Staphylococcus aureus Biofilm Formation and Inhibition - Antibiofilm Agents: From Diagnosis to Treatment and Prevention - page 240

biofilm assays to take this into account will be important to properly assess the
efficacy of new anti-biofilm therapies. Additionally, there should be consideration
of other surfaces for S. aureus biofilm formation. This pathogen has the ability to
bind human mucin proteins that are abundant in many host environments (Shuter
et al. 1996 ), and mucin has been shown to enhance biofilm capacity and antimi-
crobial tolerance of other lung pathogens (Landry et al. 2006 ). S. aureus can even
grow on some of the sugars that would be liberated from glycosylated mucins in
such an environment (Olson et al. 2013a ), and growth on sugars often favors biofilm
formation due to acid secretion (Boles and Horswill 2008 ). There also needs to be
consideration for the tremendous differences across S. aureus strain types in terms
of biofilm capacity, and there should be attempts to assess effectiveness across
various biofilm techniques, such as flow cells or the newer microfluidic-based
methods (Moormeier et al. 2013 ). The simple microtiter plastic attachment assays
are useful as an investigation starting point, but they do not always have the
robustness and consistency to make broad conclusions about S. aureus biofilms.
Beyond assays, there are other factors that should be taken into account as the
S. aureus biofilm field advances. For instance, there are few definitions of what
constitutes a S. aureus biofilm. Currently, a structure has to “look like a biofilm” by
some type of microscopy method and display enhanced resistance to antimicro-
bials. There are no uniform dimensions (size, thickness) or other standards that can
be relied upon as a general biofilm definition. As the field progresses, there should
be consideration for more standardization in S. aureus biofilm research and defining
these structures in a rigorous manner for study comparisons across the field. If
researchers had key biomarkers of biofilms to track, such as a gene or secreted
product that is only induced in a biofilm in a conserved manner, there would be
tremendous benefit to monitoring this biomarker during treatment tests in vitro or
in vivo.
In this review, natural mechanisms of S. aureus biofilm dispersal were covered,
along with many enzyme and small-molecule treatment approaches. The field is
evolving quickly and many alternative and creative strategies to prevent S. aureus
biofilms are under investigation. Phage therapy is one example that is currently
being explored to prevent or eliminate established biofilms (Kelly et al. 2012 ).
Electrical currents have shown promise in preliminary studies to prevent S. aureus
biofilms and those of other pathogens (del Pozo et al. 2009 ), and additional
mechanism studies suggest that hypochlorous acid (bleach) produced from media
salts could be the reason for the anti-biofilm activity (Sandvik et al. 2013 ). The
semimetal gallium has shown promise in preventing S. aureus biofilms in prelim-
inary in vitro studies (Baldoni et al. 2010 ). There are also many examples of
alterations of surface chemistry as an anti-biofilm strategy, and as one representa-
tive, Slippery Liquid-Infused Porous Surfaces (SLIPS) were recently shown to be
effective at preventing S. aureus attachment and biofilm development (Epstein
et al. 2012 ).
The field of S. aureus biofilms has made tremendous strides in recent years as
our understanding of surface adhesins, regulatory networks, enzyme treatments,
natural product and synthetic inhibitors, and quantitative assays continues to