Department of Molecular Medicine, "Sapienza" University Rome, Rome, Italy.
Department of Public Health and Infectious Diseases, "Sapienza" University Rome, Italy.
J Glob Antimicrob Resist. 2020 Mar;20:328-331. doi: 10.1016/j.jgar.2020.02.014. Epub 2020 Feb 24.
Pseudomonas aeruginosa is the most frequent infectious agent in cystic fibrosis patients. P. aeruginosa resistance to first line antibiotics limits therapeutic options, but the therapeutic potential of older generation antibiotics, such as fosfomycin is under investigation. Fosfomycin does not belong to any other antibiotic class and acts by inhibiting the biosynthesis of the bacterial cell wall during the initial phases. A major problem for the use of fosfomycin against P. aeruginosa is the absence of a clinical breakpoint, the last one of 32 μg/mL was proposed in 2013 by the CA-SFM (Comité de l'Antibiogramme de la Société Française de Microbiologie).
Sixty-one strains of P. aeruginosa (thirty mucoid and thirty-one non mucoid) were collected from respiratory samples of cystic fibrosis patients. All isolates were identified by MALDI-TOF (Bruker, Bremen, Germany). Fosfomycin MICs against P. aeruginosa were measured using an automated system and confirmed by the gold standard method.
There was no significant difference between mucoid and non-mucoid strains. MIC distribution and susceptibility rates were obtained by agar dilution method and from this data we measured MIC50 and MIC90 which were equal to 32 μg/mL and 64 μg/mL, respectively. From automated method results we measured a very major error (VME), major error (ME) and categorical agreement (CA) which were equal to 0%, 11% and 89%, respectively. Comparing automated and agar dilution methods, a Cohen's kappa equal to 73% (0.726) was measured.
Our data suggest that fosfomycin has good effect against mucoid and non-mucoid strains of P. aeruginosa and automated systems can be implemented in clinical microbiology laboratories to assess fosfomycin with rapid and reproducible results.
铜绿假单胞菌是囊性纤维化患者最常见的感染病原体。铜绿假单胞菌对一线抗生素的耐药性限制了治疗选择，但老一代抗生素（如磷霉素）的治疗潜力正在研究中。磷霉素不属于任何其他抗生素类别，其作用机制是在初始阶段抑制细菌细胞壁的生物合成。使用磷霉素对抗铜绿假单胞菌的一个主要问题是缺乏临床断点，最后一个断点是 2013 年由 CA-SFM（法国微生物学会抗生素委员会）提出的 32μg/ml。
从囊性纤维化患者的呼吸道样本中收集了 61 株铜绿假单胞菌（30 株粘液型和 31 株非粘液型）。所有分离株均通过基质辅助激光解吸电离飞行时间质谱（Bruker，不来梅，德国）进行鉴定。使用自动化系统测量磷霉素对铜绿假单胞菌的 MIC，并通过金标准方法进行确认。
粘液型和非粘液型菌株之间无显著差异。琼脂稀释法和从该数据中获得 MIC 分布和药敏率，我们测量的 MIC50 和 MIC90 分别为 32μg/ml 和 64μg/ml。从自动化方法的结果中，我们测量到一个非常大的错误（VME）、大错误（ME）和分类一致性（CA），分别为 0%、11%和 89%。比较自动化和琼脂稀释方法，测得的 Cohen's kappa 为 73%（0.726）。
我们的数据表明，磷霉素对粘液型和非粘液型铜绿假单胞菌有良好的疗效，自动化系统可以在临床微生物学实验室中实施，以快速、可重复的结果评估磷霉素。
