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Introduction: The ability to predict which patients with a history of coronavirus disease (COVID-19) will exhibit a high antibody titer is necessary for more efficient screening of potential convalescent plasma donors. We aimed to identify factors associated with a high immunoglobulin G (IgG) titer in Japanese convalescent plasma donors after COVID-19., Methods: This cross-sectional study included volunteers undergoing screening for convalescent plasma donation after COVID-19. Serum anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) S-protein IgG antibodies were measured using a high-sensitivity chemiluminescence enzyme immunoassay., Results: IgG antibodies were measured in 581 patients, 534 of whom had full information of selected independent variables. Multiple linear regression analysis revealed that increasing age (1.037 [1,025, 1.048]), days from symptom onset to sampling (0.997 [0.995, 0.998]), fever (1.664 [1.226, 2.259]), systemic corticosteroid use during SARS-CoV-2 infection (2.382 [1.576, 3.601]), and blood type AB (1.478 [1.032, 2.117]) predict antibody titer., Conclusion: Older participants, those who experienced fever during infection, those treated with systemic corticosteroids during infection, those from whom samples were obtained earlier after symptom onset, and those with blood type AB are the best candidates for convalescent plasma donation. Therefore, these factors should be incorporated into the screening criteria for convalescent plasma donation after SARS-CoV-2 infection., (Copyright © 2021 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.)

Urinary antigen tests are a widely used rapid diagnostic method for Legionella pneumonia. However, conventional urinary antigen tests are unable to detect anything other than Legionella pneumophila serogroup 1. The Ribotest Legionella (Ribotest) can detect all serogroups by using antibodies recognizing L. pneumophila ribosomal protein L7/L12 in addition to the conventional L. pneumophila serogroup 1 lipopolysaccharide. The aim of this study was to evaluate the performance of Ribotest against conventional urinary antigen tests, including the detection of Legionellaceae other than L. pneumophila. We investigated the detection sensitivity of various kits using in-vitro culture-soluble antigen extracts of ATCC strains and 22 clinical isolates collected from multiple medical facilities in the Kinki region of Japan. For L. pneumophila serogroup 1, four kits, including Ribotest, had a detection sensitivity of 10 5  CFU/mL, with only Check Legionella having a sensitivity of 10 6  CFU/mL. L. pneumophila non-serogroup 1 and Legionellaceae of other species were undetectable by the four conventional kits, whereas Ribotest could detect them with a sensitivity of 10 5 -10 8  CFU/mL. The Ribotest was also able to detect other species such as Legionella hackeliae, Legionella feeleii, Legionella anisa, Fluoribacter bozemanae, and Fluoribacter dumoffii, but the detection sensitivity of L. hackeliae and L. feeleii was 10 8  CFU/mL, which was much lower than that of the other strains. The Ribotest has high potential to be applied as a rapid diagnostic method for pneumonia caused by other species of Legionella and Fluoribacter., (Copyright © 2021. Published by Elsevier Ltd.)

Background: The worldwide spread of organisms with antimicrobial resistance is of concern, especially the trend of significantly increasing carbapenemase-producing Enterobacterales (CPE). In this study, we investigated the annual trend of intestinal CPE carriage rates in inpatients and healthy adults in a primary care hospital in Tenri, Japan., Methods: We collected 551 samples of feces from inpatients in our institution and 936 samples from healthy people living in Tenri city from December 2012 to April 2015. All samples were cultured on MacConkey agar plates containing 4 μg/mL ceftazidime for screening test. The colonies grown on the screening medium were detected for carbapenemase genes (bla IMP-1 , bla IMP-2 , bla VIM , bla KPC , bla GES , bla NDM , and bla OXA-48 groups) by multiplex PCR, and CPE were identified by MALDI-TOF MS. Plasmid replicon typing and pulsed-field gel electrophoresis (PFGE) were performed on PCR-positive strains., Results: The CPE carriage rate was 1.6% (9/551) in the inpatient group and 0% (0/936) in the healthy adults group. The numbers of strains positive for the carbapenemase gene were 4 for Enterobacter cloacae, 2 for Klebsiella pneumoniae, 1 for Citrobacter freundii, 1 for Raoultella ornithinolytica and 1 for Escherichia coli. In all CPE strains, the carbapenemase gene was bla IMP-6 and the plasmid replicon type was IncN. The 4 E. cloacae strains showed a similar pattern in PFGE., Conclusion: In the same city in Japan, CPE intestinal carriers were detected only in the inpatient group in this study but not in a healthy adults, suggesting that the spread of asymptomatic CPE carriers was confined to inpatients., Competing Interests: Declaration of Competing Interest None., (Copyright © 2020 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.)

Obligate anaerobes exist as resident flora in various sites in humans, but they are also emphasized as endogenous causative microorganism of infections. We performed surveillance to understand the trend of drug susceptibility in obligate anaerobic bacteria in the Kinki area of Japan. In the experiment, we used 156 obligate anaerobe isolates collected from 13 institutions that participated in the Study of Bacterial Resistance Kinki Region of Japan. MALDI Biotyper was used to identify the collected strains, and among the 156 test strains, those that could be identified with an accuracy of Score Value 2.0 or more included 6 genera, 30 species, and 144 strains (Bacteroides spp. 77 strains, Parabacteroides sp. 2 strains, Prevotella spp. 29 strains, Fusobacterium spp. 14 strains, Porphyromonas spp. 2 strains, and Clostridioides difficile 20 strains), and they were assigned as subject strains for drug susceptibility testing. The drug susceptibility test was carried out by broth microdilution method using Kyokuto Opt Panel MP ANA (Kyokuto Pharmaceutical Industrial Co., Ltd., Tokyo, Japan) and judged according to CLSI criteria. As a result, Bacteroides and Parabacteroides species showed good sensitivities to tazobactam-piperacillin, imipenem, metronidazole and chloramphenicol, and low sensitivities to ampicillin, cefoperazone and vancomycin. Prevotella species showed good sensitivities to sulbactam-ampicillin, tazobactam-piperacillin, cefmetazole, imipenem, doripenem and metronidazole. Susceptibility rates to other drugs were slightly different depending on the bacterial species. Both Fusobacterium spp. and Porphyromonas spp. showed high sensitivities to many drugs. C. difficile was highly sensitive to vancomycin and metronidazole, having MIC 90 s of 0.5 μg/mL and ≤2 μg/mL, respectively., (Copyright © 2019 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.)

Carbapenemase-producing Enterobacteriaceae (CPE) are increasing worldwide. Rapid and accurate detection of CPE is necessary for appropriate antimicrobial treatment and hospital infection control. However, CPE contains some strains that are difficult to detect depending on genotype and MIC value of carbapenem, and a detection method has not been established. The recently reported modified carbapenem inactivation method (mCIM) has been developed in CLSI M100-S27 as a phenotypic technique for detecting carbapenemase activity. In the present study, we examined mCIM as a new CPE detection method using 207 Enterobacteriaceae isolates in comparison with the three existing screening methods of modified Hodge test, Carba NP test and carbapenem inactivation method and evaluated its performance. Consequently, both the sensitivity and specificity of mCIM were 100%, indicating better results than the conventional screening methods. The mCIM is a useful tool for microbiology laboratories due to its simplicity, clear criteria, cost-effectiveness and availability at any laboratory., (Copyright © 2017 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.)

The 7-valent pneumococcal conjugate vaccine (PCV7) was introduced among children in Japan in 2010. There are no long-term multicenter surveillance studies of antimicrobial resistance in S. pneumoniae before and after the introduction of PCV7. Therefore, we examined chronological trends in antimicrobial resistance among 4534 strains of S. pneumoniae isolated from both children and adults in the Kinki region of Japan during 2001-2015. High-level penicillin and third-generation cephalosporin resistance in S. pneumoniae increased among both children and adults during the period before the introduction of PCV7 (2001-2010). Besides penicillin and cephalosporin, pneumococcal carbapenem and macrolide resistance increased among children. The rate of resistance to these antibiotics was higher among children than among adults. The introduction of PCV7 decreased the rate of non-susceptibility to β-lactam antibiotics and the rate of multidrug resistant S. pneumoniae among children, but not among adults., (Copyright © 2018 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.)

The nationwide surveillance on antimicrobial susceptibility of bacterial respiratory pathogens from the patients in Japan was conducted by Japanese Society of Chemotherapy, Japanese association for infectious diseases and Japanese society for Clinical Microbiology in 2012. The isolates were collected from clinical specimens obtained from well-diagnosed adult patients with respiratory tract infections during the period between January and December in 2012 by three societies. Antimicrobial susceptibility testing was conducted at the central reference laboratory according to the method recommended by Clinical Laboratory Standard Institutes. Susceptibility testing was evaluated in 1236 strains (232 Staphylococcus aureus, 225 Streptococcus pneumoniae, 16 Streptococcus pyogenes, 231 Haemophilus influenzae, 147 Moraxella catarrhalis, 167 Klebsiella pneumoniae and 218 Pseudomonas aeruginosa). Ratio of methicillin-resistant S. aureus was 51.3%, and those of penicillin-intermediate S. pneumoniae was 0.4%. Among H. influenzae, 5.6% of them were found to be β-lactamase-producing ampicillin-resistant strains, and 37.2% to be β-lactamase-non-producing ampicillin-resistant strains. Extended spectrum β-lactamase-producing K. pneumoniae and multi-drug resistant P. aeruginosa with metallo β-lactamase were 4.2% and 3.2%, respectively. Continuous national surveillance is important to determine the actual situation of the resistance shown by bacterial respiratory pathogens to antimicrobial agents., (Copyright © 2017 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.)

Recently, carbapenemase-producing Enterobacteriaceae (CPE) have been spreading worldwide and have become a threat in healthcare systems. We investigated the isolation frequency and molecular epidemiological characteristics of CPE isolated from clinical samples collected at a primary care hospital over the four years of 2010-2013 in Japan. CPE were detected in 17 (0.34%) of 4875 isolates by the broth microdilution method, sodium mercaptoacetate inhibition test, and modified Hodge test using meropenem disks. The frequency of CPE isolates was 0.09% in 2010, 0.17% in 2011, 0.16% in 2012 and 0.82% in 2013. Isolates positive for carbapenemase included Klebsiella pneumoniae (0.92%), Escherichia coli (0.12%), Enterobacter cloacae (0.80%), Klebsiella oxytoca (0.55%), Enterobacter aerogenes (0.81%) and Proteus mirabilis (0.08%). Antimicrobial susceptibility testing showed low MICs for piperacillin-tazobactam, amikacin, ciprofloxacin and levofloxacin, and only one multidrug-resistant strain. The carbapenemase genotype of all strains was IMP-6, and 94% of the strains were simultaneous CTX-M-2 producers. Two K. pneumoniae and 3 E. coli isolates showed the same pulsed-field gel electrophoresis group. Multilocus sequence typing detected no international high-risk clone types. Plasmid replicon typing detected IncN from all CPE strains, and IncF and IncFIB were simultaneously detected in 24% and 18%, respectively. All patients with detected CPE were inpatients, and many were elderly long-term hospitalized patients or had a history of prior vancomycin or levofloxacin antibiotic administration. The rapid spread of CPE is a concern in Japan. Preventive measures must be implemented against the spread of CPE after considering the epidemiological trend of CPE detection, antibiograms, and risk factors., (Copyright © 2017. Published by Elsevier Ltd.)

Infectious diseases caused by extended-spectrum β-lactamase (ESBL)-producing Escherichia coli are prevalent because of nosocomial infection. In addition, colonization of ESBL-producing E. coli in the intestinal tract of community dwellers due to the contamination of meat or environmental water is assumed to be one of the sources, but the causes have not been clarified. To analyze these factors, we investigated the difference in clonal groups using a combination of phylogenetic groups and multilocus sequence typing of ESBL-producing E. coli, which were obtained from the feces of an inpatient group in our hospital and a community-dwelling group living in a Japanese city. The carriage rate of ESBL-producing E. coli in the inpatient group was 12.5% (32/257), similar to that of 8.5% (42/496) in the community dwellers (P = 0.082). Of the ESBL clonal groups detected from the community dwellers, 52% (22/42) were clonal groups, including D-ST1485, D-ST70, D-ST2847, B2-ST550, B2-ST3510, A-ST93, A-ST580, A-ST716 and B1-ST2787, that have not been detected from human pathogens, meat, companion animals and environmental water, whereas all clonal groups detected from the inpatients were those that had already been reported. The rate of fluoroquinolone-resistant ESBL clonal groups colonizing the intestinal tract of the inpatient group rose as the number of hospital days increased. These results indicated that different factors were related to colonization of ESBL-producing E. coli in the feces of the inpatient group and the community-dwelling group., (Copyright © 2015 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.)

With the increase in extended spectrum β-lactamase (ESBL)-producing bacteria in the community, cases are often seen in which treatment of infectious diseases with oral antimicrobial agents is difficult. Therefore, we measured the antimicrobial activities of 14 currently available oral antimicrobial agents against ESBL-producing Escherichia coli and Klebsiella pneumoniae. Based on the standard of the Clinical and Laboratory Standards Institute (CLSI), E. coli showed high susceptibility rates of 99.4% to faropenem (FRPM). In terms of fluoroquinolones, the susceptibility rate of E. coli to levofloxacin (LVFX) was low at 32.2%, whereas it showed a good susceptibility rate of 93.1% to sitafloxacin (STFX). With respect to other antimicrobial agents, susceptibility rates to fosfomycin (FOM) and colistin (CL) were more than 90% each, whereas rates of the two antimicrobial agents expected as therapeutic agents, minocycline (MINO) and sulfamethoxazole-trimethoprim (ST), were low at 62.4% and 44.3%, respectively. Based on the CLSI standard, K. pneumoniae showed high susceptibility rates to ceftibuten (CETB) (91.89%), LVFX (86.49%), and STFX (94.6%), indicating that K. pneumoniae showed higher rates than those of E. coli, particularly to fluoroquinolones. Comparison of susceptibility rates according to E. coli genotype showed that many antimicrobial agents existed to which the CTX-M-9 group showed high susceptibility rates. However, there were many agents to which the CTX-M-1 group showed low susceptibility rates, particularly to CETB (51.1%) and LVFX (17.0%). Although there was no significant difference by genotype between FRPM, STFX, and FOM, a significant difference was observed between LVFX, MINO, and ST. Antibiotic-resistant bacteria with highly pathogenic strains have spread in the community, appropriate use of oral antimicrobial agents is required., (Copyright © 2013 Japanese Society of Chemotherapy and the Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.)