The Japanese Journal of Antibiotics
Online ISSN : 2186-5477
Print ISSN : 0368-2781
ISSN-L : 0368-2781
Volume 73, Issue 1
Displaying 1-4 of 4 articles from this issue
Original Articles
  • Yuko Sagane, Kiyoko Uneno, Takuji Fujita, Nobuhisa Fukuda, Takuya Maed ...
    2020 Volume 73 Issue 1 Pages 1-8
    Published: March 25, 2020
    Released on J-STAGE: June 20, 2024

    We investigated the detection rate of group B streptococci with reduced penicillin susceptibility (PRGBS) in the Kinki region of Japan from 2010 to 2014. We isolated 10,797 samples of group B Streptococcus (GBS; Streptococcus agalactiae) strains from clinical materials submitted to our laboratory by 427 medical institutions for identification of bacteria during this 4-year period. As a result, 506 strains of PRGBS were detected. The detection rates of PRGBS strains in the respiratory tract, blood culture, and GBS screening of vaginal swabs were 5.8% (500/8590), 2.4% (6/250), and 0% (0/1957), respectively. Furthermore, we randomly extracted 125 strains of PRGBS and 307 strains of penicillin-sensitive GBS (PSGBS) and investigated rates of antimicrobial susceptibility, and capsular antigen serotype. The antimicrobial susceptibility rate of PRGBS was low except for vancomycin and meropenem, whereas that for PSGBS was high for all drugs. We also investigated the relation between the capsular antigen serotype by material and detection frequency. From blood cultures, the most frequent serotype in 6 strains of PRGBS was III (50.0%), followed by Ia (33.3%) and Ib (16.7%), and that in 80 strains of PSGBS was Ib (40.5%), followed by III (19.0%) Ia and VI (13.9%). From the respiratory tract, the most frequent serotype in 119 strains of PRGBS was III (53.7%), followed by Ib (25.6%) and Ia (13.2%), and that in 96 strains of PSGBS was VI (34.7%), followed by III (29.5%) and Ib (24.2%). From GBS screening of vaginal swabs, the most frequent serotype in 131 strains of PSGBS was Ib (24.4%), followed by III (22.9%), Ia (22.1%), and II (13.7%), whereas PRGBS was not detected at all. We consider monitoring of future trends to be necessary from the viewpoints of the control of medically related infections and mother-to-child infections.

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  • Yoshimi Oonishi, Harumi Hisada, Takumi Kadota, Yoshiko Fukuda, Tomoaki ...
    2020 Volume 73 Issue 1 Pages 9-17
    Published: March 25, 2020
    Released on J-STAGE: June 20, 2024

    Antibacterial activities of garenoxacin (GRNX), levofloxacin (LVFX) and lascufloxacin (LSFX) against Streptococcus pneumoniae isolated from respiratory tract infection between 2016 and 2017 were measured. Based on pharmacokinetics–pharmacodynamics theory, we investigated the predicted efficacy and resistant selectivity of oral quinolones using the Monte Carlo simulation method. Mutant prevention concentration (MPC), which is the minimum concentration restricting the selection of resistance was measured.

    MIC90 of GRNX against 28 strains of S. pneumoniae was 0.0625 μg/mL, being the lowest among quinolones tested, followed by 0.125 μg/mL of LSFX, and 1 μg/mL of LVFX.

    The probability of target attainment at free-drug area under the curve (fAUC, f: ratio of protein-unbound)/MIC ratio (fAUC/MIC)=30 was calculated, and was assessed as the efficacy. The probabilities of GRNX, LSFX and LVFX were 100, 76.9, and 62.8%, respectively. At fCmax/ MIC=5, considered target value of resistance prevention, GRNX, LVFX and LSFX showed a probability of 100, 60.4, and 0.31%, respectively.

    MPC90 of GRNX, LSFX and LVFX were 0.25 μg/mL, 2 μg/mL and 4 μg/mL, respectively, and GRNX showed the lowest MPC90 among quinolones tested. Mutant selection window (MSW) of GRNX, LSFX and LVFX were 0.19 μg/mL, 1.9 μg/mL and 3.0 μg/mL, respectively. GRNX had a narrower MSW than LSFX and LVFX.

    The findings of this study suggest that the efficacy and resistant selectivity differ among oral quinolones, and GRNX is useful in terms of efficacy and resistant prevention.

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