CHALMERS J. LYONS MEMORIAL LECTUREPresented on Thursday, September 11, 1:00 pm–2:30 pm

The Role of Biofilms in Device-Relatedand Other Chronic Bacterial InfectionsJohn William Costerton, PhD, Bozeman, MT

The systematic examination of devices and tissuesremoved from device-related and other chronic bacterialand fungal infections has revealed that the organismsthat cause these very refractory infections actually growin matrix-enclosed biofilms. The refractory nature ofthese infections is now explained in terms of the inher-ent resistance of all biofilms to antibiotics, and otherantibacterial agents, and to host defense mechanisms(antibodies and phagocytes) that normally resolve acuteinfections caused by planktonic (floating) bacteria.

If we consider that all device-related infections havethis peculiar etiology, as well as many other chronicinfections (eg, otitis media, prostatitis), current esti-mates of the proportion of these biofilm infections seenby physicians in the developed world range from 65% to80%. These biofilm infections are generally characterizedby their slow development, their refractory response totherapy, their generation of repeated acute exacerba-tions (which do respond to therapy), and the necessityof the removal of the device and/or of affected tissue inorder to effect a cure.

If we harness the new concepts of biofilm science andengineering in the struggle against device-related infec-tions, there are many advantages to be gained. We knowthat biofilm formation is favored by residues of dead biofilmon surfaces, so we know that biomaterials must be scrupu-lously cleaned before they are implanted. We know that

biofilm cells grow only very poorly, when they are recov-ered from surfaces and dispersed on agar plates, so weknow that many “culture negative” presentations are actu-ally low grade biofilm infections. We know that acuteexacerbations may respond to antibiotic therapy, but thattrue biofilm cells are not killed, so we know that colonizeddevices and affected tissues must be removed before de-vice-related infections can be resolved. We know that bothultrasonic energy and DC electric fields can reduce theresistance of biofilm cells to that of planktonic cells, so wecan invoke their use in the treatment of chronic infections.We know that cells in biofilms express a profoundly differ-ent phenotype from that expressed by planktonic cells, sowe are now targeting biofilm-specific genes with newagents that will kill these matrix-enclosed organisms. Wehave discovered that the process of biofilm formation iscontrolled by simple chemical signals, and that analoguesof these compounds can be used to inhibit biofilm forma-tion, and even to induce the detachment of preformedbiofilms from surfaces. The application of these conceptsto the problem of device-related infections shows greatpromise, and we propose clinical testing of several anti-biofilm strategies.

References

Cook G, Costerton JW, Darouiche RO: Direct confocal microscopystudies of the bacterial colonization in vitro of a silver-coated heartvalve sewing cuff. Int J Antimicrobial Agents 13:169, 2000

Costerton JW, Stewart PS, Greenberg EP: Bacterial biofilms: A com-mon cause of persistent infections. Science 284:1318, 1999

Costerton JW, Stewart PS: Battling Biofilms. Scientific American285:75, 2001

SYMPOSIUM ON ADVANCES IN MAXILLARY RECONSTRUCTIONPresented on Thursday, September 11, 3:00 pm–5:45 pmModerator: George Sandor, MD, DDS, PhD, FRCD(C), FRCS(C), FACS, Toronto, Ontario, Canada

What’s Wrong With an Obturator Anyway?James Anderson, DDS, Toronto, Ontario, Canada

In a relatively short time, postoperative managementof maxillectomy patients has progressed from no man-agement at all, to near-complete restoration of tissueintegrity and function. The range of treatment optionshas greatly expanded with the development of new localand free flap designs, new bone management tech-niques, and new implant designs.

With the arrival of new options comes the temptationto apply them to as many situations as possible. Thistemptation can be driven not only by the newness of the

latest treatment option but also by the intuitive urge toregain preoperative anatomic integrity and the best pos-sible function. However, the social, functional, psycho-logical, and financial needs and values of the patient mayhave much greater impact on the treatment planningdecisions than mere restoration of tissue contour. Inother words, because a more elegant procedure hasbeen shown to produce clinical results closer to preop-erative tissue contour and better function, this is notsufficient reason to apply it in most or even any patients.The risk, morbidity, cost, and any other subjective con-siderations may render newly available techniques inap-propriate. Treatment planners must focus on the pa-tient’s perceived needs.

Symposia

10 AAOMS • 2003