Prevalence of intraoperative tissue bacterial contamination in posterior pediatric spinal deformity surgery

Circadian rhythm and daytime variation do not affect intraoperative bacterial sternal contamination and postoperative wound infections following cardiac surgery

Studies have documented various effects of circadian rhythm and daytime variations on the cardiovascular and immune system as well as wound healing. From June to December 2016, n = 367 cardiac surgery patients were enrolled. Microbiological swabs from the mediastinum and subcutaneous wound were taken before sternal closure. Patients were assigned to groups based on operation start: morning (n = 219) or afternoon (n = 135). Bacterial contamination and wound infections were studied in relation to circadian rhythm and daytime variation. We did not observe any difference in mortality (morning: 3.7%, afternoon: 3.0%, p > 0.99) and major adverse events (morning: 8.2%, afternoon: 5.9%, p = 0.53). In 27.7% of the morning group, at least one positive intraoperative swab was observed, similar to the afternoon group (25.6%, p = 0.71). The incidence of positive presternal swabs was 15.6% in the morning compared to 9.1% in the afternoon (p = 0.18). About 90% of the germs detected were part of the natural skin flora (e.g., Cutibacterium acnes and Staphylococcus epidermidis). The incidence of sternal wound infections was 7.3% (morning) and 3.0% (afternoon) (p = 0.18). We did not find differences in the incidence of intraoperative bacterial sternal contamination, nor postoperative infections, between patients who underwent cardiac surgery in the morning or afternoon.

A microbiology study on the wounds of pediatric patients undergoing spinal fusion for scoliosis

PURPOSE

Surgical site infection is a significant complication in posterior spinal fusion for scoliosis in pediatric and adolescent patients. Current literature demonstrates a lack of consensus regarding best prophylactic systemic and topical antibiotic regimens for reducing infection rates. This study aims to identify which common microbes are present at particular locations in the spine, and whether these are covered by our current systemic and topical antibiotic prophylaxis regimens.

METHODS

A prospective observational study at a National Children's Hospital was conducted on 21 consecutive patients who underwent elective surgery for spinal deformity. Swabs were taken from four layers of the spine, including the superficial skin surface at the start of the case (after surgical site preparation with povidone-iodine), the deep dermis, and the deep surgical bed at the end of exposure and again after the corrective maneuver prior to closure. At each layer, swabs were taken from the proximal, middle, and distal portion of the wound. Swabs were sent to the laboratory for culture and susceptibility testing.

RESULTS

Thirteen (62%) of patients had positive microbial growth. Two microbes were identified, Staphylococcus epidermidis (9.5% of patients) and Cutibacterium acnes (Propionibacterium acnes) (52% of patients). 100% of these microbes were sensitive to cefazolin and vancomycin. 3% of patients had positive growth at the skin layer, 32% positive at the dermal layer, 17% positive after exposure, and 40% positive at the conclusion of the case (p = 0.006). No difference was observed in microbial presence in the upper thoracic, lower thoracic and lumbar spine.

CONCLUSION

Despite adequate surgical site preparation and sterile procedure, microbial contamination remains abundant in the dermal layer and deeper in the spinal wound throughout the case.

Does the use of intrawound povidone-iodine irrigation and local vancomycin powder impact surgical site infection rate in adolescent idiopathic scoliosis surgery?

PURPOSE

Surgical site infection (SSI) is a major complication after adolescent idiopathic scoliosis (AIS) surgery, with an incidence ranging from 0.5 to 7%. Intraoperative wound decontamination with povidone-iodine (PVP-I) irrigation and/or vancomycin powder in adult spinal surgery has gained attention in the literature with controversial results. The aim of this study was to investigate the impact of using intrawound PVP-I irrigation and local vancomycin powder (LVP) on the incidence of early SSI in AIS surgery.

METHODS

All AIS patients who underwent posterior spinal fusion between October 2016 and December 2019 were retrospectively reviewed. The incidence of early SSI was reported and compared between 2 groups defined by the treating spinal surgeons' preferences: group 1-intrawound irrigation with 2L of PVP-I and application of 3 g LVP before closure and control group 2-patients that did not receive either of these measures.

RESULTS

Nine early cases of SSI (2.9%) were reported among the 307 AIS posterior spinal fusion patients. Incidence of SSI in group 1 (2/178 = 1.1%) was significantly lower than in group 2 (7/129 = 5.4%; p = 0.04). There were no adverse reactions to the use of PVP-I and LVP in our study. At latest follow-up, rate of surgical revision for mechanical failure with pseudarthrosis was significantly lower in group 1 (2/178 = 1.1%) than in group 2 (9/129 = 7.0%; p = 0.01).

CONCLUSION

Intraoperative use of intrawound PVP-I irrigation and vancomycin powder is associated with a significant reduction of early SSI after AIS spine surgery.

LEVEL OF EVIDENCE IV

Retrospective study.

Animal Models for Postoperative Implant‐Related Spinal Infection

Postoperative infections following implant‐related spinal surgery are severe and disastrous complications for both orthopaedic surgeons and patients worldwide. They can cause neurological damage, disability, and death. To better understand the mechanism of these destructive complications and intervene in the process, further research is needed. Therefore, there is an urgent need for efficient, accurate, and easily available animal models to study the pathogenesis of spinal infections and develop new and effective anti‐bacterial methods. In this paper, we provide a general review of the commonly used animal models of postoperative implant‐related spinal infections, describe their advantages and disadvantages, and highlight the significance of correctly choosing the model according to the infection aspect under investigation. These models are valuable tools contributing to the better understanding of postoperative spinal infections and will continue to facilitate the invention of novel preventative and treatment strategies for patients with postoperative spinal infections. However, although they are valid and reproducible in some respects, the current animal models present certain limitations. Future ideal spinal infection animal models may assess the bacterial load of the same animal in real‐time in vivo, and better mimic the human anatomy as well as surgical techniques. Strains other than Staphylococcus aureus account for a large proportion of postoperative spinal infections, and thus, the establishment of models to evaluate other types of microbial infections is expected in the future. Furthermore, novel transgenic models established on advancements in genome editing are also likely to be developed in the future.

Treatment strategy for surgical site infection post posterior lumbar interbody fusion: A retrospective study

Introduction

Posterior lumbar interbody fusion (PLIF) has been widely used to treat various degenerative spinal diseases. However, surgical site infection (SSI) post-PLIF is often difficult to cure. This study aimed to clarify the difference in clinical course due to the causative organism and develop a treatment strategy for SSI post-PLIF.

Methods

Between January 2011 and March 2019, 581 PLIF surgeries were performed at our hospital. Deep SSI occurred in 14 patients who were followed up for more than 2 years. Causative bacterial species were diagnosed by preoperative puncture and/or intraoperative drainage or by tissue culture in 13 patients and by intradiscal puncture in one patient who underwent conservative treatment. Of the 13 patients who underwent surgeries for infection, 10 had Propionibacterium acnes (Group A; n = 4) or coagulase-negative Staphylococcus (CNS) (Group B; n = 6) as the causative bacterial species. Groups A and B were retrospectively compared in terms of age, sex, number of segments, presence of diabetes mellitus, operation time, blood loss, C-reactive protein on hematological examination, the elapsed time to diagnosis (ETD), the presence of clinical findings such as heat, redness, swelling, and discharge from the wound and healing time.

Results

All infections were eradicated with surgery except in one patient whose causative bacteria was CNS; cages were finally removed in 11 patients. There was a significant difference (P = 0.0105) in the ETD and clinical findings (P = 0.0476) between Groups A and B. Posterior one-stage simultaneous revision (POSSR) was performed in nine patients, of whom eight were cured and one required additional surgery.

Conclusions

The ETD and clinical findings were significantly different in SSI cases caused by different bacteria, which will be useful in predicting the causative bacteria in future cases. For the treatment of deep SSI post-PLIF, POSSR was effective.

Surgical Site Infection in Children with Neuromuscular Disorders after Laparoscopic Gastrostomy: A Propensity-Matched National Surgical Quality Improvement Program Pediatrics Database Analysis

Background: Prior studies have demonstrated that children with neuromuscular scoliosis have a higher incidence of infection after spine surgery. The purpose of the study is to determine whether children with neuromuscular disorders (NMDs) have higher rate of superficial surgical site infection (SSI) or increased hospital length of stay (LOS) compared with children without NMDs following laparoscopic gastrostomy creation, a common pediatric general surgery operation. Patients and Methods: We performed a retrospective propensity-matched analysis of laparoscopic gastrostomy creation in children from National Surgical Quality Improvement Program Pediatrics database (NSQIP-P) 2018-2019. Patients were stratified based on NMD status. We performed multivariable logistic regression and ordered logistic regression to estimate the odds ratio of superficial SSI within 30 days of surgery and increased LOS. Results: We screened 252,367 patients from the NSQIP-P 2018-2019 dataset. After applying inclusion and exclusion criteria and 1:1 propensity score-matching, there were 991 children with NMDs and 991 children without NMDs. Children with NMDs had higher prevalence of superficial SSI within 30 days of gastrostomy creation: 36 (3.63%) versus 18 (1.82%); p = 0.013. Children with NMDs had increased odds of having a superficial SSI within 30 days of laparoscopic gastrostomy tube (G-tube) placement compared with children without NMD (odds ratio [OR], 2.01; 95% confidence interval [CI], 1.13-3.58; p = 0.018). There was no difference in LOS based on NMD status. Conclusion: Children with NMDs have two-fold increased odds of superficial SSI after laparoscopic gastrostomy creation compared with children without NMDs. Children with NMDs should be the aim of targeted quality improvement initiatives to reduce infection risks.

Variability in Antibiotic Treatment of Pediatric Surgical Site Infection After Spinal Fusion at A Single Institution

BACKGROUND

Recent focus on surgical site infections (SSIs) after posterior spine fusion (PSF) has lowered infection rates by standardizing perioperative antibiotic prophylaxis. However, efforts have neglected to detail antibiotic treatment of SSIs. Our aim was to document variability in antibiotic regimens prescribed for acute and latent SSIs following PSF in children with idiopathic, neuromuscular, and syndromic scoliosis.

METHODS

This study included patients who developed a SSI after PSF for scoliosis at a pediatric tertiary care hospital between 2004 and 2019. Patients had to be 21 years or younger at surgery. Exclusion criteria included growing rods, staged surgery, and revision or removal before SSI diagnosis. Infection was classified as acute (within 90 d) or latent. Clinical resolution of SSI was measured by return to normal lab values. Each antibiotic was categorized as empiric or tailored.

RESULTS

Eighty subjects were identified. The average age at fusion was 14.7 years and 40% of the cohort was male. Most diagnoses were neuromuscular (53%) or idiopathic (41%).Sixty-three percent of patients had an acute infection and 88% had a deep infection. The majority (54%) of subjects began on tailored antibiotic therapy versus empiric (46%). Patients with a neuromuscular diagnosis had 4.0 times the odds of receiving initial empiric treatment compared with patients with an idiopathic diagnosis, controlling for infection type and time (P=0.01). Ninety-two percent of patients with acute SSI retained implants at the time of infection and 76% retained them as of August 2020. In the latent cohort, 27% retained implants at infection and 17% retained them as of August 2020.

CONCLUSIONS

Patients with acute infections were on antibiotics longer than patients with latent infections. Those with retained implants were on antibiotics longer than those who underwent removal. By providing averages of antibiotic duration and lab normalization, we hope to standardize regimens moving forward and develop SSI-reducing pathways encompassing low-risk patients.

LEVEL OF EVIDENCE

Level III.

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.

Why Irrigate for the Same Contamination Rate: Wound Contamination in Pediatric Spinal Surgery Using Betadine Versus Saline

BACKGROUND

The risk of surgical site infection in pediatric posterior spine fusion (PSF) is up to 4.3% in idiopathic populations and 24% in patients with neuromuscular disease. Twenty-three percent of pediatric PSF tissue cultures are positive before closure, with a higher rate in neuromuscular patients. Our primary aim was to evaluate the feasibility of a complete randomized controlled trial to study the efficacy of surgical site irrigation with povidone-iodine (PVP-I) compared with sterile saline (SS) to reduce the bacterial contamination rate before closure in children undergoing PSF.

METHODS

One hundred seventy-five subjects undergoing PSF were enrolled in a multicenter, single-blind, pilot randomized controlled trial. We recruited patients at low-risk (LR) and high-risk (HR) for infection 3:1, respectively. Before closure, a wound culture was collected. Nonviable tissues were debrided and the wound was soaked with 0.35% PVP-I or SS for 3 minutes. The wound was then irrigated with 2 L of saline and a second sample was collected.

RESULTS

One hundred fifty-three subjects completed the protocol. Seventy-seven subjects were allocated to PVP-I (18 HR, 59 LR) and 76 to SS (19 HR, 57 LR). Cultures were positive in 18% (14/77) of PVP-I samples (2 HR, 12 LR) and in 17% (13/76) of SS samples (3 HR, 10 LR) preirrigation and in 16% (12/77) of PVP-I samples (5 HR, 7 LR) and in 18% (14/76) of SS samples (4 HR, 10 LR) postirrigation. Eight percent (3/37) HR subjects (1 PVP-I, 2 SS) experienced infection at 30 days postoperative. No LR subjects experienced infection.

CONCLUSIONS

Positive cultures were similar across treatment and risk groups. The bacterial contamination of wounds before closure remains high regardless of irrigation type. A complete randomized controlled trial would be challenging to adequately power given the similarity of tissue positivity across groups.

LEVEL OF EVIDENCE

Level II-pilot randomized controlled trial.

The Value of a Modified Wiltse Approach for Deformity Correction in Neuromuscular Scoliosis

Background

Wiltse approaches have been shown to reduce operative blood loss and enhance recovery in lumbar spinal surgery; however, their efficacy in neuromuscular scoliosis (NMS) deformity correction has never been assessed. Thus, the purpose of this study was to compare the outcomes of deformity correction requiring pelvic fixation in NMS performed through a Wiltse approach in contrast to a standard midline approach.

Methods

This is a retrospective review of 24 consecutive children with NMS undergoing deformity correction by a single surgeon in our institution. Patient demographic data, operative time, blood loss, curve correction, length of stay, and complications were recorded.

Results

In 16 children, the procedure was performed through a Wiltse approach and in 8 through a midline approach. There was no significant difference in age, sex, preoperative Cobb angle, or number of levels fused. Patients who underwent a Wiltse approach had significantly less blood loss yet similar curve correction. The hospital length of stay and complication rate were not significantly different between the groups.

Conclusions

A modified Wiltse approach can be safely used for NMS deformity correction. This approach achieves similar curve corrections to a traditional midline approach with less blood loss and no need for iliac screw connectors.

Level of Evidence

3.

The Use of a Novel Antimicrobial Implant Coating In Vivo to Prevent Spinal Implant Infection

STUDY DESIGN

A controlled, interventional animal study.

OBJECTIVE

Spinal implant infection (SII) is a devastating complication. The objective of this study was to evaluate the efficacy of a novel implant coating that has both a passive antibiotic elution and an active-release mechanism triggered in the presence of bacteria, using an in vivo mouse model of SII.

SUMMARY OF BACKGROUND DATA

Current methods to minimize the frequency of SII include local antibiotic therapy (vancomycin powder), betadine irrigation, silver nanoparticles, and passive release from antibiotic-loaded poly(methyl methacrylate) cement beads, all of which have notable weaknesses. A novel implant coating has been developed to address some of these limitations but has not been tested in the environment of a SII.

METHODS

A biodegradable coating using branched poly(ethylene glycol)-poly(propylene sulfide) (PEG-PPS) polymer was designed to deliver antibiotics. The in vivo performance of this coating was tested in the delivery of either vancomycin or tigecycline in a previously established mouse model of SII. Noninvasive bioluminescence imaging was used to quantify the bacterial burden, and implant sonication was used to determine bacterial colony-forming units (CFUs) from the implant and surrounding bone and soft tissue.

RESULTS

The PEG-PPS-vancomycin coating significantly lowered the infection burden from postoperative day 3 onwards (P < 0.05), whereas PEG-PPS-tigecycline only decreased the infection on postoperative day 5 to 10 (P < 0.05). CFUs were lower on PEG-PPS-vancomycin pins than PEG-PPS-tigecycline and PEG-PPS pins alone on both the implants (2.4 × 10, 8.5 × 10, and 1.0 × 10 CFUs, respectively) and surrounding bone and soft tissue (1.3 × 10, 4.8 × 10, and 5.4 × 10 CFUs, respectively) (P < 0.05).

CONCLUSION

The biodegradable PEG-PPS coating demonstrates promise in decreasing bacterial burden and preventing SII. The vancomycin coating outperformed the tigecycline coating in this model compared to prior work in arthroplasty models, highlighting the uniqueness of the paraspinal infection microenvironment.

LEVEL OF EVIDENCE

N/A.

Measures to reduce end-of-case wound contamination: the impact of intra-wound vancomycin powder and betadine irrigation on surgical site infections in posterior spinal fusion

STUDY DESIGN

Retrospective descriptive, single-center study.

OBJECTIVES

To determine the effect of standardized intrawound vancomycin powder and betadine irrigation on surgical site infection (SSI) rates after posterior spinal fusion (PSF) in idiopathic scoliosis. Since 2005, our pediatric spine center has implemented a series of changes to lower the risk of SSI. The most recent interventions-intrawound vancomycin powder and betadine irrigation-are applied just before closure, aiming to reduce the culture-positive bacterial contamination known to occur in many cases. We sought to determine the impact of these end-of-case measures on our center's SSI rate.

METHODS

We retrospectively reviewed patients who underwent PSF for idiopathic scoliosis at our institution from January 1, 2010, to June 30, 2018, identifying all cases that returned to the operating room for surgical debridement within 90 days of PSF. Cases were surgeon-audited to ensure inclusion of all infections that met Centers for Disease Control and Prevention (CDC) criteria for acute SSI. Vertical expandable prosthetic titanium ribs, growing rods, staged procedures, and nonidiopathic cases were excluded. Annual rates of SSIs were correlated with the initiation of each SSI prevention measure.

RESULTS

Among 740 cases of PSF for idiopathic scoliosis from 2010 to 2018, the overall acute SSI rate by CDC criteria was 0.68%. The idiopathic SSI rate dropped significantly, from 1.70 to 0.20%, after the standardized introduction of intrawound vancomycin powder and betadine irrigation before closure (p < 0.04). The implementation of these end-of-case measures in 2012-2013 was soon followed by an institution best 3.5-year SSI-free period for idiopathic cases.

CONCLUSIONS

Since intrawound vancomycin powder and betadine irrigation were added to our SSI prevention bundle, we have seen a significantly lower SSI rate after PSFs for idiopathic scoliosis. These findings suggest that anti-SSI interventions to reduce wound contamination at the end of the case may have a particularly positive impact on SSI reduction.

LEVEL OF EVIDENCE

Level III, therapeutic.

Cutibacterium acnes Infection in Orthopedics: Microbiology, Clinical Findings, Diagnostic Strategies, and Management

Cutibacterium (formerly called Propionibacterium) acnes is a human skin flora often implicated in orthopedic infections. The unique characteristics of this microorganism make the diagnosis of infection difficult. The diagnosis often is made based on clinical evidence, radiographic signs, and laboratory and/or surgical findings combined. Treatment often involves both pharmacologic and surgical methods. In addition, formation of biofilms and increased resistance to drugs exhibited by the microorganism can require combined antimicrobial therapy. Prophylactic measures are particularly important, but no single method has been shown to fully eliminate the risk of C acnes infections. Previous reports have focused on C acnes infections involving surgical implants or after certain orthopedic procedures, particularly in the shoulder and spine. This article reviews current clinical, diagnostic, and treatment principles for C acnes in orthopedics in general. [Orthopedics. 2020; 43(1):52-61.].

Operative Field Debris Often Rises to the Level of the Surgeon's Face Shield During Spine Surgery: Are Orthopedic Space Suits a Reasonable Solution?

Background

The present study intended to identify debris in the spine surgical field that frequently rises to the level of the surgeon's face during several different elective spine procedures. Unlike other areas of orthopedic surgery where infection risk is of high concern, in spine surgery the surgical team usually uses a nonsterile face mask instead of a protective space suit with a sterile face shield. It is possible that blood or bone burr particles striking the surgeon's face mask represent a potential source of infection if they ricochet back into the operative field.

Methods

We reviewed 46 consecutive, elective spine surgeries between May 2015 and August 2015 from a single-surgeon practice. For each surgery, every member of the surgical team wore sterile (space suit) personal protective equipment. After each procedure, the face shield was carefully inspected by 2 members of the surgical team to identify patient blood, tissue, or bone burr dust present on the face shield.

Results

The rate of surgeon face shield debris inspected for each case overall was 38/46 (83%). The rate of first assistant face shield debris inspected per case was 16/46 (35%). The scrub technician had a 0% rate of face mask debris on inspection. The highest debris exposure rates occurred with transforaminal lumbar interbody fusions (100%), open laminectomy and fusions (100%), and anterior cervical discectomy and fusions 43/46 (93%).

Conclusions

There is a high rate of blood and tissue debris contact that occurs during spine surgery, and it is procedure dependent. Spine surgeons may consider using sterile shields particularly in high-risk cases to protect themselves and their patients.

Level of Evidence

4.

Nasal Swab Screening for Staphylococcus aureus in Spinal Deformity Patients Treated With Growing Rods

BACKGROUND

Surgical-site infections are one of the most concerning complications in patients treated with growing rods (GR). The purpose of this study was to evaluate the use of preoperative screening for Staphylococcus aureus (SA) for all growing spine procedures, and if this would permit alteration of prophylactic antibiotics to cover the identified resistances.

METHODS

All patients were identified who had SA screening during the course of GR treatment. In otal, 34 patients [23 neuromuscular (NMS), 4 congenital, 4 idiopathic scoliosis (IS), and 3 syndromic] were identified who had 111 preoperative screenings [79 lengthenings, 23 insertions, 6 revisions, and 3 conversions to posterior spinal fusions (PSF)]. Mean age at GR insertion was 5.5 years (2 to 11 y).

RESULTS

There were 11 methicillin-resistant Staphylococcus aureus (MRSA) "+" screenings in 6 patients (5 NMS, 1 IS): 3 in 3 patients before GR insertion and 8 in 3 patients (all 3 were negative at GR insertion screening) at subsequent surgeries. There were 23 methicillin-sensitive Staphylococcus aureus (MSSA) "+" screenings in 12 patients (7 NMS, 2 congenital, 2 IS, 1 syndromic): 2 in 2 patients before GR insertion and 21 in 10 patients at subsequent surgeries (18 lengthenings, 3 revisions). Overall, 13 patients (3 MRSA+10 MSSA) were initially negative but screened positive for the first time at a subsequent surgery (12 lengthenings, 1 GR to PSF). All patients (n=5) with positive screenings before GR insertion were in patients with NMS (3 MRSA, 2 MSSA). On the basis of sensitivities, 9 patients demonstrated SA resistance to cefazolin (8 MRSA and 1 MSSA) and 6 to clindamycin (5 MRSA and 1 MSSA). Hence, if cefazolin was routinely used for all patients 26.5% of patients (9/34) would have been inadequately covered at some point during their GR treatment; clindamycin, 17.7% (6/34).

CONCLUSION

The use of SA nasal swab screening in GR patients identified 9 patients (26.5%) whose prophylactic antibiotics (cefazolin) could be altered to permit appropriate SA coverage.

LEVEL OF EVIDENCE

Level IV-retrospective case series.

A review of microscopy-based evidence for the association of Propionibacterium acnes biofilms in degenerative disc disease and other diseased human tissue

PURPOSE

Recent research shows an increasing recognition that organisms not traditionally considered infectious in nature contribute to disease processes. Propionibacterium acnes (P. acnes) is a gram-positive, aerotolerant anaerobe prevalent in the sebaceous gland-rich areas of the human skin. A ubiquitous slow-growing organism with the capacity to form biofilm, P. acnes, recognized for its role in acne vulgaris and medical device-related infections, is now also linked to a number of other human diseases. While bacterial culture and molecular techniques are used to investigate the involvement of P. acnes in such diseases, definitive demonstration of P. acnes infection requires a technique (or techniques) sensitive to the presence of biofilms and insensitive to the presence of potential contamination. Fortunately, there are imaging techniques meeting these criteria, in particular, fluorescence in situ hybridization and immunofluorescence coupled with confocal laser scanning microscopy, as well as immunohistochemistry.

METHODS

Our literature review considers a range of microscopy-based studies that provides definitive evidence of P. acnes colonization within tissue from a number of human diseases (acne vulgaris, degenerative disc and prostate disease and atherosclerosis), some of which are currently not considered to have an infectious etiology.

RESULTS/CONCLUSION

We conclude that P. acnes is an opportunistic pathogen with a likely underestimated role in the development of various human diseases associated with significant morbidity and, in some cases, mortality. As such, these findings offer the potential for new studies aimed at understanding the pathological mechanisms driving the observed disease associations, as well as novel diagnostic strategies and treatment strategies, particularly for degenerative disc disease. These slides can be retrieved under Electronic Supplementary Material.

Preventing infection in shoulder surgery

Although rare, infection after shoulder surgery can represent a devastating complication. Infection can negatively affect clinical outcomes, and eradication often requires a protracted treatment course. Staphylococcus aureus, Staphylococcus epidermidis, and Cutibacterium acnes are among the most frequently isolated pathogens. Perioperative measures can be implemented to reduce infection risk. Here we review various perioperative practices and their efficacy at reducing infection after shoulder surgery.

Propionibacterium acnes infections in patients with idiopathic scoliosis: a case-control study and review of the literature

PURPOSE

Surgical site infection (SSI) caused by Propionibacterium acnes is an infrequent but devastating complication after spinal fusion. The purpose of this study was to identify risk factors for SSI with Propionibacterium acnes after spinal fusion for juvenile and adolescent idiopathic scoliosis (JIS and AIS).

METHODS

A case-control study was performed. Each case was matched 2:1 for age, gender and diagnosis. Retrospective chart review was performed to obtain relevant demographic, surgical and clinical data for all cases and controls. Statistical analysis included paired t-test and McNemar test, as well as exact logistic regression and robust regression models.

RESULTS

This study included ten infection cases (eight AIS, two JIS) and 20 controls (16 AIS, four JIS). In total, six infected cases presented within two weeks of the index procedure (acute infection) and four infected cases presented more than one year from the index procedure (delayed infection). The most common presentation for acute infections was wound drainage, while back pain was more common in delayed infections. All infections were successfully treated with surgical irrigation and debridement and postoperative antibiotics. Hardware was removed for patients with delayed infections. The strongest risk factor for infection was increased requirement for blood transfusion, but it did not reach statistical significance.

CONCLUSION

SSI with Propionibacterium acnes is an important complication after spinal fusion for idiopathic scoliosis. These infections can be successfully treated, but larger studies are needed to further identify risk factors and establish standardized guidelines for the treatment and prevention of this complication.

Detection of Bacteria Colonizing Titanium Spinal Implants in Children

BACKGROUND

Bacterial colonization of spinal implants may cause severe complications in patients with early-onset scoliosis. Correct diagnosis and detection of microbiologic formation is crucial to prevent delayed infections caused by bacterial colonization. The purposes of this study were to estimate the rate and risk factors of colonization of vertical expandable prosthetic titanium rib (VEPTR) implants in children and to compare the different methods for detecting microbiologic formation on the spinal implants.

METHODS

We evaluated prospectively a group of 42 children with spinal deformities with an overall of 95 lengthening surgeries and applied different methods to detect potential bacterial colonization of VEPTR implants: swab of the implant, swab with culture of tissue, analysis of the removed lock, polymerase chain reaction (PCR), and confocal microscopy. Potential risk factors were evaluated.

RESULTS

Of 42 patients, 17 (40%) were rated positive for bacterial colonization with Propionibacterium acnes and coagulase-negative staphylococci being the most commonly found bacteria. Risk factors for colonization were increasing age, body height, and weight. The swab with culture of removed tissue yielded most positive results, whereas direct microscopy and PCR were the least sensitive detection methods. Furthermore, commonly used infectious blood parameters were inconclusive.

CONCLUSIONS

Although the impact of bacterial colonized implants on the health of the patients is not fully elucidated, clinicians aim for prevention of microbiologic formation on implanted devices. Therefore, reliable, inexpensive, and easy to apply diagnostic tools are indispensable to detect colonization. Based on our data, the swab together with tissue culture has the potential to become the method of choice for future diagnosis.

Novel in vivo mouse model of implant related spine infection

Post-operative spine infections are a challenge, as hardware must often be retained to prevent destabilization of the spine, and bacteria form biofilm on implants, rendering them inaccessible to antibiotic therapy, and immune cells. A model of posterior-approach spinal surgery was created in which a stainless steel k-wire was transfixed into the L4 spinous process of 12-week-old C57BL/six mice. Mice were then randomized to receive either one of three concentrations (1 × 10² , 1 × 10³ , and 1 × 10⁴ colony forming units (CFU)) of a bioluminescent strain of Staphylococcus aureus or normal saline at surgery. The mice were then longitudinally imaged for bacterial bioluminescence to quantify infection. The 1 × 10² CFU group had a decrease in signal down to control levels by POD 25, while the 1 × 10³ and 1 × 10⁴ CFU groups maintained a 10-fold higher signal through POD 35. Bacteria were then harvested from the pin and surrounding tissue for confirmatory CFU counts. All mice in the 1 × 10⁴ CFU group experienced wound breakdown, while no mice in the other groups had this complication. Once an optimal bacterial concentration was determined, mice expressing enhanced green fluorescent protein in their myeloid cells (Lys-EGFP) were utilized to contemporaneously quantify bacterial burden, and immune response. Neutrophil fluorescence peaked for both groups on POD 3, and then declined. The infected group continued to have a response above the control group through POD 35. This study, establishes a noninvasive in vivo mouse model of spine implant infection that can quantify bacterial burden and host inflammation longitudinally in real time without requiring animal sacrifice. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:193-199, 2017.

Burden of Surgical Site Infections Associated with Select Spine Operations and Involvement of Staphylococcus aureus

BACKGROUND

Spine operations may be indicated for treatment of diseases including vertebral injuries, degenerative spinal conditions, disk disease, spinal misalignments, or malformations. Surgical site infection (SSI) is a clinically important complication of spine surgery. Staphylococcus aureus, including methicillin-resistant Staphylococcus aureus (MRSA), is a leading cause of post-spinal SSIs.

METHODS

PubMed and applicable infectious disease conference proceedings were searched to identify relevant published studies. Overall, 343 full-text publications were screened for epidemiologic, mortality, health care resource utilization, and cost data on SSIs associated with specified spine operations.

RESULTS

Surgical site infection rates were identified in 161 studies from North America, Europe, and Asia. Pooled average SSI and S. aureus SSI rates for spine surgery were 1.9% (median, 3.3%; range, 0.1%-22.6%) and 1.0% (median, 2.0%; range, 0.02%-10.0%). Pooled average contribution of S. aureus infections to spinal SSIs was 49.3% (median, 50.0%; range, 16.7%-100%). Pooled average proportion of S. aureus SSIs attributable to MRSA was 37.9% (median, 42.5%; range, 0%-100%). Instrumented spinal fusion had the highest pooled average SSI rate (3.8%), followed by spinal decompression (1.8%) and spinal fusion (1.6%). The SSI-related mortality rate among spine surgical patients ranged from 1.1%-2.3% (three studies). All studies comparing SSI and control cohorts reported longer hospital stays for patients with SSIs. Pooled average SSI-associated re-admission rate occurring within 30 d from discharge ranged from 20% to 100% (four studies). Pooled average SSI-related re-operation rate was 67.1% (median, 100%; range, 33.5%-100%). According to two studies reporting direct costs, spine surgical patients incur approximately double the health care costs when they develop an SSI.

CONCLUSIONS

Available published studies demonstrate a clinically important burden of SSIs related to spine operations and the substantial contribution of S. aureus (including MRSA). Preventive strategies aimed specifically at S. aureus SSIs could reduce health care costs and improve patient outcomes for spine operations.

Preoperative MRSA Screening in Pediatric Spine Surgery: A Helpful Tool or a Waste of Time and Money?

OBJECTIVES

To review the use of preoperative screening for Staphylococcus aureus for all pediatric spine procedures that was instituted at our facility in a multimodal approach to decrease the frequency of postoperative wound infections.

SUMMARY OF BACKGROUND DATA

Four years ago at our facility, a multimodal approach to decrease the frequency of postoperative infections after pediatric spine surgery was instituted.

METHODS

A single-center, single-surgeon pediatric spine surgery database was queried to identify all patients who had preoperative S. aureus nasal swab screening. Data collected included demographic data, diagnoses, methicillin-resistant S. aureus (MRSA) swab findings, bacterial antibiotic sensitivities, and outcome of the spine surgery.

RESULTS

A total of 339 MRSA screenings were performed. Twenty (5.9%) were MRSA positive, and 55 (16.2%) were methicillin-sensitive S. aureus (MSSA) positive. In the MRSA-positive group, 13 were neuromuscular, 5 were adolescent idiopathic scoliosis (AIS), 1 congenital, and 1 infantile idiopathic scoliosis. Of the MRSA-positive screenings, 13 (65.0% of MRSA-positive screenings; 3.8% of entire cohort) of were newly identified cases (9 neuromuscular, 3 AIS, and 1 congenital diagnoses). In the 55 MSSA-positive, 6 documented resistance to either cefazolin or clindamycin. Hence, in up to 22 of the preoperative screenings (6.5% of entire cohort; 16 MRSA and 6 MSSA showed antibiotic resistance), the preoperative antibiotic regimen could be altered to appropriately cover the identified bacterial resistances. During the study period, there were 11 patients who were diagnosed with a postoperative deep wound infection, none of them having positive screenings.

CONCLUSION

The use of preoperative nasal swab MRSA screening permitted adjustment of the preoperative antibiotic regimen in up to 6.5% of patients undergoing pediatric spine surgery. This inexpensive, noninvasive tool can be used in preoperative surgical planning for all patients undergoing spinal procedures.

LEVEL OF EVIDENCE

Level IV.

Compressive spinal epidural mass caused by Propionibacterium acnes

BACKGROUND CONTEXT

Propionibacterium acnes is a gram-positive and facultative anaerobe bacillus that is found within sebaceous follicles of the human skin and recognized as a cause of infections after spinal surgery. To our knowledge, there has been no previously reported case of symptomatic compressive chronic inflammatory epidural mass caused by P. acnes in a patient with no prior spinal procedures.

PURPOSE

This study aimed to describe a case of primary spinal infection by P. acnes.

STUDY DESIGN

This study is a case report of a condition not previously described in the literature.

METHODS

We present the history, physical examination, laboratory, radiographic, and histopathologic findings of a chronic inflammatory epidural mass caused by P. acnes in an immunocompetent adult male with no history of spinal surgery.

RESULTS

A 51-year-old man presented to our clinic with sudden onset bilateral lower extremity weakness, inability to ambulate, and urinary retention. His past clinical history was remarkable only for hernia and left knee surgery but no spinal surgery. A year earlier, he had an infected draining abscess of the right axilla that was successfully managed medically. At presentation, his serum erythrocyte sedimentation rate and C-reactive protein were moderately elevated. Pan-spine magnetic resonance imaging was notable for a circumferential epidural mass from C5 to T6. He underwent emergent decompression; the mass was removed and sent for culture and pathologic evaluation. Cultures from all three specimens collected during surgery grew P. acnes, and the patient was successfully managed on intravenous ceftriaxone, while pathology revealed a chronic inflammatory reactive process.

CONCLUSIONS

This is the first reported case of a primary spinal mass with chronic inflammatory features caused by P. acnes. In cases of epidural mass of unknown origin, both pathologic specimens and cultures should be obtained as slow-growing organisms may mimic oncologic processes.

Surgical Site Infections After Pediatric Spine Surgery

Surgical site infection (SSI) after spinal deformity surgery is a complication in the pediatric population resulting in high morbidity and cost. Despite modern surgical techniques and preventative strategies, the incidence remains substantial, especially in the neuromuscular population. This review focuses on recent advancements in identification of risk factors, prevention, diagnosis, and treatment strategies for acute and delayed pediatric spine infections. It reviews recent literature, including the best practice guidelines for infection prevention in high-risk patients. Targets of additional research are highlighted to assess efficacy of current practices to further reduce risk of SSI in pediatric patients with spinal deformity.

A Novel Prevention Bundle to Reduce Surgical Site Infections in Pediatric Spinal Fusion Patients

BACKGROUND

The Surgical Care Improvement Project bundle emphasizes operative infection prevention practices. Despite implementing the Surgical Care Improvement Project bundle in 2008, spinal fusion surgical site infections (SF-SSI) continued to be prevalent for this low-volume, high-risk surgery.

OBJECTIVE

To design a combined pre-, peri-, and postoperative bundle (PPPB) that would lead to sustained reductions in SF-SSI rates.

DESIGN

Quality improvement project, before-after trial with cost-effectiveness analysis.

SETTING

Children’s hospital.

PATIENTS

All spinal fusion patients, 2008–2015.

INTERVENTION

A multidisciplinary team developed the PPPB composed of Surgical Care Improvement Project elements plus improved wound care practices, nursing standard of care, dedicated nursing unit, dermatology assessment tool and consultation, nursing education tool using “teach back” technique, and a “Back Home” kit. SF-SSI rates were compared before (2008–2010) and after (2011-February 2015) implementation of PPPB. PPPB compliance was monitored.

RESULTS

A total of 224 SF surgeries were performed from 2008 to February 2015. Pre-PPPB analysis revealed median time to SF-SSI of 28 days, secondary to skin and bowel flora. Mean 3-year pre-PPPB SF-SSI rate per 100 SF surgeries was 8.2 (8/98) (2008: 13.3 [4/30], 2009: 2.7 [1/37], 2010: 9.7 [3/31]). Mean SF-SSI rate after PPPB was 2.4 (3/126) (January 2011-February 2015); there was a 71% reduction in mean SSI rate (P=.0695). No SF-SSI occurred in neuromuscular patients (P=.008) after PPPB. Compliance with PPPB elements has been 100%.

CONCLUSIONS

PPPB led to sustained improvement in SF-SSI rates over 50 months. The PPPB could be reproduced for other surgeries.

Infect Control Hosp Epidemiol 2016;37:527–534

Propionibacterium acnes: Disease-Causing Agent or Common Contaminant? Detection in Diverse Patient Samples by Next-Generation Sequencing

Propionibacterium acnes is the most abundant bacterium on human skin, particularly in sebaceous areas. P. acnes is suggested to be an opportunistic pathogen involved in the development of diverse medical conditions but is also a proven contaminant of human clinical samples and surgical wounds. Its significance as a pathogen is consequently a matter of debate. In the present study, we investigated the presence of P. acnes DNA in 250 next-generation sequencing data sets generated from 180 samples of 20 different sample types, mostly of cancerous origin. The samples were subjected to either microbial enrichment, involving nuclease treatment to reduce the amount of host nucleic acids, or shotgun sequencing. We detected high proportions of P. acnes DNA in enriched samples, particularly skin tissue-derived and other tissue samples, with the levels being higher in enriched samples than in shotgun-sequenced samples. P. acnes reads were detected in most samples analyzed, though the proportions in most shotgun-sequenced samples were low. Our results show that P. acnes can be detected in practically all sample types when molecular methods, such as next-generation sequencing, are employed. The possibility of contamination from the patient or other sources, including laboratory reagents or environment, should therefore always be considered carefully when P. acnes is detected in clinical samples. We advocate that detection of P. acnes always be accompanied by experiments validating the association between this bacterium and any clinical condition.

Current Animal Models of Postoperative Spine Infection and Potential Future Advances

Implant related infection following spine surgery is a devastating complication for patients and can potentially lead to significant neurological compromise, disability, morbidity, and even mortality. This paper provides an overview of the existing animal models of postoperative spine infection and highlights the strengths and weaknesses of each model. In addition, there is discussion regarding potential modifications to these animal models to better evaluate preventative and treatment strategies for this challenging complication. Current models are effective in simulating surgical procedures but fail to evaluate infection longitudinally using multiple techniques. Potential future modifications to these models include using advanced imaging technologies to evaluate infection, use of bioluminescent bacterial species, and testing of novel treatment strategies against multiple bacterial strains. There is potential to establish a postoperative spine infection model using smaller animals, such as mice, as these would be a more cost-effective screening tool for potential therapeutic interventions.

Bacterial colonization of VEPTR implants under repeated expansions in children with severe early onset spinal deformities

PURPOSE

Historically, severe spinal and thoracic deformities in children were treated with early long spinal fusions. This prevented further growth of the spine and thorax and often led to small stiff thoraces. Therefore, growth-retaining implants, like vertical expandable titanium ribs (VEPTR), were developed to stimulate thoracic and spinal growth. To accommodate growth, these implants have to be expanded every 6 months. Infection rates of up to 2 % per procedure are reported. Exchange of implant parts allows analyzing the development of implant-related infections and subclinical colonizations.

METHODS

In this prospective study, all patients undergoing repeat VEPTR expansion procedures at our institution were included. Preoperatively, clinical signs of infection were documented, and blood samples were taken. The removed implants were treated by sonication and microbiologically analyzed. The clinical follow-up was documented.

RESULTS

From January 2009 to May 2012, 39 children with 163 re-operations were included. Four of the 39 patients (10 %) developed clinical apparent infections and had implant removal. These were excluded and analyzed separately. Of 144 procedures, implant parts were eligible for analysis. Implant colonization was detected by sonication in 24 of 144 (16 %) operations in 18 out of 39 (46 %) patients. Repeated detection occurred in 5 (14 %) patients. No risk factors for colonization could be identified.

CONCLUSION

The rate of implant colonization is 4.5 times higher than the rate of manifest infections in VEPTR patients. Colonization may lead to a manifest infection over time. The knowledge of persistent implant colonization may change the treatment algorithm in patients with growth-retaining implants.

Vertebral osteomyelitis and epidural abscess caused by gas gangrene presenting with complete paraplegia: a case report

Introduction

Gas gangrene is most often caused by Clostridium perfringens infection. Gas gangrene is a medical emergency that develops suddenly. The mortality rate is higher with trunk involvement than with involvement of the extremities, which carries a better prognosis. With respect to vertebral involvement, there are few reports in the literature. The purpose of this paper is to report a very rare case of vertebral osteomyelitis caused by gas gangrene.

Case presentation

A 78-year-old Japanese woman with diabetes mellitus was admitted to our hospital with the chief complaints of back pain, dysuria, and complete paralysis of both legs. A computed tomography scan showed soft tissue swelling anterolaterally at intervertebral disc level T11/12 and a gas-containing epidural abscess that compressed her spinal cord. Cultures later grew Clostridium perfringens and Escherichia coli. Hemilaminectomy was done from T10 to T12, and an epidural abscess was removed. She went on to have fusion surgery 6 weeks after the initial operation and subsequently experienced complete pain relief. She was discharged 2 months later, at which time she was able to walk with a cane. Examination 18 months after surgery showed normal gait without a cane.

Conclusions

Discitis caused by gas gangrene infection was successfully treated by immediate debridement and subsequent fusion surgery.

What is new in the diagnosis and prevention of spine surgical site infections

BACKGROUND CONTEXT

Surgical site infection (SSI) after spinal surgery can result in several serious secondary complications, such as pseudoarthrosis, neurological injury, paralysis, sepsis, and death. There is an increasing body of literature on risk factors, diagnosis, and specific intraoperative interventions, including attention to sterility of instrumentation, application of minimally invasive fusion techniques, intraoperative irrigation, and application of topical antibiotics, that hold the most promise for reduction of SSI.

PURPOSE

The purpose of this review is to identify and summarize the recent literature on the incidence, risk factors, diagnosis, prevention, and treatment of SSIs after adult spine surgery.

STUDY DESIGN

The study design included systematic review and literature synthesis.

METHODS

For the systematic reviews, a search was performed in Medline and Scopus using keywords derived from a preliminary review of the literature and Medline MeSH terms. These studies were then manually filtered to meet the study criteria outlined in each section. Studies were excluded via predetermined criteria, and the majority of articles reviewed were excluded.

RESULTS

There are a number of patient- and procedure-specific risk factors for SSI. Surgical site infection appears to have significant implications from the patients' perspective on outcome of care. Diagnosis of SSI appears to rely primarily on clinical factors, while laboratory values such as C-reactive protein are not universally sensitive. Similarly, novel methods of perioperative infection prophylaxis such as local antibiotic administration appear to be modestly effective.

CONCLUSIONS

Surgical site infections are a common multifactorial problem after spine surgery. There is compelling evidence that improved risk stratification, detection, and prevention will reduce SSIs.

Clinical Decision Making in Early Wound Drainage Following Posterior Spine Surgery in Pediatric Patients

STUDY DESIGN

Retrospective.

OBJECTIVES

To identify the clinical factors suggestive of infected and non-infected drainage to help clinical decision making.

SUMMARY OF BACKGROUND DATA

Differentiating between drainage caused by a benign seroma and deep spinal infection may be difficult in the early postoperative period.

METHODS

Institutional spine surgery database was searched to identify the cases that were taken back to the operating room for drainage from the surgical wound in the early postoperative period between 2000 and 2012.

RESULTS

A total of 38 cases of early wound drainage (within 6 weeks postoperatively) were identified that were treated with opening all layers, irrigation, and debridement. Intraoperative cultures were sent in all cases. Twenty-five patients proved to have non-infected drainage and did not require further treatment. In 13 patients, infection was confirmed with intra-operative findings and cultures; these patients were treated with serial debridements. In 4 cases, implants had to be removed after multiple debridements (after a quiescent period). The group with non-infected drainage differed from the infection group in that most patients (21 of 25) had non-neuromuscular deformities, whereas 77% of the infected group had neuromuscular etiology (10 of 13) (p = .0004). Average number of days to revision was 8.5 (range, 5-14 days) for the non-infected group. Of the 25 patients, 23 presented in the first 10 days. In the infected group, average number of days to revision was 19. Ten of the 13 patients presented on postoperative day 14 or later. Logistic regression analysis showed a significant association between increased likelihood of infection and increased time from the index procedure (p = .0085).

CONCLUSIONS

The findings suggest that early presenting drainage in pediatric idiopathic spine deformity is often not infected. Drainage, especially presenting after the second postoperative week in neuromuscular patients, proved to be mostly deep spinal wound infections.

Should we start treating chronic low back pain with antibiotics rather than with pain medications?

For those of us who have read the 2 recently published articles by a Danish - British research group, it might appear that we are observing an impending paradigm shift on the origins of chronic low back pain. The results of this research indicate, that chronic low back pain associated with bone marrow edema in vertebral endplates that are adjacent to herniated intervertebral discs may be caused by infections with anaerobic bacteria of low virulence. According to these articles, treatment with certain antibiotics is significantly more effective than placebo against this low back pain. If these findings are to hold true in repeat studies by other researchers, they stand to fundamentally change our concepts of low back pain, degenerative disc disease and in consequence the suitable therapies for these entities. It may in fact require pain specialists to become familiarized with the details of antibiotic treatments and their specific risks in order to be able to properly counsel their patients. While this seems hard to believe at first glance, bacteria have been implicated in the pathogenesis of other conditions that do not primarily impose as infectious diseases such as gastric ulcers. While the authors refer to a few previous studies pointing into the same direction, the relevant research is really only from one group of collaborating scientists. Therefore, before we start prescribing antibiotics for chronic low back pain, it is imperative that other researchers in different institutions confirm these results.