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Sato N.,Nagoya University | Kawamura K.,Nagoya University | Nakane K.,Nagoya University | Nakane K.,Okazaki City Public Health Center | And 2 more authors.
Microbial Drug Resistance | Year: 2013

We examined the prevalence and mechanism of fosfomycin resistance in CTX-M-producing Escherichia coli isolates from healthy Japanese individuals. One hundred thirty-eight CTX-M-producing E. coli isolates were subjected to fosfomycin susceptibility testing. The presence of acquired fosfomycin resistance genes such as fosA, fosA3, and fosC2 was explored, and the transmissibility of fosfomycin resistance, replicon type of plasmid, and genetic environment of fosA3 were investigated. Eight isolates (5.8%) showed resistance to fosfomycin, five of which harbored fosA3, which was in genetic linkage with blaCTX-M. The replicon types of the five transferred fosA3-carrying plasmids were as follows: IncI1 (n=2), IncN (n=1), and IncFII (n=2). Each fosA3 gene was located close to the blaCTX-M gene and was flanked by IS26 elements. These genetic environments of fosA3 in E. coli from healthy individuals were quite similar to those observed in the clinical and veterinary settings. Our results indicate that fosA3 genes possibly inserted by small mobile genetic elements flanked by two IS26 elements have already spread throughout the plasmids along with the blaCTX-M genes of commensal E. coli colonizing in healthy Japanese people. © Mary Ann Liebert, Inc. Source

Nakane K.,Nagoya University | Nakane K.,Okazaki City Public Health Center | Kawamura K.,Nagoya University | Goto K.,Nagoya University | Arakawa Y.,Nagoya University
Applied and Environmental Microbiology | Year: 2016

The actual state of intestinal long-term colonization by extended-spectrum β-lactamase (ESBL)-producing Escherichia coli in healthy Japanese people remains unclear. Therefore, a total of 4,314 fecal samples were collected from 2,563 food handlers from January 2010 to December 2011. Approximately 0.1 g of each fecal sample was inoculated onto a MacConkey agar plate containing cefotaxime (1 μg/ml). The bacterial colonies that grew on each plate were checked for ESBL production by the double-disk synergy test, as recommended by the Clinical and Laboratory Standards Institute. The bacterial serotype, antimicrobial susceptibility, pulsotype, sequence type (ST), and ESBL genotype were checked, and the replicon types of plasmids harboring the ESBL gene were also determined after conjugation experiments. ESBL producers were recovered from 70 (3.1%) of 2,230 participants who were checked only once. On the other hand, ESBL producers were isolated at least once from 52 (15.6%) of 333 participants who were checked more than twice, and 13 of the 52 participants carried ESBL producers for from more than 3 months to up to 2 years. Fluoroquinolone (FQ)-resistant E. coli strains harboring blaCTX-M were repeatedly recovered from 11 of the 13 carriers of blaCTX-M-harboring E. coli. A genetically related FQ-resistant E. coli O25b:H4-ST131 isolate harboring blaCTX-M-27 was recovered from 4 of the 13 carriers for more than 6 months. Three FQ-resistant E. coli O1:H6-ST648 isolates that harbored blaCTX-M-15 or blaCTX-M-14 were recovered from 3 carriers. Moreover, multiple CTX-M-14- or CTX-M-15-producing E. coli isolates with different serotypes were recovered from 2 respective carriers. These findings predict a provable further spread of ESBL producers in both community and clinical settings. © 2016, American Society for Microbiology. All Rights Reserved. Source

Ohnishi T.,Japan National Institute of Health Sciences | Lim B.,Jeju National University | Nojima N.,Center for Inspection of Imported Foods and Infectious Deseases | Kunitoshi O.,Center for Inspection of Imported Foods and Infectious Deseases | And 10 more authors.
Biocontrol Science | Year: 2016

Kudoa septempunctata is the causative agent of a food-borne disease associated with the ingestion of raw olive flounder. As the current qRT-PCR method for its detection is time-consuming, a rapid and simple method is required. Recently, a new real-time loop-mediated isothermal amplification (LAMP) method and an immunochromatography method, whose sensitivities are intended to be compatible with that designated in the official analytical method (105 spores/g olive flounder), have been developed. To validate these new methods, we performed an inter-laboratory study across seven laboratories. Both methods could not detect less than 104 spores/g; however, these methods were able to detect more than 105 spores/g in olive flounder samples. These results demonstrated that the sensitivities of these methods were compatible with the designated level in the official analytical method. We concluded that these new methods were acceptable as the screening methods for K. septempunctata. Source

Osaka A.,Nagoya University | Ueyama J.,Nagoya University | Kondo T.,Nagoya University | Nomura H.,Nagoya University | And 8 more authors.
Environmental Research | Year: 2016

The use of neonicotinoid (NEO) insecticides has increased over the past decade not only in Japan but also worldwide, while organophosphate (OP) and pyrethroid (PYR) insecticides are still conventionally used in agriculture and domestic pest control. However, limited data are currently available on the NEO exposure levels, especially in children, who are particularly vulnerable to environmental toxicants. Thus, the purpose of this study was to characterize the exposure to NEOs, as well as OPs and PYRs, in three-year-old Japanese children by assessing the range, distribution, and seasonal differences of the urinary concentrations of seven NEOs (acetamiprid, clothianidin, dinotefuran, thiacloprid, thiamethoxam, imidacloprid, and nitenpyram); four OP metabolites (dialkylphosphates [DAPs]), including dimethylphosphate, dimethylthiophosphate, diethylphosphate, and diethylthiophosphate; and three PYR metabolites (3-phenoxybenzoic acid, trans-chrysanthemumdicarboxylic acid, and 3-(2,2-dichlorovinyl)-2,2- dimethylcyclopropane carboxylic acid). Urine samples were collected from 223 children (108 males and 115 females) in the summer and winter months. The detection rates of NEOs were 58% for dinotefuran, 25% for thiamethoxam, 21% for nitenpyram, and <16% for all other NEOs. The median and maximum concentrations of the sum of the seven NEOs (σNEO) were 4.7 and 370.2 nmol/g creatinine, respectively. Urinary σNEO, dimethylphosphate, and all PYR metabolite concentrations were significantly higher in the summer than in the winter (p<0.05). The creatinine-adjusted concentration of σNEO significantly correlated with those of all DAPs (p<0.05) but not with those of the PYR metabolites. Moreover, the NEO-detected group showed higher urinary σDAP (sum of four OP metabolites) concentrations than the group without NEO detection. These findings suggest that children in Japan are environmentally exposed to the three major insecticide lines, and that the daily exposure sources of NEOs are common to those of OPs. © 2016 Elsevier Inc. Source

Ueyama J.,Nagoya University | Saito I.,Food Safety and Quality Research Center | Takaishi A.,Okazaki City Public Health Center | Nomura H.,Nagoya University | And 9 more authors.
Environmental Health and Preventive Medicine | Year: 2014

Objectives: Biological monitoring of organophosphorus insecticide (OP) metabolites, specifically dialkylphosphates (DAP) in urine, plays a key role in low-level exposure assessment of OP in individuals. The aims of this study are to develop a simple and sensitive method for determining four urinary DAPs using high-performance liquid chromatography with tandem mass spectrometry (LC–MS/MS), and to assess the concentration range of urinary DAP in Japanese children.Methods: Deuterium-labeled DAPs were used as internal standards. Urinary dimethylphosphate (DMP) and diethylphosphate (DEP), which passed through the solid-phase extraction (SPE) column, and dimethylthiophosphate (DMTP) and diethylthiophosphate (DETP), which were extracted from a SPE column using 2.5 % NH3 water including 50 % acetonitrile, were prepared for separation analysis. The samples were then injected into LC–MS/MS. The optimized method was applied to spot urine samples from 3-year-old children (109 males and 116 females) living in Aichi Prefecture in Japan.Conclusions: The present high-throughput method is simple and reliable, and can thereby further contribute to development of an exposure assessment of OP. The present study is the first to reveal the DAP concentrations in young Japanese children.Results: Results from the validation study demonstrated good within- and between-run precisions (<10.7 %) with low detection limits (0.4 for DMP and DMTP, 0.2 for DEP and 0.1 μg/L for DETP). The geometric mean values and detection rates of the urinary DAPs in Japanese children were 14.4 μg/L and 100 % for DMP, 5.3 μg/L and 98 % for DMTP, 5.5 μg/L and 99 % for DEP, and 0.6 μg/L and 80 % for DETP, respectively. © 2014, The Japanese Society for Hygiene. Source

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