Microbial Biofilms: A Potential Source for Alloplastic Device Failure

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LOUIS G. MERCURI

J Oral Maxillofac Surg 64:1303-1309, 2006

Microbial Biofilms: A Potential Source for Alloplastic Device Failure Louis G. Mercuri, DDS, MS* A biofilm is defined as an assemblage of surface-associated (not easily removed) microbial cells that are enclosed in a protective extracellular primarily polysaccharide matrix. Biofilms may form on a wide variety of surfaces, including living tissues, natural aquatic systems, industrial or potable water system piping, or implanted medical devices.1 Direct observations have established that bacteria that cause medical device-related infections grow in these matrix-enclosed biofilms. The diagnostic and therapeutic strategies that are used to eradicate acute planktonic bacterial infections do not yield accurate data or favorable outcomes when applied to biofilm infections.2 The imperative that drove early medical biofilm microbiology communities to investigate this phenomenon was the emergence of device-related, other chronic bacterial infections and the inability of the infectious disease community to control these infections or explain their refractory nature. The acute epidemic diseases that affected the human race in the first half of the 20th century gradually gave way to a host of low-grade infections caused by common environmental organisms that resisted host defenses and antibiotic therapy.3 Bacteria that were isolated from these infections were seen to be susceptible to killing by phagocytosis, antibodies, and antibiotics when they were cultured as freely suspended (planktonic) cells in “pure culture,” but host defenses and antibiotic therapy were generally ineffective. Morphologic techniques were used to locate these organisms and determine their mode of growth, *Professor of Surgery, Department of Surgery, Division of Oral and Maxillofacial Surgery, Stritich School of Medicine, Loyola University Medical Center, Maywood, IL; and Clinical Consultant, TMJ Concepts, Ventura, CA. Address correspondence and reprint requests to Dr Mercuri: Department of Surgery, Division of Oral and Maxillofacial Surgery, Stritich School of Medicine, Loyola University Medical Center, 2160 South First Avenue 105-1814, Maywood, IL 60153; e-mail: [email protected] © 2006 American Association of Oral and Maxillofacial Surgeons

0278-2391/06/6408-0026$32.00/0 doi:10.1016/j.joms.2006.04.004

and biofilms were found on virtually all infected devices and compromised tissues.4 It is essential that the reconstructive maxillofacial surgeon who uses abiotic devices (eg, dental implants, plates and screws, partial and total temporomandibular joint devices, etc) know of the existence of biofilms, understand their microbiology and their management. Therefore, this article presents the author’s experience with total alloplastic temporomandibular joint (TMJ) biofilm infections to illustrate these points.

Microbial Biofilms In 1684, van Leeuwenhoek first described the microbiologic phenomenon that micro-organisms attach and grow universally on exposed surfaces. He discovered that freely suspended (planktonic) micro-organisms, when dispersed from his own dental plaque (biofilm) into an antimicrobial solution such as vinegar, lost all motility. However, when he rinsed his mouth with vinegar, thereby exposing the intact dental plaque (biofilm), he found that the vinegar-exposed plaque continued to teem with life.5 This and other similar later observations eventually led to studies that showed surface-associated microorganisms (biofilms) exhibit distinct phenotypes with respect to gene transcription and growth rates. Biofilms have been shown to elicit specific mechanisms for initial attachment to a surface, development of community structure and ecosystem, and detachment.6-12 Over 100 years ago, Robert Koch developed the methods for creating a solid nutrient medium in order to grow and isolate “pure cultures” of micro-organisms. The common perception that micro-organisms are unicellular life forms is primarily based on this “pure culture” mode of growth of planktonic life forms. Because micro-organisms can be diluted to a single cell and studied in liquid culture, this mode of growth has overwhelmingly predominated the study of microbial physiology and pathogenesis. However, a majority of microbes in their natural habitats persist attached to surfaces within a structured biofilm ecosystem and not as free-floating (planktonic) organisms.1

1304 Micro-organisms, like most other organisms, exist in assemblages or communities where a variety of interactions exist. Mutualism, commensalisms, antagonism, and saprophytism are but a few of the more common interactions known to exist among microorganisms and multicellular organisms.13 Major principle of microbial survival: “Being attached rather than suspended makes a world of difference.” Recently, there has been an increased recognition of the role microbial biofilms play in human medicine and it has been estimated that as many as 65% of all human microbial infections may involve biofilms.1

The Microbiology of Biofilm Infections of Medical Devices Most often, colonizing organisms of infected medical devices (IMDs) are normal commensals of humans, which facilitates their encounter with most implanted biomaterials. In other instances, the devices become contaminated prior to or during implantation because of manipulation by medical personnel. To colonize any implanted medical device, pioneering planktonic microcolonies must first adhere to biomaterial surfaces. The biomaterial properties affecting initial adhesion range from chemical properties to hydrophobicity to surface roughness. Because these biomedical devices are usually surrounded by bodily fluids, their surfaces acquire a glycoproteinaceous conditioning film after implantation.14 This conditioning film could confer chemical characteristics that are completely different from those of the original biomaterial. The initial attachment of planktonic cells to biomaterials surfaces is mediated by nonspecific factors (eg, cell surface hydrophobicity and electrostatic forces) and by specific adhesions on the organic surface, recognizing ligands in the conditioning film; these include serum proteins (fibrinogen and fibronectin) and salivary factors. Additionally, cells can coaggregate and/or bind to sessile bacteria already colonizing these devices.15 The initial focal attachment of individual cells to a substratum is closely followed by cell division, proliferation, and biofilm development. Mature biofilms exhibit a complex 3-dimensional structure and extensive heterogeneity with a typical microcolony/water channel architecture and are encased within exopolymeric material.16 This structural complexity represents an optimal special arrangement for influx of nutrients, disposal of waste products, and establishment of microniches throughout the biofilm of microcolonies and ramifying water channels. Quorum sensing plays an important role in maintaining and disaggregating the biofilm microcolonies. Disaggregation is a function of the

MICROBIAL BIOFILMS

growth phase of the individual cells, colony size, nutrient conditions, changes in extracellular polysaccharide polymer production, and hemodynamic and mechanical shear forces of the bulk fluid (blood) flow.17

Microbiology of IMD Biofilms Table 1 shows the magnitude of the problem of implanted medical device infections. The pathogenesis of IMDs centers on the interaction of bacterial, device, and host factors.18 BACTERIAL FACTORS

The most common pathogens associated with biofilm IMDs are Staphylococcus epidermidis, Staphylococcus aureus, Pseudomonas aerugenosa, and the Enterococcus species and, occasionally, Candida species. The relative frequency of infection depends somewhat on the location of the device, but S. epidermidis is nearly always the most frequently isolated organism. Staphylococcus epidermidis is a normal member of the human skin flora and, as such, is considered nonpathogenic. This organism is frequently isolated from IMDs. Staphylococcus aureus is also a frequent perpetrator associated with infections of prosthetic devices, though it colonizes the mouths, noses and ears of a large portion of the healthy population in a nonpathogenic manner. Although less commonly isolated than S. epidermidis in association with biomedical implants, in most cases, the abundance of toxins, adhesive molecules, and other virulence factors expressed by S. aureus contributes to implanted biomedical device morbidity and failure.19 The pathogenic potential of prosthetic device-associated Staphylococci is directly related to the ability of these organisms to form multilayered cellular communities, or biofilms, on surfaces of foreign bodies in vivo. Early reports of “mucoid” growth by S. epidermidis

Table 1. DEVICE-RELATED INFECTIONS IN US

Device

Usage/yr

Risk (%)

Cardiac assist devices Bladder catheters Fracture fixators Dental implants C-V catheters Vascular grafts Cardiac pacemakers Prosthetic heart valves Joint prostheses

700 ⬎30 million 2 million 1 million 5 million 450,000 400,000 85,000 600,000

50-100 10-30 5-10 5-10 3-8 2-10 1-5 1-3 1-3

NOTE. Adapted from Thomas JG et al.17 Louis G. Mercuri. Microbial Biofilms. J Oral Maxillofac Surg 2006.

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indicate that investigators were aware of staphylococcal biofilms before they were recognized as such.20 S. epidermidis infections tend to be chronic and less acute, while S. aureus infections make themselves known more quickly because of other virulence factors that create damage to host tissues and/or induce more acute immune response in the host. Sessile cells in biofilms are physiologically active, metabolically coordinated, and unaccountably resistant to antibacterial agents on molecular (peptides, antibiotics), particulate (bacteriophage), and cellular (amoebae, phagocytes) scales. Direct examination of the surfaces of devices is a much more sensitive method for biofilm detection than the traditional culture methods. When examining tissue from chronic bacterial infections, refractory to host defenses or antibiotic therapy, similar biofilms are also found.19 Bacteria may adopt a profoundly different phenotype when they adhere to surfaces and form biofilms and they may activate a large number of new genes in addition to those necessary for matrix production and heterogeneity.19 Bacteria imbedding in a biofilm are often orders of magnitude more resistant to antibiotic agents. In addition, the increased incidence of methicillin-resistant Staphylococci and emerging vancomycin-insensitive strains further complicates the problem of treating patients with IMDs.20 Metabolic heterogeneity may account for the phenomenal success of microbial biofilms in nature and in device-related and other chronic bacterial infections, and it may be the major factor in the inherent resistance of medical biofilms to antibiotics.21 Suci et al22 reported that antibiotics entered biofilms very readily and that diffusion resistance was not the reason why biofilms display resistance to antibiotic therapy. Stewart23 suggested that a reaction with the matrix material was the cause of the failure of the antibiotics to kill the organisms. The anomaly of the resistance of biofilms to levels of antibiotics as much as 1,000 times higher than those that kill planktonic cells of the same species has been reported.24

Table 2. DEVICE-RELATED FACTORS

Surface of Device Material Irregular ⬎ regular Textured ⬎ smooth Hydrophobic ⬎ hydrophilic Synthetic ⬎ biologic Polymetric tubing ⬎ wire mesh NOTE. Adapted from Darouiche RO.18 Louis G. Mercuri. Microbial Biofilms. J Oral Maxillofac Surg 2006.

Table 3. HOST-RELATED FACTORS

Systemic* Chronic debilitating disease Immune deficiency syndromes High-inflammatory arthritis Intraop† Direct contamination Indirect contamination (ie, skin, ear, salivary gland) Postop† Surgical site infection Nosocomial infections *Gillespie WJ.31 †Berberi EF et al.25 Louis G. Mercuri. Microbial Biofilms. J Oral Maxillofac Surg 2006.

DEVICE-RELATED FACTORS

Table 2 exhibits the device-related factors that may favor bacterial adherence. Analysis of the date on bacterial adherence and surface modification of the device yields 5 major principles18: ● ● ● ●

●

Different bacteria may adhere differently to the same device material. The same bacteria may adhere differently to different device materials. The same bacteria may adhere differently to the same material under different circumstances. In vitro inhibition of bacterial colonization of a device does not ensure in vivo antibacterial effectivity. The clinical benefit of a particular surface-modifying approach may differ from one application to another.

HOST-RELATED FACTORS

Table 325 outlines the host-related factors that may favor implanted medical device biofilm formation. Systemic debilitating metabolic and endocrine diseases, immune deficiency syndromes, and high inflammatory arthritis have been implicated in the development of all medical device biofilm formation. Assuring that any systemic disease process is well controlled preoperatively and maintaining absolute sterility intraoperatively are essential to alloplastic implantation success in such instances. Local factors have also been implicated in this insidious process. Direct contamination of the devices before implantation from improper handling in the operating room (OR) environment, and indirect contamination during implantation from the skin, ear, or saliva are the more likely culprits. In the case of alloplastic TMJ reconstruction, minimizing the through-the-wound “try-ins” of the device components (an advantage of a patient-fitted system),

1306 careful preoperative preparation of the areas where incisions are to be made (eg, keeping the hair out of the surgical site), and careful preparation of the ear preoperatively (pinna and external auditory canal with occlusion of the latter throughout the procedure) will decrease the potential for a device biofilm infection. Parotid gland tissue is always encountered with both the preauricular and retromandibular/submandibular incisions in alloplastic TMJ reconstruction. Care should be taken during dissection and retraction to avoid injury to this tissue that might result in the contamination of the surrounding tissue and devices by bacteria-laden saliva. It is absolutely essential that sterility of the implantation sites be maintained during any intraoperative potential contaminating maneuvers such as going from the mouth back to the wounds while “checking the occlusion” without changing gown and glove. Draping techniques have been developed to make these maneuvers less threatening. Copious irrigation with or without an antibiotic solution before and after implantation of the device components may provide some assistance in decreasing the potential for local contamination, although no definitive studies to prove or disprove this have been published in the TMJ reconstruction literature to date. Postoperatively, “stitch abscesses” and seromas must be dealt with aggressively before they affect the deeper tissues and their organisms involve the device components. While nosocomial infections are difficult to predict and manage, meticulous wound care and personal hygiene (hand washing) by both the surgeon and patient both during and after hospitalization are essential.

Clinical Consequences of Biofilm Infections Reduced antimicrobial sensitivity in biofilms is the consequence of the combination of antimicrobial and antimicrobial depletion through reactions with the biofilm constituents, poor antimicrobial penetration of the sessile component of the biofilm, slow-growth or stationary-phase existence in the biofilm, adaptive stress responses of the organisms, and formation of protected persister cells.26 The sessile bacteria within biofilms have increased resistance up to 1,000-fold higher than planktonic phenotype leading to colonization resistance, increased opportunity for gene transfer resulting in new and sometimes more virulent phenotypes within a biofilm resistant to both immunologic and nonspecific defense mechanisms.26

MICROBIAL BIOFILMS

Management of Biofilm IMD Factors influencing biofilm susceptibility to antibiotic management are biofilm thickness, the thicker the less susceptible; biofilm age, the older the less susceptible; biofilm density, the denser the less susceptible; biofilm species composition and genotype, the mixed species biofilms are more protected than single species biofilms;26 and the antimicrobial dose concentration, brief but relatively high concentrations of antimicrobial agents are more effective than prolonged lower doses.27 Therefore, when a biofilm IMD is suspected, the following should be considered when initiating systemic antibiotic treatment: ● ● ●

Broad-spectrum agents are used prior to microbiology laboratory results. Specific antibiotics are used when identification is made and susceptibility is known. Vancomycin is most successfully used against coagulase-negative staphylococcus species.27

Despite promising early reports of physical and chemical debridement to remove the sessile component from a biofilm IMD,28,29 salvage of such devices using these methods has been poor. In orthopedic total joint replacement, it has been reported that the costs of management of a primary joint replacement that becomes infected are 8 to 10 times those of a successful, uninfected replacement.30 Hence, arthrodesis after explantation of the IMD is often considered.31 This is not a consideration in the TMJ. Explantation of a biofilm IMD, placement of an antibiotic-impregnated orthopedic bone cement spacer, long-term systemic antibiotic therapy, and replacement of the prosthetic device followed by another course of systemic antibiotic therapy has been recommended for the management of such cases.17,18,32 Studies in infected total knee replacement patients using beads or spacers showed some beneficial effect in such cases.33-35 Other studies reported improvement when a cement spacer block impregnated with antibiotics was used after removal of the IMD and prior to replacement with a new device.36,37 Device coatings can strengthen the capabilities of many of today’s medical products. Some coatings add such properties as lubricity, biocompatibility, and antimicrobial action to device surfaces. Other coatings can be used to release drugs or make implanted devices more visible to imaging systems. Considering the clinical morbidity and costs of removal and replacement of biofilm IMDs, approaches to combat biofilms prophylactically have centered on rendering the surface toxic to colonizing bacteria, or im-

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swelling and by 1987 both implants were removed and found to be fragmented. No replacement tissue or alloplast was placed. By 1999, he complained of increasing TMJ pain and decreasing mandibular function. Clinically, he had developed decreased mandibular vertical, lateral, and protrusive range of motion and an anterior open bite. Imaging showed severe bilateral post-failed Proplast-Teflon TMJ degeneration with loss of posterior vertical dimension. Medically, he was under the care of a rheumatologist for an undetermined autoimmune disorder characterized by low immunoglobulin levels. In order to manage the mandibular dysfunctional aspects of D.B.’s concerns, bilateral alloplastic TMJ reconstruction with patient-fitted devices (TMJ Concepts, Ventura, CA) was proposed and implanted in October 1999. D.B. did well until May 2000, when he reported that he started swelling in the right submandibular region and noted drainage from the right submandibular incision. Culture of this drainage returned a report of a coagulase negative Staphylococcus aureus with sensitivity to ampicillin/ sulbactam. Despite a course of this antibiotic and 2 surgical debridements, the drainage persisted. The diagnosis of a biofilm-infected alloplastic right TMJ device was made and he was taken to the OR, the right fossa and ramus components removed, he was placed in maxillomandibular fixation (MMF) and polymethylmethacrylate (PMMA) orthopedic cement impregnated with 1 gram of vancomycin was inserted into the right fossa as a spacer. Gentamicin was administered via a peripherally inserted central catheter line and he was monitored by the Infectious Disease service for 3 months. During that time, because the biofilm had colonized the polyethylene portion of this component, the fossa component was remade. The all-metal ramus component was passivated and resterilized by TMJ Concepts. In October 2000, the new fossa and passivated ramus components were reimplanted and the patient was maintained on ciprofloxacin for 3 more months. This patient has been closely followed and has shown no signs of any further infection. At his last visit, October 2005, he reported on a visual analog scale (VAS) a 90% decrease in TMJ pain, 90% increase in mandibular function, and 100% increase in diet consistency from preop October 2000. His maximum incisal opening (MIO) was measured at 40 mm (17 mm preoperative, October 2000).

peding their ability to adhere to the surfaces of the device. Examples of the former approach include the investigation of surface coatings containing silver compounds, antimicrobials such as benzalkonium chloride, and such antibiotics as minimycin, rifampin, ciprofloxacin, and cephalosporin.38 Investigation into the latter approach is to interfere with matrix formation by attacking the signaling mechanism by which the bacteria coordinate their film-building activities and virulence by using socalled quorum-sensing inhibitors such as RNA III inhibitor protein both alone and with antimicrobial peptide dermaeptin b to inhibit production of biofilms and exotoxins produced by S. aureus and S. epidermidis.39-41 Another approach, along the same lines, has been the use of an enzyme called dispepsin B, which cleaves the polysaccharide molecules that hold the biofilm together.42 While these technological advances may prove helpful in decreasing the biofilm involvement of implanted medical devices, most are still in the investigatory stages. They will be costly, and Food and Drug Administration approval as a class of drugs still is a question with which to be reckoned. However, it must be remembered and emphasized that antimicrobials, antibiotics, and technology are never a substitute for appropriate surgical technique.

Report of Cases The following 3 cases illustrate the points made above (Table 4). CASE 1 D.B. is a 49-year-old male who, after a 1973 direct sports-related trauma to his mandible, developed bilateral TMJ pain and dysfunction. After failure of noninvasive management, he underwent bilateral discectomy and placement of Proplast-Teflon interpositional TMJ disc implants (Vitek, Houston, TX) at another institution in 1984. He thereafter developed increasing bilateral preauricular pain and

Table 4. TOTAL ALLOPLASTIC TMJ DEVICE BIOFILM CASES

Diagnosis TMJ history Medical history Onset PO Organism Management

Postop

D.B. 49 y/o WM

J.H. 53 y/o WF

C.W. 29 y/o WF

Severe DJD Proplast-Teflon ? Immune deficient 7 months S. aureus (coag neg) Removal vancomycin spacer 3 mo. gentamicin Remake Reimplant 5 yr

Apertognathia Progressive RA 2 months S. epidermidis Removal vancomycin spacer 3 mo. linezolid Remake Reimplant 3 yr

Ankylosis Multiple sxs OR RN 2 months S. aureus (coag neg) Removal vancomycin spacer 3 mo. linezolid Remake Reimplant 2 yr

Louis G. Mercuri. Microbial Biofilms. J Oral Maxillofac Surg 2006.

1308 CASE 2 J.H. is a 53-year-old rheumatoid arthritis patient who originally presented in May 2001 with a chief complaint of difficulty eating and speaking due to the increasing open bite deformity she was developing characteristic of this disease process, which imaging confirmed. After orthodontic leveling and alignment, J.H. underwent uneventful bilateral alloplastic TMJ reconstruction with patient-fitted devices (TMJ Concepts, Ventura, CA) in February 2002. Two months postoperative the patient presented with drainage from the left preauricular incision line. Culture reported Staphylococcus epidermidis sensitive to ciprofloxacin. After a 2-week course of ciprofloxacin, surgical debridement and daily wet/dry packing, the left preauricular drainage stopped, but within a week similar drainage started from a sinus tract that had developed just posterior to the left tragus in the external auditory canal. Probing this sinus led directly to the articulating aspect of the device. The patient refused removal of the device, wishing to continue wet/dry debridement and antibiotic therapy. Ear, nose and throat consultation and comanagement were obtained. Finally, in September 2002, after no change in the persistent drainage, the patient agreed to removal of the left TMJ device, placement of MMF and a PMMA/vancomycin spacer. The Infectious Disease service placed her on linezolid for 3 months. In December 2002, J.H. underwent reimplantation of the remade fossa and passivated ramus components of the left TMJ patient-fitted device. She remained on ciprofloxacin for 3 more months thereafter. At routine follow-up in September 2005, J.H. reported from pre-February 2002, a 100% decrease in TMJ pain, 100% increase in mandibular function, and 100% increase in diet consistency. Her MIO was 40 mm, and she continues to be pleased with the esthetic results. CASE 3 C.W. is a 29-year-old OR nurse who had by history sustained significant bilateral TMJ trauma that resulted in multiple bilateral open arthrotomies, ultimately leading to bilateral autogenous rib grafts at another institution. When she initially presented in November 2001, both rib grafts had ankylosed. Bilateral alloplastic patient-fitted (TMJ Concepts, Ventura, CA) TMJ devices were implanted in late February 2002. In early April 2002, C.W. returned with drainage from the right preauricular incision site. An endodontic gutta percha point was placed into the sinus tract and a posterior-anterior cephalometric film made, which showed the point entering the articulating space of the right TMJ device. The diagnosis of a biofilm-infected right TMJ alloplastic device was made. Culture of the drainage showed coagulase-negative Staphylococcus aureus. Attempted surgical debridement at another institution without removal of the device components failed to resolve the drainage, so in September 2003, the right TMJ device components were removed, she was placed in MMF and a PMMA/vancomycin spacer implanted. The Infectious Disease service placed her on linezolid for 3 months. In December 2003, the remade right fossa and the passivated right ramus patient-fitted components were reimplanted and she was placed on ciprofloxacin from 3 more months. In September 2005, C.W. returned for routine postoperative follow-up with no complaints. On VAS, she reported 89% decease in pain, 90% increase in mandibular function, and 100% increase in diet consistency from preoperative

MICROBIAL BIOFILMS February 2002. Her MIO was measured at 36 mm (12 mm preoperative, February 2002). Modern reconstructive surgery would be unthinkable without the availability of alloplastic prostheses. Along with all of the advantages these devices offer our patients, come some relative disadvantages, including the potential for biofilm infections. With the surgical, diagnostic, and management options discussed and illustrated by the cases presented in this article, the reconstructive maxillofacial surgeon will be better prepared now and in the future to deal with this entity.

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