Takayuki Konno

Virulence gene profiling of enteroaggregative Escherichia coli heat-stable enterotoxin 1-harboring E. coli (EAST1EC) derived from sporadic diarrheal patients

Between 2007 and 2009, a total of 2168 Escherichia coli strains derived from diarrheal patients, defined as putative diarrheagenic E. coli (DEC), were collected from medical institutions in Akita prefecture, Japan. Thirty five of the strains lacked typical pathogenic determinants of DEC other than astA, which encodes enteroaggregative E. coli (EAggEC) heat-stable enterotoxin 1 (EAST1). These E. coli strains are referred to as EAST1EC. Several studies have suggested a role of EAST1 in diarrhea; however, the correlation between diarrhea and the presence of astA remains inconclusive. To investigate whether EAST1EC strains derived from diarrheal patients shared pathogenic factors other than EAST1, virulence gene profiling of 12 virulence genes - iha, lpfA, ldaG, pilS, pic, pet, irp2, daa, aah, aid, cdtB and hlyA - was carried out. PCR analysis revealed that four of the 35 EAST1EC strains harbored only astA, 24 harbored genes associated with adhesins and intestinal colonization, three strains harbored the gene for α-hemolysin, and 24 strains harbored the gene for a siderophore. These results indicated that some EAST1EC strains harbor various virulence genes associated with distinct E. coli pathotypes, primarily enterohemorrhagic E. coli and EAggEC, which may represent additional pathogenic determinants of EAST1EC.

The ORF1 gene located on the class-1-integron-associated gene cassette actually represents a novel fosfomycin resistance determinant.

The class 1 integrons are genetic elements capable of integrating gene cassettes by a site-specific recombination mechanism ([1][1]). Gene cassettes are mobile units composed of a gene, most often an antibiotic resistance gene, and a recombination site, the 59-base element ([1][1]). We have

Prevalence and Characteristics of Salmonella and Campylobacter in Retail Poultry Meat in Japan

This study was performed to determine the prevalence, antimicrobial susceptibility, and genetic relatedness of Salmonella enterica subsp. enterica and Campylobacter spp. in poultry meat, and to analyze the association of genetic types of these bacteria with their geographical distribution and antimicrobial resistance profiles. Salmonella and Campylobacter isolates have been detected, respectively, in 54 and 71 samples out of 100 samples tested. Nine Salmonella serotypes were found, including S. enterica subsp. enterica serovar Infantis (33%), Schwarzengrund (12%), Manhattan (9%), and others. Campylobacter jejuni and C. coli were detected in 64 (64%) and 14 (14%) samples, respectively. S. enterica subsp. enterica isolates were very frequently resistant to tetracycline (78.3%) and streptomycin (68.3%). Many C. jejuni and C. coli isolates were resistant to sulfamethoxazole/trimethoprim (90.5%), nalidixic acid (47.3%), ampicillin (45.9%), and ciprofloxacin (40.5%). Cluster analysis was performed for the Salmonella isolates using pulsed-field gel electrophoresis (PFGE) data. For Campylobacter isolates, the cluster analysis was based on both PFGE and comparative genomic fingerprinting. The molecular typing results were compared with the information about antimicrobial resistance and geographical locations in which the poultry meat was produced. This analysis revealed that C. jejuni strains with a particular genotype and antimicrobial resistance profile are spreading in specific areas of Japan.

Phylogenetic Characteristics of Mycobacterium tuberculosis Clinical Isolates in Akita Prefecture, Japan, on the Basis of the Preliminary Detection of Beijing Family Strains

Tuberculosis is one of the major infectious diseases and remains a public health concern. Mycobacterium tuberculosis is transmitted via airborne particles and spreads easily; therefore, surveillance of tuberculosis is important for the early detection of a possible epidemic and preventing the spread of the infection. Variable-number tandem-repeat (VNTR) analysis is frequently used to elucidate the molecular epidemiology of M. tuberculosis. VNTR analysis facilitates identification of the transmission of M. tuberculosis, being useful for regional surveillance of tuberculosis. In Japan, 12 loci of VNTR, designated as the Japan Anti-Tuberculosis Association (JATA) 12-VNTR, have been proposed to discriminate Beijing family strains (1). On the other hand, the phylogeny of M. tuberculosis is also useful for understanding various epidemiological tendencies. Among the lineages of M. tuberculosis, Beijing family strains within East Asian lineages possess high virulence and drug-resistance (2). Beijing family strains are an evolving lineage of M. tuberculosis spreading worldwide, including Japan (2–4). However, there is a lack of local data on the population structure of Beijing family strains in Akita Prefecture, located in the northern part of Japan. In this study, we phylogenetically characterized a total of 157 M. tuberculosis isolates from a hospital that represents a half of all tuberculosis beds in Akita Prefecture, by means of JATA12-VNTR and maximum a posteriori (MAP) estimation based on an individual VNTR profile (5). These isolates were collected for 4 years between 2012 and 2015 and derived from distinct cases. The MAP estimation classified the M. tuberculosis strains into 4 ancient Beijing sublineages (ST11/ST26, STK, ST3, and ST25/ST19), modern Beijing sublineages, and other lineages (non-Beijing family, designated nBj). The purpose of this study was to determine phylogenetic characteristics of M. tuberculosis isolates to understand the trends of tuberculosis in Akita Prefecture. This study was approved by a project research evaluation committee and the Research Ethics Committee

Molecular Epidemiology of Monophasic Salmonella enterica serovar O7: -: 1, 5 Isolates in Akita Prefecture, Japan

Accepted December 14, 2015. J-STAGE Advance Publication January 8, 2016 DOI: 10.7883/yoken.JJID.2015.566 *Corresponding author: Mailing address: Akita Prefectural Research Center for Public Health and Environment, 6-6 Sensyu kubota-machi, Akita 010-0874, Japan. Tel: +8118-832-5005, Fax: +81-18-832-5938, E-mail: konnotakayuki@pref.akita.lg.jp Fig. 1. Number of Salmonella clinical isolates in each area of Akita prefecture in 2010. Area divided into jurisdictions by the public health center. Jpn. J. Infect. Dis., 69, 161–163, 2016