The Use of DNA Methods to Characterize Biofilm Infection - Antibiofilm Agents: From Diagnosis to Treatment and Prevention - page 22

The clinical concern relative to the synergies of polymicrobial biofilm is that the
infection will be more severe and recalcitrant to treatment. There are many exam-
ples which show that this is indeed the case. Low levels of P. aeruginosa mixed
with Staphylococcus aureus increased infection rates in a rat model (Hendricks
et al. 2001 ). In the mouse model, Prevotella increases the pathogenicity of S. aureus
(Mikamo et al. 1998 ). Escherichia coli produced marked increase in the size of
abscess formation with Bacteroides fragilis in a diabetic mouse model
(Mastropaolo et al. 2005 ). There also is clinical evidence to suggest

that

polymicrobial infections are more severe (Tuttle et al. 2011 ).
The synergies and general recalcitrance produced by polymicrobial infections
argue for the full evaluation of every infection. This means not only identification
of all species present but also their quantification. However, there is currently not
enough information to give clear direction on which microorganisms are important
to treat. Also, therapeutic tools for managing polymicrobial infections in conjunc-
tion with or separate from antibiotics are generally not available. If a clinician has
no specific tools to address all the diversity of a polymicrobial infection then is it
valuable to get the test in the first place?

4 The Clinical Use of Molecular Methods: Two Eyes

Identifying and quantitating the microorganisms present in an infection are only
part of the diagnosis of an infection. Clinical findings play the major role in
determining if the microorganisms present are harming the host. It is only through
stereoscopic vision of laboratory results and clinical observation that we can clearly
see the power of the detailed information provided by molecular methods. Just as
when sophisticated imaging technologies emerged such as MRI, the full meaning
and nuances of the images provided could not be appreciated until there was clinical
application and experience.
Clinicians seem to be divided by the information provided by DNA-based
testing. The unfamiliar microbes can both elucidate and complicate the diagnosis
of chronic infections produced by biofilm. Through years of use of molecular
methods in real-world chronic infections (mainly chronic wounds) several impor-
tant principles have emerged. Uncommon bugs occur commonly in chronic wounds
and many chronic infections. The clinical challenge of treating rare microbes is
more difficult but doable. Literature searches usually will yield usable treatment
options for the genera that are identified. Even though we like to know the species
identification, most antibiotics, biocides, quorum-sensing inhibitors, and ancillary
treatments work at the genus or even the family level for many microbes. That is, a
treatment that would kill a rat would in general kill a mouse. Therefore, unfamiliar
microbes for treatment purposes can be grouped with closely related microbes
which are more familiar (e.g., Raoultella planticola and Klebsiella spp.) or cate-
gorized by common groupings such as gram negative, gram positive, anaerobic, etc.
But all of the grouping and comparing of microbes to form a treatment plan