118) of children 6 to 23 months old, and from 1% (1 of 75) of children greater than 23 months old. EPEC strains of known serogroups were isolated from 18% (15 of 85) of children less than 6 months old, from 11% (13 of 118) of children 6 to 23 months old, and from 9% (7 of 75) of children greater than 23 months old. E. coli strains that hybridized with the EIEC probe were isolated from three children who were 20, 36, and 48 months old. Examining E. coli for hybridization with DNA probes for virulence determinants is a practical way of conducting nationwide surveillance of diarrhea-causing E. coli. Since only 33% (13 of 39) of EPEC serogroups hybridized with the EAF probe and none hybridized with the SLT probes, identification of EPEC by serogroups analysis, followed by serotyping, should continue to be used in the identification of EPEC.

Child, Preschool↗
PubMed1990

Structures of agglomerins.

Structures of a series of new antibiotics, agglomerins A, B, C and D, which are active against a variety of anaerobic bacteria, were determined to be 1-acyl-2,3-dihydroxy-1,3-butadiene-1-carboxylic acid, (1----3)-gamma-lactones, i.e., 2-acyl-4-ylidenetetronic acids with different hydrocarbon chains in the acyl group. Their common chromophore exhibited tautomerism in solution. The relationship of their structure to the activity against anaerobes is discussed.

4-Butyrolactone↗