Immunological responses following the third dose of the BNT162b2 SARS-CoV-2 vaccine among Japanese healthcare workers.

INTRODUCTION: A limited number of studies have shown a decline in antibody titers in healthcare workers beyond six months after the second dose of the BNT162b2 vaccine, and has been insufficiently investigated yet in the respective Asian ethnic groups. METHODS: We conducted a longitudinal observational study on 187 healthcare workers and other personnel and healthy adults at least eight months after vaccination at the International University of Health and Welfare. RESULTS: The baseline (before the third dose of BNT162b2) anti-receptor binding domain (RBD) IgG level was 569[377-943] AU/mL 245[240-250] days after the second dose. The mean antibody titer of participants aged 20-29 years was 4.6 times higher than that of participants aged 70-79 years. After booster vaccination, serum anti-RBD antibody levels were elevated in all participants with a median titer of 23,250[14,612-33,401] AU/mL 21[19-23] days after the third dose. The median post-booster antibody titers in the 20-29, 30-39, 40-49, 50-59, 60-69, and 70-79 years age groups were 30.6, 33.0, 33.8, 27.4, 50.1, and 90.3 times, respectively, higher than the pre-booster ones. Antibody levels were 15% lower in daily drinkers compared to nondrinkers, suggesting that daily alcohol consumption can prevent antibody levels from increasing after vaccination. Our results show decreased antibody titers after two doses of the vaccine, especially in the elderly; however, the third dose of the vaccine resulted in a significant increase in antibody titers in all age groups. CONCLUSIONS: We provided information on antibody responses following primary and booster doses of the BNT162b2 mRNA COVID-19 vaccine in Japan.

[Efforts and Prospects for the Globalization of the Japanese Association of Medical Technologists (JAMT)].

The Japanese Association of Medical Technologists (JAMT) has joined the International Federation of Bi- omedical Laboratory Science (IFBLS) and Asia Association of Medical Laboratory Scientists (AAMLS). JAMT has concluded an agreement with the Korean Association of Medical Technologists (KAMT) and coop- erates with the Japan International Medical Technology Foundation (JIMTEF). In addition, JAMT is prepar- ing for the 32nd World Congress of Biomedical Laboratory Science. JAMT founded an international section for globalization, and started the foundation of an overseas short- term program for studying abroad, exchange with the Taiwanese Association of Medical Technologists (TAMT), and support for developing countries. From an academic aspect, we placed the "Japanese Journal of Medical Technology" on the J-STAGE. JAMT nurtures global medical technologists through international exchanges and support from developing countries. [Review].

Loop-mediated isothermal amplification assay for 16S rRNA methylase genes in Gram-negative bacteria.

Using the loop-mediated isothermal amplification (LAMP) method, we developed a rapid assay for detection of 16S rRNA methylase genes (rmtA, rmtB, and armA), and investigated 16S rRNA methylase-producing strains among clinical isolates. Primer Explorer V3 software was used to design the LAMP primers. LAMP primers were prepared for each gene, including two outer primers (F3 and B3), two inner primers (FIP and BIP), and two loop primers (LF and LB). Detection was performed with the Loopamp DNA amplification kit. For all three genes (rmtA, rmtB, and armA), 10(2) copies/tube could be detected with a reaction time of 60 min. When nine bacterial species (65 strains saved in National Institute of Infectious Diseases) were tested, which had been confirmed to possess rmtA, rmtB, or armA by PCR and DNA sequencing, the genes were detected correctly in these bacteria with no false negative or false positive results. Among 8447 clinical isolates isolated at 36 medical institutions, the LAMP method was conducted for 191 strains that were resistant to aminoglycosides based on the results of antimicrobial susceptibility tests. Eight strains were found to produce 16S rRNA methylase (0.09%), with rmtB being identified in three strains (0.06%) of 4929 isolates of Enterobacteriaceae, rmtA in three strains (0.10%) of 3284 isolates of Pseudomonas aeruginosa, and armA in two strains (0.85%) of 234 isolates of Acinetobacter spp. At present, the incidence of strains possessing 16S rRNA methylase genes is very low in Japan. However, when Gram-negative bacteria showing high resistance to aminoglycosides are isolated by clinical laboratories, it seems very important to investigate the status of 16S rRNA methylase gene-harboring bacilli and monitor their trends among Japanese clinical settings.

Emergence of fluoroquinolone-resistant Streptococcus pyogenes in Japan by a point mutation leading to a new amino acid substitution.

OBJECTIVES: Streptococcus pyogenes causes various diseases in humans. While the prevalence of fluoroquinolone-resistant S. pyogenes isolates has been increasing since 2000 in the USA and Europe, it has remained very low in Japan. We isolated a fluoroquinolone-resistant S. pyogenes strain and analysed its genetics. METHODS: TU-296, a strain of S. pyogenes resistant to levofloxacin (MIC 16 mg/L), was isolated from the throat of a patient in their thirties with pharyngitis in autumn 2007. We carried out susceptibility tests for various antimicrobial agents and PCR analysis of the genes gyrA, gyrB, parC and parE in the quinolone resistance-determining region, followed by sequencing of the PCR products to find mutation(s) and the resulting amino acid substitution(s). We then sequenced the PCR product of the emm gene and determined the emm genotype. RESULTS: S. pyogenes TU-296 was found to have the following mutations and amino acid substitutions: adenine 476 to cytosine in gyrA and cytosine 367 to thymine in parC, resulting in Glu-85→Ala in GyrA and Ser-79→Phe in ParC. The genotype of the isolate was emm11. CONCLUSIONS: Amino acid substitutions in fluoroquinolone-resistant S. pyogenes have already been reported from Europe and the USA, including Ser-81→Phe or Tyr and Met-99→Leu in GyrA, as well as Ser-79→Phe, Tyr or Ala and others in ParC. Numerous point mutations were found in parC and parE of S. pyogenes TU-296. In addition, a new amino acid substitution was detected (Glu-85→Ala in GyrA). To our knowledge, there have been no previous reports of this substitution in a clinical isolate of S. pyogenes.

[Activities for laboratory medicine support after the Great East Japan Earthquake by the Japanese Society of Laboratory Medicine].

The Great East Japan Earthquake caused a tragic tsunami and resulted in serious damage to north region of Japan on March 11, 2011. The Japanese Society of Laboratory Medicine, JSLM launched an ad hoc Committee to support Laboratory Medicine affairs in the affected area. We expected that laboratory testing demands would increase during the weeks following the disaster. We decided to support the use of Point-of-Care Testing. Many POCT devices use battery-powered analyzers. This is definite advantage for their use in areas with limited access to power and water supplies. We contacted many companies about the possibility of providing POCT devices, IVD reagents and/or any laboratory supplies including disposable materials. Finally, forty companies agreed to support this project and we received list of reagents materials for more than one hundred IVD tests. We entered this information on our web site and continued to update it as additional support was received. Once a request of support was received, communication were made to confirm the amount of material, the method of shipping/receipt and if any specific training that would be required for its use at the testing site. Also, we dispatched volunteer Medical Technologists for eight weeks to assist in the laboratory work. Some of the crucial points in recruiting volunteer laboratory professions are expenses and accommodations. We prepared not only accommodations but also transportation methods and covered all expenses including insurance and meals. Our relief activities have shown that Laboratory Medicine and Medical Technologists are useful in disaster-affected area.

[Nationwide susceptibility surveillance of ciprofloxacin and various parenteral antimicrobials against bacteria isolated from patients with severe infections--third ciproxan injection special survey (2005)].

We conducted 3 nationwide surveillance studies between 2001 and 2005 at 39 participating institutions throughout Japan according to the special survey plan to investigate susceptibility to ciprofloxacin (CPFX) and various parenteral antimicrobials using clinical isolates from patients with severe infection during the reexamination period of parenteral CPFX. Results of the first special survey (2001) were already reported in this journal. The current third special survey (2005) was conducted at 34 participating institutions throughout Japan to determine susceptibility to CPFX and 22 various parenteral antimicrobials with the use of the microdilution method with respect to 1696 strains isolated and identified from various clinical specimens between January and June 2005. The results of CPFX in this survey were compared with those in the first and second special surveys. The minimum inhibitory concentration of CPFX at which 90% of isolates were susceptible (MIC90) ranged from < or =0.063 to 2 microg/mL for methicillin-susceptible Staphylococcus aureus, Streptococcus pneumoniae, Streptococcus pyogenes, Moraxella catarrhalis, Haemophilus influenzae, Klebsiella spp., Citrobacter freundii, Enterobacter spp., Proteus spp., Serratia marcescens, and Acinetobacter baumannii, revealing no marked change from results of the first and second surveys. However, the CPFX-susceptibility rate of Escherichia coli decreased in the second and third surveys compared to that in the first survey. For Morganella morganii and Pseudomonas aeruginosa, the MIC90 of CPFX tended to increase with time. The CPFX-susceptibility rates calculated from the pneumonia breakpoint were 85.2% for P. aeruginosa and 67.9% for Stenotrophomonas maltophilia. With the exception of these 2 species, major causative organisms of respiratory tract infection had susceptibility rates as high as 90% or more for CPFX, which were similar to results of the first and second special surveys. These susceptibility rates for CPFX were similar to the rates for cefozopran and imipenem. These values generally indicated favorable CPFX susceptibility testing results of major bacteria and the potent antimicrobial activity of CPFX particularly against Gram-negative bacteria. Further surveillance is required regarding the trend in susceptibility of E. coli, M. morganii, and P. aeruginosa, which tended to become less susceptible with time.

Usefulness of adult bovine serum for Helicobacter pylori culture media.

Fetal bovine serum (FBS) and adult bovine serum (BS) exhibited bactericidal activity against Helicobacter pylori at various levels, which were higher in BS than in FBS. The bactericidal activity was inactivated by heat treatment at 56 degrees C for 30 min. Our results demonstrated that heat-treated BS is a useful serum source of H. pylori culture medium.

[The combination effects of antibacterial agents against clinical isolated multiple-drug resistant Pseudomonas aeruginosa].

The effectiveness of antibacterial agents against 70 strains of clinically isolated multiple-drug resistant Pseudomonas aeruginosa (MDRP) was measured by the micro dilution method. Fifty of all strains (71%) produced metallo-beta-lactamase and the IMP-1 gene was detected by polymerase chain reaction (PCR). The MIC90 (the minimum inhibitory concentration of an antibiotic necessary to inhibit the growth of 90% of bacterial strains) values of biapenem (BIPM), meropenem (MEPM), tazobactam/piperacillin (TAZ/PIPC), sulbactam/ cefoperazone (SBT/CPZ), cefepime (CFPM), ciprofloxacin (CPFX), pazufloxacin (PZFX), amikacin (AMK) and aztreonam (AZT) were found to be 265, 512, 256, 512, 512, 64, 128, 128 and 128 microg/mL, respectively. The in vitro combination effects of antibacterial agents were examined against 62 strains of MDRP and the synergy or additive effects were evaluated by fractional inhibitory concentration (FIC) index calculated by the checkerboard method. The combination of AMK and AZT showed synergy effects on 15/59 (25.4%) strains of MDRP. The synergy and additive effects on the MDRP strains were also found by the other antibacterial agents combination such as TAZ/PIPC and AMK, CFPM and AMK, and SBT/CPZ and AZT. These results suggested the necessity of further investigation of clinical usefulness.

[Reliability of Amplicor Mycobacteria Kit for detection of Mycobacterium tuberculosis complex and Mycobacterium intracellulare: results of cooperative study among 331 laboratories in 2000].

Amplicor Mycobacterium Kit (Roch Diagnostics: Japan) is the most widely used kit in Japan for the diagnosis of mycobacteria infections, especially those caused by Mycobacterium tuberculosis, Mycobacterium avium and Mycobacterium intracellulare. We evaluated the reliability of the kit in co-operation with 331 laboratories using the kit in routine examination. We distributed specially prepared 4 test samples to each laboratories. The negative sample was NALC-NaOH treated sputum which showed "negative" when tested by this kit and positive samples were NALC-NaOH treated sputum containing M. bovis or M. intracellurare. False-positive results were reported in 6 out of 331 laboratories (1.8%) and false-negative results were reported from 7 laboratories (2.1%). (The details were 1 out of 331 labs for TB-H sample, 5 out of 331 labs for TB-L sample and 1 out of 316 in MIN sample.) Statistical significance between MWP method and COBAS method was not significant. After receiving and evaluating the test results on the 4 samples, the follow up questionnaires were sent out to 22 laboratories which reported incorrect results and low optical density (O.D.) on positive control. Results of this questionnaire suggested that it was important to follow the package insert instructions and to follow the correct procedures for PCR assay. These results suggested that Amplicor Mycobacterium Kit is reliable for rapid diagnosis of Mycobacteria infections.