Department of Infectious Diseases, Medical Microbiology and Hygiene, Heidelberg University Hospital, 69120, Heidelberg, Germany.
Laboratory Enders and Partners, 70193, Stuttgart, Germany.
Antimicrob Resist Infect Control. 2020 Dec 9;9(1):197. doi: 10.1186/s13756-020-00859-7.
Long-term treatment with azithromycin is a therapeutic option in Cystic Fibrosis (CF) patients chronically infected with P. aeruginosa. It was recently shown that azithromycin has direct antimicrobial activity when P. aeruginosa isolates are tested in Roswell Park Memorial Institute medium supplemented with fetal calf serum (RPMI 1640/FCS) by broth microdilution. We now investigated whether (i) azithromycin might also be active against multidrug resistant (MDR) P. aeruginosa isolated from CF patients and (ii) how in vitro sensitivity assays perform in synthetic cystic fibrosis sputum medium (SCFM), a medium that mimics the particular CF airway environment. In 17 (59%) out of 29 MDR P. aeruginosa CF isolates MICs for azithromycin ranged between 0.25 and 8 μg/ml and 12 isolates (41%) showed a MIC ≥512 μg/ml when measured in RPMI/FCS. In contrast, MICs were ≥ 256 μg/ml for all P. aeruginosa MDR isolates when tested in either SCFM or in conventional cation-adjusted Mueller Hinton Broth. High MIC values observed in CF adapted medium SCFM for both PAO1 and MDR P. aeruginosa CF isolates, as opposed to findings in RPMI, argue against routine azithromycin MIC testing of CF isolates.
长期使用阿奇霉素治疗是慢性铜绿假单胞菌感染囊性纤维化（CF）患者的一种治疗选择。最近的研究表明，当在含有胎牛血清（RPMI 1640/FCS）的罗氏培养基中通过肉汤微量稀释法对铜绿假单胞菌分离株进行测试时，阿奇霉素具有直接的抗菌活性。我们现在研究了（i）阿奇霉素是否也可能对来自 CF 患者的多药耐药（MDR）铜绿假单胞菌有效，以及（ii）体外药敏试验在合成囊性纤维化痰培养基（SCFM）中的表现如何，该培养基模拟了特定的 CF 气道环境。在 29 株 MDR 铜绿假单胞菌 CF 分离株中，有 17 株（59%）的阿奇霉素 MIC 范围在 0.25 至 8μg/ml 之间，而 12 株（41%）在 RPMI/FCS 中检测时 MIC 为≥512μg/ml。相比之下，当在 SCFM 或常规阳离子调整的 Mueller Hinton 肉汤中测试时，所有 MDR 铜绿假单胞菌 CF 分离株的 MIC 均≥256μg/ml。在 CF 适应培养基 SCFM 中观察到的高 MIC 值，与在 RPMI 中的结果相反，表明不应常规对 CF 分离株进行阿奇霉素 MIC 测试。
