Introduction: S. epidermidis is one of the main causes of nosocomial infections associated with the
use of medical devices, due to its ubiquitous presence in human skin and mucosae and capacity to form
biofilms. Biofilms are a major concern in healthcare systems, since they present higher antimicrobial
tolerance and ability to evade host immune defenses, leading to recurrent and relapsing infections.
Moreover, the presence of dormant bacteria in biofilms increases their pathogenicity, by decreasing the
effectiveness of both host immune response and antimicrobial therapy.
Hypothesis and aims: It was earlier found that a gene encoding a protein of the mazEF complex was
upregulated in S. epidermidis biofilms with induced dormancy. Herein, we proposed to study the role
of mazEF system in S. epidermidis biofilms dormancy.
Methodology: S. epidermidis strain 1457 was used to construct a mazEF mutant and its respective
complemented strain. Then, we studied the influence of mazEF in biofilms dormancy, by assessing the
number of viable and culturable cells and the optical density (OD) of the biofilms, under induced (excess
glucose) or prevented (addition of MgCl2) dormancy conditions.
Results: All S. epidermidis populations tested (wild type, mazEF mutant and complemented strains)
showed a higher ratio of cultivable/live cells when dormancy was prevented, comparing to the dormant
state. The mutant strain showed the higher ratio of cultivable/live cells in the dormancy state.
Conclusion: Dormancy affects the number of cultivable cells in biofilms, despite maintaining the
number of total cells of the biofilm, as well as its OD. MazEF seems to impact biofilm dormancy, since
the most significant difference in the number of cultivable cells between the two conditions was found
in the mutant strain.info:eu-repo/semantics/publishedVersio
