MEDICINE
Biofilms & Urinary Tract Infections…
A Sticky Situation
Kelly E. O’Neill, DVM
Mary Anna Labato, DVM, DACVIM
Linda Ross, DVM, DACVIM
Tufts University
What is a biofilm and how does it affect
the urinary tract of animals?
Article reprinted with the permission of Clinician’s Brief. The article was originally
printed in August 2014. CB is published by Brief Media. CB is the official publication
of the NAVC. CB provides relevant diagnostic and treatment information for small
animal practitioners. All rights reserved
A biofilm is a structured community of bacterial, fungal, or
other cells enclosed in a self-produced polymeric matrix adherent to an inert or living surface.1 Biofilms are common in
living organisms, including animals, but can also be found in
other environments. Biofilms alter the function and pathogenicity of bacteria. Growing evidence suggests they may
play a substantial role in infections, especially those that are
recurrent or difficult to treat.2
From the perspective of bacteria, becoming part of a biofilm confers certain advantages. Within the biofilm, bacteria
are able to pool their resources and receive protection from
the immune system, antimicrobials, harsh environments
and other stressors. However, being part of a community
may also decrease access to water and oxygen, especially
at depths further from the surface, and lead to an accumulation of waste products.3 Adjusting to these disadvantages
may ultimately enable bacteria to thrive in this environment
and increase problems for veterinary patients.
Bacteria change from free-living (or planktonic) organisms
to ones that can adhere to surfaces (ie, to establish a colony) in order to form a biofilm; in doing so their behavior
and structure alter. As the community grows, autoinducers,
chemical-signaling molecules that enable bacteria to sense
one another and regulate one another’s activities, accumulate. As they accumulate, the autoinducers induce changes
in bacterial surface attachments, the extracellular polymeric
matrix, and the amount and type of virulence factors that are
expressed. Alterations in gene expression lead to phenotypic
changes in flagella, the structure of cell walls, and the production of enzymes. Up to 40% of cell wall proteins appear
to be different in bacteria found in a biofilm compared with
their plankt ۚX