論文 - 井口 純
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Iguchi A., Ueno Y., Hoshinoo K., Okuno M., Uemura R., You G., Ogura Y., Takamatsu D.
Scientific Reports 15 ( 1 ) 2025年4月
担当区分：筆頭著者, 責任著者 記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Scientific Reports
The bovine respiratory disease complex (BRDC) is a global issue affecting dairy and beef farms and is of major concern due to the high morbidity and mortality rates in calves, as well as decreased production it causes, resulting in significant economic losses. Mannheimia haemolytica is one of the secondary pathogens associated with BRDC. M. haemolytica is classified into 12 serotypes based on capsular antigens. In addition to the prevalent serotypes A1, A2, and A6, strains belonging to other serotypes also cause respiratory diseases in cattle and other ruminants, necessitating a method for their rapid and easy identification. In this study, we organized the capsule biosynthesis genes based on genome information from all serotype strains and designed 11 PCR primer pairs targeting serotype-specific genes, which could individually identify serotypes A14/A16, which possess homologous genes, as well as all other serotypes. Additionally, we developed two multiplex PCR kits that include these serotype-specific and M. haemolytica species-specific primers. Specificity testing using reference strains confirmed that these kits can simultaneously and clearly identify both the species and their serotypes. The PCR-based system described here could be a valuable tool for subtyping M. haemolytica strains in epidemiological studies and surveillance efforts in cattle and other reservoir animals. This study also carefully compared and discussed the differences between the capsule synthesis genes of A8 and A14 from previously published and those obtained in this study.
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Infectious endophthalmitis associated with umbilical infection in Japanese black calf: a case report 査読あり 国際共著
Sato R., Iguchi A., Uemura R., Tsujita H., Steiner A.
Frontiers in Veterinary Science 12 2025年4月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Frontiers in Veterinary Science
A 3-day-old Japanese black calf presented with a swollen and tender umbilical cord and diffusely cloudy and keratoconus eyes. Abdominal ultrasonography confirmed mild enlargement of both umbilical arteries and the urachus with a hyperechoic lumen. Additionally, a hyperechogenic structure suggestive of pus was noted near the abdominal wall. Fluorescein staining revealed corneal epithelial injury, whereas slit lamp examination identified corneal edema, increased corneal thickness, and keratitis with vascularization of the corneal stroma. Based on these findings, diagnoses of omphaloarteritis, omphalourachitis, and bullous keratitis were made. Both umbilical arteries and the urachus were surgically removed; both ocular globes were covered with a third eyelid flap, which was released 30 days postoperatively. On the follow-up, ocular ultrasonography indicated bleeding or fibrin deposits in the vitreous body of the right ocular globe. Because intraocular inflammation was suspected, anterior aqueous humor was collected from the right ocular globe, and bacterial examination was performed with the umbilical artery abscess, urachal abscess, and intraabdominal pus collected intraoperatively. Escherichia coli was isolated from the umbilical artery abscess, urachal abscess, intraabdominal pus, and aqueous humor, and all isolates exhibited identical genotypes. These findings suggest that endophthalmitis occurred as a result of the hematogenous spread of bacteria originating from septic umbilical cord remnants and that ocular ultrasonography is useful for assessing intraocular pathologies.
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Elbastawesy A.M., Awasthi S.P., Hatanaka N., Hinenoya A., Iguchi A., Ombarak R.A., Deeb A.M.M., Yamasaki S.
International Dairy Journal 162 2025年3月
掲載種別：研究論文（学術雑誌） 出版者・発行元：International Dairy Journal
Milk and dairy products are popular in Egyptian diets, but their contamination with Escherichia coli, poses health risks. This study investigated the prevalence of potentially pathogenic and antimicrobial-resistant E. coli in raw milk and dairy products from Kafrelsheikh and Algarbia Governorates, Egypt. Two hundred ten samples including raw buffalo milk, goat milk, Domiati cheese, Domiati cheese with pepper, rayeb, and yogurt were analyzed. The prevalence of E. coli was 26.2%, with the highest occurrence in buffalo milk (68.0%) and the lowest in rayeb (7.5%). Based on ERIC-PCR, eighty-four non-clonal E. coli strains were selected and further characterized. Among tested virulence genes, adhesion genes such as lpfAO113 and ehaA, were the most prevalent. Toxin-encoding genes such as astA, cdt, cnf, and hlyA were also detected. The cytotoxic and hemolytic activity of cdt, cnf, and hylA carrying E. coli were confirmed on CHO cells and sheep blood agar, respectively. Twenty-three (27.4%) strains showed resistance to one or more antimicrobials, and 10 (11.9%) strains exhibited multidrug resistance (MDR). Among 12 antimicrobials tested resistance against ampicillin, streptomycin and tetracycline was the highest. Phylogenetic analysis and O-genotyping indicated clinically significant strains such as Og103, Og157 and OgGp9. Notably, two OgGp9 strains were OgGp9:Hg18 and phylogenetic group D, like those associated with a large diarrheal outbreak caused by milk consumption in Japan, in 2021. Interestingly, these two strains harbored a complete type 3 secretion system 2 locus (ETT2) and one of these strains was MDR. These findings indicate that these dairy products were contaminated with potentially pathogenic and multidrug-resistant E. coli. This is the first report to analyze E. coli contamination in Domiati cheese with pepper and detect OgGp9:Hg18 outbreak-associated strains with ETT2 and MDR in Egypt.
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下痢原性大腸菌食中毒事例におけるO血清群およびH型の遺伝子型判定PCR検査法の活用 査読あり
小田切 正昭, 加藤 直樹, 曽根 美紀, 土屋 彰彦, 近藤 貴英, 井口 純
日本食品微生物学会雑誌 41 ( 3 ) 119 - 123 2024年9月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：日本食品微生物学会
Diarrheagenic <i>Escherichia coli</i> strains are mainly classified into the following five pathotypes; enteropathogenic <i>E. coli</i>, enterotoxigenic <i>E. coli</i>, enteroinvasive <i>E. coli</i>, enterohemorrhagic <i>E. coli</i> and enteroaggregative <i>E. coli</i>. <i>E. coli</i> strains of various pathotypes can be further classified by their serotypes combined by O-serogroup and H-type. Generally in Japan, the commercial O-antisera and H-antisera are used to serotype strains. These serotypes provide useful information in investigations of outbreaks and epidemiological studies. In May 2021, a large-scale food poisoning outbreak thought to be caused by <i>E. coli</i> occurred in Saitama City. Serotyping of 21 <i>E. coli</i> strains carrying virulence genes isolated from patients and an asymptomatic cooking worker was carried out using a commercially available kit, but most of the strains (57%) could not be serotyped. Therefore, in this study, we tried the multiplex PCR methods including <i>E. coli</i> O-genotyping PCR and <i>E. coli</i> H-genotyping PCR. As a result, only 5% of strains could not be determined their Og-types, and the main genotype in this case was found to be Og104:Hg4 (12/21 strains) carrying <i>astA</i>+<i>aggR</i> or <i>estA2</i>+<i>elt</i>+<i>astA</i>+<i>aggR</i>. In conclusion, we believe that Og-typing PCR and Hg-typing PCR are effective methods in investigating cases caused by pathogenic <i>E. coli</i> belonging to rare pathotypes.
DOI： 10.5803/jsfm.41.119
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Lee K., Iguchi A., Terano C., Hataya H., Isobe J., Seto K., Ishijima N., Akeda Y., Ohnishi M., Iyoda S.
Microbiology spectrum 12 ( 1 ) 2024年1月
掲載種別：研究論文（学術雑誌） 出版者・発行元：Microbiology spectrum
IMPORTANCE: Hemolytic uremic syndrome (HUS) is a life-threatening disease caused by Shiga toxin-producing Escherichia coli (STEC) infection. The treatment approaches for STEC-mediated typical HUS and atypical HUS differ, underscoring the importance of rapid and accurate diagnosis. However, specific detection methods for STECs other than major serogroups, such as O157, O26, and O111, are limited. This study focuses on the utility of PCR-based O-serotyping, serum agglutination tests utilizing antibodies against the identified Og type, and isolation techniques employing antibody-conjugated immunomagnetic beads for STEC isolation. By employing these methods, we successfully isolated a STEC strain of a minor serotype, O76:H7, from a HUS patient.
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Iguchi A., Takemura T., Ogura Y., Nguyen T.T.H., Kikuchi T., Okuno M., Tokizawa A., Iwashita H., Pham H.Q.A., Doan T.H., Tran N.L., Tran T.L., Nguyen T.H., Tran T.H., Pham T.N.L., Dao T.D., Vu T.M.H., Nguyen T.N., Vu H., Nguyen V.T., Vu T.T.H., Le T.H., Lai T.A., Ngo T.C., Hasebe F., Nguyen D.T., Yamashiro T.
PLoS Neglected Tropical Diseases 17 ( 4 ) 2023年4月
掲載種別：研究論文（学術雑誌） 出版者・発行元：PLoS Neglected Tropical Diseases
Background Diarrheagenic Escherichia coli (DEC) is a group of bacterial pathogens that causes life-threatening diarrhea in children in developing countries. However, there is limited information on the characteristics of DEC isolated from patients in these countries. A detailed genomic analysis of 61 DEC-like isolates from infants with diarrhea was performed to clarify and share the characteristics of DEC prevalent in Vietnam. Principal findings DEC was classified into 57 strains, including 33 enteroaggregative E. coli (EAEC) (54.1%), 20 enteropathogenic E. coli (EPEC) (32.8%), two enteroinvasive E. coli (EIEC) (3.3%), one enterotoxigenic E. coli (ETEC), and one ETEC/EIEC hybrid (1.6% each), and surprisingly into four Escherichia albertii strains (6.6%). Furthermore, several epidemic DEC clones showed an uncommon combination of pathotypes and serotypes, such as EAEC Og130: Hg27, EAEC OgGp9:Hg18, EAEC OgX13:H27, EPEC OgGp7:Hg16, and E. albertii EAOg1:HgUT. Genomic analysis also revealed the presence of various genes and mutations associated with antibiotic resistance in many isolates. Strains that demonstrate potential resistance to ciprofloxacin and ceftriaxone, drugs recommended for treating childhood diarrhea, accounted for 65.6% and 41%, respectively. Significance Our finding indicate that the routine use of these antibiotics has selected resistant DECs, resulting in a situation where these drugs do not provide in therapeutic effects for some patients. Bridging this gap requires continuous investigations and information sharing regarding the type and distribution of endemic DEC and E. albertii and their antibiotic resistance in different countries.
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Suzuki Y., Shimizu H., Tamai S., Hoshiko Y., Maeda T., Nukazawa K., Iguchi A., Masago Y., Ishii S.
Environmental Monitoring and Assessment 195 ( 2 ) 2023年2月
掲載種別：研究論文（学術雑誌） 出版者・発行元：Environmental Monitoring and Assessment
Waterborne diseases due to pathogen contamination in water are a serious problem all over the world. Accurate and simultaneous detection of pathogens in water is important to protect public health. In this study, we developed a method to simultaneously detect various pathogenic Escherichia coli by sequencing the amplicons of multiplex PCR. Our newly designed multiplex PCR amplified five genes for pathogenic E. coli (uidA, stx1, stx2, STh gene, and LT gene). Additional two PCR assays (for aggR and eae) were also designed and included in the amplicon sequencing analysis. The same assays were also used for digital PCR (dPCR). Strong positive correlations were observed between the sequence read count and the dPCR results for most of the genes targeted, suggesting that our multiplex PCR-amplicon sequencing approach could provide quantitative information. The method was also successfully applied to monitor the level of pathogenic E. coli in river water and wastewater samples. The approach shown here could be expanded by targeting genes for other pathogens.
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Habets A., Touzain F., Lucas P., Huong N.T.T., Iguchi A., Crombé F., Korsak N., Piérard D., Saulmont M., Cox E., Engelen F., Mainil J., Thiry D.
Veterinary Sciences 9 ( 9 ) 2022年9月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Veterinary Sciences
Enteropathogenic Escherichia coli (EPEC) produce attaching/effacing (AE) lesions and cause non-bloody diarrhea in mammals. A minority of bovine EPEC belong to one of the ten classical serotypes of human and bovine AE-STEC. The purpose of this study was to identify five non-classical O serotypes (O123/186, O156, O177, O182, and O183) among bovine EPEC and to characterize their virulence repertoires by whole genome sequencing. Around 40% of the 307 EPEC from 307 diarrheic calves, 368 EPEC from 47 healthy cattle, and 131 EPEC from 36 healthy calves in dairy farms were analyzed. Serotype O177 was the most frequent among EPEC from diarrheic and healthy calves, while the O156 was the most frequent in healthy cattle. The genomic analysis identified different H serotypes, MLSTypes, and/or eae gene subtypes among the O156 and O177 EPEC, while the O182 was homogeneous. The virulence gene profiles of bovine EPEC were closely related to each other and to the profiles of ten bovine and human AE-STEC. These results emphasize the need for additional studies to identify more O:H serotypes of bovine EPEC and to elucidate their origin and evolution of EPEC with regard to AE-STEC belonging to the same O:H serotypes.
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Murase K., Arakawa E., Izumiya H., Iguchi A., Takemura T., Kikuchi T., Nakagawa I., Thomson N.R., Ohnishi M., Morita M.
Microbial Genomics 8 ( 8 ) 2022年8月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Microbial Genomics
Approximately 200 O-serogroups of Vibrio cholerae have already been identified; however, only 2 serogroups, O1 and O139, are strongly related to pandemic cholera. The study of non-O1 and non-O139 strains has hitherto been limited. Nevertheless, there are other clinically and epidemiologically important serogroups causing outbreaks with cholera-like disease. Here, we report a comprehensive genome analysis of the whole set of V. cholerae O-serogroup reference strains to provide an overview of this important bacterial pathogen. It revealed structural diversity of the O-antigen biosynthesis gene clusters located at specific loci on chromosome 1 and 16 pairs of strains with almost identical O-antigen biosynthetic gene clusters but differing in serologi-cal patterns. This might be due to the presence of O-antigen biosynthesis-related genes at secondary loci on chromosome 2.
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Ono T., Taniguchi I., Nakamura K., Nagano D.S., Nishida R., Gotoh Y., Ogura Y., Sato M.P., Iguchi A., Murase K., Yoshimura D., Itoh T., Shima A., Dubois D., Oswald E., Shiose A., Gotoh N., Hayashi T.
Microbial genomics 8 ( 3 ) 2022年3月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Microbial genomics
Serratia marcescens is an important nosocomial pathogen causing various opportunistic infections, such as urinary tract infections, bacteremia and sometimes even hospital outbreaks. The recent emergence and spread of multidrug-resistant (MDR) strains further pose serious threats to global public health. This bacterium is also ubiquitously found in natural environments, but the genomic differences between clinical and environmental isolates are not clear, including those between S. marcescens and its close relatives. In this study, we performed a large-scale genome analysis of S. marcescens and closely related species (referred to as the 'S. marcescens complex'), including more than 200 clinical and environmental strains newly sequenced here. Our analysis revealed their phylogenetic relationships and complex global population structure, comprising 14 clades, which were defined based on whole-genome average nucleotide identity. Clades 10, 11, 12 and 13 corresponded to S. nematodiphila, S. marcescens sensu stricto, S. ureilytica and S. surfactantfaciens, respectively. Several clades exhibited distinct genome sizes and GC contents and a negative correlation of these genomic parameters was observed in each clade, which was associated with the acquisition of mobile genetic elements (MGEs), but different types of MGEs, plasmids or prophages (and other integrative elements), were found to contribute to the generation of these genomic variations. Importantly, clades 1 and 2 mostly comprised clinical or hospital environment isolates and accumulated a wide range of antimicrobial resistance genes, including various extended-spectrum β-lactamase and carbapenemase genes, and fluoroquinolone target site mutations, leading to a high proportion of MDR strains. This finding suggests that clades 1 and 2 represent hospital-adapted lineages in the S. marcescens complex although their potential virulence is currently unknown. These data provide an important genomic basis for reconsidering the classification of this group of bacteria and reveal novel insights into their evolution, biology and differential importance in clinical settings.
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Diversity of the Tellurite Resistance Gene Operon in Escherichia coli 査読あり
Nguyen T.T.H., Kikuchi T., Tokunaga T., Iyoda S., Iguchi A.
Frontiers in Microbiology 12 2021年5月
担当区分：責任著者 記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Frontiers in Microbiology
Tellurite is highly toxic to most bacteria owing to its strong oxidative ability. However, some bacteria demonstrate tellurite resistance. In particular, some Escherichia coli strains, including Shiga toxin-producing E. coli O157:H7, are known to be resistant to tellurite. This resistance is involved in ter operon, which is usually located on a prophage-like element of the chromosome. The characteristics of the ter operon have been investigated mainly by genome analysis of pathogenic E. coli; however, the distribution and structural characteristics of the ter operon in other E. coli are almost unknown. To clarify these points, we examined 106 E. coli strains carrying the ter operon from various animals. The draft genomes of 34 representative strains revealed that ter operons were clearly classified into four subtypes, ter-type 1–4, at the nucleotide sequence level. Complete genomic sequences revealed that operons belonging to three ter-types (1, 3, and 4) were located on the prophage-like elements on the chromosome, whereas the ter-type 2 operon was located on the IncHI2 plasmid. The positions of the tRNASer, tRNAMet, and tRNAPhe indicated the insertion sites of elements carrying the ter operons. Using the PCR method developed in this study, 106 strains were classified as type 1 (n = 66), 2 (n = 13), 3 (n = 8), and 4 (n = 17), and two strains carried both types 1 and 2. Furthermore, significant differences in the minimum inhibitory concentration (MIC) of tellurite were observed between strains carrying ter-type 4 and the others (p < 0.05). The ter-type was also closely related to the isolation source, with types 2 and 4 associated with chickens and deer, respectively. This study provided new insights related not only to genetic characteristics of the ter operons, but also to phenotypic and ecological characteristics that may be related to the diversity of the operon.
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Le P.Q., Awasthi S.P., Hatanaka N., Hinenoya A., Hassan J., Ombarak R.A., Iguchi A., Tran N.T.T., Dao K.V.T., Vien M.Q., Le H.X., Do H.T., Yamamoto Y., Yamasaki S.
International Journal of Food Microbiology 346 2021年5月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：International Journal of Food Microbiology
The aim of the study was to assess the presence of genes in ESBL-producing E. coli (ESBL-Ec) isolated from retail raw food in Nha Trang, Vietnam. A total of 452 food samples comprising chicken (n = 116), pork (n = 112), fish (n = 112) and shrimp (n = 112) collected between 2015 and 2017 were examined for the prevalence of ESBL-Ec. ESBL-Ec were detected in 46.0% (208/452) of retail food samples, particularly in 66.4% (77/116), 55.4% (62/112), 42.0% (47/112) 19.6% (22/112) of chicken, pork, fish and shrimp, respectively. Sixty-five out of the 208 (31.3%) ESBL-Ec isolates were positive for mcr genes including mcr-1, mcr-3 and both mcr-1 and mcr-3 genes in 56/208 (26.9%), 1/208 (0.5%) and 8/208 (3.9%) isolates, respectively. Particularly, there was higher prevalence of mcr-1 in ESBL-Ec isolates from chicken (53.2%, 41/77) in comparison to shrimp (22.7%, 5/22), pork (11.3%, 7/62) and fish (6.4%, 3/47). mcr-3 gene was detected in co-existence with mcr-1 in ESBL-Ec isolates from shrimp (9.1%, 2/22), pork (8.1%, 5/62) and fish (2.1%, 1/47) but not chicken. The 65 mcr-positive ESBL-Ec (mcr-ESBL-Ec) were colistin-resistant with the MICs of 4–8 μg/mL. All mcr-3 gene-positive isolates belonged to group A, whereas phylogenetic group distribution of isolates harboring only mcr-1 was B1 (44.6%), A (28.6%) and D (26.8%). PFGE analysis showed diverse genotypes, although some isolates demonstrated nearly clonal relationships. S1-PFGE and Southern hybridization illustrated that the mcr-1 and mcr-3 genes were located either on chromosomes or on plasmids. However, the types of mcr genes were harbored on different plasmids with varied sizes of 30–390 kb. Besides, the ESBL genes of CTX-M-1 or CTX-M-9 were also detected to be located on plasmids. Noteworthy, co-location of CTX-M-1 with mcr-1 or mcr-3 genes on the same plasmid was identified. The conjugation experiment indicated that the mcr-1 or mcr-3 was horizontally transferable. All mcr-ESBL-Ec isolates were multidrug resistance (resistance to ≥3 antimicrobial classes). Moreover, β-Lactamase-encoding genes of the CTX-M-1 (78.5%), CTX-M-9 (21.5%), TEM (61.5%) groups were found in mcr-ESBL-Ec. The astA gene was detected in 27 (41.5%) mcr-ESBL-Ec isolates demonstrating their potential virulence. In conclusion, mcr-1 and mcr-3 genes existed individually or concurrently in ESBL-Ec isolates recovered from retail raw food in Nha Trang city, which might further complicate the antimicrobial-resistant situation in Vietnam, and is a possible health risk for human.
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Lee K., Iguchi A., Uda K., Matsumura S., Miyairi I., Ishikura K., Ohnishi M., Seto J., Ishikawa K., Konishi N., Obata H., Furukawa I., Nagaoka H., Morinushi H., Hama N., Nomoto R., Nakajima H., Kariya H., Hamasaki M., Iyoda S.
Emerging Infectious Diseases 27 ( 5 ) 1509 - 1512 2021年5月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Emerging Infectious Diseases
We report a fatal case of hemolytic uremic syndrome with urinary tract infection in Japan caused by Shiga toxin- producing Escherichia coli. We genotypically identifi ed the isolate as OX18:H2. Whole-genome sequencing revealed 3 potentially pathogenic lineages (OX18:H2, H19, and H34) that have been continuously isolated in Japan.
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OKUNO Kentaro, AWASTHI Sharda Prasad, KOPPRIO Germán A., IGUCHI Atsushi, HATANAKA Noritoshi, HINENOYA Atsushi, LARA Rubén José, YAMASAKI Shinji
Ｔｈｅ Ｊｏｕｒｎａｌ ｏｆ Ｖｅｔｅｒｉｎａｒｙ Ｍｅｄｉｃａｌ Ｓｃｉｅｎｃｅ 2021年4月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：公益社団法人 日本獣医学会
The aims of this study were to investigate prevalence, O-genotype, and virulence gene profile including Shiga toxin 2 gene-subtype of Stx-producing <i>Escherichia coli</i> (STEC) in beef cattle from the Bahía Blanca in Argentina. Rectal swabs were collected from 283 beef cattle in 2012. <i>stx</i> genes were detected in 90 (32%) out of the 283 rectal swabs by <i>stx</i> gene-specific PCR assay. The positive cases were 13 with <i>stx1</i>, 58 with <i>stx2,</i> and 19 with both <i>stx1</i> and <i>stx2</i>. Among 90 <i>stx</i> gene-positive samples, 45 STEC strains were isolated, which included 3 <i>stx1</i>, 34 <i>stx2</i>, and eight <i>stx1</i> and <i>stx2 </i>genes positive isolates. O-genotyping grouped 45 STEC strains into 19 different O-genotypes such as Og8, Og145, Og171, Og185 (4 from each), Og22, Og153, Og157 (3 from each) and others. Various <i>stx2</i> gene-subtypes were identified in 42 STEC strains: 13 positive cases for <i>stx2a</i>, 11 for <i>stx2c</i>, 3 for <i>stx2g</i>, 10 for <i>stx2a</i> and <i>stx2d</i>, 4 for <i>stx2a</i> and <i>stx2c</i>, and 1 for <i>stx2b</i>, <i>stx2c</i> and <i>stx2g</i>. <i>efaI</i> gene, generally prevalent in clinical strains, was detected in relatively high in the STEC strains. These data suggest that <i>stx2a</i> and <i>stx2c</i> were distributed not only in O145 and O157 but also in minor O-genotypes of STEC in Argentina.
DOI： 10.1292/jvms.21-0002
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Virulence profile of diarrhoeagenic <i>Escherichia coli</i> from the Western region of Ghana 査読あり
Prah Isaac, Iwanaga Shiroh, Ablordey Anthony, Saito Ryoichi, Ayibieke Alafate, Huong Nguyen Thi Thu, Iguchi Atsushi, Mahazu Samiratu, Sato Wakana, Hayashi Takaya, Yamaoka Shoji, Suzuki Toshihiko
Japanese Journal of Infectious Diseases 74 ( 2 ) 115 - 121 2021年3月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：国立感染症研究所 Japanese Journal of Infectious Diseases 編集委員会
Diarrhoeagenic <i>Escherichia coli</i> (DEC), an important agent of infectious diarrhoea, is constantly evolving, making it necessary for its periodic monitoring. Unfortunately, DEC genotypes in Ghana remain uncharacterised. We focused on characterising the molecular serotypes, virulence factors, multilocus sequence types, and the phylogenetic relatedness among different DEC pathotypes recovered from stool samples of paediatric patients with diarrhoea symptoms from the Western region of Ghana. We detected all five common DEC pathotypes, with majority being enterotoxigenic <i>E. coli</i> (ETEC) isolates harbouring the heat-labile enterotoxin gene. The DEC strains exhibited a diverse serotypic identity with novel and other outbreak strains. Sequence type (ST)38, ST316, and ST1722 were the most prevalent STs, and clonal complex (CC)10 was the most common CC. A close evolutionary distance was observed among most of the isolates. Coli surface antigen 6 was the most prevalent (44%, n = 11) ETEC-specific colonisation factor. Nearly all of the isolates harboured <i>lpfA</i>, and the frequencies of other virulence genes, such as <i>pap</i> and <i>cnf1,</i> were 7.9% and 18.4%, respectively. This study provides insights into the important and novel genotypes circulating in the Western region of Ghana that should be monitored for public health.
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Nguyen T.T.H., Iguchi A., Ohata R., Kawai H., Ooka T., Nakajima H., Iyoda S.
Journal of Clinical Microbiology 59 ( 3 ) 2021年3月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Clinical Microbiology
Shiga toxin-producing Escherichia coli (STEC) is an important foodborne pathogen. Although most cases of STEC infection in humans are due to O157 and non-O157 serogroups, there are also reports of infection with STEC strains that cannot be serologically classified into any O serogroup (O-serogroup untypeable [OUT]). Recently, it has become clear that even OUT strains can be subclassified based on the diversity of O-antigen biosynthesis gene cluster (O-AGC) sequences. Cattle are thought to be a major reservoir of STEC strains belonging to various serotypes; however, the internal composition of OUT STEC strains in cattle remains unknown. In this study, we screened 366 STEC strains isolated from healthy cattle by using multiplex PCR kits including primers that targeted novel O-AGC types (Og types) found in OUT E. coli and Shigella strains in previous studies. Interestingly, 94 (25.7%) of these strains could be classified into 13 novel Og types. Genomic analysis revealed that the results of the in silico serotyping of novel Og-type strains were perfectly consistent with those of the PCR experiment. In addition, it was revealed that a dual Og81OgSB17-type strain carried two types of O-AGCs from E. coli O8 and Shigella boydii type 17 tandemly inserted at the locus, with both antigens expressed on the cell surface. The results of this comprehensive analysis of cattle-derived STEC strains may help improve our understanding of the strains circulating in the environment. Additionally, the DNA-based serotyping systems used in this study could be used in future epidemiological studies and risk assessments of other STEC strains.
DOI： 10.1128/JCM.02624-20
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Iguchi A., Nishii H., Seto K., Mitobe J., Lee K., Konishi N., Obata H., Kikuchi T., Iyoda S.
Journal of Clinical Microbiology 58 ( 11 ) 2020年10月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Clinical Microbiology
The O-serogrouping of pathogenic Escherichia coli is a standard method for subtyping strains for epidemiological studies and controls. O-serogroup diversification shows a strong association with the genetic diversity in some O-antigen biosynthesis gene clusters. Through genomic studies, in addition to the types of O-antigen biosynthesis gene clusters (Og-types) from conventional O-serogroup strains, a number of novel Og-types have been found in E. coli isolates. To assist outbreak investigations and surveillance of pathogenic E. coli at inspection institutes, in previous studies, we developed PCR methods that could determine almost all conventional O-serogroups and some novel Og-types. However, there are still many Og-types that may not be determined by simple genetic methods such as PCR. Thus, in the present study, we aimed to develop an additional Og-typing PCR system. Based on the novel Og-types, including OgN32, OgN33, and OgN34, presented in this study, we designed an additional 24 PCR primer pairs targeting 14 novel and 2 diversified E. coli Og-types and 8 Shigella-unique Og-types. Subsequently, we developed 5 new multiplex PCR sets consisting of 33 primers, including the aforementioned 24 primers and 9 primers reported in previous studies. The accuracy and specificity of the PCR system was validated using approximately 260 E. coli and Shigella O-serogroup and Og-type reference strains. The Og-typing PCR system reported here can determine a wide range of Og-types of E. coli and may help epidemiological studies, in addition to the surveillance of pathogenic E. coli.
DOI： 10.1128/JCM.01493-20
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Jikumaru A., Ishii S., Fukudome T., Kawahara Y., Iguchi A., Masago Y., Nukazawa K., Suzuki Y.
Journal of Bioscience and Bioengineering 130 ( 1 ) 76 - 81 2020年7月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Bioscience and Bioengineering
The quantification of pathogens is important for assessing water safety and preventing disease outbreaks. Culture-independent approaches, such as quantitative PCR (qPCR) and digital PCR (dPCR), are useful techniques for quantifying pathogens in water samples. However, since pathogens are usually present at low concentrations in water, it is necessary to concentrate microbial cells before extracting their DNA. Many existing microbial concentration methods are inefficient or take a long time to perform. In this study, we applied a coagulation and foam separation method to concentrate environmental water samples of between 1000 and 5000 mL to 100 μL of DNA (i.e., a 1–5 × 10 -fold concentration). The concentration process took <1 h. The DNA samples were then used to quantify various target pathogens using dPCR. One gene, the Shiga toxin gene (stx ) of Shiga toxin-producing Escherichia coli, was detected at 32 copies/100 mL in a river water sample. The coagulation and foam concentration method followed by dPCR reported herein is a fast, sensitive, and reliable method to quantify pathogen genes in environmental water samples. 4 2
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飼育犬から分離された<i>Escherichia albertii</i> の性状
Duangtathip Karn, Nguyen Thi Thu Huong, 井口 純, 三澤 尚明, 谷口 喬子
日本獣医師会雑誌 73 ( 4 ) 191 - 194 2020年4月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：公益社団法人 日本獣医師会
<i>Escherichia albertii</i> は新しく認定された腸管病原性細菌で，わが国でも集団食中毒事例が報告されている．本菌は特徴的な生化学性状に乏しく，腸管病原性大腸菌（EPEC）や腸管出血性大腸菌（EHEC）との鑑別が難しい．われわれは，健康な飼育犬の糞便から，<i>E. albertii</i> を分離・同定した．本分離株は，病原性関連遺伝子（<i>eae</i> ）及び細胞膨張化致死毒素（<i>cdt</i> ）を保有していたが，志賀毒素遺伝子（<i>stx2f</i> ）は保有していなかった．また，既報と同様，ペニシリン，アンピシリン及びエリスロマイシンに耐性を示した．飼育犬から<i>E. albertii</i> が分離されたことより，犬が人への感染源となり得る可能性が示唆された．
DOI： 10.12935/jvma.73.191
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Ooka T, Seto K, Ogura Y, Nakamura K, Iguchi A, Gotoh Y, Honda M, Etoh Y, Ikeda T, Sugitani W, Konno T, Kawano K, Imuta N, Yoshiie K, Hara-Kudo Y, Murakami K, Hayashi T, Nishi J.
Microbial genomics 5 ( 11 ) e000314 - - 2019年11月
記述言語：英語 掲載種別：研究論文（学術雑誌）