Department of Infectious Diseases, National Institute of Health Doctor Ricardo Jorge (INSA), Lisbon, Portugal.
ECDC Fellowship Programme, Public Health Microbiology Path (EUPHEM), European Centre for Disease Prevention and Control (ECDC), Stockholm, Sweden.
Eur J Clin Microbiol Infect Dis. 2024 Jul;43(7):1297-1308. doi: 10.1007/s10096-024-04789-9. Epub 2024 May 2.
Although not fully investigated, studies show that Legionella pneumophila can develop antibiotic resistance. As there is limited data available for Portugal, we determined the antibiotic susceptibility profile of Portuguese L. pneumophila serogroup 1 (LpnSg1) isolates against antibiotics used in the clinical practice in Portugal.
Minimum inhibitory concentrations (MICs) were determined for LpnSg1 clinical (n = 100) and related environmental (n = 7) isolates, collected between 2006-2022 in the context of the National Legionnaire´s Disease Surveillance Programme, against azithromycin, clarithromycin, erythromycin, levofloxacin, ciprofloxacin, moxifloxacin, rifampicin, doxycycline, tigecycline, and amoxicillin/clavulanic acid, using three different assays. Isolates were also PCR-screened for the presence of the lpeAB gene.
Twelve isolates had azithromycin MICs above the EUCAST tentative highest WT MIC, 9 of which were lpeAB negative; for erythromycin and clarithromycin, all isolates tested within the susceptible range. The number of isolates with MICs above the tentative highest WT MIC for the remaining antibiotics was: ciprofloxacin: 7; levofloxacin: 17; moxifloxacin: 8; rifampicin: 11; doxycycline: 82; tigecycline: 4. EUCAST breakpoints are not available for amoxicillin/clavulanic acid. We estimated the ECOFFs and one isolate had a MIC eightfold higher than the E-test ECOFF. Additionally, a clinical isolate generated three colonies growing on the E-test inhibition zone that resulted in MICs fourfold higher than for the parental isolate.
We report, for the first time, elevated MICs against first-line and other antibiotics (including azithromycin, fluoroquinolones and amoxicillin/clavulanic acid commonly used to treat pneumonia patients in Portugal) in Portuguese L. pneumophila strains. Results point towards decreased susceptibility in circulating strains, justifying further investigation.
虽然尚未充分研究，但有研究表明嗜肺军团菌可能会产生抗生素耐药性。由于葡萄牙的相关数据有限，我们确定了葡萄牙嗜肺军团菌血清群 1（LpnSg1）分离株对抗生素的药敏谱，这些抗生素在葡萄牙的临床实践中被使用。
我们使用三种不同的方法，测定了 2006 年至 2022 年间国家军团病监测计划收集的临床（n=100）和相关环境（n=7）LpnSg1 分离株对阿奇霉素、克拉霉素、红霉素、左氧氟沙星、环丙沙星、莫西沙星、利福平、多西环素、替加环素和阿莫西林/克拉维酸的最低抑菌浓度（MIC），并对 lpeAB 基因进行 PCR 筛查。
12 株分离株的阿奇霉素 MIC 高于欧盟药敏试验暂定最高 WT MIC，其中 9 株为 lpeAB 阴性；红霉素和克拉霉素的所有分离株均在敏感范围内。其余抗生素的 MIC 高于暂定最高 WT MIC 的分离株数量为：环丙沙星：7 株；左氧氟沙星：17 株；莫西沙星：8 株；利福平：11 株；多西环素：82 株；替加环素：4 株。尚未为阿莫西林/克拉维酸建立欧盟药敏试验的折点。我们估计了 ECOFFs，一个分离株的 MIC 是 E 试验 ECOFF 的 8 倍。此外，一个临床分离株在 E 试验抑菌圈上生成了 3 个菌落，导致 MIC 比亲本分离株高 4 倍。
我们首次报道了葡萄牙嗜肺军团菌菌株对一线抗生素和其他抗生素（包括阿奇霉素、氟喹诺酮类和阿莫西林/克拉维酸，这些抗生素常用于治疗葡萄牙肺炎患者）的 MIC 升高。结果表明循环菌株的敏感性降低，有理由进一步调查。
