Borisova Dayana, Strateva Tanya, Dimov Svetoslav G, Atanassova Borjana, Paunova-Krasteva Tsvetelina, Topouzova-Hristova Tanya, Danova Svetla T, Tropcheva Rositsa, Stoitsova Stoyanka
The Stephan Angeloff Institute of Microbiology, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 25, 1113 Sofia, Bulgaria.
Department of Medical Microbiology "Corr. Mem. Prof. Ivan Mitov, MD, DMSc", Faculty of Medicine, Medical University of Sofia, 2 Zdrave Str., 1431 Sofia, Bulgaria.
Microorganisms. 2025 Mar 24;13(4):730. doi: 10.3390/microorganisms13040730.
This study examines the impact of inhaled tobramycin therapy on the within-host changes in strains isolated from Bulgarian patients with CF prior to and post treatment. Genotypic comparison by RAPD-PCR indicated that most of the pre-treatment isolates had a high similarity and were genetically comparatively close to strains from other countries with known increased morbidity or treatment requirements. Most of the post-treatment isolates were, however, genetically distant from their pre-treatment counterparts, showing genotypic diversification after the treatment. Phenotypic comparisons showed a lower ODmax reached during groswth and an increased lag-time in the post-treatment isolates. All strains were capable of invasion and intracellular reproduction within A549 cultured cells. The addition of sub-inhibitory amounts (1/4 or 1/2 MIC) of tobramycin during growth showed the higher relative fitness (as a percentage of the untreated control) of the post-treatment strains. The effects of sub-MICs on biofilm growth did not show such a pronounced trend. However, when a resazurin-based viability test was applied, the advantage of the post-treatment strains was confirmed for both broth and biofilm cultures. In spite of that, according to the determined MIC values, all isolates were tobramycin-sensitive, and the data from this study imply the development of tolerance to the antibiotic in the strains that survived the treatment.
本研究考察了吸入用妥布霉素治疗对保加利亚囊性纤维化（CF）患者治疗前后体内分离菌株变化的影响。随机扩增多态性DNA聚合酶链反应（RAPD-PCR）的基因型比较表明，大多数治疗前分离株具有高度相似性，并且在基因上与来自其他已知发病率增加或有治疗需求国家的菌株相对接近。然而，大多数治疗后分离株在基因上与其治疗前的对应株相距较远，显示出治疗后基因型的多样化。表型比较显示，治疗后分离株在生长过程中达到的最大光密度（ODmax）较低，延迟期延长。所有菌株都能够在A549培养细胞内侵袭和进行细胞内繁殖。在生长过程中添加亚抑菌浓度（1/4或1/2最低抑菌浓度[MIC]）的妥布霉素显示，治疗后菌株具有更高的相对适应性（相对于未处理对照的百分比）。亚抑菌浓度对生物膜生长的影响未显示出如此明显的趋势。然而，当应用基于刃天青的活力试验时，治疗后菌株在肉汤和生物膜培养中均具有优势。尽管如此，根据所测定的MIC值，所有分离株对妥布霉素均敏感，本研究数据表明，在治疗后存活的菌株中出现了对抗生素的耐受性。
