National Veterinary Assay Laboratory

Kokubunji, Japan

National Veterinary Assay Laboratory

Kokubunji, Japan
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Usui M.,National Veterinary Assay Laboratory | Asai T.,National Veterinary Assay Laboratory | Sato S.,Scientific Feed Laboratory
Microbiology and Immunology | Year: 2011

We investigated the mechanism responsible for bile susceptibility in three deoxycholate-sensitive (DCs) strains of Salmonella enterica subspecies enterica serovar Pullorum isolated in 1958 in Japan. Of the genes encoding the AcrAB-TolC efflux system, the expression of acrB mRNA was 10-fold lower in the DCs strains than in a deoxycholate-resistant (DCr) strain, whereas those of the acrA and tolC genes were two-fold lower. These results suggested that low expression of acrB was strongly correlated with bile susceptibility in the DCs strains. In addition, the increase in tolC expression levels was not detected in the DCr mutants derived from the DCs strains, suggesting that difference in the expression levels of tolC is not associated with bile susceptibility. © 2011 The Societies and Blackwell Publishing Asia Pty Ltd.

Noda T.,Fukuoka Institute of Health Environmental | Murakami K.,Fukuoka Institute of Health Environmental | Ishiguro Y.,Fukuoka Institute of Health Environmental | Asai T.,National Veterinary Assay Laboratory
Foodborne Pathogens and Disease | Year: 2010

Background: The study sets out to either confirm or refute a recent study's findings that chicken meat is an unlikely source of Salmonella enterica subspecies enterica serovar Infantis (Salmonella Infantis) in humans in the Kyushu-Okinawa region, Japan. Methods: A total of 74 Salmonella Infantis isolates (30 from human and 44 from other sources), mainly from the Kyushu-Okinawa region in south-western Japan, were analyzed using a molecular-epidemiological approach combining two fingerprinting methods, namely pulsed-field gel electrophoresis and amplified fragment length polymorphism (AFLP), a novel polymerase chain reaction-based technique. Results: The resulting pulsed-field profiles showed that 17 of 30 human isolates were similar to those found in chicken meat, whereas there were no common pulsed-field profiles between human and chicken egg isolates. Overall, 3 of 18 AFLP profiles included 7 human isolates and 14 chicken egg isolates. In addition, the combined results of the pulsed-field gel electrophoresis and AFLP analyses showed that 8 human Salmonella Infantis and 13 chicken meat isolates belonged to the same clonal lines. Conclusions: These results suggest that chicken meat is an infection source of Salmonella Infantis for humans in the Kyushu-Okinawa region, Japan. The results also showed the relatively high suitability of AFLP for application to epidemiological studies of Salmonella Infantis. © Copyright 2010, Mary Ann Liebert, Inc.

Hiki M.,National Veterinary Assay Laboratory | Usui M.,National Veterinary Assay Laboratory | Kojima A.,National Veterinary Assay Laboratory | Ozawa M.,National Veterinary Assay Laboratory | And 2 more authors.
Foodborne Pathogens and Disease | Year: 2013

Broad-spectrum cephalosporin (BSC) resistance has increased in Escherichia coli isolates from broiler chickens in Japan since 2004. The purpose of this study was to understand the epidemiology of BSC-resistant E. coli in livestock animals. Among 3274 E. coli isolates from 1767 feces of apparently healthy animals on 1767 farms between 2004 and 2009, 118 ceftiofur (CTF)-resistant isolates (CTF MIC ≥4 μg/mL) were identified on 74 farms. After elimination of apparently clonal isolates from a single animal, 75 selected CTF-resistant isolates (62 isolates from 61 broiler chickens, 10 isolates from 10 layer chickens, two isolates from two cows, and one isolate from a pig) were characterized. The blaCMY-2 gene was most frequently detected in 50 isolates, followed by blaCTX-M (CTX-M-2: six isolates; CTX-M-14: four isolates; CTX-M-25: two isolates; CTX-M-1: one isolate) and blaSHV (SHV-12: seven isolates; SHV-2, SHV-2a, SHV-5: one isolate each). In particular, 42 of 62 broiler chicken isolates harbored blaCMY-2. Pulsed-field gel electrophoresis analyses using XbaI revealed divergent profiles among the BSC-resistant isolates. The incompatibility groups of blaCMY-2 plasmids from 34 of the 42 broiler chicken isolates belonged to IncIγ (10 isolates), IncA/C (nine isolates), IncB/O (seven isolates) and IncI1 (six isolates), or were nontypeable (two isolates). Co-transmission of resistance to non-β-lactam antibiotics was observed in transconjugants with IncA/C plasmids, but not with IncI1, IncIγ, and IncB/O plasmids except for one isolate with IncB/O. Our findings suggest that the blaCMY-2 gene is a key player in BSC-resistant E. coli isolates and that coselection is unlikely to be associated with the abundance of blaCMY-2 plasmids, except for IncA/C plasmids. © Mary Ann Liebert, Inc.

Narushima R.,National Veterinary Assay Laboratory | Shimazaki T.,Chiyoda Corporation | Takahashi T.,Nippon Veterinary and Life Science University
Biologicals | Year: 2011

It is known that certain feline cell lines, such as the Crandell-Rees feline kidney cell, produce an RD-114-like virus. As a feline endogenous retrovirus, RD114 virus, exists in the genome of all cats, it can be assumed that contamination with the virus in feline and canine live vaccines manufactured by culturing cells of feline origin occurs.To detect an infectious RD114 virus in vitro, a LacZ marker rescue assay has recently been established. In feline and canine live vaccines approved in Japan, feline cell lines are widely used to produce vaccines, especially those containing canine parvovirus components. The LacZ marker rescue assay detects infectious viral particles, but the real-time reverse-transcription-PCR detects both infectious and defective viruses. The canine live vaccines manufactured in cells of feline origin showed positive results for the env gene by the real-time reverse-transcription-PCR, including all of the 8 vaccines produced in feline cell lines that were negative in the LacZ marker rescue assay. In conclusion, the present investigation suggests that the newly developed method has the advantages of shorter time requirements and can be applied as a valuable screening method to detect RD114 viral RNA in vaccines. © 2011 The International Association for Biologicals.

Usui M.,National Veterinary Assay Laboratory
Japanese journal of infectious diseases | Year: 2012

Bacteriocin-producing Escherichia coli (donors) rapidly kill conventional recipient E. coli DH5α in conjugation experiments. To evaluate plasmid transferability of bacteriocin-producing donors, we established 2 different bacteriocin-resistant mutants derived from E. coli DH5α and used them as recipients. When the bacteriocin-resistant mutants were used in conjugation experiments, the transconjugant recovery from 20 bacteriocin-producing donors increased from 5% (1/20) to 65% (13/20), and the transfer frequencies increased. These results showed that bacteriocins inhibited the transfer of the R-plasmid from bacteriocin-producing donors. Thus, application of bacteriocin-resistant recipients might aid the evaluation of the potential transferability of plasmids from bacteriocin-producing donors.

Gamoh K.,National Veterinary Assay Laboratory | Nakamura S.,National Veterinary Assay Laboratory
Biologicals | Year: 2015

The basic countermeasures used to control highly pathogenic avian influenza (HPAI) are early detection procedures and the culling of affected chickens. However, if successive HPAI outbreaks occur, the vaccination may be an option for controlling HPAI. Therefore, avian influenza (AI) vaccines are stocked by the Japanese government. By contrast, equine influenza (EI) vaccine is an effective tool for preventing or controlling EI. Because antigenic drifts affect the efficacy of AI and EI vaccines, the vaccine strains should be updated rapidly. However, the development and registration of veterinary vaccines usually takes several years. In response to this issue, the Ministry of Agriculture, Forestry, and Fisheries (MAFF) established a system that allows AI and EI vaccine strains to be updated rapidly. National Veterinary Assay Laboratory, MAFF, established a vaccine strains selection committee for veterinary influenza vaccine. The main agendas involve determining whether the current vaccine strains need to be updated and selecting the most appropriate vaccine strains. The committee concluded that A/duck/Hokkaido/Vac-3/2007(H5N1) was added to the strains of stockpiled AI vaccines and that the EI vaccine strains did not need to be changed, but that the clade 2 viruses of the Florida sub-lineage strain, A/equine/Yokohama/aq13/2010(H3N8) was added to the EI vaccine strain. © 2014.

Ozawa M.,National Veterinary Assay Laboratory | Makita K.,Rakuno Gakuen University | Tamura Y.,Rakuno Gakuen University | Asai T.,National Veterinary Assay Laboratory
Preventive Veterinary Medicine | Year: 2012

To determine associations between antimicrobial use and antimicrobial resistance in Campylobacter coli, 155 isolates were obtained from the feces of apparently healthy grow-finish pigs in Japan. In addition, data on the use of antibiotics collected through the national antimicrobial resistance monitoring system in Japan were used for the analysis. Logistic regression was used to identify risk factors to antimicrobial resistance in C. coli in pigs for the following antimicrobials: ampicillin, dihydrostreptomycin, erythromycin, oxytetracycline, chloramphenicol, and enrofloxacin. The data suggested the involvement of several different mechanisms of resistance selection. The statistical relationships were suggestive of co-selection; use of macrolides was associated with enrofloxacin resistance (OR=2.94; CI95%: 0.997, 8.68) and use of tetracyclines was associated with chloramphenicol resistance (OR=2.37; CI95%: 1.08, 5.19). The statistical relationships were suggestive of cross-resistance: use of macrolides was associated with erythromycin resistance (OR=9.36; CI95%: 2.96, 29.62) and the use of phenicols was associated with chloramphenicol resistance (OR=11.83; CI95%: 1.41, 99.44). These data showed that the use of antimicrobials in pigs selects for resistance in C. coli within and between classes of antimicrobials. © 2012 Elsevier B.V.

Baba K.,National Veterinary Assay Laboratory | Ishihara K.,Rakuno Gakuen University | Ozawa M.,National Veterinary Assay Laboratory | Tamura Y.,Rakuno Gakuen University | Asai T.,National Veterinary Assay Laboratory
International Journal of Antimicrobial Agents | Year: 2010

Meticillin-resistant Staphylococcus aureus (MRSA) sequence type (ST) 398 is widely prevalent in swine in Europe and North America. To determine the prevalence of MRSA, and specifically ST398, in Japanese swine, a total of 115 nasal swabs and 115 faecal samples from swine reared at 23 farms located in eastern Japan were investigated. MRSA was isolated from a nasal sample (0.9%) but not from any faecal samples. The strain of MRSA was classified as ST221 by multilocus sequence typing and as t002 by spa typing. The MRSA isolate exhibited resistance to ampicillin, meticillin and dihydrostreptomycin. Interestingly, it remained susceptible to cefazolin, ceftiofur, imipenem, gentamicin, kanamycin, chloramphenicol, oxytetracycline, erythromycin, azithromycin, tylosin, vancomycin, enrofloxacin and trimethoprim. The prevalence of MRSA amongst swine was low and MRSA ST398 was not recovered in the present study. © 2010 Elsevier B.V. and the International Society of Chemotherapy.

Ozawa M.,National Veterinary Assay Laboratory | Baba K.,National Veterinary Assay Laboratory | Shimizu Y.,National Veterinary Assay Laboratory | Asai T.,National Veterinary Assay Laboratory
Microbial Drug Resistance | Year: 2010

We analyzed in vitro activities and pharmacokinetics/pharmacodynamics (PK/PD) parameters of veterinary fluoroquinolones against avian pathogenic Escherichia coli (APEC) strains from cases of avian colibacillosis. The median of minimum inhibitory concentration (MIC 50) values against APEC strains for enrofloxacin (ERFX) and danofloxacin (DNFX) were 0.25 μg/ml and for norfloxacin (NFLX) and ofloxacin (OFLX) were 0.5 μg/ml. The percentage of resistant strains for ERFX, DNFX, NFLX, and OFLX were 24.4%, 23.6%, 22.8%, and 23.6%, respectively. Scattergrams of the MICs of ERFX compared to DNFX, NFLX, and OFLX for 127 strains demonstrate a clear correlation between the MIC of ERFX and that of other fluoroquinolones. The differences in amino acid substitution in GyrA may play a role in the variation of MIC values for fluoroquinolones. The ratios of peak serum concentration to MIC (C max:MIC) and ratios of area under the curve to MIC (AUC:MIC) were relatively high in ERFX and OFLX compared to other fluoroquinolones. These results indicate that although the in vitro activities of these fluoroquinolones against APEC isolates are slightly different, the PK/PD values vary with PK parameters. Therefore, we need to consider the PK/PD parameters in the choice of fluoroquinolones during treatment of avian colibacillosis. © Copyright 2010, Mary Ann Liebert, Inc. 2010.

Harada K.,National Veterinary Assay Laboratory | Harada K.,Nippon Veterinary and Life Science University | Asai T.,National Veterinary Assay Laboratory
Journal of Biomedicine and Biotechnology | Year: 2010

The use of antimicrobial agents in the veterinary field affects the emergence, prevalence, and dissemination of antimicrobial resistance in bacteria isolated from food-producing animals. To control the emergence, prevalence, and dissemination of antimicrobial resistance, it is necessary to implement appropriate actions based on scientific evidence. In Japan, the Japanese Veterinary Antimicrobial Resistance Monitoring System (JVARM) was established in 1999 to monitor the antimicrobial susceptibility of foodborne and commensal bacteria from food-producing animals. The JVARM showed that the emergence and prevalence of resistant Escherichia coli were likely linked to the therapeutic antimicrobial use in food-producing animals through not only direct selection of the corresponding resistance but also indirect selections via cross-resistance and coresistance. In addition, relevant factors such as host animals and bacterial properties might affect the occurrence and prevalence of antimicrobial-resistant E. coli under the selective pressure from antimicrobial usage. This paper reviews the trends in antimicrobial resistance in E. coli and consumption of antimicrobials agents in Japan and introduces the relationship between antimicrobial usage and prevalence of antimicrobial-resistant bacteria, from food-producing animals under the JVARM program. In this paper, we will provide the underlying information about the significant factors that can help control antimicrobial resistance in bacteria in veterinary medicine. Copyright © 2010 K. Harada and T. Asai.

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