[Drug sensitivity test of Campylobacter jejuni strains isolated from human diarrheal stools, chicken meat, and chicken feces, and gene mutation of quinolone-resistant strains].

In basic studies on campylobacteriosis, we tested 53 strains from human diarrhea stools and 102 strains from chicken meat and feces obtained between 2002 and 2006 for drug sensitivity to different drugs and gene mutation in quinolone-resistant strains. 1) Of 15 drugs tested, all were resistant to one or more of the following 10 drugs: CEX, 99.4%: ABPC, 59.4%; NA, 40.6%; NFLX, 40.0%; TC and CPFX, 39.4%; PIPC, 38.1%; MINO, 30.3%; KM, 3.2%; and SM, 2.6%. 2) Of 155 drug-resistant strains, 28 (18.1%) were resistant to single drugs and 127 (81.9%) were resistant to multiple drugs. The most frequent pattern of multipledrug resistance was ABPC/PIPC/CEX, followed by ABPC/PIPC/CEX/TC/MINO/NA/NFLX/CPFX. 3) Mutation of GyrA (Thr86 --> Ile) was detected in 43 (97.7%) of 44 quinolone-resistant strains. We found that resistance to beta-lactams, quinolones, and tetracycline antibiotics was high, and most resistant strains were resistant to multiple drugs. We also found that most quinolone-resistant strains had GyrA mutation.

[An epidemiological study of outbreaks of Salmonella enterica serovar paratyphi A occurred in two Chinese families after traveled to different areas of China].

We reported two familial clusters of paratyphoid fever after travel to China occurring in the same Yokohama ward from September to October 2002. Six Salmonella enterica serovar Paratyphi A (S. Paratyphi A) strains, 3 each from 2 clusters, were isolated and their characteristics analyzed using phage typing, susceptibility to antibiotics, and patterns of restriction endonuclease-digested DNA fragments in agarose gel following pulsed-field gel electrophoresis (PFGE). Mutations in genes for gyrA and parC, which determine sensitivity to fluoroquinolones, were also investigated. All isolates showed the same characteristics, i.e. "untypable", employing bacteriophages, resistant to antibiotics nalidixic acid and fosfomysin, and decreased susceptibility to fluoroquinolones. No difference was observed in PFGE patterns after digesting with 4 restriction enzymes, Xba I, Bin I, Spe I, and Xho I. We also found that the gyrA gene, which is one of the quinolone-resistance-determining regions (QRDR), was mutated at position 83 from serine to phenylalanine (from TTC to TCC) in all 6 strains. Other QRDR's, parC were not mutated commonly in them. Hearing from patients and family members, it was apparent that these 2 families had been contacted neither in Japan nor in China during ill or incubation period of paratyphoid fever, although a member of one cluster had a familial relationship with one of another family. It was also reported by them that typhoid fever is endemic in both of the areas of their visits. From these results, it was suggested that these 2 cluster cases were infected separately in China with the progeny of the same clone which is endemic in these regions.

[Shigella boydii strains possessing a new serovar (SM00-27) isolated from diarrhea of overseas travelers in Japan].

Five Shigella strains isolated from stool cultures of five sporadic imported diarrheal cases in Japan during 1999-2001, did not react to any antisera of the established Shigella serovars. These strains had the typical biochemical characteristics of Shigella boydii, and were biochemically identical. All strains were positive in a PCR assay and a cultured-cell invasion test for invasiveness; these indicate that they can cause shigellosis in humans. The results of antigenic analysis revealed that they did not belong to any of the recognized or provisional serovars, and were serologically indistinguishable. Strain SM00-27 is designated as the test strain for this new S. boydii serovar.

[Molecular epidemiological investigation of vero toxin-producing Escherichia coli (VTEC) isolated from diarrhea patients and dairy cattle].

To elucidate the source and route of VTEC infection, we performed pulse field gel electrophoresis (PFGE) an 50 isolates from human diarrhea typed as serotypes O157, O111, and O26, which were very frequently isolated from patients with VTEC infection between 1986 and 1997, and 32 isolates from dairy cattle, a total of 82 isolates. The isolates were genetically analyzed based on the electrophoresis patterns of DNA, and a phylogenetic tree was prepared. The isolates were classified based on similarity > or = 89. The following results of the molecular epidemiological investigation were obtained. 1) Based on the electrophoresis patterns of DNA obtained by PFGE, 34 of the 49 O157 isolates (69.4%) were divided into groups 1-9, 15 of the 18 O111 isolates (83.3%) were divided into groups 1-3, and 12 of the 15 O26 isolates (80%) were divided into groups 1-3. Of the grouped isolates, group 8 of O157, groups 2 and 3 of O111, and group 3 of O26 included isolates from human diarrhea and dairy cattle, but the other groups included isolates from only one of the two sources. 2) With regard to regional investigation, groups 6 and 9 of O157 included human diarrhea-derived isolates from Yokohama and Ehime, and group 8 included a human diarrhea-derived isolate from Yokohama and a dairy cattle-derived isolate from Tokushima. Group 3 of O111 included a human diarrhea-derived isolate from Ehime and a dairy cattle-derived isolate from Hokkaido. Group 3 of O26 included human diarrhea-derived isolate from Ehime and dairy cattle-derived isolate from Sagamihara and Hokkaido. Since the above findings showed that although the frequency was low, isolates from human diarrhea and dairy cattle were included in the same groups, it was demonstrated that dairy cattle are closely related to the human infectious disease of the intestinal tract as a source of infection. However, classification using the PFGE method is difficult due to diversity of the electrophoresis pattern of DNA. It is necessary to investigate the classification by a combination of the PFGE method with phage typing, ribotyping, and RAPD-PCR, and to investigate more numbers of patient-derived and animal-derived isolates.