Department of Internal Medicine, Infectious Diseases, University Hospital Frankfurt, Goethe University, Frankfurt am Main, Germany.
German Center for Infection Research, Research Center Borstel, Borstel, Germany; Molecular and Experimental Mycobacteriology, Research Center Borstel, Borstel, Germany; National and WHO Supranational Reference Center for Mycobacteria, Research Center Borstel, Borstel, Germany.
Int J Infect Dis. 2020 Apr;93:320-328. doi: 10.1016/j.ijid.2020.02.059. Epub 2020 Mar 5.
Phenotypic (Sensititre Myco, pDST) and genotypic drug susceptibility testing (GenoType NTM DR, gDST) in M. avium complex (MAC) have become available as standardized assays, but comparable data is needed. This study aimed to investigate the phenotypic and genotypic drug susceptibility patterns in MAC clinical isolates.
Overall, 98 isolates from 85 patients were included. pDST and gDST were performed on all isolates and results compared regarding specificity and sensitivity using pDST as a reference method. The impact of drug instability on pDST results was studied using a biological assay over 14 days. In addition, the evolution of antimicrobial resistance was investigated in sequential isolates of 13 patients.
Macrolide resistance was rare, 1.2% (95% CI 0.7-7.3) of isolates in the base cohort. No aminoglycoside resistances were found, but 14.1% of the studied isolates (95% CI 7.8-23.8) showed intermediate susceptibility. The GenoType NTM DR identified two out of four macrolide-resistant isolates. Antibiotic stability was demonstrated to be poor in rifampicin, rifabutin, and doxycycylin.
pDST results in NTM for unstable antibiotics must be interpreted with care. A combination of pDST and gDST will be useful for the guidance of antimicrobial therapy in MAC-disease.
在 MAC 临床分离株中，表型（Sensititre Myco，pDST）和基因型药物敏感性测试（GenoType NTM DR，gDST）已成为标准化检测方法，但需要进行比较。本研究旨在调查 MAC 临床分离株的表型和基因型药物敏感性模式。
共纳入 85 例患者的 98 株分离株。对所有分离株进行 pDST 和 gDST，并使用 pDST 作为参考方法比较特异性和敏感性。通过 14 天的生物测定研究药物不稳定性对 pDST 结果的影响。此外，还对 13 例患者的连续分离株进行了抗菌药物耐药性的演变研究。
大环内酯类耐药罕见，基础队列中 1.2%（95%CI0.7-7.3）的分离株耐药。未发现氨基糖苷类耐药，但研究的 14.1%（95%CI7.8-23.8）的分离株显示中度敏感性。GenoType NTM DR 鉴定出 4 株大环内酯类耐药分离株中的 2 株。利福平、利福布汀和强力霉素的抗生素稳定性较差。
对于不稳定抗生素的 NTM 药敏试验结果必须谨慎解释。pDST 和 gDST 的联合应用将有助于 MAC 疾病的抗菌治疗指导。
