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Usui M.,National Veterinary Assay Laboratory
Japanese journal of infectious diseases

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. Source

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

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. Source

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

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. Source

Sasaki Y.,Chiyoda Corporation | Ikeda A.,Chiyoda Corporation | Ishikawa K.,Chiyoda Corporation | Murakami M.,Chiyoda Corporation | And 3 more authors.
Epidemiology and Infection

This study determined the prevalence and antimicrobial susceptibility of Salmonella isolated from broiler flocks in Japan. Caecal dropping samples were collected from 288 broiler flocks between November 2007 and February 2010. Salmonella was prevalent in 248 (861%) broiler flocks. The top three serovars were S. Infantis, S. Manhattan and S. Schwarzengrund. S. Infantis was found in all regions tested in this study. However, S. Manhattan and S. Schwarzengrund were frequently found only in the western part of Japan. High antimicrobial resistance rates were observed against oxytetracycline (902%), dihydrostreptomycin (867%) and ampicillin (365%), and 258 (905%) of 285 isolates were resistant to two or more antimicrobial agents. Interestingly, 263% of isolates were resistant to ceftiofur, especially 381% of S. Infantis isolates, although its use in broilers has not been approved in Japan. This study showed that Salmonella is highly prevalent (861%) in Japanese broiler flocks, that 905% of Salmonella isolates were multidrug-resistant, and that S. Infantis frequently exhibited resistance to cephalosporin antimicrobial agents. © Copyright Cambridge University Press 2012. Source

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

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. Source

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