Bacteriology and Risk Factors for Development of Late (Greater Than One Year) Deep Infection Following Spinal Fusion With Instrumentation

Positive Cutibacterium acnes Intervertebral Discs Are Not Associated with Subsidence Following Anterior Cervical Discectomy and Fusion at 3 or 6 Months

Background/Objectives:Cutibacterium acnes (C. acnes), formerly known as Propionibacterium acnes (P. acnes), is an anaerobic, low-virulent bacterium that has been associated with postoperative infections of the shoulder, knee, and cervical spine. Recent studies have highlighted an association between C. acnes and the development of degenerative disc disease (DDD). The aim of this study is to ascertain whether C. acnes increases the risk of subsidence following anterior cervical discectomy and fusion (ACDF). Methods: After IRB approval, consecutive patients undergoing elective ACDF for DDD from 2017 to 2018 were enrolled in this prospective cohort study. Intervertebral disc samples were taken at each affected level and cultured. A total of 66 patients with radiographic follow-ups were included in the final analysis. The extent of subsidence and cervical lordosis was determined immediately postoperatively and at the 3- and 6-month follow-ups. Results: No significant difference in subsidence was observed at 3 months (p = 0.07) or 6 months (p = 0.11) between culture-positive and -negative cohorts. Additionally, there was no significant difference detected in the change in cervical lordosis observed at 3 months (p = 0.16) or 6 months (p = 0.27) between culture-positive and -negative cohorts. For the most inferiorly fused segment, there was a significant difference in subsidence observed at 3 months (1.5 mm, 95% CI: 0.2-2.7 mm, p = 0.02) but not at 6 months (p = 0.17). Conclusions: Intervertebral discs with a positive C. acnes culture were not associated with greater levels of subsidence at 3 or 6 months following ACDF for DDD. Further research is necessary to endorse these results and to gauge the clinical significance of C. acnes infection.

Does hydrogen peroxide help mitigate the incidence of Cutibacterium acnes in cervical spine surgeries?

Background

Surgical site infection (SSI) is a common yet serious complication of cervical spine surgery. While initially thought to be clinically insignificant, Cutibacterium acnes (C. acnes) is an important cause of infection. The purpose of this study was to investigate the ability of a hydrogen peroxide (H2O2) application during standard presurgical skin preparation to reduce the burden of C. acnes in patients undergoing cervical spine surgery.

Methods

This was a retrospective review of prospectively collected data. Subjects were randomly assigned to either standard surgical preparation plus H2O2 (experimental) or without H2O2 (control). Prescrub, postscrub, and dermal cultures were obtained to assess the C. acnes burden after cultures on an aerobic and anaerobic growth medium were held for 21 days. Multivariate analysis was conducted to determine factors associated with presence of C. acnes. Outcome measures included the results of intraoperative cultures and the development of a SSI within 90 days postoperatively.

Results

Patients (n=86) undergoing elective 2- or 3-level fusion via anterior approach were included. Prior to application of the antiseptic solution, 65% (28/43) of the experimental cohort and 77% (33/43) of the control cohort had positive C. acnes cultures (p=.34). Following application of antiseptic solution, there were no differences in positive C. acnes culture rates between the experimental and control cohorts in the epidermal (30% vs. 28%, p=1.00) or dermal (40% vs. 42%, p=1.00) cultures. No differences in the rates of C. acnes eradication from preantiseptic to postantiseptic application occurred for epidermal (p=1.00) or dermal (p=1.00) skin layers. None of the factors were associated with positive C. acnes epidermal cultures on multivariable logistic regression analysis (p>.05).

Conclusions

While there is potential for H2O2 to reduce the positive culture rate of C. acnes in cervical spine patients, no difference was seen when compared to standard surgical skin preparation.

Implant-associated Infection After Pediatric Spine Deformity Surgery: Is Removal of Hardware Indicated?

BACKGROUND

Postoperative spinal implant infection following pediatric spinal surgery often presents a management dilemma. We aimed to characterize our experience in this cohort of patients, hoping to provide further insight when approaching these challenging cases.

METHODS

A retrospective, observational study was performed of all children who underwent spinal surgery from January 2015 to June 2021 in a tertiary pediatric spinal surgery referral center in Queensland, Australia. Records were reviewed to identify cases of postoperative surgical site infection, with particular focus on children with infection directly involving implants. Preoperative prophylaxis, microbiology, clinical course and outcomes were analyzed.

RESULTS

A total of 580 children underwent 933 procedures during the study period. The most common pathology requiring surgery was idiopathic scoliosis in 257 children (44.3%) followed by neuromuscular scoliosis in 192 children (33.1%). There were 35 cases of surgical site infection (6.03%), and 9 were implant-associated (1.55%). Infection rate among children with neuromuscular spinal deformity was almost 3-fold higher (11.5%) than idiopathic (3.89%). Methicillin-sensitive Staphylococcus aureus was the most commonly isolated organism (n = 15). Four implant-associated infections were successfully managed with retention of implant; all were diagnosed within 32 days (median = 20 days) and cultured either Staphylococcus aureus or Pseudomonas aeruginosa . Conversely, infections that necessitated implant removal had a more indolent onset (median = 175 days), and more often cultured Cutibacterium acnes and coagulase-negative Staphylococci .

CONCLUSIONS

Postoperative spinal implant infection can be treated successfully with hardware retention in select cases. Earlier presentation and recognition appear to be associated with better rates of retention and are linked to certain organisms. Further exploration of specific preventative strategies may be key in preventing devastating late-onset infections.

Silver carboxylate-doped titanium dioxide-polydimethylsiloxane coating decreases Cutibacterium acnes adherence and biofilm formation on polyether ether ketone

BACKGROUND CONTEXT

Cutibacterium acnes (C. acnes) is a gram-positive facultative anaerobe found in the deep sebaceous follicles of the skin on the shoulder and back. C. acnes has been increasingly recognized as a pathogen in spinal surgical site infection (SSI) especially in the presence of instrumentation.

PURPOSE

This study assesses whether a silver carboxylate-doped titanium dioxide-polydimethylsiloxane (TiO₂-PDMS) coating can decrease C. acnes adherence and biofilm formation on PEEK and four other commonly used spinal implant materials, stainless steel, cobalt chromium, titanium, and titanium alloy.

STUDY DESIGN

We compared the adherence of C. acnes over 24 hours between uncoated, 95:5 TiO₂ to PDMS ratio with 10× silver carboxylate coating and a 100% silver carboxylate coating on each implant material, which were uniformly saw cut and sterilized. Implants were then subjected to scanning electron microscopy (SEM) and confocal scanning laser microscopy (CSLM).

METHODS

Samples were coated using 95:5 TiO₂-PDMS 10× silver carboxylate, 100% silver carboxylate, or left uncoated. C. acnes was applied onto the samples and allowed to adhere for periods of 4, 8, 12, 16, or 20 hours. Nonadherent bacteria were then washed from the samples. These samples were then allowed to continue incubating for a total of 24 hours. SEM and confocal laser scanning microscope were used to visualize all samples for the presence of biofilm and quantification of C. acnes adherence at each time point.

RESULTS

The 95:5 TiO₂-PDMS 10× silver carboxylate coating was able to significantly decrease C. acnes adherence on PEEK after 8, 12, 16, and 20 hours of adherence. No statistical difference was found between the 95:5 TiO₂-PDMS 10× silver carboxylate coating and the 100% silver carboxylate positive control. We previously observed extensive C. acnes biofilm formation on uncoated PEEK, but none on PEEK coated with either the 95:5 TiO₂-PDMS 10× silver carboxylate or 100% Ag coating . Furthermore, no biofilm formation was observed on stainless steel, cobalt chromium, titanium, and titanium alloy coated with 95:5 TiO₂-PDMS 10× silver carboxylate or 100% Ag coating.

CONCLUSION

A 95:5 TiO₂-PDMS 10× silver carboxylate coating decreases C. acnes adhesion and prevents biofilm formation on PEEK and other common orthopedic implant materials.

CLINICAL SIGNIFICANCE

A 95:5 TiO₂-PDMS 10× silver carboxylate coating may help decrease spinal SSI due to C. acnes, especially in procedures with instrumentation.

Is Propionibacterium acnes becoming the most common bacteria in delayed infections following adolescent idiopathic scoliosis surgery?

STUDY DESIGN

Retrospective review of hospital charts.

OBJECTIVE

(1) To determine the microbiological profile of patients with surgical site infections following posterior spinal fusion surgery (PSF) for Adolescent Idiopathic scoliosis (AIS). (2) To study the treatment outcome of patients with surgical site infections (SSI) following surgery for AIS. (3) To identify the key differences in presentation and management of acute and delayed SSI following AIS surgery. There has been increasing evidence of the role of P. acnes in deep surgical site infections. Literature related to this is abundant in relation to shoulder arthroplasty; however, it is sparse in relation to spine surgery.

METHODS

We conducted a retrospective review of all patients treated for AIS during a 5-year period (2010-2014) at our institution, with a minimum of 2-year follow-up after the index surgery. Patients with a postoperative infection following their index surgery were included. Charts of AIS patients with post-op infections were reviewed for details of the index surgery, time to presentation of the infection, presenting signs/symptoms, microbiology details, details of surgical and antibiotic treatment, and outcomes.

RESULTS

Nine (2.8%) post-op infections were identified out of 315 cases for AIS during this period. Seven (2.2%) involved P. acnes. Two (0.6%) involved MSSA. The average time for cultures to show growth was 6.1 days (range 5-8 days) in P. acnes group and 2-3 days in MSSA group. Patients with P. acnes infections were treated with implant removal, debridement and antibiotics. All patients achieved solid fusion except two patients from the P. acnes group had pseudoarthrosis and had to undergo revision fusion.

CONCLUSION

Propionibacterium acnes was the single most common bacteria isolated from delayed surgical site infection following PSF in AIS patients. Optimal treatment consists of debridement, implant removal and antibiotics. These patients have high incidence of pseudoarthrosis.

LEVEL OF EVIDENCE

Level IV.

The Prevalence of Bacterial Infection in Patients Undergoing Elective ACDF for Degenerative Cervical Spine Conditions: A Prospective Cohort Study With Contaminant Control

STUDY DESIGN

Prospective cohort study.

OBJECTIVES

To determine the prevalence of bacterial infection, with the use of a contaminant control, in patients undergoing anterior cervical discectomy and fusion (ACDF).

METHODS

After institutional review board approval, patients undergoing elective ACDF were prospectively enrolled. Samples of the longus colli muscle and disc tissue were obtained. The tissue was then homogenized, gram stained, and cultured in both aerobic and anaerobic medium. Patients were classified into 4 groups depending on culture results. Demographic, preoperative, and postoperative factors were evaluated.

RESULTS

Ninety-six patients were enrolled, 41.7% were males with an average age of 54 ± 11 years and a body mass index of 29.7 ± 5.9 kg/m². Seventeen patients (17.7%) were considered true positives, having a negative control and positive disc culture. Otherwise, no significant differences in culture positivity was found between groups of patients. However, our results show that patients were more likely to have both control and disc negative than being a true positive (odds ratio = 6.2, 95% confidence interval = 2.5-14.6). Propionibacterium acnes was the most commonly identified bacteria. Two patients with disc positive cultures returned to the operating room secondary to pseudarthrosis; however, age, body mass index, prior spine surgery or injection, postoperative infection, and reoperations were not associated with culture results.

CONCLUSION

In our cohort, the prevalence of subclinical bacterial infection in patients undergoing ACDF was 17.7%. While our rates exclude patients with positive contaminant control, the possibility of contamination of disc cultures could not be entirely rejected. Overall, culture results did not have any influence on postoperative outcomes.

Risk factors for Cutibacterium acnes spinal implant-associated infection: a case-case-control study

OBJECTIVES

The aim was to determine the characteristics of patients who developed Cutibacterium acnes spinal implant-associated infection (SIAI) and the associated risk factors.

METHODS

We conducted two parallel case-control studies comparing 59 patients with SIAI caused by C. acnes (cases 1) and 93 patients with SIAI caused by other microorganisms (cases 2) diagnosed during 2010-2015 with 302 controls who underwent spinal instrumentation without subsequent infection.

RESULTS

Late-onset infections (median time to diagnosis, 843 days versus 23 days; p < 0.001) were more common in cases 1 than in cases 2. However, 20/59 (34%) of cases 1 occurred within the first 3 months after the index surgery. In addition, cases 1 were less likely to have fever (27%, 16/59 versus 58%, 54/93; p 0.001) or wound inflammation (39%, 23/59 versus 72%, 67/93; p < 0.001). Moreover, 24/59 (40%) of cases 1 presented with polymicrobial infections, and staphylococcal pathogens accounted for 22/24 (92%) of the co-infections. By comparing and contrasting the two multivariate risk models (cases 1 versus controls and cases 2 versus controls), the following factors associated with C. acnes SIAI development were identified: age <54 years (adjusted odds ratio (aOR) 2.43, 95% confidence interval (CI) 1.09-5.58, p 0.03), a body mass index <22 kg/m² (aOR 2.47, 95% CI 1.17-5.29, p 0.02), and thoracic instrumentation (aOR 16.1, 95% CI 7.57-37.0, p < 0.001).

CONCLUSIONS

Future therapeutic and prophylactic studies on C. acnes SIAI should focus on young, thin patients who undergo spinal instrumentation procedures involving the thoracic spine.

Cutibacterium acnes in Spine Pathology: Pathophysiology, Diagnosis, and Management

Cutibacterium acnes, long thought to be skin flora of pathological insignificance, has seen a surge in interest for its role in spine pathology. C acnes has been identified as a pathogen in native spine infection and osteomyelitis, which has implications in the management compared with more commonly recognized pathogens. In addition, It has also been recognized as a pathogen in postoperative and implant-associated infections. Some evidence exists pointing to C acnes as an unrecognized source of otherwise aseptic pseudarthrosis. Recently, it is hypothesized that low virulent organisms, in particular C acnes, may play a role in degenerative disk disease and the development of Modic end plate changes found in MRI. To this end, controversial implications exist in terms of the use of antibiotics to treat certain patients in the setting of degenerative disk disease. C acnes continues to remain an expanding area of interest in spine pathology, with important implications for the treating spine surgeon.

Management of late (>1 y) deep infection after spinal fusion: a retrospective cohort study

BACKGROUND

The incidence of late infection published in the literature varies from 1% to 12% with varying definition of late infection (range, 3 mo to 1 y). Current evidence suggests implant removal and antibiotic therapy is necessary to clear these infections. A high incidence of late (>1 y) deep infection after instrumented spinal fusion was identified at our institution. We sought to evaluate the efficacy of our management of these patients.

METHODS

A total of 1390 patients underwent instrumented spinal fusion from 2000 to 2009. Forty-two patients developed deep infection >1 year after index procedure (3%) and had surgical debridement. Clinical records and microbiology reports were reviewed for details of operative and postoperative management.

RESULTS

Advanced imaging was only obtained in 6 patients (5 computed tomography, 1 magnetic resonance imaging). Offending organisms were identified in 39/42 patients, 27 of these grew Propionibacterium acnes. P. acnes grew in culture at a median of 6 days (range, 3 to 10 d), significantly longer than all other organisms, which grew in a median of 1 day (range, 0 to 8 d) (P<0.001). Implants were removed at the index hospitalization in 41 patients. Implant retention was attempted in 1 patient and failed. Primary closure was carried out in 37 patients; the remainder had undergone multiple debridements (4 planned, 1 unplanned). VAC closure was utilized in 2 patients. All patients were treated with organism-specific intravenous antibiotics and transitioned to oral antibiotics on average in 34 days (range, 2 to 186 d). Total length of antibiotic therapy was an average of 141 days (range, 34 to 413 d).

CONCLUSIONS

P. acnes was the most common organism identified and took nearly 1 week to grow in culture. Treatment is generally successful with thorough debridement, removal of implants, and antibiotic treatment.

LEVEL III

retrospective comparative study.