Increased Mutability of Staphylococci in Biofilms as a Consequence of Oxidative StressReportar como inadecuado




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Objectives

To investigate the development of mutational resistance to antibiotics in staphylococcal biofilms.

Methods

Mutation frequencies to resistance against mupirocin and rifampicin were determined for planktonic cultures and for biofilms generated using either a novel static biofilm model or by continuous flow. DNA microarray analysis was performed to detect differences in transcriptional profiles between planktonic and biofilm cultures.

Results

The mutability of biofilm cultures increased up to 60-fold and 4-fold for S. aureus and S. epidermidis, respectively, compared with planktonic cultures. Incorporation of antioxidants into S. aureus biofilms reduced mutation frequencies, indicating that increased oxidative stress underlies the heightened mutability. Transcriptional profiling of early biofilm cultures revealed up-regulation of the superoxide dismutase gene, sodA, also suggestive of enhanced oxidative stress in these cultures. The addition of catalase to biofilms of S. aureus SH1000 reduced mutation frequencies, a finding which implicated hydrogen peroxide in increased biofilm mutability. However, catalase had no effect on biofilm mutability in S. aureus UAMS-1, suggesting that there is more than one mechanism by which the mutability of staphylococci may increase during the biofilm mode of growth.

Conclusion

Our findings suggest that biofilms represent an enriched source of mutational resistance to antibiotics in the staphylococci.



Autor: Victoria J. Ryder, Ian Chopra, Alex J. O’Neill

Fuente: http://plos.srce.hr/



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