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Diagnosis of device-associated biofilms

There are two groups of diagnostic methods to detect biofilms on medical devices that will be discussed herein and are summarized in Table 8.1. The first group comprises in vitro traditional and state-of-the-art methodologies used to isolate and identify/ visualize biofilm-forming bacteria associated with infected medical devices. The second group includes state-of-the-art technologies, still under development, for in vivo detection/visualization of biofilms on medical devices.

Traditional detection, visualization, and isolation of bio film-forming bacteria from medical devices

Microbiological methods, including culture and bacterial staining combined with microscopy, are the most widely use techniques to detect bacteria from infected

Table 8.1 Methods for the diagnosis of biofilm formation on medical devices

Category

Method

Characteristics

In vitro detection of biofilm-forming bacteria

Culture

  • • Device sampling
  • • Low specificity and sensitivity
  • • Enhancement of bacterial recovery with sonication

Microscopy

  • • Limited used
  • • High sensitivity but low specificity

Molecular

biology

  • • Rapid pathogen detection
  • • High specificity but low sensitivity
  • • Lack of distinction between live and dead cells
  • • Susceptible to inhibitory substances in biological systems

Immunological

  • • Need to develop specific antibodies
  • • Increased sensitivity and specificity

In vivo detection of biofilms

Improved biofilm imaging

  • • Under development, limited clinical use
  • • Expensive equipment and associated software
  • • Need confirmatory testing

Biosensors, smart catheters

  • • Under development, not in clinical use
  • • Complex and expensive systems
  • • High risk of false positives and need for confirmatory testing

devices. However, the rate of false negatives from clinical data, when these methods are used, is high and many microorganisms are either not detected, not visible or not noncultivable (Oliver, 2010). Other approaches have been developed for biofilm detection on medical surfaces such as immunological and molecular biological techniques and combinations of these techniques.

 
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