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Background: Pre-exposure prophylaxis (PrEP) with tenofovir/emtricitabine (TDF/FTC) has been recommended worldwide. We evaluated the safety and efficacy of daily PrEP with TDF/FTC in Tokyo., Methods: This single-center, single-arm study was performed with 124 men who have sex with men (MSM) between January 2017 and March 2021. MSM who entered into an MSM cohort from January 2017 through March 2018 and had a pre-PrEP observational period of 1 year were eligible and recruited to the study between April 2018 and March 2019 and followed for 2 years. The primary outcome was the incidence of HIV infection (per 100 person-years). Secondary outcomes were the incidence of sexually transmitted infections and adverse events, and the rate of retention and adherence to PrEP., Results: There were 309 MSM registered in the cohort (mean age, 36.6 years); 124 fulfilled the criteria and were included in the study. The remaining patients were continuously followed. There was a significant decrease in incidental HIV infection among PrEP users (0 infections, 235.5 person-years) compared to non-PrEP users (11 infections [3.4%/year], 318.9 person-years; p = 0.01). The average adherence rate was consistently greater than 95%, and the retention rate at two years was approximately 80%., Conclusions: The present study showed a high prophylactic effect against HIV infection, retention, and adherence to PrEP. PrEP is feasible and highly recommended in Japan., Trial Registration: UMIN Clinical Trials Registry (UMIN000031040, www.umin.ac.jp), Japan Registry of Clinical Trials (jRCTs031180134)., (Copyright © 2022 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.)

Objectives: To compare the effectiveness of doxycycline 100 mg twice daily for 7 days and azithromycin 1 g single dose for the treatment of rectal Chlamydia trachomatis infection among MSM in a real clinical setting., Methods: A prospective study was performed to compare the effectiveness of doxycycline and azithromycin for the treatment of rectal C. trachomatis among MSM in Tokyo, Japan. Subjects diagnosed with rectal C. trachomatis infection were treated and test-of-cure examination (TOC) was performed at least 3 weeks after the treatment. Treatment of rectal C. trachomatis infection was decided prospectively in a time-dependent manner; in the period between January 2017 and October 2018, azithromycin was administered to all subjects, whereas from October 2018 through March 2020, doxycycline was administered to all subjects. Effectiveness of these treatments was calculated by the number of rectal C. trachomatis-negative subjects at TOC divided by the number of subjects treated., Results: Two hundred and ninety-six MSM with rectal C. trachomatis infection were treated with azithromycin (80 patients) and doxycycline (216 patients) in a time-dependent manner. Of the 296 MSM, 274 (92.6%) were treated successfully [67 (83.7%, 95% CI = 79.6%-87.9%) in the azithromycin group versus 207 (95.8%, 95% CI = 94.5%-97.2%) in the doxycycline group, P < 0.001]. To evaluate factors associated with treatment failure, we performed logistic regression analysis. In univariate and multivariate analysis, only doxycycline treatment was inversely associated with treatment failure (OR = 0.29, 95% CI = 0.084-0.976, P = 0.046)., Conclusions: The treatment with doxycycline 100 mg twice daily for 7 days was superior to that with azithromycin 1 g single dose for rectal C. trachomatis among MSM in a real-world setting., (© The Author(s) 2020. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Background: Amebiasis, which is caused by Entamoeba histolytica , is a re-emerging public health issue owing to sexually transmitted infection (STI) in Japan. However, epidemiological data are quite limited., Methods: To reveal the relative prevalence of sexually transmitted E. histolytica infection to other STIs, we conducted a cross-sectional study at a voluntary counselling and testing (VCT) centre in Tokyo. Seroprevalence of E. histolytica was assessed according to positivity with an ELISA for E. histolytica -specific IgG in serum samples collected from anonymous VCT clients., Results: Among 2083 samples, seropositive rate for E. histolytica was 2.64%, which was higher than that for HIV-1 (0.34%, p<0.001) and comparable to that for syphilis (rapid plasma reagin (RPR) 2.11%, p=0.31). Positivity for Chlamydia trachomatis in urine by transcription-mediated amplification (TMA) was 4.59%. Seropositivity for E. histolytica was high among RPR/ Treponema pallidum hemagglutination (TPHA)-positive individuals and it was not different between clients with and without other STIs. Both seropositivity of E. histolytica and RPR were high among male clients. The seropositive rate for anti- E. histolytica antibody was positively correlated with age. TMA positivity for urine C. trachomatis was high among female clients and negatively correlated with age. Regression analysis identified that male sex, older age and TPHA-positive results are independent risk factors of E. histolytica seropositivity., Conclusions: Seroprevalence of E. histolytica was 7.9 times higher than that of HIV-1 at a VCT centre in Tokyo, with a tendency to be higher among people at risk for syphilis infection. There is a need for education and specific interventions against this parasite, as a potentially re-emerging pathogen., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

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.

A total of 341 Shigella sonnei strains consisting of 94 domestic strains and 247 imported strains isolated during 1990-1997 in Tokyo, were examined regarding their colicine-type, drug-resistance and ornithine-utilization. The colicine typing results showed that the domestic strains were classified into 7 types, and the imported strains were classified into 13 types. Among the colicine-types identified, 8-type, 0-type, 6-type and 12-type were predominant in the domestic strains, whereas 6-type, 0-type, 8-type, 9A-type and 12-type were predominant in the imported strains. The drug-resistance test using 9 drugs (CP, TC, SM, KM, ABPC, ST, NA, FOM and NFLX) showed that 89.4% of the domestic strains and 85.4% of the imported strains were resistant to some of the drugs except FOM and NFLX. Drugs with a high resistant rate were SM, TC and ST for both groups. Drug-resistance patterns of the resistant strains varied in 22 types. Among those, a triple drug-resistance type with TC.SM.ST was found in the most frequent pattern in both groups. The results of the ornithine-utilization test revealed that 28.7% of the domestic strains and 8.1% of the imported strains were negative. The ornithine-negative strains in the same source had a similar plasmid-profile, but generally there was no correlation between the different sources.

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.

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.

Since 1989, outbreaks of Salmonella ser. Enteritidis food poisoning has dramatically increased in Tokyo, and a total of 95 outbreaks has been reported between 1989 and 1993. As the results of examination of phage type by the method of Ward, et al., strains isolated from 31 (32.6%) of 95 outbreaks were phage type 34 which is a very rare type in Europe and America. To characterize these unique strains of phage type (PT) 34, 302 isolates obtained from patients and vehicle foods of the outbreaks, eggs and environments in Tokyo were examined for plasmid DNA profiles and antimicrobial resistance patterns. Plasmid DNA was extracted by the Kado's method, and analysed by agalose gel electrophoresis. Antimicrobial susceptibility was tested for CP, TC, SM, KM, ABPC, NA, SXT, FOM and NFLX by the K-B disc method. The strains of PT 34 were further subdivided to 4 types by plasmid profile and antibiogram. The prevalent pattern of PT 34 strains was type plasmid profile which carried 2 different plasmids (> 250 and 60 kb) and was streptomysin-resistant. A total of 28 (90.3%) of 31 outbreaks were found to be caused by this specific type of Salmonella ser. Enteritidis. Several kinds of egg-related foods were suspected for the vehicles of transmission among 12 outbreaks. Especially, in 5 outbreaks, this specific type (type B plasmid profile and streptomysin resistant) of Salmonella ser. Enteritidis strains were isolated both from patients and incriminated food which were cooked with eggs. The phase type of Salmonella ser. Enteritidis strains isolated from raw egg and poultry or environmental specimens from poultry farm showed that the prevailing phage types were almost the same as those of foods poisoning outbreaks. This strongly suggests that these foods may be considered as a source of infection in Salmonella ser. Enteritidis outbreaks.

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.

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.