Department of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy.
MicroMiB Biorepository, University of Milano-Bicocca, Associated Member of the JRU MIRRI-IT, Via Cadore, 20900 Monza, Italy.
Int J Environ Res Public Health. 2021 Sep 4;18(17):9352. doi: 10.3390/ijerph18179352.
is ubiquitous in aquatic environments and responsible for severe pneumonia in humans through inhalation of aerosol containing spp. Macrolides and fluoroquinolones are frequently used antimicrobials, but treatment failures are increasingly being reported. As susceptibility testing is not routinely performed, this study aimed to determine the minimum inhibitory concentrations (MICs) on 58 environmental strains (24 of serogroup 1 and 34 of non-serogroup 1) isolated in Northern Italy. MICs of azithromycin, erythromycin, ciprofloxacin, levofloxacin, and rifampicin were determined by the microdilution method using buffered yeast extract broth supplemented with α-ketoglutarate (BYEα). Seventy-five percent of isolates showed MIC values below the tentative highest MICs indicated by the European Committee on Antimicrobial Susceptibility Testing (EUCAST); rifampicin was the most active agent with MIC values below 0.008 mg/L. Interestingly, one isolate was tested and found to be PCR-positive for the azithromycin LpeAB active efflux system, further confirmed by the reserpine/resazurin microtiter assay. In conclusion, this study has provided additional susceptibility data for environmental isolates from Northern Italy demonstrating, in general, low MICs values for the tested antimicrobials, although one strain tested was shown to possess the LpeAB resistance determinant, indicating that future surveillance studies are warranted.
在水生环境中普遍存在，通过吸入含有 spp. 的气溶胶，导致人类发生严重肺炎。大环内酯类和氟喹诺酮类是常用的抗菌药物，但越来越多的治疗失败报告。由于未常规进行药敏试验，本研究旨在确定意大利北部分离的 58 株环境 株（1 型血清群 24 株和非 1 型血清群 34 株）的最低抑菌浓度（MIC）。采用含α-酮戊二酸（BYEα）缓冲酵母提取物肉汤的微量稀释法测定阿奇霉素、红霉素、环丙沙星、左氧氟沙星和利福平的 MIC。75%的 分离株的 MIC 值低于欧洲抗菌药物敏感性试验委员会（EUCAST）暂定的最高 MIC 值；利福平是最有效的药物，MIC 值低于 0.008 mg/L。有趣的是，一个分离株经 PCR 检测为阿奇霉素 LpeAB 主动外排系统阳性，并通过利血平和 Resazurin 微量滴定法进一步证实。总之，本研究为意大利北部的环境 分离株提供了额外的药敏数据，表明大多数测试的抗菌药物的 MIC 值较低，但有一株分离株被证明携带 LpeAB 耐药决定因子，表明需要进行未来的监测研究。
