BackgroundWe investigate the evolving molecular epidemiology of metallo-β-lactamase (MBL)-producing Pseudomonas aeruginosa isolates collected in a 100 institution, nationwide surveillance study in Japan from 2004 to 2006.ResultsMBL-producers were detected in 23/996 isolates (2.3%) in 2004 and 21/992 (2.1%) in 2006. Antimicrobial resistance (specifically, carbapenem resistance) rates between two periods did not differ significantly. MBL-producers were more prevalent in urinary tract isolates. blaIMP-1 group was the most predominant (38 isolates, 80%), followed by 3 blaIMP-7, 2 blaIMP-11 group, and 1 blaVIM-1. All MBL genes were identified in 16 different class 1 integrons, most of which were novel to INTEGRALL database. A total of 17 isolates of sequence type (ST) 235, a recognized worldwide drug-resistant lineage, were distributed in 5 geographic regions across Japan. ST235 isolates included a sublineage associated with In113-like integron. ST357 was identified in 14 isolates, 9 of which harboring a sole blaIMP-1 gene cassette (In994) were recovered from Chugoku region in 2004. ST357 isolates with blaIMP-11 group or ST235 with blaIMP-7 emerged in 2006. We also report for the first time the presence of novel fosI gene cassette in strains other than Mycobacterium spp.ConclusionsOur data give an important “snapshot” of the molecular characteristics and dynamics of MBL-producing lineages in P. aeruginosa in Japan. The significant association of specific genotypes and integrons implies that dissemination and transmission of the preexisting resistant lineage, rather than horizontal gene transfer in situ, might largely explain their endemicity.

ME1071, a maleic acid derivative, is a novel specific inhibitor for metallo-␤-lactamases (MBL). In this study, the potentiation of ME1071 in combination with several ␤-lactams was evaluated using MBL-producing Pseudomonas aeruginosa isolates. The rates of susceptibility of MBL producers to carbapenems (imipenem, biapenem, and doripenem) and ceftazidime were increased by 8 to 27% in the presence of 32 g/ml of ME1071. The corresponding resistance rates were decreased by 13 to 46%, respectively. On the other hand, ME1071 showed weaker or no potentiation with non-MBL producers. The K i value of ME1071 for IMP-1 was 0.4 M, significantly lower than the K m values of carbapenems for the IMP-1 enzyme. On the other hand, the K i value of ME1071 for VIM-2 was 120 M, higher than the K m values of carbapenems for the VIM-2 enzyme. Results of this study indicate that ME1071 can potentiate the activity of ceftazidime and carbapenems against MBL-producing strains of P. aeruginosa.

This is the first confirmed report of terbinafine low susceptibility Trichophyton rubrum, BGUTR13, in Japan collected from the whole sole of the elderly over 65s with cotton swab sampling method at the special nursing care-home in 2016. We revealed BGUTR13 showed low susceptibility MIC, >128 µg/mL against terbinafine. But, BGUTR13 exhibited normal susceptibility to itraconazole, did not showed cross-resistance. Also, the squalene epoxidase gene of terbinafine low susceptibility strain BGUTR13 which is the target of terbinafine contained newly confirmed one mismatch. We suggested the possibility that the resistance mechanism of terbinafine low susceptibility strains is due to the loss of sensitivity of squalene epoxidase inhibitors and does not affect antifungal drugs with other different mechanisms of action.

どに感染する (1, 2)。白癬の中でも，足部(足底部や 趾間部)に生じる白癬を足白癬と呼び，その主な原 因 菌 は Trichophyton rubrum (T. rubrum) や Trichophyton mentagrophytes (T. mentagrophytes) で，最も高頻度に分 離される皮膚糸状菌は T. rubrum である (2)。 本邦において足白癬や爪白癬の罹患率は非常に高く， 高温多湿や共同浴場利用等などの環境的または文化的要 因が関与するとも報告されている (3, 4)。足白癬及び爪 白癬への注目度は本邦において高く，今日まで白癬に対 する多くの疫学調査が行われてきた。Japan foot week 研 究会が行った疫学調査は，皮膚科外来患者の 40% が足

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