Shuhei Ueda

Wide dissemination of extended-spectrum β-lactamase-producing Escherichia coli in community residents in the Indochinese peninsula

Recent studies have reported a widespread distribution of extended-spectrum β-lactamase (ESBL)-producing bacteria, not only in the nosocomial setting, but also in the community; some local communities in Southeast Asia have been reported to show a high prevalence of ESBL-producing bacteria. However, the details regarding the quantitative/qualitative state of ESBL-producing bacterial spread in Southeast Asia are currently unclear. Thus, the aim of this study was to assess the state of ESBL-producing bacterial spread in community residents from the Indochinese peninsula, as a representative region of Southeast Asia. In order to achieve this aim, local community residents in Laos and Vietnam were examined for fecal carriage of ESBL-producing Enterobacteriaceae, and the findings were compared with data from a previous study in Thailand which was conducted in the same manner as this study. Between 47.0%–70.2% of the Laotian and Vietnamese residents carried ESBL-producing CTX-M genotype Enterobacteriaceae. The most common sub-genotypes of CTX-M were CTX-M-1 (33.0%–47.5%) and CTX-M-9 (47.5%–64.1%), and these rates were similar among all three countries. Taken together, these results confirmed that ESBL-producing Enterobacteriaceae are widely disseminated in Indochinese countries, such as Thailand, Laos, and Vietnam.

Carriage of Escherichia coli Producing CTX-M-Type Extended-Spectrum β-Lactamase in Healthy Vietnamese Individuals

ABSTRACT Healthy carriage of CTX-M-type extended-spectrum β-lactamase (ESBL)-producing Escherichia coli was examined by thrice collecting fecal samples from the same 199 healthy Vietnamese subjects every 6 months. Using pulsed-field gel electrophoresis (PFGE), identical PFGE patterns throughout the three samplings were not observed, although prevalence of E. coli in the subjects was around 50% in the three samplings. Our results suggested a short carriage period of the CTX-M-type ESBL-producing E. coli in healthy Vietnamese subjects.

Limited Transmission of blaCTX-M-9-Type-Positive Escherichia coli between Humans and Poultry in Vietnam

ABSTRACT We examined whether Escherichia coli isolates that produce CTX-M-9-type extended-spectrum β-lactamases (ESBL) are transferred between humans and chickens in a Vietnamese community. The phylogenetic group compositions, sequence types, antimicrobial resistance profiles, the prevalence of plasmid antibiotic resistance genes, and the plasmid replicon types generally differed between the human and chicken E. coli isolates. Our results suggest that transmission of the blaCTX-M-9-positive E. coli between humans and poultry was limited.

High Prevalence of Chromosomal blaCTX-M-14 in Escherichia coli Isolates Possessing blaCTX-M-14

Kouta Hamamoto, Shuhei Ueda, Takehiko Toyosato, Yoshimasa Yamamoto, Itaru Hirai Laboratory of Microbiology, School of Health Sciences, Faculty of Medicine, University of the Ryukyus, Okinawa, Japan; Japan Agency for Medical Research and Development/Japan International Cooperation Agency, Science and Technology Research Partnership for Sustainable Development, Tokyo, Japan; Nursing for Home Care and Chronic Nursing, School of Health Sciences, Faculty of Medicine, University of the Ryukyus, Nakagimi, Okinawa, Japan; Osaka Prefectural Institute of Public Health, Higashinari-ku, Osaka, Japan

Evaluation of a Method Using Three Genomic Guided Escherichia coli Markers for Phylogenetic Typing of E. coli Isolates of Various Genetic Backgrounds

ABSTRACT Genotyping and characterization of bacterial isolates are essential steps in the identification and control of antibiotic-resistant bacterial infections. Recently, one novel genotyping method using three genomic guided Escherichia coli markers (GIG-EM), dinG, tonB, and dipeptide permease (DPP), was reported. Because GIG-EM has not been fully evaluated using clinical isolates, we assessed this typing method with 72 E. coli collection of reference (ECOR) environmental E. coli reference strains and 63 E. coli isolates of various genetic backgrounds. In this study, we designated 768 bp of dinG, 745 bp of tonB, and 655 bp of DPP target sequences for use in the typing method. Concatenations of the processed marker sequences were used to draw GIG-EM phylogenetic trees. E. coli isolates with identical sequence types as identified by the conventional multilocus sequence typing (MLST) method were localized to the same branch of the GIG-EM phylogenetic tree. Sixteen clinical E. coli isolates were utilized as test isolates without prior characterization by conventional MLST and phylogenetic grouping before GIG-EM typing. Of these, 14 clinical isolates were assigned to a branch including only isolates of a pandemic clone, E. coli B2-ST131-O25b, and these results were confirmed by conventional typing methods. Our results suggested that the GIG-EM typing method and its application to phylogenetic trees might be useful tools for the molecular characterization and determination of the genetic relationships among E. coli isolates.

Genotypic Characterization of HIV-1 Prevalent in Kepulauan Riau, Indonesia

Kepulauan Riau is a famous tourist destination in Indonesia. The epidemic of human immunodeficiency virus type 1 (HIV-1) infection is gradually increasing in this region. We collected peripheral blood samples from 62 antiretroviral therapy-experienced individuals. The amplification of viral genomic fragments, HIV-1 subtyping, and the detection of HIV drug resistance (HIVDR) were performed. Viral subtyping revealed that the most prevalent HIV-1 subtype/circulating recombinant form (CRF) was CRF01_AE (55.6%), followed by recombinants between CRF01_AE and subtype B (17.8%) and then subtype B (15.6%). Recombinants containing CRF02_AG gene fragments were also detected (11.1%). Regarding HIVDR, no drug resistance-associated major mutations were found in pol genes encoding protease, although minor mutations were frequently detected. Furthermore, major mutations, including M184V (2.2%) and Y188L (2.2%), were identified in the viral pol gene encoding reverse transcriptase derived from a study participant, suggesting that the prevalence of HIVDR is low in the region.