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Biomedical subjects

Haruo Watanabe

Publications and source records attributed to Haruo Watanabe.

108 records · Page 6Linked to original sources
PubMed2002

Clonal association of Staphylococcus aureus causing bullous impetigo and the emergence of new methicillin-resistant clonal groups in Kansai district in Japan.

A molecular epidemiological analysis was performed to reveal the clonal association of Staphylococcus aureus strains isolated from patients with bullous impetigo. Pulsed-field gel electrophoresis with cluster analysis, genetic and phenotypic characterizations, and antimicrobial susceptibility profiling of 88 S. aureus strains isolated from outpatients at 4 hospitals in the Kansai district in Japan were undertaken. Three distinct clonal groups were identified: 2 of them carried the exfoliative toxin (ET) A gene (eta), and the other carried the ETB gene (etb). The former groups represent 2 eta-positive clonal groups that have not been described previously. All the strains in the more dominant eta-positive clonal group and some of the strains in the etb-positive clonal group were methicillin-resistant S. aureus (MRSA) showing borderline-to-moderate resistance to beta-lactams. These MRSA strains appear to be emerging clonal groups that have not been considered in previous epidemiological studies of ET-producing S. aureus in Japan and thus pose a significant threat for future treatment of patients with bullous impetigo and/or staphylococcal scalded-skin syndrome.

Blister↗
PubMed2002

Silkworm larvae as an animal model of bacterial infection pathogenic to humans.

Silkworm larvae, Bombyx mori, were examined as an animal model of human infection with pathogenic bacteria. When 3 x 10(7) cells of Staphylococcus aureus (S. aureus), Pseudomonas aeruginosa, or Vibrio cholerae were injected into the blood of fifth instar silkworm larvae, over 90% of the larvae died within 2 days, whereas over 90% survived for 5 days after injection of the same amount of Escherichia coli. Growth of S. aureus was observed in larvae blood and tissues. Immunostaining analysis revealed that S. aureus proliferated at the surface of the midgut. Infection of silkworm larvae by methicillin-sensitive S. aureus was cured by ampicillin, oxacillin, and vancomycin, whereas infection by methicillin-resistant S. aureus was not cured by ampicillin or oxacillin, although vancomycin was effective. Disinfectants were not effective because of toxicity against the larvae. Thus, silkworm larvae are useful for evaluating antibiotics for pathogenic bacterial infection in humans.

Animals↗
PubMed2002

Levels of thermostable direct hemolysin produced by Vibrio parahaemolyticus O3:K6 and other serovars grown anaerobically with the presence of a bile acid.

Twenty-three V. parahaemolyticus strains, including 12 pandemic O3:K6 strains, were examined for their growth and production of thermostable direct hemolysin (TDH) under an anaerobic culture condition with or without presence of a bile acid, taurocholic acid (TCA). Both bacterial growth and TDH production were markedly enhanced by TCA for a majority of the strains, but the scale of the TDH production was disproportionately greater than that of the corresponding growth for 14 strains. Such enhancement was, however, not specific to the pandemic strains.

Aerobiosis↗
PubMed2002

A broad-host-range vector of incompatibility group Q can work as a plasmid vector in Neisseria meningitidis: a new genetical tool.

Plasmid pHT128, a derivative of the broad-host-range IncQ vector pGSS33, was successfully introduced into Neisseria meningitidis. Under optimal conditions, pHT128 was transferred from Escherichia coli to N. meningitidis by triparental conjugation at a frequency of 10(-5)-10(-6). The copy number of pHT128 in N. meningitidis was almost the same as in E. coli, in which the copy number of IncQ plasmids per chromosome is estimated to be 10. pHT128 was maintained as an episome in N. meningitidis in the presence of chloramphenicol, a marker of the plasmid. It was also shown that an opc or pilE1 gene cloned on pHT128 could be expressed in N. meningitidis under control of the tac promoter and could complement a mutation of opc or pilE1, respectively. In addition, the conjugational introduction of pHT128 into N. meningitidis was demonstrated to be independent of natural transformation competence. All the results indicate that pHT128 is a useful vector for N. meningitidis as a new genetical tool.

Conjugation, Genetic↗
PubMed2002

[Epidemiological and bacteriological investigation of enterohemorrhagic Escherichia coli infection in the Chugoku-Shikoku area].

We investigated the occurring tendency of enterohemorrhagic Escherichia coli (EHEC) infection in the prefectural and municipal public health institutes in the Chugoku-Shikoku area from 1996 to 1999, and the bacteriological characteristics of EHEC isolated from these cases. Consequently, epidemiological analysis of the EHEC infection in this district was performed. 22 outbreaks in the various facilities showed the tendency occurred in infants and aged groups, and the serotypes of EHEC isolated from these outbreaks were O26, O111 etc. as well as O157. In 4 cases, EHEC were isolated from specimens of buckwheat noodles, salad, sand box, and goat feces, and these were determined as the source of infection. In 898 sporadic cases, including familial infection, the EHEC isolates were classified into 24 serotypes, and the genotypes of EHEC O157:H7 isolates by pulsed-field gel electrophoresis (PFGE) also varied. Moreover, since many asymptomatic carriers were detected in the adult group with familial infection, the existence of healthy carriers is as important as the source of infection. The drug-resistance test of EHEC isolates showed that 24% of the 924 isolates were resistant to drugs.

Adult↗
PubMed2002

[PulseNet Japan: surveillance system for the early detection of diffuse outbreak based on the molecular epidemiological method].

As the foods are stocked below freezing and widely distributed, a kind of food-borne outbreak which occurs in separate regions or in different time, so called "diffuse outbreak", has been found at the present day. Unless the outbreak is early recognized, the number of victims would increase. Some methods have been developed to analyze the relatedness of bacteria isolated from the patients of enteric infections. PFGE, pulsed-field gel electrophoresis, is one of the methods and powerful to discriminate the difference in nucleotide sequences among bacterial genomes. Availability of PFGE analysis is appreciated to examine the linkage of each incident of food-borne infections in epidemiological investigation. A PFGE network, PulseNet Japan, is now under construction among National Institute of Infectious Diseases, local Health Institutes and Ministry of Health, Labour and Welfare.

DNA, Bacterial↗
PubMed2002

DNA sequence analysis of DNA gyrase and DNA topoisomerase IV quinolone resistance-determining regions of Salmonella enterica serovar Typhi and serovar Paratyphi A.

The mutations that are responsible for fluoroquinolone resistance in the gyrA, gyrB, parC, and parE genes of Salmonella enterica serovar Typhi and serovar Paratyphi A were investigated. The sequences of the quinolone resistance-determining region of the gyrA gene in clinical isolates which showed decreased susceptibilities to fluoroquinolones had a single mutation at either the Ser-83 or the Asp-87 codon, and no mutations were found in the gyrB, parC, and parE genes.

Anti-Infective Agents↗
PubMed2002

Dissemination of the phage-associated novel superantigen gene speL in recent invasive and noninvasive Streptococcus pyogenes M3/T3 isolates in Japan.

In Japan, more than 10% of streptococcal toxic shock-like syndrome (TSLS) cases have been caused by Streptococcus pyogenes M3/T3 isolates since the first reported TSLS case in 1992. Most M3/T3 isolates from TSLS or severe invasive infection cases during 1992 to 2001 and those from noninvasive cases during this period are indistinguishable in pulsed-field gel electropherograms. The longest fragments of these recent isolates were 300 kb in size, whereas those of isolates recovered during or before 1973 were 260 kb in size. These 260- and 300-kb fragments hybridized to each other, suggesting the acquisition of an about 40-kb fragment by the recent isolates. The whole part of the acquired fragment was cloned from the first Japanese TSLS isolate, NIH1, and its nucleotide sequence was determined. The 41,796-bp fragment is temperate phage phiNIH1.1, containing a new superantigen gene speL near its right attachment site. The C-terminal part of the deduced amino acid sequence of speL has 48 and 46% similarity with well-characterized erythrogenic toxin SpeC and the most potent superantigen, SmeZ-2, respectively. None of 10 T3 isolates recovered during or before 1973 has speL, whereas all of 18 M3/T3 isolates recovered during or after 1992 and, surprisingly, Streptococcus equi subsp. equi ATCC 9527 do have this gene. Though plaques could not be obtained from phiNIH1.1, its DNA became detectable from the phage particle fraction upon mitomycin C induction, showing that this phage is not defective. A horizontal transfer of the phage carrying speL may explain the observed change in M3/T3 S. pyogenes isolates in Japan.

Amino Acid Sequence↗
PubMed2002

Modification of the structure and activity of lipid A in Yersinia pestis lipopolysaccharide by growth temperature.

Yersinia pestis strain Yreka was grown at 27 or 37 degrees C, and the lipid A structures (lipid A-27 degrees C and lipid A-37 degrees C) of the respective lipopolysaccharides (LPS) were investigated by matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) mass spectrometry. Lipid A-27 degrees C consisted of a mixture of tri-acyl, tetra-acyl, penta-acyl, and hexa-acyl lipid A's, of which tetra-acyl lipid A was most abundant. Lipid A-37 degrees C consisted predominantly of tri- and tetra-acylated molecules, with only small amounts of penta-acyl lipid A; no hexa-acyl lipid A was detected. Furthermore, the amount of 4-amino-arabinose was substantially higher in lipid A-27 degrees C than in lipid A-37 degrees C. By use of mouse and human macrophage cell lines, the biological activities of the LPS and lipid A preparations were measured via their abilities to induce production of tumor necrosis factor alpha (TNF-alpha). In both cell lines the LPS and the lipid A from bacteria grown at 27 degrees C were stronger inducers of TNF-alpha than those from bacteria grown at 37 degrees C. However, the difference in activity was more prominent in human macrophage cells. These results suggest that in order to reduce the activation of human macrophages, it may be more advantageous for Y. pestis to produce less-acylated lipid A at 37 degrees C.

Animals↗
PubMed2002

Selective amplification of tyv (rfbE), prt (rfbS), viaB, and fliC genes by multiplex PCR for identification of Salmonella enterica serovars Typhi and Paratyphi A.

The PCR primers for O, H, and Vi antigen genes, tyv (rfbE), prt (rfbS), fliC-d, fliC-a, and viaB, were designed and used for the rapid identification of Salmonella enterica serovars Typhi and Paratyphi A with multiplex PCR. The results showed that all the clinical isolates examined of Salmonella serovars Typhi and Paratyphi A were accurately identified by this assay.

Antigens, Bacterial↗
PubMed2002

Isolation from a healthy carrier and characterization of a Neisseria meningitidis strain that is deficient in gamma-Glutamyl aminopeptidase activity.

gamma-Glutamyl aminopeptidase (GGT) activity is used as a specific marker for the identification of Neisseria meningitidis. We isolated from a healthy carrier and characterized an N. meningitidis isolate which lacked the activity due to the insertional mutation of the ggt gene, suggesting that naturally occurring N. meningitidis isolates do not always possess GGT activity.

Adult↗
PubMed2002

Effects of repeated subculturing and prolonged storage at room temperature of enterohemorrhagic Escherichia coli O157:H7 on pulsed-field gel electrophoresis profiles.

Three clinical strains of enterohemorrhagic Escherichia coli O157:H7 which were subcultured repeatedly or stored at room temperature over a 25-week period showed appreciable variations in their pulsed-field gel electrophoresis fragment patterns. The variations could be explained by a couple of spontaneous genetic events at most and thus did not invalidate the genetic lineage of the strains.

DNA, Bacterial↗
PubMed2002

High genomic diversity of enterohemorrhagic Escherichia coli isolates in Japan and its applicability for the detection of diffuse outbreak.

Genotyping of 1,102 enterohemorrhagic Escherichia coli isolates by the use of pulsed-field gel electrophoresis (PFGE) carried out from January to November 2000 has revealed the high genomic diversity of these isolates in Japan. By combining the results of genotyping of the isolates with the information from other epidemiological investigations of the cases, we identified a diffuse outbreak in Japan in the year 2000 that seemed to be sporadic but was actually linked. Isolates with only the Shiga toxin 2 gene derived from patient specimens and the contaminated food involved in this diffuse outbreak showed an indistinguishable PFGE profile and the same phage type. Based on the diversity of genotypes among the isolates of enterohemorrhagic E. coli O157:H7/- in Japan, we suggest the presence of a few other possible diffuse outbreaks due to the organisms, showing indistinguishable genotypes.

Disease Outbreaks↗
PubMed2002

[PulseNet Japan--network system for the utilization of epidemiological information and the results of pulsed-field gel electrophoresis].

Since 1996, we have been analyzing DNA pattern of enterohemorrhagic Escherichia coli(EHEC) O157: H7 isolates in Japan by the use of pulsed-field gel electrophoresis. The method, capable of discriminating genotypical difference of the isolates, enabled us to find the contaminated food such as salmon roe which was the causative agent for the multiprefectual outbreaks in Japan. These outbreaks which we are referring as diffuse outbreaks seem to be increasing in number, because it reflects that some of widely distributed or mass-produced food products are being contaminated by pathogens such as EHEC. In order to find a diffuse outbreak promptly and prevent it becoming large, we are constructing a network, called PulseNet Japan, for sharing the results of pulsed-field gel electrophoresis and epidemiological information among municipal public health institutes and National Institute of Infectious Diseases.

Colitis↗
PubMed2000

Genotypic variations of Shiga toxin-converting phages from enterohaemorrhagic Escherichia coli O157: H7 isolates.

Pulsed-field gel electrophoresis (PFGE) analysis revealed that enterohaemorrhagic Escherichia coli (EHEC) O157:H7 strains had considerable variations in their genomes. This study investigated whether or not the molecular profile of Shiga toxin (Stx) 1- and Stx2-converting phages isolated from EHEC O157:H7 strains, derived from various sources in the USA and Japan, corresponded to the variations of host strains' genotypes as determined by PFGE. A total of 51 Stx-converting phages including 12 Stx1-converting phages and 37 Stx2-converting phages was isolated from seven USA isolates and 20 Japanese isolates. The average Dice coefficient values showed 44% similarity between phage DNAs in Stx2-converting phages digested with SmaI and 55% in Stx1-converting phages digested with HindIII, indicating considerable variation among phage DNA. In particular, restriction fragment length polymorphism (RFLP) patterns of Stx2-converting phage DNA varied according to the PFGE type of their host strain, which suggests that the phage genomes have altered their genotypic characteristics with those of host genomes. However, there are several exceptions: the RFLP patterns of some Stx2-converting phages were quite similar irrespective of the different genotypes of the host strains, indicating that horizontal transfer of Stx2-converting phage may also occur under some circumstances.

Bacterial Toxins↗