ABSTRACT
(1)
Background:
Disinfection of
medical devices designed for clinical use associated or not with the growing area of
tissue engineering is an urgent need. However, traditional
disinfection methods are not always suitable for some
biomaterials, especially those sensitive to chemical, thermal, or
radiation. Therefore, the objective of this study was to evaluate the minimal concentration of
ozone gas (O3) necessary to control and kill a set of sensitive or multi-resistant Gram-positive and
Gram-negative bacteria. The
cell viability,
membrane permeability, and the levels of reactive intracellular
oxygen (ROS) species were also investigated; (2) Material and
Methods:
Four standard
strains and a clinical MDR
strain were exposed to low doses of
ozone at different concentrations and times. Bacterial inactivation (cultivability,
membrane damage) was investigated using colony counts, resazurin as a metabolic
indicator, and
propidium iodide (PI). A
fluorescent probe (H2DCFDA) was used for the ROS analyses; (3)
Results:
No reduction in the count colony was detected after O3 exposure compared to the
control group. However, the
cell viability of E. coli (30%), P. aeruginosa (25%), and A. baumannii (15%) was reduced considerably. The bacterial
membrane of all
strains was not affected by O3 but presented a significant increase of ROS in E. coli (90 ± 14%), P. aeruginosa (62.5 ± 19%), and A. baumanni (52.6 ± 5%); (4)
Conclusion:
Low doses of
ozone were able to interfere in the
cell viability of most
strains studied, and although it does not cause damage to the bacterial
membrane, increased levels of reactive ROS are responsible for causing a detrimental effect in the
lipids,
proteins, and
DNA metabolism.
