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Background and Aim: The Helicobacter pylori stool antigen (HpSA) test is useful for initial diagnosis of H. pylori infection, but there is disagreement regarding its diagnostic accuracy after eradication therapy. The aim of the present study was to evaluate the diagnostic accuracy of the HpSA test before and after eradication therapy. Methods: One hundred and thirty-six patients underwent upper gastrointestinal endoscopy with biopsies for the diagnosis of H. pylori infection using culture, histology and the rapid urease test. Fifty-four H. pylori-positive patients were treated with 1-week triple therapy. Six to 10 weeks after the end of therapy, the patients underwent re-endoscopy and received the same biopsy-based methods. In addition, the 13C-urea breath test was performed. The HpSA test was performed before and 6–10 weeks after the end of therapy. In 23 patients, the HpSA test was also performed at the end of therapy. Results: Before therapy, the sensitivity and specificity of the HpSA test was 98.3% (95% confidence interval (CI): 95.9–100%) and 95.0% (95% CI: 75.1–99.9%), respectively. At the end of therapy, the HpSA tests were all negative both for eradication and non-eradication patients. The sensitivity and specificity of the HpSA test after eradication therapy were 90% (95% CI: 55.5–99.7%) and 97.7% (95% CI: 93.3–100%), respectively. Conclusions: The HpSA test is a useful method for the diagnosis of H. pylori infection before and after eradication therapy.

Recently, the increase in the number of resistant strains of Campylobacter jejuni to fluoroquinolone has been reported in European countries. We also studied antimicrobial susceptibilities of 600 clinical isolates of Campylobacter jejuni isolated during a 6 year period from 1989 through 1994 in four Tokyo Metropolitan Hospitals. The susceptibility to 6 antimicrobial agents, norfloxacin (NFLX), ofloxacin (OFLX), ciprofloxacin (CPFX), nalidixic acid (NA), erythromycin (EM) and tetracycline (TC) were examined. The overall resistant rates were as follows: NFLX, 45 strains (7.5%); OFLX, 45 strains (7.5%); CPFX, 44 strains (7.3%); NA, 62 strains (10.3%); EM, 4 strains (0.6%) and TC, 259 strains (43.2%). The number of resistant strains to fluoroquinolones and NA has increased significantly since 1993 in Japan, but the susceptibility to erythromycin has still remained the same level during the past 6 years. The susceptibility to TC was variable, and MICs gave a bimobal distribution, as pointed out previously. The resistance pattern of NFLX, OFLX, CPFX and NA were observed most frequently in those isolates.

In April 1991, an outbreak of acute gastroenteritis due to group C rotavirus occurred at an elementary school in Tokyo. Fifty-one (13%) of 393 students became ill. The main clinical symptoms were diarrhea (100%), abdominal pain (68%) and vomiting (56%). No enteropathogenic bacteria were found in the fecal specimens. However, the virus particles morphologically indistinguishable from conventional rotavirus were detected in 6 of 11 fecal specimens by electron microscopy. Immune electron microscopy showed that these virions aggregated with anti-group C rotavirus serum. The RNA pattern of the virus particles involved in this outbreak showed a pattern similar to that of typical group C rotavirus on polyacrylamide gel electrophoresis.

Helicobacter pylori urease was recovered as a single peak by DEAE-Sepharose column chromatography and Sephacryl S-200 gel filtration. The purified urease was obtained by fast protein liquid chromatography using a Mono Q column. The purified urease preparation gave a single band in polyacrylamide gel disc electrophoresis. Latex particles were sensitized with anti-urease immunoglobulin. The sensitized latex particles were agglutinated with the purified urease and by cell sonicates obtained from 55 strains of H. pylori which were isolated from the gastric mucosa of patients with gastric and duodenal disorders, while they did not react with those obtained from related bacteria known to be urease producers, such as Helicobacter mustelae and urease- positive "Campylobacter lari variants", or by urease of some strains of Enterobacteriae. We have developed a specific and sensitive method for detecting the urease by using the reversed passive latex agglutination technique, in order to identify of the organism.

We determined the MICs of clarithromycin for 32 Helicobacter pylori strains isolated from gastric mucosa of patients, by using microdilution broth method under different microaerobic conditions (CO2: 5% and 15%). The pH of broth was more acidic at 15% CO2 than that of at 5% CO2. The MICs of clarithromycin for all H. pylori strains at 15% CO2 condition were higher than that of clarithromycin at 5% CO2 condition. Comparing the MICs with the results of eradication therapy, we concluded that the measurement of MIC under 5%CO2 condition is more useful for expecting the clinical outcome.

Since the first outbreak in 1990, the incidence of Salmonella ser. Enteritidis (S. Enteritidis) phage type (PT) 1 food poisoning has gradually increased in Tokyo and has reached approximately 30% of the total S. Enteritidis outbreaks reported. To characterise these S. Enteritidis PT1 food poisoning, a total of 198 strains obtained from 44 outbreaks between 1990 and 1996 were examined for antimicrobial resistance, acid producibility from glycols (propylene and ethylene glycol) and plasmid DNA profiles. The 44 PT1 outbreaks analysed were further subdivided into 11 types by epidemiological markers. The most common patterns were type A (plasmid profile carrying only one plasmid (60 kb). SM and TC resistance and non producibility from glycols), and type B (plasmid profile carrying two plasmids (60 and 20 kb), SM resistance and no producibility from glycols) and were responsible for 21 (47.7%) and 15 (34.1%) outbreaks, respectively. In 11 of 44 outbreaks, strains carrying identical epidemiological markers were isolated both from patients and vehicle foods, environments, and/or food-handlers. Similar to PT4 and PT34 outbreaks reported in Japan, egg and egg-related foods were also suspected in 8 of these 11 outbreaks. Of interest, chicken which were not pointed out in PT4 and PT 34 outbreaks was also suspected as a vehicle of transmission in two outbreaks.

Since 1989, outbreaks of Salmonella ser. Enteritidis (S. Enteritidis) food poisoning have dramatically increased in Tokyo, and a total of 31 outbreaks has been reported in 1989. Twenty-one of these 31 outbreaks were caused by S. Enteritidis PT34, but 8 outbreaks were caused by S. Enteritidis PT4. After 1990 instead of SE PT34, food poisoning due to PT4, which was a very common phage type in the UK, has increased in Tokyo. Between 1989 and 1995, there were 144 food poisoning outbreaks caused by S. Enteritidis, and 64 of these outbreaks were by due to S. Enteritidis PT4, which was one of the main phage types in Tokyo. To characterize these strains of phage type (PT) 4,293 isolates from patients, and vehicle foods, eggs and environment in Tokyo were examined for plasmid DNA profiles, acid productivity from glycols (propylene and ethylene) and antimicrobial resistance patterns. Plasmid DNA was extracted by Kado's method, and analyzed by agarose gel electrophoresis. The acid productivity from propylene glycol or ethylene glycol were tested using Barsicow medium with 1% propylene glycol or ethylene glycol. Antimicrobial susceptibility to AM, CP, TC, SM, KM, NA, ST, FOM and NFLX was tested by the K-B disc method. The strains of PT4 were further subdivided into 9 types by those epidemiologic marker analysis. The prevalent pattern of PT4 strains was type A plasmid profile carrying only one plasmid (60 kb) and there were 2 kinds of antibiograms. One was SM resistant, while the other was susceptible. A total of 56 (87.5%) of 64 outbreaks was found to have been caused by these types of S. Enteritidis. Several kinds of egg-related foods were suspected as the vehicles of transmission among 24 outbreaks. Especially, in 5 outbreaks, S. Enteritidis strains were isolated both from patients and suspected food which were cooked with egg. This strongly suggests that these foods may be the potential source of infection in S. Enteritidis PT4 outbreaks.

In order to establish a national reference system for Campylobacter serotyping in Japan, 7 local institutes of public health collaborated to prepare 30 serogrouping antisera including 26 antisera of Lior's serogrouping system and 4 antisera of TCK serogrouping system which was developed by the Tokyo Metropolitan Research Laboratory of Public Health. A total of 603 strains (92.2%) out of 654 isolates from 23 outbreaks of C. jejuni throughout Japan were serogrouped by the 30 antisera. Out of 1,198 strain isolated from sporadic cases of Camplyobacter gastroenteritis, 883 (73.7%) were typed and 298 strains (24.9%) were untypable. The remaining 17 strains belong to rough form were not used for serogrouping. A hundred thirteen out of 883 strains have reacted with more than one typing serum. Among C. jejuni isolated from 7 prefecture, Lior's serogroup 4 was most common followed by Lior's serogroup 4, 2, 11, 1 and TCK serogroup 1 and 12. We conclude from the experiment described above that this Lior's serogrouping system by combining with TCK serogroup for Campylobacter jejuni/coli is useful in epidemiological investigations in Japan.

Campylobacter jejuni strains isolated from gastroenteritis at 4 general hospitals of Tokyo Metropolitan during the period from 1981 to 1987 were serotype according to the slide agglutination test (TCK system) developed by the Tokyo Metropolitan Research Laboratory of Public Health. Two thousand four hundred seventy-nine strains isolated from sporadic cases among infants and children, 1,962 (78.5%) were typed by 33 typing sera numbered TCK 1 through TCK 33 and leaving 537 strains (21.5%) untypable. Out of the typable strains, 1,643 strains reacted with only single serum, while 319 strains reacted with 2 or more antisera. The most common serogroups included TCK 21, 20, 7, 1, 4, 23, 24, 10, 30 and 12. Out of the 1,250 strains isolated from sporadic cases among adults, 974 strains (77.9%) were typed and 276 strains were untypable. The most common serogroups were similar to those of infants and children. Serogroups TCK 1, 7, 4 and 21 were consistently the common serogroups every year during the 7 year study. Isolation frequency of serogroup TCK 30 have increased remarkably since 1986, while TCK 23, 14 and 9 have decreased.

Biopsy specimens of human gastric mucosa of patients with gastric complaints and subjected to endoscopic examination were cultured microaerobically, and Campylobacter pyloridis was detected in 46 out of 80 cases (57.5%). The organism was found in 13 out of 22 patients with gastritis, 11 out of 16 with gastric ulcer scar, 7 out of 16 with gastric ulcer, 3 out of 9 with gastric polyp, 4 out of 5 with gastric carcinoma, 2 out of 2 with esophagus carcinoma, and 6 out of 9 with other gastric diseases. The isolates were identified as C. pyloridis, demonstrating its characteristic features such as positive for oxidase and catalase, negative for reduction of nitrite and nitrate, positive for urease, no growth at 25 C, growth at 37 C, not tolerant to 1% glycine, and resistant to nalidixic acid. Positive alkaline phosphatase activity was considered as an additional feature characteristic for the strains of C. pyloridis. The major cellular fatty acids were tetradecanoic acid and 19-carbon-cyclopropane acid. This pattern is unique among Campylobacter species. The survival of the organism for a longer period than 60 min at pH 2.5 indicates its significant resistance to acidic environment.