General Session: Tumor, Trauma, and Infection

Presented by: C. Dowe - View Audio/Video Presentation (Members Only)


C. Dowe(1), T. Callanan(1), S. Grinberg(1), R. Simon(1), D. Lebl(1), F. Cammisa(1), C. Abjornson(1)

(1) Hospital for Special Surgery, Integrated Spine Research Program, New York, NY, United States


Introduction: Although pre- and peri-operative antibiotics and skin preparation is performed on all patients undergoing surgery, surgical site infections (SSI) are still occurring following surgical procedures. One of the most common organisms associated with postoperative infections in orthopedic surgery is Propionibacterium acnes (P. acnes), which has been identified in 70-95% of healthy human skin. P.acnes is a slow-growing, gram-positive bacteria that is capable of adherence and biofilm formation around instrumentation, which gives surgical patients higher risks of infection. Identifying the prevalence of P. acnes or other bacteria in the skin or tissues, even after standard surgical prep, would change our surgical prep methods, intra-operative wound management, and even surgical techniques and equipment used during surgery.

Purpose: The objective of this study was to identify the presence of colonized bacteria on the skin and in the dermal, subcutaneous fat, ligamentum flavum, and the cancellous bone of the vertebral body utilizing anaerobic long cultures in primary lumbar spine surgery procedures.

Methods: Under IRB approval, 54 participants underwent primary lumbar spine fusions at the Hospital for Special Surgery. Prior to their surgeries, participants underwent standard surgical prep, using either Betadine or Chloraprep at the incision site as well as taking Ancef antibiotics prior to surgery. While undergoing surgery, the surgeons took culture swabs of the skin prior to the incision, the dermal layer of the skin after the incision was made, as well as samples of subcutaneous fat, ligamentum flavum, and bone to be sent for aerobic and anaerobic long cultures. Data was analyzed using Binary logistic regression to estimate the incidence of P.acnes in the samples. We hypothesized that preoperative surgical skin prep would be unable to eradicate the P.acnes bacteria due to its location below the skin.

Results: Occult adherent bacteria were found in 26% of patients undergoing primary spine surgery. P. acnes was the most prevalent but other bacterias including Klebsiela pneumoniae, Staphylococcus simulans, Staphylococcus epidermidis, and Staphylococcus capitis were found. All of the patients that tested positive for occult adherent bacteria were found to have multiple types bacteria in the removed tissues. A higher percentage of male patients tested positive than female patients. P. acnes was identified in all tissues types that were collected.

Discussion: The results have shown that P.acnes bacteria is still present at the surgical site, despite the efforts of using standard preoperative skin preparation. This data supports our hypothesis that P.acnes is present in many tissues below the skin prior to surgery. After coming across this data, more studies can be done in order to see how P. acnes as well as other bacteria can be eradicated from the body prior to surgery. Findings from these future studies can possibly change surgical prep methods, intra-operative wound management, patient management, as well as surgical techniques for surgical procedures. With these changes, we could be able to find a decrease in the incidences of post-surgical infections.

Conclusion: This study has shown that P.acnes cannot be eradicated via methods of standard pre-operative surgical skin preparation. More information and alternative methods are needed in order to prevent surgical site infections from happening due to the presence of P.acnes bacteria.