Bioluminescent Imaging of Bacterial Biofilm Infections In Vivo - Bacterial Pathogenesis: Methods and Protocols - page 211

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Bioluminescent Imaging of Bacterial Biofilm Infections
In Vivo
Jagath L. Kadurugamuwa and Kevin P. Francis
Summary
Whole body biophotonic imaging (BPI) is a technique that has contributed significantly
to the way researchers study bacterial pathogens and develop pre-clinical treatments to
combat their ensuing infections in vivo . Not only does this approach allow disease profiles
and drug efficacy studies to be conducted non-destructively in live animals over the entire
course of the disease, but in many cases, it enables investigators to observe disease profiles
that could otherwise easily be missed using conventional methodologies. The principles
of this technique are that bacterial pathogens engineered to express bioluminescence
(visible light) can be readily monitored from outside of the living animal using specialized
low-light imaging equipment, enabling their movement, expansion and treatment to be
seen completely non-invasively. Moreover, because the same group of animals can be
imaged at each time-point throughout the study, the overall number of animals used is
dramatically reduced, saving lives, time, and money. Also, as each animal acts as its own
control over time, the issues associated with animal-to-animal variation are circumvented,
thus improving the quality of the biostatistical data generated. The ability to monitor
infections in vivo in a longitudinal fashion is especially appealing to assess chronic
infections such as those involving implanted devices. Typically, bacteria grow as biofilms
on these foreign bodies and are reputably difficult to monitor with conventional methods.
Because of the non-destructive and non-invasive nature of BPI, the procedure can be
performed repeatedly in the same animal, allowing the biofilm to be studied in situ
without detachment or disturbance. This ability not only allows unique patterns of disease
relapse to be seen following termination of antibiotic therapy but also in vivo resistance
development during prolonged treatment, both of which are common occurrences with
device-related infections. This chapter describes the bioluminescent engineering of both
Gram-positive and Gram-negative bacteria and overviews their use in device-associated
infections in several anatomical sites in a variety of animal models.