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S Yamai

Publications and source records attributed to S Yamai.

At least 55 records · Page 3Linked to original sources
PubMed1997

Rapid screening method for identification of cholera toxin-producing Vibrio cholerae O1 and O139.

A novel method of identifying cholera enterotoxin (CT)-producing Vibrio cholerae serogroups O1 and O139 was developed. The method uses degradation of NAD as a specific biochemical marker for the CT-producing strains. The substrate NAD at a concentration of 100 mumol/liter was markedly degraded when it was incubated at 37 degrees C for 2 h with the CT-producing stains at a final cell density equivalent to that of a twofold dilution of a McFarland no. 1 standard. NAD degradation was monitored by an enzyme-amplified color development assay. Subsequent tests conducted with a total of 119 strains of V. cholerae, including both clinical and environmental isolates, confirmed a significant correlation between NAD degradation and CT production for all V. cholerae strains belonging to serogroups O1 and O139. Since 2 of 11 non-O1, non-O139 V. cholerae strains not carrying the CT gene degraded NAD, serotyping of the strains prior to the test is recommended.

Bacterial Typing Techniques↗
PubMed1997

[Studies on enrichment broth for verotoxin-producing Escherichia coli (VTEC) O157].

Growth of verotoxin-producing Escherichia coli (VTEC) O157 in conventionally recommended pre-enrichment broth media at different temperatures was evaluated. In addition, sensitivity of VTEC O157 isolates to several antibacterial drugs, which were added to the selective enrichment broth, was tested. All five isolates of VTEC O157 tested grew well in trypticase soy broth (TSB) at 36 degrees C and 42 degrees C, while the growth of one isolate was markedly suppressed in TSB supplemented with cefixime (CFIX), potassium tellurite (PT), and vancomycin (TSB-CTV) even at 36 degrees C. A significant growth suppression was also observed in three of the isolates cultured in novobiocin (NB)-supplemented modified EC broth (mEC-NB) at 42 degrees C. In mEC-NB after 24-hr incubation at 36 degrees C, the five VTEC O157 isolates grew well, although one isolate was slightly suppressed during the first 8 hours. Minimum growth inhibitory concentrations of CFIX, NB and PT for a total of 90 clinical and environmental isolates of VTEC O157 were all above the concentrations usually prescribed for mEC-NB and TSB-CTV. These findings suggest that mEC-NB and TSB-CTV should be used at 36 degrees C for growth of VTEC O157 and that use of a nonselective pre-enrichment broth medium (i.e. TSB) together with a selective one (i.e. TSB-CTV or mEC-NB) is necessary for successful isolation of VTEC O157 from various specimens.

Aeromonas↗
PubMed1996

An epidemiological study of Salmonella enteritidis by pulsed-field gel electrophoresis (PFGE): several PFGE patterns observed in isolates from a food poisoning outbreak.

An epidemiological analysis of Salmonella enteritidis from a food poisoning was done using pulsed-field gel electrophoresis (PFGE) of BlnI- or XbaI-digested fragments of chromosomal DNA of isolates. S. enteritidis isolates obtained from 19 patients had identical PFGE patterns. Therefore, a strain giving the same pattern was considered to be the causative agent of this outbreak. In addition, four isolates that had different BlnI-digested PFGE patterns were obtained from three patients, suggesting that the observed variations in PFGE patterns might occur as the result of some point mutations of chromosomal DNA during growth or from the existence of several S. enteritidis strains from various sources. Subsequent PFGE analysis of continuously subcultured strains supported the former possibility. These observations indicate that PFGE analysis on multiple numbers of colonies from each patient are necessary for the epidemiologic investigation of S. enteritidis.

DNA, Bacterial↗
PubMed1996

[Isolation and incidence of Vibrio cholerae from river water].

The prevalence of Vibrio cholerae contamination in river water derived from 20 sites of 18 rivers in Kanagawa, Japan, was investigated during a period from July to September, 1987, and from one of the 20 sites in August, 1988 and in February, 1989, V. cholerae non-O1 was found in all samples at concentrations of 0.9-->1,400 MPN/100 ml. Higher amounts of the organism were observed in the samples from estuaries. V. cholerae O1 was detected in samples collected in August, 1988 and in February, 1989 at concentrations of 150 MPN/100 ml and 1.5 MPN/100 ml, respectively. From 1989 to 1995, water samples were collected monthly from 10 sites of 10 rivers to detect V. cholerae. V. cholerae O1 and non-O1 were detected in 3.6% (30 of 840) and in 61.1% (513 of 840) in the water samples examined, respectively. Overall, V. cholerae was found in 62.9% (528 of 840). Both types, O1 and non-O1, of organisms were detected in 15 samples. These results indicated that river water was contaminated frequently with V. cholerae non-O1 and sporadically with V. cholerae O1 throughout the year. Only one strain of V. cholerae O1 out of 543 V. cholerae strains was found to be a producer of cholera toxin. During these studies, the selectivity of 3 media for V. cholerae O1 was evaluated, and PMT agar was found to be the best.

Japan↗
PubMed1996

[Rapid detection of the hemolysin genes in Aeromonas sobria by the polymerase chain reaction].

The hemolysin of Aeromonas sobria is one of the important virulence factors in this organism. Rapid detection and identification test for A. sobria is important for early and specific diagnosis of this infectious disease. We evaluated the polymerase chain reaction (PCR) for the rapid detection of A. sobria. Two pairs of synthetic oligonucleotide primers (ASA1-s and a; AerAAS-s and a) were used in PCR technique to detect the different hemolysin genes (ASA1 and aerAAS) in A. sobria. The PCR identified 91% of ASA1-positive and 23.4% of aerAAS-positive strains in beta-hemolytic A. sobria. Other species of Aeromonas, Plesiomonas shigelloides, Vibrio cholerae O1 and V. parahaemolyticus tested were negative in the PCR with two pairs of primers. The PCR technique for detection of two hemolysin genes suggested the possibility of application of this method for detection of A. sobria in A. sobria-associated infections.

Aeromonas↗
PubMed1996

[An outbreak of waterborne Cryptosporidiosis in Kanagawa, Japan].

An outbreak of diarrhea due to infection with Cryptosporidium occurred among the staff members and customers who visited one of the 10 public houses or a dancing school in a building in Hiratsuka, Kanagawa Prefecture, at the end of summer in 1994. The epidemiological surveys by a questionnaire revealed that 461 out of 736 persons investigated complained of cholera-like or flu-like illness. The clinical manifestations included mucous and/or watery diarrhea (96.7%), abdominal pain (61.6%), fever (54.2%: lower than 39 degrees C = 84.1%, higher than 39 degrees C = 15.9%), malaise (37.1%), nausea (32.8%) and headache (29.3%). The polluted drinking water was strongly suspected to be the immediate cause of infection. Although several species of pathogenic bacteria were isolated both from stool and water samples, they were not supposed to be linked to the outbreak. No known enteropathogenic virus was found in either of the samples. Oocysts of Cryptosporidium parvum were identified in 12 (48.0%) of the 25 stool samples. The oocysts were also found in tap water and other water samples from a receiving tank which was directly connected with the public waterworks, and an elevated tank on the roof, a wastewater pits, a soil pit and artesianspring water tank. These tanks and pits except for the elevated tank were built adjucent to each other on an underground floor of the building. These tanks and pits were connected with openings in the upperpart of the tank walls. These openings might have functioned to discharge excess of drinking water in the receiving tank to the wastewater pit. The water level of the wastewater pit is kept down below the openings by pumping out the sanitary sewage to the public drain. According to the declaration of the owner of the building, however, the wastewater pump was broken at the time of outbreak. Accidental malfunction of the drainage system caused contamination of drinking water with sanitary sewage through the connecting pipes.

Adolescent↗
PubMed1996

Occurrence of urease-positive Vibrio parahaemolyticus in Kanagawa, Japan, with specific reference to presence of thermostable direct hemolysin (TDH) and the TDH-related-hemolysin genes.

A total of 132 strains of V. parahaemolyticus isolated from patients and from the suspected causal food items of past food poisoning cases occurring in Kanagawa Prefecture, Japan, were examined for the ability to hydrolyze urea, with specific reference to the presence of the thermostable direct hemolysin gene (tdh) and the gene for thermostable direct hemolysin-related hemolysin (trh). Ten strains belonging to five different O-antigen serotypes were positive for urea hydrolysis (UH+), and four of these strains did not carry tdh. A total of 106 strains carried tdh, but less than 6% of them were UH+, whereas all trh-carrying strains were UH+. The evidence suggests that urea hydrolysis is not a reliable marker for identifying tdh-carrying V. parahaemolyticus strains in Japan (the Pacific Northeast) but may be a marker for trh-carrying strains.

Bacterial Proteins↗
PubMed1996

Production of thermostable direct hemolysin by Vibrio parahaemolyticus enhanced by conjugated bile acids.

The effects of conjugated bile acids, glycocholic acid, and taurocholic acid (TC) on production of thermostable direct hemolysin (TDH) by Vibrio parahaemolyticus were determined by a reversed passive latex agglutination assay against TDH. The amount of TDH excreted in growth medium containing either glycocholic acid or taurocholic acid (5 mM/liter) was, on a per-cell basis, 4- to 16-fold greater than that excreted in medium without the bile acids. The amounts of TDH released from lysed cells grown with the bile acids (5 mM/liter) were 4- to 32-fold greater than those from lysed cells grown without, suggesting that the bile acids enhanced synthesis of TDH within bacterial cells. These data imply that the conjugated bile acids play a key role in the pathogenicity of V. parahaemolyticus.

Glycocholic Acid↗
PubMed1995

Evaluation of DNA fingerprinting by PFGE as an epidemiologic tool for Salmonella infections.

To evaluate DNA fingerprinting as an epidemiologic tool, pulsed-field gel electrophoresis (PFGE) was performed on isolates of Salmonella, including S. typhimurium, S. thompson, and S. enteritidis. Chromosomal DNA was digested with the restriction endonucleases Bln I and Xba I. The patterns of S. thompson and S. typhimurium isolates from various sources were different from one another. There was no correlation between the phage type and the digestion pattern of S. enteritidis isolates. Some strains belonging to one phage type were distinguished by their PFGE pattern in this study. These results suggest that the Bln I and Xba I digestion patterns of chromosomal DNA are useful for epidemiological analysis of an outbreak of Salmonella infection or food poisoning.

DNA Fingerprinting↗
PubMed1995

[Detection of Mycoplasma pneumoniae from throat swab by polymerase chain reaction].

Polymerase chain reaction (PCR) with primers directed against the 16S-rRNA gene of Mycoplasma pneumoniae was used to diagnose M. pneumoniae infections, and the results were compared with those of culture and serology methods. Eighty (22%) of 363 throat swab samples from patients with acute respiratory complaints gave positive results by using the PCR method. Sixty-seven (18.5%) of the samples were positive in culture method. Of 35 samples which were unreliable culture results due to contamination with other bacteria, 13 gave positive results in the PCR method. Of the 97 cases obtained throat swabs and paired sera, 28 (28.9%) showed positive results by the PCR assay, and 29 (29.9%) by serology method (particle agglutination test). The positive rate was increased to 36% by using both the PCR and the serology methods. From these results it was concluded that the PCR method is useful for laboratory diagnosis of M. pneumoniae infections.

Base Sequence↗
PubMed1995

[Causative agent of the so-called "light disease of shrimps" is luminescent Vibrio cholerae non-O1].

A number of luminous fresh-water shrimps were found in a fish preserve in Lake Biwa, Shiga Prefecture, in the middle of July, 1994, and most of them died within several hours after collection (the so-called "light disease of shrimp"). Four luminous organisms were isolated from a dead shrimp. Although the phenotypic properties of these strains were similar to those of V. cholerae or V. mimicus, a representative strain, 838-94, was shown to have a high level (79%) of DNA homology with V. cholerae type strain, ATCC 14035 and a low level (45%) of relatedness to V. mimicus type strain, ATCC 33653. Therefore, these isolates were identified as V. cholerae. The four strains fell into serogroup O28 of V. cholerae. On the other hand, none of the isolates had CT nor NAG-ST genes. The results obtained herein clearly demonstrate that these organisms isolated from luminous shrimps are luminescent V. cholerae serogroup O28.

Animals↗
PubMed1994

[Application of urine sediment for diagnosis of gonococcal urethritis by enzyme immunoassay].

We evaluated the usefulness of urine sediment from male gonorrhea patients for detecting gonococcal antigens by enzyme immunoassay, Gonozyme (Abbott Laboratories). Experiments for dilution rate of urine sediment with buffer provided in a kit indicated that dilution of sediment at 1:4-6 would be practical in performing Gonozyme. All urine sediment specimens from 18 gonorrhea patients showed positive by Gonozyme, and 68, except for 3, culture-negative control urine sediments, including 8 sediments from patients with chlamydial urethlitis, were negative. Based on comparing results of Gonozyme with those of culture, sensitivities and specificity were 88.9-100% and 95.6%, respectively. During storage of urine sediment at 5 degrees C for 7 days, absorbance values were stable. Therefore, urine sediment could be preserved or transported. We conclude that urine sediment is useful for diagnosis of gonococcal urethritis in males by Gonozyme.

Antigens, Bacterial↗
PubMed1994

[Survival of Vibrio cholerae O139 Synonym Bengal in water from a river].

Survival of five strains of Vibrio cholerae, including serotypes O139 Synonym Bengal, O1 El Tor, and non-O1 were compared in water from a river. These bacteria were mixed with water from a river and the water filtered through 0.45 micron millipore filters, respectively, to yield a concentration of 10(6) CFU/ml and incubated at 5 degrees C and 20 degrees C for 21 days. The survival curve of V. cholerae O139 was almost the same with V. cholerae O1 and non-O1. The number of these bacilli decreased to less than 10(2) CFU/ml at 7 days of the incubation at 20 degrees C. When incubated at 5 degrees, however, these bacilli survived much longer and the number decreased to the same value after 14 days. Therefore, these results indicated that the temperature during the incubation greatly affects the survival of V. cholerae. On the other hand, when the water was filtered and used for the experiment, V. cholerae survived longer than in the polluted water. From these observations, if the river is polluted with V. cholerae O139 in the future, it is suggested that the distribution of V. cholerae O139 in the river may be the same as the present condition with V. cholerae O1 and non-O1.

Fresh Water↗
PubMed1990

In vivo 13C imaging enhanced by polarization transfer.

Carbon-13 NMR imaging has been combined with 1H-13C polarization transfer to improve image quality. Natural-abundance carbon images of Fischer rat bodies were obtained within a few minutes. Next 13C-labeled glucose was administered orally to rats, and spatial distributions of glucose and its derivatives were observed with this technique.

Animals↗
PubMed1990

Carbon-13 NMR imaging study of in-vivo glucose metabolism.

Carbon-13 NMR spectroscopy and chemical shift selective imaging studies of in vivo glucose metabolism were performed at 2.0 T. Some metabolite peaks were observed in 13C NMR spectra, and carbon NMR imaging focused in the spectral region attributed to D-1-13C-glucose were also performed. A 13C NMR signal accumulated in the liver was detected and the average time resolution of these spectra and images were 10 and 30 minutes, respectively.

Animals↗
PubMed1989

In vitro effect of menfegol on Neisseria gonorrhoeae.

Bacteriostatic and bactericidal effect of Menfegol, which has been used as a spermicide, on Neisseria gonorrhoeae was investigated in vitro. The distribution of the MICs of N. gonorrhoeae to Menfegol consisted of 2 groups. Resistant strains showed the MICs of more than 3200 micrograms/ml while the MICs of sensitive strains were less than or equal to 200 micrograms/ml. When the resistant strains were suspended in several concentrations of Menfegol and were incubated at 35 degrees C, no concentrations inactivated gonococci completely. However, the number of organisms was remarkably decreased within 30 minutes.

Drug Resistance, Microbial↗