Diversification of <i>Pseudomonas aeruginosa</i> After Inhaled Tobramycin Therapy of Cystic Fibrosis Patients: Genotypic and Phenotypic Characteristics of Paired Pre- and Post-Treatment Isolates
This study examines the impact of inhaled tobramycin therapy on the within-host changes in <i>P. aeruginosa</i> 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 simi...
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| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-03-01
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| Series: | Microorganisms |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2076-2607/13/4/730 |
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| Summary: | This study examines the impact of inhaled tobramycin therapy on the within-host changes in <i>P. aeruginosa</i> 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. |
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| ISSN: | 2076-2607 |