Publications by authors named "Yutaka Shiraki"

5 Publications

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Bacterial Distribution and Community Structure in Beef Cattle Liver and Bile at Slaughter.

J Food Prot 2021 Nov 24. Epub 2021 Nov 24.

National Institute of Health Sciences 3-25-26 Tonomachi, Kawasaki-ku, Kawasaki, JAPAN Kanagawa 210-9501 +81442706563.

In this study, the distribution of hygienic indicator bacteria in cattle livers and bile was examined at slaughterhouses. First, 127 cattle livers with gallbladders were carefully eviscerated from the carcasses at 10 slaughterhouses. Microbiological examination showed that 9 bile (7.1%) and 19 liver parenchyma (15.0%) samples were positive for the family Enterobacteriaceae (EB) with means ± SD of 3.68 ± 4.63 log CFU/mL and 1.59 ± 2.47 log CFU/g, respectively; thus, bacterial contamination was apparent even at the postevisceration stage. Subsequently, 70 cattle livers were obtained at the postprocessing/storage stage from 7 of the ten slaughterhouses; microbiological analysis revealed greater means of EB in the liver parenchyma (means ± SD of 3.00 ± 3.89 log CFU/g, P =0.011) than those at postevisceration stage, suggesting that bacterial dissemination and/or replication occurred in the liver parenchyma during processing and storage. According to 16S rRNA ion semiconductor sequencing analysis of representative samples from 12 cattle, Proteobacteria , Firmicutes , and Actinobacteria were dominant in both the parenchyma and bile, in which EB/ Escherichia coli were predominate among EB-rich livers. These results suggest that bile plays a role as a vehicle for bacterial transmission to the liver parenchyma. This is the first study to demonstrate bacterial distribution and community structure in the liver and biliary microecosystem of cattle at slaughter. Our data provide possible implication of EB testing in bile to screen cattle livers contaminated with high levels of fecal indicator bacteria.
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http://dx.doi.org/10.4315/JFP-21-288DOI Listing
November 2021

Phylogenetic Clades 6 and 8 of Enterohemorrhagic Escherichia coli O157:H7 With Particular stx Subtypes are More Frequently Found in Isolates From Hemolytic Uremic Syndrome Patients Than From Asymptomatic Carriers.

Open Forum Infect Dis 2014 Sep 12;1(2):ofu061. Epub 2014 Aug 12.

Department of Bacteriology I , National Institute of Infectious Diseases , Tokyo , Japan.

Background: Enterohemorrhagic Escherichia coli (EHEC) O157:H7 infection causes severe diseases such as bloody diarrhea and hemolytic uremic syndrome (HUS). Although EHEC O157:H7 strains have exhibited high genetic variability, their abilities to cause human diseases have not been fully examined.

Methods: Clade typing and stx subtyping of EHEC O157:H7 strains, which were isolated in Japan during 1999-2011 from 269 HUS patients and 387 asymptomatic carriers (ACs) and showed distinct pulsed-field gel electrophoresis patterns, were performed to determine relationships between specific lineages and clinical presentation.

Results: Clades 6 and 8 strains were more frequently found among the isolates from HUS cases than those from ACs (P = .00062 for clade 6, P < .0001 for clade 8). All clade 6 strains isolated from HUS patients harbored stx2a and/or stx2c, whereas all clade 8 strains harbored either stx2a or stx2a/stx2c. However, clade 7 strains were predominantly found among the AC isolates but less frequently found among the HUS isolates, suggesting a significant association between clade 7 and AC (P < .0001). Logistic regression analysis revealed that 0-9 year old age is a significant predictor of the association between clade 8 and HUS. We also found an intact norV gene, which encodes for a nitric oxide reductase that inhibits Shiga toxin activity under anaerobic condition, in all clades 1-3 isolates but not in clades 4-8 isolates.

Conclusions: Early detection of EHEC O157:H7 strains that belonged to clades 6/8 and harbored specific stx subtypes may be important for defining the risk of disease progression in EHEC-infected 0- to 9-year-old children.
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http://dx.doi.org/10.1093/ofid/ofu061DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4281788PMC
September 2014

[Analysis of Salmonella Saintpaul and nonmotile Salmonella serogroup O4 isolates from an outbreak].

Kansenshogaku Zasshi 2008 Jul;82(4):347-50

Gifu Prefectural Institute of Health and Environmental Sciences.

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http://dx.doi.org/10.11150/kansenshogakuzasshi1970.82.347DOI Listing
July 2008

[Epidemiological analysis of Salmonella enteritidis isolates using pulsed-field gel electrophoresis and bacteriophage typing over the period of April 2000 to March 2003 in Gifu Prefecture].

Kansenshogaku Zasshi 2004 Aug;78(8):690-8

Gifu Prefectural Institute of Health and Environmental Sciences.

We examined a total of 151 Salmonella enterica serovar Enteritidis strains isolated in Gifu Prefecture during the period from April 2000 to March 2003 by using bacteriophage typing and pulsed-field gel electrophoresis (PFGE). Bacteriophage typing classified them into twelve phage types (PT) and RDNC (reacted but did not conform). The predominant phage type was PT47 (34.4%) followed by PT1 (21.9%), PT4 (16.6%) and RDNC (11.3%). XbaI- and BlnI-digested PFGE analyses identified 17 and 44 PFGE patterns, respectively, indicating that PFGE with BlnI had more discriminating power than that with XbaI. Combination of the phage types and PFGE types of BlnI could make 53 subtypes. Some isolates with the same phage type were subdivided into different PFGE types, but those with PT47 were not. PT47 isolates were derived from sporadic patients with gastroenteritis, food poisoning outbreaks and healthy carriers through the years. This suggests that PT47 is highly clonal and disseminates over our prefecture.
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http://dx.doi.org/10.11150/kansenshogakuzasshi1970.78.690DOI Listing
August 2004

Escherichia coli producing CTX-M-2 beta-lactamase in cattle, Japan.

Emerg Infect Dis 2004 Jan;10(1):69-75

Gifu Prefectural Office of Meat Inspection, Gifu, Japan.

From November 2000 to June 2001, Escherichia coli strains producing CTX-M-2 beta-lactamase were isolated from 6 (1.5%) of 396 cattle fecal samples and 2 (0.7%) of 270 surface swabs of cattle carcasses in Japan. The blaCTX-M-2 gene responsible for CTX-M-2 production was encoded on transferable plasmids, and the gene was transferred to E. coli CSH2 with a very high frequency (2 x 10(-4) to 6 x 10(-1) per donor cells) by conjugation. Random amplified polymorphic DNA analysis of nine isolates showed at least five different patterns. These findings suggest that CTX-M-2 producers might have originated from cattle through the use of cephalosporins such as ceftiofur and that cattle could be a reservoir of CTX-M-2-producing E. coli. Continuous and strategic surveillance of antimicrobial-resistant bacteria in livestock is essential to suppress further dissemination of these bacteria into society at large.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3322752PMC
http://dx.doi.org/10.3201/eid1001.030219DOI Listing
January 2004
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