Clade analysis of enterohemorrhagic Escherichia coli serotype O157:H7/H- strains and hierarchy of their phylogenetic relationships.

Enterohemorrhagic Escherichia coli serotype O157:H7/H-(O157) strains isolated in Chiba prefecture, Japan, during 2002-2009 were studied by lineage, subgroup, cluster, and clade analysis. Lineage analysis of 470 O157 strains with no known epidemiological relationships using lineage specific polymorphism assay-6 showed that there were 242 lineage I strains, 160 lineage I/II strains, 67 lineage II strains, and 1 atypical strain. Clade analysis of these strains by single nucleotide polymorphism in eight loci showed that lineage I contained all the clade 1, clade 2, and clade 3 strains, and some of the clade 4/5 strains.

Biased distribution of IS629 among strains in different lineages of enterohemorrhagic Escherichia coli serovar O157.

The distribution of insertion sequence (IS) 629 among strains of enterohemorrhagic Escherichia coli serovar O157 (O157) was investigated and compared with the strain lineages defined by lineage specific polymorphism assay-6 (LSPA-6) to demonstrate the effectiveness of IS629 analysis for population genetics analysis. Using pulsed-field gel electrophoresis and variable-number tandem repeat typing, 140 strains producing both VT1 and VT2 and 98 strains producing only VT2 were selected from a total of 592 strains isolated from patients and asymptomatic carriers in Chiba Prefecture, Japan, during 2003-2008. By LSPA-6 analysis, six strains had atypical amplicon sizes in their Z5935 loci and five strains had atypical amplicon sizes in their arp-iclR intergenic regions.

Detection of enteroaggregative Escherichia coli by loop-mediated isothermal amplification.

A novel gene amplification method, loop-mediated isothermal amplification (LAMP), has been recently developed as a rapid, specific diagnostic method for various infectious diseases. We have investigated whether LAMP can be used to detect small numbers of enteroaggregative Escherichia coli (EAEC) cells contaminated in food samples. Primers for LAMP reaction were designed with EAEC aggR gene sequences (available in GenBank).

Variable number of tandem repeats and pulsed-field gel electrophoresis cluster analysis of enterohemorrhagic Escherichia coli serovar O157 strains.

Ninety-five enterohemorrhagic Escherichia coli serovar O157 strains, including 30 strains isolated from 13 intrafamily outbreaks and 14 strains isolated from 3 mass outbreaks, were studied by pulsed-field gel electrophoresis (PFGE) and variable number of tandem repeats (VNTR) typing, and the resulting data were subjected to cluster analysis. Cluster analysis of the VNTR typing data revealed that 57 (60.0%) of 95 strains, including all epidemiologically linked strains, formed clusters with at least 95% similarity.

[The risk of pertussis and diphtheria infections among pediatric healthcare workers in Japan].

For infection control in pediatric hospitals, we investigated the risk of pertussis and diphtheria infections among pediatric healthcare workers. Forty-nine Japanese pediatric healthcare workers in 12 general hospitals were screened for antibodies of pertussis toxin (PT), filamentous hemagglutinin (FHA), and diphtheria toxin (DT). The seropositive rates of anti-PT IgG (protective level, > 10 U/mL), anti-FHA IgG (> 10 U/ mL), and anti-DT (> 0.

[Molecular epidemiological analysis of an outbreak of Campylobacter jejuni using restriction enzyme double-digestion technique for genotyping of isolates by pulsed-field gel electrophoresis].

In an outbreak of gastroenteritis in elementary school students and their families in Chiba Prefecture, Japan, Campylobacter jejuni was isolated from the stools of 14 patients who developed diarrheal illness after a one-day bus trip. C. jejuni was also isolated from the stools of 3 patients not going on the bus trip.

[Cluster analysis of restriction fragment length polymorphism patterns of Mycobacterium tuberculosis isolated in Chiba prefecture].

Methods for cluster analysis of IS6110 based restriction fragment length polymorphism (RFLP) patterns of Mycobacterium tuberculosis isolates were studied for an epidemiological investigation in Chiba prefecture. To normalize patterns, external size markers were adopted instead of typical internal size markers used in the standard method. RFLP patterns were run on 1.

Comparison between agarose gel electrophoresis and capillary electrophoresis for variable numbers of tandem repeat typing of Mycobacterium tuberculosis.

Variable numbers of tandem repeat (VNTR) typing of Mycobacterium tuberculosis was performed on 54 strains including 23 strains derived from 9 outbreaks. PCR amplicon sizes of 12 mycobacterial interspersed repetitive unit tandem repeat loci were measured using both agarose gel electrophoresis and capillary electrophoresis. Similarities using agarose gel electrophoresis of Euclidian distances among the 23 strains derived from the 9 outbreaks were significantly lower than that using capillary electrophoresis (Wilcoxon signed ranks test, P < 0.

[Comparison between biotype of Vibrio cholerae O1 and genotype using polymerase chain reaction].

To compare between biotype of Vibrio cholerae O1 and genotype using polymerase chain reaction (PCR), 9 classical and 81 El Tor biovar strains were investigated for hemolysis, agglutination of avian erythrocytes, VP test reactivity, sensitivity to both polymyxin B and classical phage IV, and genotype using PCR amplification of hlyA, tcpA, rtxA and rtxC. One classical biovar strain showed atypical reaction upon agglutination of avian erythrocytes. Eighteen El Tor biovar strains showed atypical reactions, with the exception of sensitivity to polymyxin B.