Spinal Surgical Site Infection Research Articles

Risk Factors for Surgical Site Infection in Spinal Surgery and Interventions: A Retrospective Study.

Surgical site infection following spinal surgery causes prolonged delay in recovery after surgery, increases cost, and sometimes leads to additional surgical procedures. We investigated risk factors for the occurrence of surgical site infection events in terms of patient-related, surgery-related, and postoperative factors. This retrospective study included 1000 patients who underwent spinal surgery in our hospital between April 2016 and March 2019. Patient-related factors were dementia, length of preoperative hospital stay (≥ 14 days), and diagnosis at the time of surgery (traumatic injury or deformity). The one surgery-related factor was multilevel surgery (≥ 9 intervertebral levels), and the one postoperative factor was time to ambulation (≥ 7 days) were statistically significant risk factors for spinal surgical site infection. One risk factor identified in this study that is amenable to intervention is time to ambulation. As delayed ambulation is a risk factor for postoperative surgical site infection, how medical staff can intervene in postoperative ambulation to further reduce the incidence of surgical site infection is a topic for future research.

Effectiveness of Topical Vancomycin in the Prevention of Spinal Surgical Site Infections: A Retrospective Cohort Study

Introduction: The risk of surgical site infections (SSIs), particularly methicillin-resistant Staphylococcus aureus (MRSA) SSIs, post spinal surgeries is one of the most daunting experiences to patients and surgeons. In some practices, vancomycin powder is applied directly on the wound before skin closure to minimize the risk of SSIs; however, this practice is not supported by well-established evidence. This study sought to assess the effectiveness of topical (intra-wound) vancomycin in minimizing the risk of SSIs in patients who underwent spinal surgeries at a private Saudi hospital.
 Methodology: A retrospective cohort study was conducted using the hospital database. Patients who underwent spinal surgeries between September 2013 and September 2019 were included and followed-up for up to 30 (for surgeries without implantation) or 90 (for surgeries with implantation) days. The odds ratio (OR) of the first SSI observed in the follow-up period between vancomycin users versus nonusers was estimated using logistic regression adjusting for the measured confounders. A sensitivity analysis was conducted using a propensity score analysis.
 Result: We included 81 vancomycin users versus 375 nonusers with 28 infections. The adjusted OR of SSIs between the two groups was 0.40 (95% confidence interval [CI] 0.11–1.34). The result of the propensity score analysis was consistent (OR: 0.97 [95% CI 0.35–2.68]).
 Conclusion: We could not find a lower association of SSIs with intra-wound vancomycin in patients who underwent spinal surgeries. Conducting larger multicenter studies would add more emphasis to the findings of this study.

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

BACKGROUND CONTEXTCutibacterium 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. PURPOSEThis 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 DESIGNWe 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). METHODSSamples 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. RESULTSThe 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. CONCLUSIONA 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 SIGNIFICANCEA 95:5 TiO2-PDMS 10× silver carboxylate coating may help decrease spinal SSI due to C. acnes, especially in procedures with instrumentation.

Effectiveness of topical vancomycin in the prevention of spinal surgical site infections: a retrospective cohort study

BackgroundThe risk of surgical site infections (SSIs), particularly methicillin-resistant Staphylococcus aureus (MRSA) SSIs, after spinal surgeries is one of the most daunting experiences to patients and surgeons. Some authors suggest applying vancomycin powder on the wound before skin closure to minimize the risk of SSIs; however, this practice is not supported by well-established evidence. This study sought to assess the effectiveness of topical (i.e. intra-wound) vancomycin in minimizing the risk of SSIs in patients who underwent spinal surgeries at a Saudi hospital.MethodsA retrospective cohort study was conducted using the hospital database. Patients who underwent spinal surgeries from the period of 09/2013 to 09/2019 were included and followed up (observed from the time of the surgery) to 30 days (surgeries without implants) or 90 days (with implants). The odds ratio (OR) of the primary outcome between vancomycin treated versus non-treated patients was estimated using a logistic regression model adjusting for the measured confounders. A sensitivity analysis was conducted using propensity score analysis (inverse probability of treatment weighting [IPTW] with stabilized weights) to control for confounding by indication. All study analyses were completed using RStudio Version 1.2.5033.ResultsWe included 81 vancomycin treated vs. 375 untreated patients with 28 infections (8/81 vs. 20/375; respectively). The adjusted OR of SSIs between the two groups was 0.40 (95% confidence interval [CI] 0.11 to 1.34). The result of the propensity score analysis was consistent (OR: 0.97 [95% CI 0.35 to 2.68]).ConclusionsWe could not find a lower association of SSIs with intra-wound vancomycin in patients who underwent spinal surgeries. Further studies are needed to assess benefits of using topical vancomycin for this indication vs. the risk of antimicrobial resistance.

Interleukin-6 as inflammatory marker of surgical site infection following spinal surgery.

In order to elucidate whether serum inflammatory markers identify patients with local surgical site infection(SSI) as underlying disease for recurrent or new symptomatology following spine surgery, we evaluated the diagnostic potential of interleukin-6(IL-6) as a marker of SSI. The diagnostic significance of IL-6 was compared to the standard serum inflammatory markers C-reactive protein(CRP) and white blood cell count (WBCC). Ninety-eight consecutive patients with readmission due to recurrent or new symptomology after spinal surgery of degenerative spine disorders entered the study. Baseline patients' characteristics and the abovementioned inflammatory markers were collected, and arithmetical means with standard deviation, area under the curve (AUC), thresholds, sensitivity, specificity, positive(+)likelihood ratio (LR), and negative(-)LR with corresponding 95% confidence interval(95%CI) were calculated and correlated with presence or absence of SSI. Nine patients suffered from a SSI, whereas the remaining 89 patients had a recurrent/adjacent-segment degenerative disorder without evidence of infection. The most significant parameter for diagnosing a SSI was serum IL-6 (cut-off value > 15.3pg/ml, AUC = 0.954, SE = 85.7%, SP = 97.3%), followed by CRP (cut-off value = 0.8mg/dl, AUC = 0.916, SE = 88.9%, SP = 84.5%) CONCLUSIONS: In the case of recurrent or new symptomatology following spinal surgery, serum IL-6 has the highest diagnostic potential for diagnosing spinal SSI.

Correlation between lumbar multifidus fat infiltration and lumbar postoperative infection: a retrospective case\u2013control study

BackgroundThe aim of this study was to investigate the correlation between lumbar multifidus fat infiltration and lumbar postoperative surgical site infection (SSI). Several clinical studies have found that spine postoperative SSI is associated with age, diabetes, obesity, and multilevel surgery. However, few studies have focused on the correlation between lumbar multifidus fat infiltration and SSI.MethodA retrospective review was performed on patients who underwent posterior lumbar interbody fusion (PLIF) between 2011 and 2016 at our hospital. The patients were divided into SSI and non-SSI groups. Data of risk factors [age, diabetes, obesity, body mass index (BMI), number of levels, and surgery duration] and indicators of body mass distribution (subcutaneous fat thickness and multifidus fat infiltration) were collected. The degree of multifidus fat infiltration was analyzed on magnetic resonance images using Image J.ResultsUnivariate analysis indicated that lumbar spine postoperative SSI was associated with urinary tract infection, subcutaneous fat thickness, lumbar multifidus muscle (LMM) fat infiltration, multilevel surgery (≥2 levels), surgery duration, drainage duration, and number of drainage tubes. In addition, multiple logistic regression analysis revealed that spine SSI development was associated with sex (male), age (> 60 years), subcutaneous fat thickness, LMM fat infiltration, and drainage duration. Receiver operating characteristic curve analysis indicated that the risk of SSI development was higher when the percentage of LMM fat infiltration exceeded 29.29%. Furthermore, Pearson’s correlation analysis demonstrated that LMM fat infiltration was correlated with age but not with BMI.ConclusionIndicators of body mass distribution may better predict SSI risk than BMI following PLIF. Lumbar Multifidus fat infiltration is a novel spine-specific risk factor for SSI development.

Meta-analysis of topical vancomycin powder for microbial profile in spinal surgical site infections.

To systematically evaluate the impact of topical vancomycin powder for microbial profile in spinal surgical site infections. All available literature regarding the topical use of vancomycin powder to prevent postoperative spinal infections was retrieved from the MEDLINE, EMBASE, and Cochrane databases starting from the creation date and up until September 30, 2018. A total of 21 studies involving 15,548 patients were reviewed. The combined odds ratio showed that topical use of vancomycin powder was effective for reducing the incidence of gram-positive bacterial infections in spinal surgical sites (OR 0.41, P < 0.00001) without affecting its efficacy in the prevention of polymicrobial infections (OR 0.30, P = 0.03). Additionally, it could significantly reduce the infection rate of methicillin-resistant staphylococcus (OR 0.34, P < 0.0001). However, topical vancomycin powder showed no advantage for preventing gram-negative bacterial infections (OR 0.94, P = 0.75). Topical administration of vancomycin powder may not increase the rates of gram-negative bacterial or polymicrobial infections in spinal surgical sites. On the contrary, it can significantly reduce the infection rates of gram-positive bacteria, methicillin-resistant staphylococcus (MRS) and microorganism. Of course, the topical vancomycin powder cannot change the rates of gram-negative bacterial infections, which may be related to the antimicrobial spectrum of vancomycin. Due to the limited number of articles included in this study, additional large-scale and high-quality studies are needed to provide more reliable clinical evidence.

Risk factors for postoperative spinal infection: A retrospective analysis of 5065 cases.

Background:Multiple factors increase the risk for spinal surgical site infection (SSI): prior SSI, obesity, diabetes mellitus, advanced age, American Society of Anesthesiologists class, alcohol abuse, low prealbumin levels, smoking, history of cancer, chronic steroids, immunosuppressive drugs, rheumatoid arthritis, and hypothyroidism.Methods:Here, we performed a retrospective medical record review at one facility involving 5065 patients from 2010 to 2015. In 2011, there was an increase in the infection rate (1.07%) which prompted this analysis, resulting in the subsequent introduction of a protocol to reduce the infection risk.Results:The overall infection rate in this series was 0.59%. The lowest infection rate was 0.00% for anterior cervical discectomy and fusion. The highest rate of infections occurred among patients undergoing posterior cervical fusions, lumbar fusions, and tumor resections. Higher infection rates were also correlated with diabetes mellitus, obesity, and increased surgical time.Conclusions:Since 2011, we instituted a protocol to limit the risks of spinal SSIs, particularly for patients exhibiting increased medical comorbidities.

Anterior cervical spine surgical site infection and pharyngoesophageal perforation. Ten-year incidence in 1475 patients

BackgroundSurgical site infection is reputed to be infrequent in anterior cervical spine surgery. Data on pathophysiological mechanism and risk factors are sparse. The relationship between local site infection and pharyngoesophageal perforation is unclear. The present study aimed: (1) to estimate the incidence of surgical site infection in anterior cervical spine surgery, (2) estimate the incidence of associated pharyngoesophageal perforation, and (3) suggest a decision-tree for early management of this two-fold issue. HypothesisAlthough with very low incidence, anterior cervical spine surgical site infection and pharyngoesophageal perforation are frequently associated. Material and methodsA 2-center retrospective study included all anterior cervical spine surgeries between January 1, 2007 and December 31, 2016. Data were provided by the two medical information departments. Patients undergoing anterior revision surgery on the cervical spine were included. Files were analyzed to determine whether the revision surgery was secondary to surgical site infection. ResultsIn total, 1475 patients with anterior cervical spine surgery were identified: 1180 in center A (80%) and 295 in center B (20%). The rate of revision surgery for surgical site infection was 0.34% (5/1475). There were 3 cases of pharyngoesophageal perforation (0.2%). DiscussionThe incidence of revision surgery for anterior cervical spine surgical site infection was comparable to rates in the international literature (0.07–1.6%). An association between surgical site infection and pharyngoesophageal perforation was frequent, but not statistically significant. This complication is extremely serious, requiring urgent multidisciplinary management. Level of evidenceIV, retrospective study.

Ultrasound-triggered antibiotic release from PEEK clips to prevent spinal fusion infection: Initial evaluations

Despite aggressive peri-operative antibiotic treatments, up to 10% of patients undergoing instrumented spinal surgery develop an infection. Like most implant-associated infections, spinal infections persist through colonization and biofilm formation on spinal instrumentation, which can include metal screws and rods for fixation and an intervertebral cage commonly comprised of polyether ether ketone (PEEK). We have designed a PEEK antibiotic reservoir that would clip to the metal fixation rod and that would achieve slow antibiotic release over several days, followed by a bolus release of antibiotics triggered by ultrasound (US) rupture of a reservoir membrane. We have found using human physiological fluid (synovial fluid), that higher levels (100–500 μg) of vancomycin are required to achieve a marked reduction in adherent bacteria vs. that seen in the common bacterial medium, trypticase soy broth. To achieve these levels of release, we applied a polylactic acid coating to a porous PEEK puck, which exhibited both slow and US-triggered release. This design was further refined to a one-hole or two-hole cylindrical PEEK reservoir that can clip onto a spinal rod for clinical use. Short-term release of high levels of antibiotic (340 ± 168 μg), followed by US-triggered release was measured (7420 ± 2992 μg at 48 h). These levels are sufficient to prevent adhesion of Staphylococcus aureus to implant materials. This study demonstrates the feasibility of an US-mediated antibiotic delivery device, which could be a potent weapon against spinal surgical site infection. Statement of SignificanceSpinal surgical sites are prone to bacterial colonization, due to presence of instrumentation, long surgical times, and the surgical creation of a dead space (≥5 cm3) that is filled with wound exudate. Accordingly, it is critical that new approaches are developed to prevent bacterial colonization of spinal implants, especially as neither bulk release systems nor controlled release systems are available for the spine. This new device uses non-invasive ultrasound (US) to trigger bulk release of supra-therapeutic doses of antibiotics from materials commonly used in existing surgical implants. Thus, our new delivery system satisfies this critical need to eradicate surviving bacteria, prevent resistance, and markedly lower spinal infection rates.

Surgical Site Infection in Spine Surgery: Who Is at Risk?

Study Design:Retrospective literature review of spine surgical site infection (SSI).Objective:To perform a review of SSI risk factors and more specifically, categorize them into patient and surgical factors.Methods:A review of published literature on SSI risk factors in adult spine surgery was performed. We included studies that reported risk factors for SSI in adult spinal surgery. Excluded are pediatric patient populations, systematic reviews, and meta-analyses. Overall, we identified 72 cohort studies, 1 controlled-cohort study, 1 matched-cohort study, 1 matched-paired cohort study, 12 case-controlled studies (CCS), 6 case series, and 1 cross-sectional study.Results:Patient-associated risk factors—diabetes mellitus, obesity (body mass index >35 kg/m2), subcutaneous fat thickness, multiple medical comorbidities, current smoker, and malnutrition were associated with SSI. Surgical associated factors—preoperative radiation/postoperative blood transfusion, combined anterior/posterior approach, surgical invasiveness, or levels of instrumentation were associated with increased SSI. There is mixed evidence of age, duration of surgery, surgical team, intraoperative blood loss, dural tear, and urinary tract infection/urinary catheter in association with SSI.Conclusion:SSIs are associated with many risk factors that can be patient or surgically related. Our review was able to identify important modifiable and nonmodifiable risk factors that can be essential in surgical planning and discussion with patients.

Enterobacter Infection after Spine Surgery: An Institutional Experience

Gram-negative surgical site infections (SSI) following spine surgery are becoming increasingly more common owing to a broad perioperative antibiotic usage targeting gram-positive organisms. Enterobacter species have been reported to be the most common gram-negative bacteria following spine surgery. We queried our institutional database for Enterobacter SSIs after spine surgery at a single institution from 2009-2016. Relevant demographic, clinical, and operative variables were collected. We compared this cohort to patients who had non-Enterobacter SSI during the same period. Enterobacter species were isolated in 16 patients (9 males) diagnosed with SSI after undergoing spine surgery. This group represented 0.2% of all spine cases and 14.5% of all spinal SSIs. Seven patients (43.8%) required multiple irrigations and debridements (I&Ds) (range: 2-8), whereas only 17 of 94 patients (18.1%) with non-Enterobacter SSI required multiple I&Ds (range: 2-5, P= 0.043). Those infected with Enterobacter were associated with higher BMI (37.6 ± 12.7 vs. 31.7 ± 8, P= 0.036), earlier wound dehiscence (14.8 vs. 24.6 days, P= 0.01), polymicrobial infections (37.5% vs. 10.6%, P= 0.012), and longer length of stay (18 days [9.5-31.5] vs. 5 days [3-8], P= 0.01) when compared to non-Enterobacter SSI cohort. At an average of 24.2 months follow-up, all 15 surviving patients were infection free with no further revision surgeries needed. Enterobacter SSI cases were associated with higher BMI, earlier wound breakdown, polymicrobial infection and longer length of stay. Nevertheless, with vigilant surveillance and timely I&Ds, these challenging infections can be treated successfully with original implant retention in almost all cases.

Successful 6-Week Antibiotic Treatment for Early Surgical-site Infections in Spinal Surgery.

The incidence of spinal surgical site infections (SSIs) remains stable at less than 10%. Surgical reinterventions may be hampered by decubitus, treatment-related adverse events, and cost. In the context of emergence of bacterial resistance, a short duration of antimicrobial treatment is of critical importance. If the duration of treatment for SSI is currently 12 weeks, the aim of our study was to assess the efficacy of an antimicrobial treatment shortened to 6 weeks. This prospective study was carried out from November 2014 to July 2016 in an 827-bed teaching hospital. After surgical management of SSIs, patients received broad-spectrum antibiotics intravenously for 10 days and orally for the remainder, for a total of 6 weeks. Success was defined as absence of relapse, superinfection, or surgical failure at the end of treatment and at 1-year follow-up. Eighty-five patients were included in this study. The median delay between initial surgery and diagnosis of SSI was 16 days. In 65 cases (76.4%), SSIs were monomicrobial; among these, Staphylococcus aureus was found in 30 cases (46%). Failure was observed in 7 cases (8.2%), with more than half caused by anaerobic bacteria. Surgical management of SSI followed by a 6-week antibiotic treatment is associated with favorable outcome. Anaerobic bacteria seem to play a role in the occurrence of relapses. A 6-week reduction in antibiotic treatment leads to reduction in cost and, likely, also to reduction in the emergence and spread of resistant microorganisms.

The impact of prophylactic intraoperative vancomycin powder on microbial profile, antibiotic regimen, length of stay, and reoperation rate in elective spine surgery

Background ContextThere is growing concern that the microbial profile of surgical site infection (SSI) in the setting of prophylactic vancomycin powder may favor more resistant and uncommon organisms. PurposeTo demonstrate the impact of prophylactic intraoperative vancomycin powder on microbial profile, antibiotic regimen, length of stay (LOS), and reoperation rate in spine surgical site infection. Study Design and/or SettingRetrospective cohort study. Patient Sample: the study included 115 postoperative spine patients who were required to return to the operating room for SSI. Outcome MeasuresThe outcome measures were microbial profile, reoperation rate, antibiotic regimen, and LOS for patients with postoperative spine infection who either did (treated) or did not (untreated) receive prophylactic vancomycin powder during their index procedure. MethodsA retrospective review of patients who underwent posterior thoracic and/or lumbar spine surgery between 2010 and 2017 was conducted. Those undergoing surgical treatment of SSI were identified, and patients were divided into two groups - those who were treated with intraoperative vancomycin (treated) and those who were not (untreated). The organism profile for each group was compared. The average LOS, reoperation rate, and number of patients requiring more than 1 antibiotic were calculated for each patient in both groups. ResultsThere were 5,909 procedures performed. One hundred and fifteen SSIs were identified, resulting in a 1.9% infection rate. Prophylactic vancomycin powder was used in the index procedure for 42 of those cases. 23.8% of cultures in the vancomycin group were polymicrobial and 16.7% were gram-negative compared with 9.6% (p=0.039) and 4.1% (p=0.021) in the untreated group, respectively. In the vancomycin-treated group, 26.1% of patients underwent repeat irrigation and debridement compared with 38.4% in the untreated group (p=0.184). The percentage of patients in the treatment and untreated group who required more than 1 antibiotic was 26.0% and 26.1%, respectively (p=0.984). Mean LOS in the treatment group was 8.0 versus 7.9 for the untreated group (p=0.945) ConclusionsIn this series, vancomycin powder was associated with a higher prevalence of gram-negative and polymicrobial organisms in patients that ultimately developed postoperative SSI. However, this did not adversely affect the need for multiple reoperations, antibiotic regimen, or LOS for these patients.

Preoperative measures to prevent/minimize risk of surgical site infection in spinal surgery.

Background:Multiple measures prior to spine surgery may reduce the risks of postoperative surgical site infections (SSIs).Methods:The incidence of SSI following spinal surgery (including reoperations and readmissions) may be markedly reduced by performing less extensive procedures and avoiding fusion where feasible. Preoperative testing up to 3 weeks postoperatively should include other studies to limit the perioperative SSI risk; cardiac stress tests (e.g., older patients/cardiac comorbidities), starting tamsulosin in males over 60 (e.g. avoid urinary retention due to benign prostatic hypertrophy), albumin/prealbumin levels (e.g., low levels increase SSI risk), and HBA1C levels to identify new/treat known diabetics (normalize/reduce preoperative levels).Results:Other measures include the timely administration of preoperative antibiotics (e.g., cefazolin 2 g nonpenicillin allergic), one dose of gentamicin (adjusted dose/weight), nasal cultures for methicillin-resistant Staphylococcus aureus (patients/health-care workers), and bathing 2 weeks preoperatively with chlorhexidine gluconate 4% (not just night before/morning of surgery). Additionally, prior to surgery, the following medications that increase the bleeding risk should be stopped (e.g. for varying periods); anticoagulants, antiplatelet therapies (e.g., aspirin for at least 7–10 days), nonsteroidal anti-inflammatories (NSAIDS: timing depends on the drug), vitamin E, and herbal supplements. Additionally, avoiding elective spinal surgery in morbidly obese patients and recognizing other major medical contraindications to spinal surgery should help reduce infection, morbidity, and mortality rates.Conclusions:Appropriate preoperative and intraoperative prophylactic maneuvers may reduce the risk of postoperative spinal SSI. Specific attention to these details may avoid infections and improve outcomes.

A Dose-Response Curve for a Gram-Negative Spinal Implant Infection Model in Rabbits.

A randomized complete block animal spinal implant infection model with internal control. The aim of this study was to develop a spinal implant animal infection model to simulate postoperative gram-negative wound infection. Implant-associated surgical site infections (SSIs) remain a dreaded complication of spinal surgery. Currently, over 30% of all spine SSIs are secondary to gram-negative bacteria. Traditional animal models have utilized gram-positive inoculums to simulate postoperative infection, but there exists no model in the literature for gram-negative infection in the setting of spinal instrumentation. Five New Zealand white female rabbits underwent simulated partial laminectomies and implantation of a 5 mm titanium wire adjacent to the spinous processes of vertebra T4, T9, L1, and L6 to mimic posterior spinal instrumentation. The second site, T9, was used as the sterile internal control sites, while all other sites were challenged with varying inoculums of Escherichia coli (EC American Type Culture Collection 25922): 10, 10, 10, 10, and 10 Colony Forming Units (CFU). The rabbits were sacrificed 4 days postoperatively and bacterial loads were assayed from the implants and surrounding tissue. No evidence for infection was observed in any of the sterile control sites. The lowest inoculum of E. coli (10 CFU) did not produce a reliable infection. Inoculation with 10 CFU created a consistent soft tissue infection, but inconsistent infection on implants. Inoculation with 10 CFU was required to consistently produce both soft tissue and implant infection. Consistent soft tissue and implant infection was produced with inoculation of 10 CFU of E. coli. Gram-negative infections represent greater than 30% of all spinal SSIs, and this animal model can reliably reproduce such infections with spinal instrumentation that can guide future development of anti-infective therapies. 2.

Efficacy of Target Drug Delivery and Dead Space Reduction Using Antibiotic-loaded Bone Cement for the Treatment of Complex Spinal Infection.

A retrospective study. We have treated complex cases of surgical site infection (SSI) successfully using antibiotic-loaded bone cement to avoid the need for implant removal. In the present study, we describe a new treatment option for SSI. Although there are several treatment options for SSI after spinal surgery involving instrumentation, several types of problems may arise and are difficult to cure. Eleven patients with SSI after undergoing spinal surgery involving instrumentation were studied. All had been refractory to conventional treatments, including intravenous antibiotic administration and conventional debridement and irrigation. Antibiotic-loaded bone cement was placed on and around the instrumentation to cover them and to occupy the surrounding dead space. Two general types of antibiotics were loaded into the polymethylmethacrylate bone cement. The recipes for the mixture were changed depending on the bacterial cultures. Sensitive antibiotics were administered generally for 2-6 weeks until the C-reactive protein level was normalized. All patients were treated successfully using antibiotic-loaded bone cement. Only 1 patient needed a repeat of this procedure to treat an infection. Antibiotic-loaded bone cement was placed in situ in all patients during the follow-up period and there were no significant adverse events. Antibiotic-loaded bone cement treatment reduces the dead space and achieves the targeted drug delivery simultaneously. Treatment using antibiotic-loaded bone cement is an effective treatment option for complex spinal SSI.

Risk factors for implant removal after spinal surgical site infection.

Few studies have investigated the risk factors for implant removal after treatment for spinal surgical site infection (SSI). Therefore, there is no firmly established consensus for the management of implants. We aimed to investigate the incidence and risk factors for implant removal after SSI managed with instrumentation, and to examine potential strategies for avoiding implant removal. Following a survey of seven spine centers, we retrospectively reviewed the records of 55 patients who developed SSI and were treated with reoperation, out of 3967 patients who had spinal instrumentation between 2003 and 2012. We examined implant survival rate and applied logistic regression analysis to assess the potential risk factors for implant removal. The overall rate of implant retention was 60% (33/55). A higher implant retention rate was observed for posterior cervical surgery than for posterior-thoracic/lumbar surgery (100 vs. 49%, P<0.001). On univariate analysis, significant risk factors for implant removal included greater blood loss, delay of reoperation, and delay of intervention with effective antibiotics. Multivariate analysis revealed that a delay in administering effective antibiotics was an independent and significant risk factor for implant removal in posterior-thoracic/lumbar surgery (odds ratio 1.17; 95% confidence interval 1.02-1.35, P=0.028). Patients with SSI who underwent posterior cervical surgery are likely to retain the implants. Immediate administration of effective antibiotics improves implant survival in SSI treatment. Our findings can be applied to identify SSI patients at higher risk for implant removal.

A novel risk severity score to predict pediatric spine surgical site infection in patients with cerebral palsy ranges from 0.88% to 23.3%

A novel risk severity score to predict pediatric spine surgical site infection in patients with cerebral palsy ranges from 0.88% to 23.3%

Predictors of increased cost and length of stay in the treatment of postoperative spine surgical site infection

Background ContextAlthough many risk factors are known to contribute to the development of a postoperative surgical site infection (SSI) following spinal surgery, little is known regarding the costs associated with the management of this complication, or the predictors for which patients will require increased resources for the management of SSI. PurposeThe aim of this study was to identify specific risk factors for increased treatment costs and length of stay in the management of a postoperative SSI. Study Design/SettingThis is a retrospective cohort study of all patients undergoing spine surgery at a single institution for 3 consecutive years. Patient SampleThe study included 90 patients who were required to return to the operating room following spine surgery for postoperative SSI. Outcome MeasuresThe primary outcome measure was length of stay and hospital costs for patients with postoperative SSI following spine surgery at a single institution. MethodsA retrospective review of all patients undergoing spine surgery at a single institution for 3 consecutive years was performed to identify patients requiring secondary surgical intervention for SSI. Demographic and financial data from both the index admission and all subsequent readmissions within 2 years of the index procedure were reviewed. Independent variables abstracted from patient records were analyzed to determine the nature and the extent of their associations with total direct hospital costs and length of stay. ResultsA total of 90 patients were identified that resulted in 110 readmissions, and these patients cumulatively underwent 138 irrigation and debridement (I&D) procedures for the management of postoperative spine SSI. The average length of stay for the index operation and secondary readmissions were 6.9 and 9.6 days, respectively. The mean direct cost of the treatment for SSI was $16,242. The length of stay, the number of levels fused, methicillin-resistant Staphylococcus aureus (MRSA), decreased serum albumin on readmission, and the number of I&D procedures required were significantly associated with increased treatment costs. ConclusionsPreoperative nutritional status assessment and MRSA colonization screening with targeted prophylaxis represent potentially modifiable risk factors in the treatment of SSI. Further study is needed to investigate the relationship between poor nutrition status and increased length of stay and total costs in the treatment of SSI following spine surgery.