| Autor: |
Zaborskyte, Greta, Andersen, Jens Bo, Kragh, Kasper Nørskov, Ciofu, Oana |
| Zdroj: |
Antimicrobial Agents and Chemotherapy; February 2017, Vol. 61 Issue: 3 |
| Abstrakt: |
ABSTRACTBiofilm infections caused by Pseudomonas aeruginosaare frequently treated with ciprofloxacin (CIP); however, resistance rapidly develops. One of the primary resistance mechanisms is the overexpression of the MexCD-OprJ pump due to a mutation in nfxB, encoding the transcriptional repressor of this pump. The aim of this study was to investigate the effect of subinhibitory concentrations of CIP on the occurrence of nfxBmutants in the wild-type PAO1 flow cell biofilm model. For this purpose, we constructed fluorescent reporter strains (PAO1 background) with an mCherrytag for constitutive red fluorescence and chromosomal transcriptional fusion between the PmexCDpromoter and gfpleading to green fluorescence upon mutation of nfxB. We observed a rapid development of nfxBmutants by live confocal laser scanning microscopy (CLSM) imaging of the flow cell biofilm (reaching 80 to 90% of the whole population) when treated with 1/10 minimal biofilm inhibitory concentration of CIP for 24 h and 96 h. Based on the observed developmental stages, we propose that nfxBmutants emerged de novoin the biofilm during CIP treatment from filamentous cells, which might have arisen due to the stress responses induced by CIP. Identical nfxBmutations were found in fluorescent colonies from the same flow cell biofilm, especially in 24-h biofilms, suggesting selection and clonal expansion of the mutants during biofilm growth. Our findings point at the significant role of high-enough antibiotic dosages or appropriate combination therapy to avoid the emergence of resistant mutants in biofilms. |
| Databáze: |
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