Introduction: Chronic infections in which bacteria have formed biofilms have demonstrated delayed bone healing and failed fusion. These slime-enclosed communities isolate bacteria from the body’s immune responses, which can cause antibiotic resistance. Biofilm bacteria are extremely difficult to detect by culture methods used in the hospital setting. These persistent bacteria pose significant risk for postoperative care, particularly for surgical implants, which can require additional surgery if infected. The purpose of this study is to determine if and to what degree biofilms are present on spine instrumentation.

Methods: Wound cultures taken from each specimen underwent microbiological analysis. Polymerase chain reaction (PCR) electrospray ionization-mass spectrometry (ESI-MS) was performed. Based on the PCR/ESI-MS results, specific crossed immune electrophoresis detected the bacterial species within biofilms observed on the removed devices. Fluorescent in situ hybridization (FISH) probes corresponding to specific bacterial species were used with confocal microscopy to visualize the bacteria in tissues (within 50 microns).

Results: Fifteen patients presented for surgical revision of spinal implantation: five for clinical infection, six for adjacent segment disease (ASD), one with ASD and pseudarthrosis (PA), two with only PA, and one for pain. A specimen from a participant with ASD was lost and excluded from the results. Infections were diagnosed with PCR/ESI-MS for all five who presented with an infection, as well as for four patients for whom infection was not clinically suspected. The positive predictive value for clinical signs of infection compared to the PCR/ESI-MS was 100%. The negative predictive value was 55.6%. Of the presumed non-infected hardware, 44.4% demonstrated the presence of infectious biofilms. Half of revisions due to pseudoarthrosis are shown to harbor biofilms.

Conclusions: Culture was inadequate as a diagnostic modality to detect biofilm infections of the spine. The PCR/ESI-MS results for bacterial detection were all confirmed using direct species-specific microscopic techniques for DNA and antigen.

Patient Care: The implications of this research topic are highly significant due to the risk that infections pose to postoperative patient outcomes. Biofilms clearly have a larger presence than current methodology would lead one to believe, providing the basis for a more targeted approach to combating the infections and complications arising from sessile bacteria. As these types of infections can be antibiotic resistant with increased morbidity and mortality rates, there is a demonstrated need for improved therapeutic measures. Other complications include non-fusion and reduced bone healing, as in pseudoarthrosis. Half of the pseudoarthrosis cases in this study had bacteria present, demonstrating yet another area in need of additional research to explore the association with biofilms. Future studies focused on current sterilization techniques, as well as materials used for implantation, could further reduce the effects felt by patients by eliminating the origin of biofilms entirely. With the increasing utilization of implantation procedures to correct defects across specialties, it is becoming exceedingly imperative that the scientific community places a spotlight on biofilm research. The results of this study suggest that it will prove to be pivotal in the development of neurosurgical views on bacteria.

Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the identifiable characteristics of a biofilm 2) Explain the importance of biofilm identification 3) Identify the implications that biofilms have on patient care

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