Spinal infection: state of the art and management algorithm

[Infections of the spine : Therapeutic strategies]

Spinal infections are relatively rare entities but the incidence is significantly increasing due to the rapidly growing numbers of interventions on the spine. Primary infections of intervertebral discs (spondylodiscitis) and vertebral bodies (spondylitis) are distinguished from secondary postinterventional infections. Treatment relies primarily on either conservative or surgical management. In the absence of indications for surgery, a conservative approach is indicated when the patient is neurologically intact and the bony destruction is minimal. Conservative therapeutic options are based on the microbiological diagnosis and use of antibiotics, immobilization, analgesics and orthotics. Indications for a surgical intervention are the presence of neurological deficits, intraspinal abscesses, extensive osseous destruction and failure of conservative management. Surgical therapy focusses on the decompression of neural structures, debridement and eradication of the focus of infection, pathogen identification, correction of the deformity and restoration of a physiological spinal profile. Following a postoperative infection a timely diagnosis including assessment of the extent of infection is crucial. In the case of a purely superficial infection, antibiotic prophylaxis and close monitoring is indicated. If findings are pronounced surgical revision, debridement together with antibiotic therapy and if necessary vacuum-assisted closure as well as revision ranging from exchange of implants to complete removal of osteosynthetic material are required. Spinal infections are severe conditions frequently with residual long-term sequelae, whether the patients are managed conservatively or surgically.

Spondylodiscitis revisited

Spondylodiscitis may involve the vertebral bodies, intervertebral discs, paravertebral structures and spinal canal, with potentially high morbidity and mortality rates.

A rise in the susceptible population and improved diagnosis have increased the reported incidence of the disease in recent years.

Blood cultures, appropriate imaging and biopsy are essential for diagnosis and treatment.

Most patients are successfully treated by conservative means; however, some patients may require surgical treatment.

Surgical indications include doubtful diagnosis, progressive neurological deficits, progressive spinal deformity, failure to respond to treatment, and unresolved pain.

Cite this article: EFORT Open Rev 2017;2:447–461. DOI: 10.1302/2058-5241.2.160062

Novel rat tail discitis model using bioluminescent Staphylococcus aureus

Management of spondylodiscitis is a challenging clinical problem requiring medical and surgical treatment strategies. The purpose of this study was to establish a rat model of spondylodiscitis that utilizes bioluminescent Staphylococcus aureus (S. aureus), thus permitting in vivo surveillance of infection intensity. Inocula of the bioluminescent S. aureus strain XEN36 were created in concentrations of 10² CFU/0.1 ml, 10⁴  CFU/0.1 ml, and 10⁶  CFU/0.1 ml. Three groups of rats were injected with the bacteria in the most proximal intervertebral tail segment. The third most proximal tail segment was injected with saline as a control. Bioluminescence was measured at baseline, 3 days, and weekly for a total of 6 weeks. Detected bioluminescence for each group peaked at day 3 and returned to baseline in 21 days. The average intensity was highest for the experimental group injected with the most concentrated bacterial solution (10⁶  CFU/0.1 ml). Radiographic analysis revealed loss of intervertebral disc space and evidence of osseous bridging. Saline-injected spaces exhibited no decrease in intervertebral spacing as compared to distal sites. Histologic analysis revealed neutrophilic infiltrates, destruction of the annulus fibrosus and nucleus pulposus, destruction of vertebral endplates, and osseous bridging. Saline-injected discs exhibited preserved annulus fibrosus and nucleus pulposus on histology. This study demonstrates that injection of bioluminescent S. aureus into the intervertebral disc of a rat tail is a viable animal model for spondylodiscitis research. This model allows for real-time, in vivo quantification of infection intensity, which may decrease the number of animals required for infection studies of the intervertebral disc. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2075-2081, 2017.

Errors in Diagnosis of Spinal Epidural Abscesses in the Era of Electronic Health Records

PURPOSE

With this study, we set out to identify missed opportunities in diagnosis of spinal epidural abscesses to outline areas for process improvement.

METHODS

Using a large national clinical data repository, we identified all patients with a new diagnosis of spinal epidural abscess in the Department of Veterans Affairs (VA) during 2013. Two physicians independently conducted retrospective chart reviews on 250 randomly selected patients and evaluated their records for red flags (eg, unexplained weight loss, neurological deficits, and fever) 90 days prior to diagnosis. Diagnostic errors were defined as missed opportunities to evaluate red flags in a timely or appropriate manner. Reviewers gathered information about process breakdowns related to patient factors, the patient-provider encounter, test performance and interpretation, test follow-up and tracking, and the referral process. Reviewers also determined harm and time lag between red flags and definitive diagnoses.

RESULTS

Of 250 patients, 119 had a new diagnosis of spinal epidural abscess, 66 (55.5%) of which experienced diagnostic error. Median time to diagnosis in error cases was 12 days, compared with 4 days in cases without error (P <.01). Red flags that were frequently not evaluated in error cases included unexplained fever (n = 57; 86.4%), focal neurological deficits with progressive or disabling symptoms (n = 54; 81.8%), and active infection (n = 54; 81.8%). Most errors involved breakdowns during the patient-provider encounter (n = 60; 90.1%), including failures in information gathering/integration, and were associated with temporary harm (n = 43; 65.2%).

CONCLUSION

Despite wide availability of clinical data, errors in diagnosis of spinal epidural abscesses are common and involve inadequate history, physical examination, and test ordering. Solutions should include renewed attention to basic clinical skills.

Medical management of spinal epidural empyema in five dogs

CASE DESCRIPTION 5 dogs were examined because of clinical signs of myelopathy, including signs of pain associated with the spinal region and rapidly progressive neurologic deficits. CLINICAL FINDINGS In all dogs, results of MRI were consistent with spinal epidural empyema. Concurrent infectious processes were identified at adjacent or distant sites in all dogs, including diskospondylitis, prostatitis, dermatitis, paraspinal infection following a penetrating injury, urinary tract infection, and pyothorax. Bacteria were isolated from 3 dogs; Escherichia coli was isolated from blood, urine, and prostatic wash samples from 1 dog; a Pasteurella sp was isolated from a percutaneous aspirate from an adjacent infected wound in a second dog; and a Corynebacterium sp was isolated from a thoracic fluid sample from a third dog. For the remaining 2 dogs, results of bacterial culture were negative. TREATMENT AND OUTCOME All dogs showed clinical improvement within 2 weeks after initiation of antimicrobial treatment, and all had an excellent long-term outcome. CLINICAL RELEVANCE In dogs, spinal epidural empyema has previously been regarded as a surgical emergency. Findings for dogs in the present report suggested that, as is the case for humans, selected dogs with spinal epidural empyema may be successfully managed with medical treatment alone.

Evolution and Progression of Spondylodiskitis: A Case Presentation

Pyogenic infection of the spinal column is a relatively rare condition. Spondylodiskitis is characterized by infection of the intervertebral disk and the adjacent vertebrae. Diagnosis is often delayed because the symptoms are often nonspecific and also because of the high incidence of nonspecific low back pain in the general population. We report the case of a 42-year-old woman who developed low back pain secondary to spondylodiskitis. Her diagnosis was delayed because of a lack of supporting findings on initial magnetic resonance imaging. The case highlights the clinical scenario in which maintaining a high index of suspicion may lead to follow-up imaging and an accurate diagnosis.

LEVEL OF EVIDENCE

V.

Recent Developments in the Treatment of Spinal Epidural Abscesses

Spinal epidural abscess (SEA) is a serious condition that can be challenging to diagnose due to nonspecific symptomology and delayed presentation. Despite this, it requires prompt recognition and management in order to prevent permanent neurologic sequelae. Several recent studies have improved our understanding of SEA. Herein, we summarize the recent literature from the past 10 years relevant to SEA diagnosis, management and outcome. While surgical care remains the mainstay of treatment, a select subset of SEA patients may be managed without operative intervention. Multidisciplinary management involves internal medicine, infectious disease, critical care, and spine surgeons in order to optimize care.

[Spondylodiscitis : Current strategies for diagnosis and treatment]

Spondylodiscitis is a severe infectious disease of the intervertebral discs and of the adjacent parts of the vertebral bodies, culminating in destruction of the mobile segment. It is accompanied by a mortality rate of approximately 15%. Severe courses of the disease can also lead to abscess formation and dispersal of sepsis. Malpositioning of the axis organ and deficits in neurological function up to paraplegia are also possible complications. Timely diagnostics and targeted therapy contribute to minimizing the risk of significant health disorders. This review article gives a summary of important algorithms in the diagnostics and treatment and discusses them against the background of currently available literature. According to the current state of knowledge the surgical treatment of spondylodiscitis provides many advantages and is therefore the method choice, even if a conservative approach can be successful in selected cases. The endpoints of treatment are cleansing of the infection with normalization of laboratory parameters of inflammation and the osseous fusion of the mobile segment.

Prevotella osteomyelitis after dental capping procedure

We present a 49 year old man who presented to the emergency department with severe lower back pain of 5 days duration. One week prior he had been diagnosed with a right psoas muscle abscess and was discharged with a 28 day course of moxifloxacin after the preliminary culture from the psoas grew an anaerobic organism. MRI of the lumbar spine showed marrow edema in the L2 body, occupying most of the anterior two thirds of the body, with cortical erosion at the anteroinferior aspect of L1. Blood cultures were negative and bone biopsy of L2 showed neutrophilic invasion and reactive changes. Cultures grew Prevotella oralis. Hematogenous spread from a composite bonding procedure for exposed teeth roots is thought to be the source for the vertebral osteomyelitis. This is a plausible spread of infection in our case because it was thought that the osteomyelitis occurred first and spread to the psoas muscle.

New classification for the treatment of pyogenic spondylodiscitis: validation study on a population of 250 patients with a follow-up of 2 years

PURPOSE

Pyogenic spondylodiscitis (PS) is still burdened by a high rate of orthopedic and neurological complications. Despite the rising incidence, the choice of a proper orthopedic treatment is often delayed by the lack of clinical data. The aim of this study was to propose a clinical-radiological classification of pyogenic spondylodiscitis to define a standard treatment algorithm.

METHODS

Based on data from 250 patients treated from 2008 to 2015, a clinical-radiological classification of pyogenic spondylodiscitis was developed. According to primary classification criteria (bone destruction or segmental instability, epidural abscesses and neurological impairment), three main classes were identified. Subclasses were defined according to secondary criteria. PS without segmental instability or neurological impairment was treated conservatively. When significant bone loss or neurological impairment occurred, surgical stabilization and/or decompression were performed. All patients underwent clinical and radiological 2-year follow-up.

RESULTS

Type A PS occurred in 84 patients, while 46 cases were classified as type B and 120 as type C. Average time of hospitalization was 51.94 days and overall healing rate was 92.80%. 140 patients (56.00%) were treated conservatively with average time of immobilization of 218.17 ± 9.89 days. Both VAS and SF-12 scores improved across time points in all classes. Residual chronic back pain occurred in 27 patients (10.80%). Overall observed mortality was 4.80%.

CONCLUSIONS

Standardized treatment of PS is highly recommended to ensure patients a good quality of life. The proposed scheme includes all available orthopedic treatments and helps spine surgeons to significantly reduce complications and costs and to avoid overtreatment.

Pathogen Identification in Suspected Cases of Pyogenic Spondylodiscitis

Pyogenic spinal infection continues to represent a worldwide problem. In approximately one-third of patients with pyogenic spondylodiscitis, the infectious agent is never identified. Of the cases that lead to organismal identification, bacteria are more commonly isolated from the spine rather than fungi and parasites. This study applied universal prokaryotic 16S rRNA PCR as a rapid diagnostic tool for the detection of bacterial agents in specimens from patients suspected of pyogenic spondylodiscitis. Gram and Ziehl-Neelsen staining were used as a preliminary screening measure for microbiologic evaluation of patient samples. PCR amplification targeting 16S rRNA gene was performed on DNA extracted from 57 cases including specimens from epidural abscesses, vertebral, and disc biopsies. Positive samples were directly sequenced. MRI findings demonstrated that disc destruction and inflammation were the major imaging features of suspected pyogenic spondylodiscitis cases, as 44 cases showed such features. The most common site of infection was the lumbar spine (66.7%), followed by thoracic spine (19%), the sacroiliac joint (9.5%), and lumbar-thoracic spine (4.8%) regions. A total of 21 samples amplified the 16S rRNA-PCR product. Sanger sequencing of the PCR products identified the following bacteriological agents: Mycobacterium tuberculosis (n = 9; 42.9%), Staphylococcus aureus (n = 6; 28.5%), Mycobacterium abscessus (n = 5; 23.8%), and Mycobacterium chelonae (n = 1; 4.8%). 36 samples displayed no visible 16S rRNA PCR signal, which suggested that non-bacterial infectious agents (e.g., fungi) or non-infectious processes (e.g., inflammatory, or neoplastic) may be responsible for some of these cases. The L3–L4 site (23.8%) was the most frequent site of infection. Single disc/vertebral infection were observed in 9 patients (42.85%), while 12 patients (57.15%) had 2 infected adjacent vertebrae. Elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) inflammatory markers were noted in majority of the patients. In conclusion, microbiological methods and MRI findings are vital components for the proper diagnosis of pyogenic spondylodiscitis. Our findings suggest that molecular methods such as clinical application of 16S rRNA PCR and sequencing may be useful as adjunctive diagnostic tools for pyogenic spondylodiscitis. The rapid turnaround time of 16S rRNA PCR and sequencing submission and results can potentially decrease the time to diagnosis and improve the therapeutic management and outcome of these infections. Although S. aureus and M. tuberculosis were the most common causes of pyogenic spinal infections in this study, other infectious agents and non-infectious etiologies should be considered. Based on study results, we advise that antibiotic therapy should be initiated after a definitive etiological diagnosis.

Spondylitis transmitted from infected aortic grafts: a review

Graft infection following aortic aneurysms repair is an uncommon but devastating complication; its incidence ranges from <1% to 6% (mean 4%), with an associated perioperative and overall mortality of 12% and 17.5-20%, respectively. The most common causative organisms are Staphylococcus aureus and Escherichia coli; causative bacteria typically arise from the skin or gastrointestinal tract. The pathogenetic mechanisms of aortic graft infections are mainly breaks in sterile technique during its implantation, superinfection during bacteremia from a variety of sources, severe intraperitoneal or retroperitoneal inflammation, inoculation of bacteria during postoperative percutaneous interventions to manage various types of endoleaks, and external injury of the vascular graft. Mechanical forces in direct relation to the device were implicated in fistula formation in 35% of cases of graft infection. Partial rupture and graft migration leading to gradual erosion of the bowel wall and aortoenteric fistulas have been reported in 30.8% of cases.

Rarely, infection via continuous tissues may affect the spine, resulting in spondylitis. Even though graft explantation and surgical debridement is usually the preferred course of action, comorbidities and increased perioperative risk may preclude patients from surgery and endorse a conservative approach as the treatment of choice. In contrast, conservative treatment is the treatment of choice for spondylitis; surgery may be indicated in approximately 8.5% of patients with neural compression or excessive spinal infection. To enhance the literature, we searched the related literature for published studies on continuous spondylitis from infected endovascular grafts aiming to summarize the pathogenesis and diagnosis, and to discuss the treatment and outcome of the patients with these rare and complex infections.

Spinal Epidural Abscess: A Review with Special Emphasis on Earlier Diagnosis

Spinal epidural abscess (SEA) is an uncommon but serious condition with significant morbidity and mortality. The prognosis of SEA is highly dependent on the timeliness of its diagnosis before neurological deficits develop. Unfortunately, often due to its nonspecific presentation, such as back pain, the diagnosis of SEA may be delayed in up to 75% of cases. Although many risk factors for SEA can be found in the published literature, their utility is limited by their frequent lack of objective evidence, numerousness, and absence in a significant proportion of cases. In this review, we call for a more discriminate evidence-based use of the term "risk factor" when discussing SEA and explore several approaches to its earlier diagnosis, including a simple algorithm based on its pathophysiology and serum C-reactive protein or erythrocyte sedimentation rate.

Multidisciplinary management of spontaneous spinal infections: is there a correlation between timing, type of treatment and outcome?

BACKGROUND

Spontaneous spinal infections (SSIs) represent a rare and serious pathological entity. We tried to study a correlation between type of treatment, timing of treatment and clinical outcome through a multivariate analysis of an observational cohort study with the aim to define what is the optimal clinico-therapeutic management.

METHODS

We performed a retrospective observational cohort study on all consecutive patients observed in our Institute in a period of 13 years; from 2001 to 2014 we enrolled 50 consecutive patients with symptomatic spontaneous spinal infections (no previous surgery or recent infection in other site), confirmed with diagnostic imaging. The inclusion parameters were: diagnostic imaging, signs and symptoms positive for SSI, no history of recent infection or surgery. Of each parameter analyzed, we calculated mean and standard deviation and when necessary correlation (ρ), covariance (σ) and relation coefficient between type of treatment, timing of treatment and clinical outcome.

RESULTS

Our results suggest that an increase of one day from the onset of symptoms and the start of therapy leads to an increase in the Oswestry Disability Index Scale both at 6 months than at 1 year, with a statistical relevance, so our experience shows a statistically significant correlation and a positive co-variance between timing and outcome at 6 months and 1 year.

CONCLUSIONS

SSI are rare, very difficult to diagnose and represent a significant clinical problem. If not properly managed, they may lead to significant impact in the quality of life. The most relevant problem is not the treatment, conservative or surgical, but early diagnosis, so a careful physical, laboratory and imaging examination is fundamental, with an important help provided by isolation of the pathogen and histology. In our experience early diagnosis has a fundamental role. In the light of this, current treatment protocols may require a prompt and multidisciplinary management including infectivologists, neuroradiologists and spine surgeons.

Risk factors for surgical site infection in elective routine degenerative lumbar surgeries

BACKGROUND CONTEXT

Surgical site infection (SSI) is one of the most serious complications of spine surgery. Its predisposing factors, especially in routine surgeries, are less reported. However, a number of patient- and procedure-related risk factors could be avoided or at least determined preoperatively. Moreover, the patient-specific risk for SSI could be estimated before the elective surgery.

PURPOSE

The aim of the present study was to analyze the preoperatively determinable risk factors for SSI in patients who require elective routine surgery related to lumbar disc degeneration and to build a multivariable model for the individual risk prediction.

STUDY DESIGN

Analysis of prospectively collected standardized clinical data and the validation of the results on an independent prospective cohort were performed.

PATIENT SAMPLE

One thousand thirty (N=1,030) patients were included in the study. All subjects underwent primary lumbar single- or two-level decompression, microdiscectomy, or instrumented fusion.

OUTCOME MEASURES

Occurrence of an SSI defined according to the current Centers for Disease Control and Prevention guidelines that required surgical or nonsurgical therapy.

METHODS

The effect of preoperative patient characteristics, comorbidities, disease history, and invasiveness of the elective surgery on the risk of SSI was determined in uni- and multivariate logistic regression models in the test cohort (N=723). The performance of the final multivariable regression model was assessed by measuring its discriminative ability (c-index) in receiver operating characteristic analysis. Performance of the multivariable risk estimation model was tested on the validation (N=307) cohort.

RESULTS

The prevalence of SSI was 3.5% and 3.9% in the test and in the validation cohorts, respectively. The final multivariable regression model predictive (p=.003) for SSI contained the patient's age, body mass index (BMI), and the presence of 5 comorbidities, such as diabetes, ischemic heart disease, arrhythmia, chronic liver disease, and autoimmune disease as risk factors. The c-index of the model was 0.71, showing good discriminative ability, and it was confirmed by the data of the independent validation cohort (c=0.72).

CONCLUSIONS

Predisposing factors for SSI were older age, higher BMI, and the presence of certain comorbidities in the present study. The cumulative number of risk factors significantly associated with the increasing risk for an SSI (p<.0001). Our model needs further validation but it may be used for individual risk assessment and reduction in the future.

Safety and efficacy of polyetheretherketone (PEEK) cages in combination with posterior pedicel screw fixation in pyogenic spinal infection

BACKGROUND

To date, there is growing consensus that PEEK material may be used for interbody fusion in spinal infections. Data supporting that claim are however restricted to a few very small clinical series. The aim of this study is to evaluate the outcome of surgical treatment of pyogenic spinal infections with PEEK cages in combination with posterior pedicel screw fixation.

METHODS

Between 2006 and 2013, a total of 211 patients suffering from spondylodiscitis underwent surgical debridement and instrumentation. There were 52 cases where PEEK cages were used. Laboratory and physical examinations were assessed at a 3-month follow-up. Last follow-up was performed with at a minimum of 12 months after surgery via a telephone interview.

RESULTS

Mean age at presentation was 67 years, with 19 (37 %) male patients and 33 (63 %) female. Distribution of the infection was lumbar in 29 (56 %%), thoracic in 3 (6 %) and cervical in 11 (21 %) cases. Nine patients (17 %) had concomitant non-contiguous spondylodiscitis. Epidural abscess was found in 17 patients (33 %); 48 (92 %%) had pain; neurological deficits were found in 20 patients (38 %). All patients in this series underwent surgical debridement with instrumentation of the spine. Postoperative intravenous antibiotics were administered for 15.4 ± 6.8 days followed by 2.9 ± 0.5 months of oral antibiotics. Complete resolution of the infection was achieved in all cases. Of the 28 patients with neurological deficits, 6 had full recovery and 10 had improved incompletely after surgery. One patient suffered from a pulmonary embolism postoperatively. There were no mortalities.

CONCLUSIONS

Use of PEEK cages for interbody fusion is feasible and safe in patients suffering from a pyogenic spinal infection.

Infectious Spondylodiscitis by Uncommon Pathogens: A Pitfall of Empirical Antibiotics

Objective

The goal of this study is to evaluate the prevalence of spondylodiscitis (SD) caused by uncommon pathogens and review the efficacy of the treatment strategy including the coverage by usual empirical broad-spectrum antibiotic therapy.

Methods

Ninety-nine consecutive patients diagnosed and treated for infectious SD between January 2007 to May 2015 were reviewed retrospectively. The prevalence of uncommon SD, predisposing factors, antibiotics sensitivity, and clinical outcome were analyzed in comparison with that of common SD.

Results

Among 99 patients, 68 patients were culture positive. Out of 68 patients with positive culture results, 54 of them(79.4%) were common pathogen and 14 (20.6%) were uncommon pathogen. Postoperative SDs were significantly prevalent in uncommon SD(42.9%) than common SD(27.8%). Recurrence rate was higher in uncommon pathogen SD(14.3%) than common SD group (2.3%), and it showed statistically significant difference (p=0.025). Empirical antibiotics of vancomycin and 3rd or 4th generation cephalosporin covered 100% of nontuberculous common SD and 14.3% of uncommon SD.

Conclusion

In our study, the prevalence of uncommon SD was relatively high uncommon (20.5% of culture positive SD and 14.1% of total cases) and the coverage rate of empirical antibiotics for them were only 14.3%. In particular, the possibility of SD with fun gal, polymicrobial, or multiple drug resistant organism should be considered in SD unresponsive to broad spectrum antibiotics therapy.

Posterior Titanium Screw Fixation without Debridement of Infected Tissue for the Treatment of Thoracolumbar Spontaneous Pyogenic Spondylodiscitis

Study Design

Retrospective study.

Purpose

The aim of our study was to analyze the safety and effectiveness of posterior pedicle screw fixation for treatment of pyogenic spondylodiscitis (PSD) without formal debridement of the infected tissue.

Overview of Literature

Posterior titanium screw fixation without formal debridement of the infected tissue and anterior column reconstruction for the treatment of PSD is still controversial.

Methods

From March 2008 to June 2013, 18 patients with PSD underwent posterior titanium fixation with or without decompression, according to their neurological deficit. Postero-lateral fusion with allograft transplantation alone or bone graft with both the allogenic bone and the autologous bone was also performed. The outcome was assessed using the visual analogue scale (VAS) for pain and the Frankel grading system for neurological status. Normalization both of C-reactive protein (CRP) and erythrocyte sedimentation rate was adopted as criterion for discontinuation of antibiotic therapy and infection healing. Segmental instability and fusion were also analyzed.

Results

At the mean follow-up time of 30.16 months (range, 24–53 months), resolution of spinal infection was achieved in all patients. The mean CRP before surgery was 14.32±7.9 mg/dL, and at the final follow-up, the mean CRP decreased to 0.5±0.33 mg/dL (p <0.005). Follow-up computed tomography scan at 12 months after surgery revealed solid fusion in all patients. The VAS before surgery was 9.16±1.29 and at the final follow-up, it improved to 1.38±2.03, which was statistically significant (p <0.05). Eleven patients out of eighteen (61.11%) with initial neurological impairment had an average improvement of 1.27 grades at the final follow-up documented with the Frankel grading system.

Conclusions

Posterior screw fixation with titanium instrumentation was safe and effective in terms of stability and restoration of neurological impairment. Fixation also rapidly reduced back pain.

Risk factors for diskospondylitis in dogs after spinal decompression surgery for intervertebral disk herniation

OBJECTIVE To determine the incidence of and risk factors for development of postoperative diskospondylitis (POD) in dogs that underwent spinal decompression surgery for intervertebral disk herniation (IVDH). DESIGN Retrospective single cohort study. ANIMALS 372 dogs that underwent spinal decompression surgery for IVDH between January 2007 and January 2011. PROCEDURES Medical records of dogs were retrospectively reviewed. Data regarding signalment, type and anatomic site of IVDH, severity of neurologic signs, type of surgery, duration of anesthesia, esophageal temperature during surgery, and use of corticosteroid drugs were analyzed for associations with POD. RESULTS POD developed in 8 of 372 (2.2%) dogs. Univariate analysis revealed that German Shepherd Dogs had 9.8 times the odds of POD, compared with the odds for other breeds. In addition, dogs > 8.8 years of age, weighing > 20 kg (44 lb), or having disk protrusions were at higher risk of developing POD than were other dogs. The only factor that retained a significant association with POD after controlling for other factors in multivariate analysis was body weight > 20 kg. CONCLUSIONS AND CLINICAL RELEVANCE Factors identified in this study may be useful for prediction of POD, an apparently uncommon outcome, in dogs undergoing spinal decompression surgery for IVDH. Dogs at higher risk than others, particularly those weighing > 20 kg, should be monitored carefully in the immediate postoperative period, and signs of worsening neurologic condition after initial improvement should be promptly investigated.

How Best to Manage the Spinal Epidural Abscess? A Current Systematic Review

BACKGROUND

A spinal epidural abscess is a medical emergency. Despite urgent surgical intervention and adjuvant antibiotic therapy, neurologic prognosis remains variable and guarded. The optimal approach to managing this condition is debated with substantial variability in clinical practice, dependent on patient demographic and pretreatment neurologic status as well as radiologic appearance.

METHODS

A systematic search in MEDLINE and similar databases was conducted for literature published from 1990 to 2015 using the search term "spinal epidural abscess", limiting the search results to human studies published in the English language. Case series that consisted of fewer than 10 patients were excluded. The evidence strength was graded according to the Grades of Recommendation Assessment, Development, and Evaluation criteria.

RESULTS

The search yielded 1843 patients from 34 retrospective case series. Ten studies compared surgical and medical management, with no significant difference in patients with good outcome (odds ratio, 0.65; P = 0.11) or neurologic improvement (odds ratio, 1.11; P = 0.69). However, failure rates after initial medical management requiring surgical intervention ranged from 10% to 50%. Three of 4 studies evaluating timing of surgery reported large effect sizes for neurologic outcome if early surgery was performed (P < 0.01). Other prognostic factors from a neurologic perspective included admission neurologic status, patient age, and diabetes mellitus.

CONCLUSIONS

Surgery with adjuvant antibiotics remains the optimal treatment for the neurologically symptomatic patient with spinal epidural abscess. If antibiotic therapy alone is considered for the neurologically intact patient, we recommend interdisciplinary medical and surgical consultations with an in-depth dialogue on the potential for failure in isolated medical management and the recommendation for close neurologic monitoring.

The Pitfalls of Febrile Jaundice. A Case Report

Jaundice in sepsis is usually caused by cholestasis, and its onset can precede other manifestations of the infection. Inflammation-induced cholestasis is a common complication in patients with an extrahepatic infection or those with inflammatory processes. We describe the case of a 47 years old female who presented with low back pain and paravertebral muscular contracture. She subsequently developed a cholestatic syndrome with clinical manifestations such as jaundice, followed by fever and sepsis with multiple organ dysfunction. Initially labeled as biliary sepsis, the diagnosis was crucially reoriented as the blood cultures were positive for Streptococcus pyogenes and the magnetic resonance imaging (MRI) findings suggested spondylodiscitis as well as a paravertebral abscess.

Lumbosacral spondylodiscitis due to rectal fistula following mesh penetration 7 years after colpopexy

INTRODUCTION

The primary source of spondylodiscitis cannot always be identified. However, not treating the original focus might preclude successful healing due to further spread of the causative microorganisms.

CASE REPORT

An 80-year-old woman presented with lumbar spondylodiscitis. She received surgical debridement and stabilization with transforaminal lumbar interbody fusion and tailored antibiotic therapy after isolation of Enterococcus spp. Despite appropriate treatment, the patient's condition continued to worsen. An extensive search for the primary infection source finally revealed a rectal fistula caused by a synthetic mesh that had been inserted 7 years before for abdominal sacrocolpopexy. Only after removal of the fistula and protective ileostomy did the patient's condition improved, allowing successful healing of the spondylodiscitis. After a follow-up period of one year no infection relapse was observed.

CONCLUSION

In cases of spondyodiscitis that are resistant to adequate treatment, a search for infection source must be continued until the focus is found and treated. The presence of uncommon enteric microorganisms causing spondylodiscitis, such as Enterococcus spp., is suggestive of contiguous spread and should therefore be further investigated.

Antimicrobial Effect of Polymer-Based Silver Nanoparticle Coated Pedicle Screws: Experimental Research on Biofilm Inhibition in Rabbits

STUDY DESIGN

Antimicrobial effect of a novel silver-impregnated pedicle screw in rabbits.

OBJECTIVE

A novel spine implant model was designed to study the antimicrobial effect of a modified Titanium (Ti) pedicle screws with methicillin-resistant Staphylococcus aureus (MRSA) in multiple surgical sites in the lumbar spine of a rabbit.

SUMMARY OF BACKGROUND DATA

Infection in spinal implant is of great concern. Anti-infection strategies must be tested in relevant animal models that will lead to appropriate clinical studies.

METHODS

Fourteen New Zealand white rabbits were divided into 2 groups: group 1: infected unmodified Ti screw group (n =  6), and group 2: infected polyethylene glycol grafted, polypropylene-based silver nanoparticle (PP-g-PEG-Ag) covered Ti screw group (n = 6), and 2 rabbits as sterile (sham-operated and control) group. In all groups, left L4-right L6 vertebra levels were exposed and screws were drilled to transverse processes after contamination of burr holes and surrounding tissue with 0.1 mL of 10 colony forming units (CFU) MRSA solutions in groups 1 and 2. After 21 days, samples were collected and infection was analyzed via light and scanning electron microscopy and culturing. Silver nanoparticles (Ag-NP) on the screws and tissues were assayed pre and postoperatively.

RESULTS

The bacterial colony count for modified-Ti screw group was lower than for unmodified Ti screw (17.2 versus 200 x 10(3) CFU/mL, P = 0.029) with less biofilm formation. There was no difference in duration of surgery among groups and within the surgical sites. Ag-NPs were detected on the screw surface postoperatively.

CONCLUSION

This novel experimental design of implantation in rabbits is easy to apply and resembles human stabilization technique. Modified Ti screws were shown to have antimicrobial effect especially inhibiting the biofilm formation. This anchored Ag NPs that remained after 21st day of implantation shows that it is resistant to tapping forces of the screw.

Neurosurgical approaches to spinal infections

Spinal infection is rare. Clinical suspicion is important in patients with nonmechanical neck and/or back pain to make the proper diagnosis in early disease. Before planning surgery, a thorough evaluation of the spinal stability, alignment, and deformity is necessary. Timing of surgery, side of approach, appropriate surgical technique, and spinal instruments used are crucial. Biomechanical preservation of the spinal column during and after the infection is a significant issue. Postoperative spine infection is another entity of which spinal surgeons should be aware of. Proper septic conditions with meticulous planning of surgery are essential for successful spine surgery and better outcome.

Spondylodiscitis

Spondylodiscitis is an infection of the spine that has been known since ancient times. Its incidence is rising, due to the increases in life expectancy and debilitating conditions. Its age distribution is bimodal, affecting persons younger than 20 years of age or persons aged 50-70 years. According to its origin, it is classified as pyogenic, granulomatous or parasitic, though the first form is the most common, usually caused by Staphylococcus aureus or Escherichia coli. The clinical presentation is insidious, resulting in a delayed diagnosis, particularly in tuberculous spondylodiscitis. The initial onset usually involves inflammatory back pain, though the disease may course with fever, asthenia and neurological deficit, these being the most severe complications. Diagnosis is based on clinical, radiological, laboratory, microbiological and histopathological data. Magnetic resonance imaging is the technique of choice for the diagnosis of spondylodiscitis. The differential diagnosis involves, among other conditions, intervertebral erosive osteochondrosis, tumour, axial spondyloarthropathy, haemodialysis spondyloarthropathy, Modic type 1 endplate changes and Charcot's axial neuroarthropathy. Treatment is based on eliminating the infection with antibiotics, preventing spinal instability with vertebral fixation, and ample debridement of infected tissue to obtain samples for analysis.

Is There an Association Between Magnetic Resonance Imaging and Neurological Signs in Patients With Vertebral Osteomyelitis?: A Retrospective Observational Study on 121 Patients

Neurological complications can occur in up to 51% of vertebral osteomyelitis (VO) in surgical series. The aim of our study was to estimate the frequency of neurological signs in a nonselected population of patients with VO and to assess clinical and MRI changes associated with these complications.We reviewed medical charts of patients with VO from 2007 to 2014 in our University Hospital and their MRIs were analyzed by a radiologist blinded from clinical data. Neurological status was defined as follow: normal, minor signs (radiculalgia or sensory loss), and major signs (motor deficit and/or sphincter dysfunction).A total of 121 patients were included. Mean age was 64.3 years. Overall, 50 patients (40%) had neurological signs, 26 were major signs (21.5%). Neurological signs were present at the time of admission in 37 patients and happened secondarily in 13 cases. MRI changes associated with major neurological signs were: Cervical involvement (P = 0.011), dural sac compression (P = 0.0012), ventral effacement of the subarachnoidal space (P < 0.001), compressive myelopathy (P = 0.006). More than 50% of the vertebral body destruction (P = 0.017), angular kyphosis (P = 0.016) partial or complete destruction of posterior arch (P = 0.032) were also associated with these signs. Neither epidural abscesses, multifocal lesions, loss of disk height, nor nerve roots compression were associated with major neurological signs.Neurological signs occurred in 40% of our patients with one half being major signs. Cervical involvement, vertebral destruction, angular kyphosis, dural compression, effacement of subarachnoid space and compressive myelopathy on MRI were risk factors associated with neurological complications.

Single-stage debridement and spinal fusion using PEEK cages through a posterior approach for eradication of lumbar pyogenic spondylodiscitis: a safe treatment strategy for a detrimental condition

Background

Pyogenic infections of the lumbar spine are a rare but critical pathology, yet with considerably high mortality rates. In cases indicating surgical therapy, the implantation of titanium cages or autologous bone grafts represent today's gold standard. Although non-metallic implants such as poly-ether-ether-ketone (PEEK) have proven to be advantageous in diverse degenerative conditions, their saftey and practicability in lumbar spine infection remains questionable. Moreover, the efficacy of a single-step radical debridement of the infected disc space with subsequent fusion from a strictly posterior approach continues to be an issue of debate. We therefore sought to evaluate the feasibility, clinical and radiological outcome of a single-step TLIF procedure using oblique PEEK cages in the surgical management of patients with lumbar pyogenic spondylodiscitis.

Methods

From January 2009 through December 2013, all patients meeting the indication for surgical treatment of lumbar pyogenic spondylodiscitis were included. Patients demonstrating intact cortical bone on preoperative CT received a single-step radical debridement of the infected intervertebral disc space, posterior screw-and-rod instrumentation and implantation of an oblique PEEK cage using the TLIF technique. Oral antibiotics were continued for 12 weeks postoperatively and clinical and radiological results recorded throughout a minimum 1-year clinical follow-up.

Results

A total of 104 patients were admitted to receive surgical therapy for lumbar pyogenic spondylodiscitis. Within this patient population, 18 patients met the diagnostic criteria to receive the implantation of an oblique PEEK cage. Pathogens were detected in 13 cases with Staph. aureus being the predominant causative organism. All patients were discharged to recover in their domestic environment. Throughout the first year of clinical and radiological follow-up and beyond, none of the 18 patients demonstrated any signs of residual neurologic deficits or recurrent infection. Furthermore, two-plane conventional X-rays showed no significant implant subsidence or failure at any of the given time-points in up to 5 years postoperatively.

Conclusions

In patients meeting the criteria for surgical treatment of lumbar pyogenic spondylodiscitis, the implantation of PEEK cages using a single-step TLIF approach is a safe and feasible procedure. Based on our experience, the concern of a recurrent infection when implanting non-metallic cages may be refuted in carefully selected patients.

Positron emission tomography in spinal infections

Magnetic resonance imaging is the imaging method of choice for diagnosing infection of the spine in unoperated cases. 2-[(18)F]-fluoro-2deoxy-d-glucose positron emission tomography/computed tomography study is recommended to distinguish between spinal infection and common Modic change in patients with metallic implants and prosthetic replacements and for differentiating tuberculous from pyogenic spondylitis in ambiguous cases, reflecting the activity of the infection. Also, it seems to have a strong clinical impact in more than half of patients with infectious spondylitis, while it is superior to other imaging techniques in revealing residual disease after treatment and early response to therapy. New tracers as well as new hybrid modalities are under investigation.

The indications and timing for operative management of spinal epidural abscess: literature review and treatment algorithm

OBJECT

Delayed or inappropriate treatment of spinal epidural abscess (SEA) can lead to serious morbidity or death. It is a rare event with significant variation in its causes, anatomical locations, and rate of progression. Traditionally the treatment of choice has involved emergency surgical evacuation and a prolonged course of antibiotics tailored to the offending pathogen. Recent publications have advocated antibiotic treatment without surgical decompression in select patient populations. Clearly defining those patients who can be safely treated in this manner remains in evolution. The authors review the current literature concerning the treatment and outcome of SEA to make recommendations concerning what population can be safely triaged to nonoperative management and the optimal timing of surgery.

METHODS

A PubMed database search was performed using a combination of search terms and Medical Subject Headings, to identify clinical studies reporting on the treatment and outcome of SEA.

RESULTS

The literature review revealed 28 original case series containing at least 30 patients and reporting on treatment and outcome. All cohorts were deemed Class III evidence, and in all but two the data were obtained retrospectively. Based on the conclusions of these studies along with selected smaller studies and review articles, the authors present an evidence-based algorithm for selecting patients who may be safe candidates for nonoperative management.

CONCLUSIONS

Patients who are unable to undergo an operation, have a complete spinal cord injury more than 48 hours with low clinical or radiographic concern for an ascending lesion, or who are neurologically stable and lack risk factors for failure of medical management may be initially treated with antibiotics alone and close clinical monitoring. If initial medical management is to be undertaken the patient should be made aware that delayed neurological deterioration may not fully resolve even after prompt surgical treatment. Patients deemed good surgical candidates should receive their operation as soon as possible because the rate of clinical deterioration with SEA is notoriously unpredictable. Although patients tend to recover from neurological deficits after treatment of SEA, the time point when a neurological injury becomes irreversible is unknown, supporting emergency surgery in those patients with acute findings.

Topical intrawound application of vancomycin powder in addition to intravenous administration of antibiotics: A meta-analysis on the deep infection after spinal surgeries

BACKGROUND

The intrawound application of vancomycin powder in addition to intravenous administration of antibiotics has been reported to be an easy and cost-efficient technique for reducing the deep infection, which is a serious complication of spinal surgeries. The aim of the present meta-analysis was to derive a preliminary estimation on the clinical performance of this technique.

HYPOTHESIS

The intrawound application of vancomycin powder in addition to intravenous administration of antibiotics may significantly reduce the risk of deep infection after spinal surgeries.

MATERIALS AND METHODS

Studies were identified from PubMed and EMBASE searches. After comprehensive review, data were extracted from eligible studies. A meta-analysis was performed to generate pooled odds ratio (OR) of this technique.

RESULTS

Eight studies (4592 patients) were included. The pooled OR (95% CI) was 0.22 (0.07-0.63). I(2) value was 65.2% (P=0.005). The pooled ORs were stable in sensitivity analyses. No analysis of subgroup, meta-regression or publication bias was performed because of inadequate included studies.

DISCUSSION

The intrawound application of vancomycin powder in addition to intravenous administration of antibiotics may significantly reduce the risk of deep infection after spinal surgeries. Further studies with large sample size and high quality are needed to provide more evidences.

LEVEL OF EVIDENCE

II.

Extensive thoracolumbosacral vertebral osteomyelitis after Lemierre syndrome

PURPOSE

To present a unique case of multilevel vertebral osteomyelitis after Lemierre syndrome.

METHODS

A previously healthy 27-year-old man presented in the Emergency Department in septic shock because of Lemierre syndrome for which he was subsequently treated with intravenous benzylpenicillin for 2 months. Two and a half months later, the patient was readmitted with severe back pain without neurological deficits or fever. Imaging revealed an extensive vertebral osteomyelitis of the complete thoracic, lumbar and sacral spine.

RESULTS

Although the blood cultures obtained at the initial admission for Lemierre syndrome revealed Fusobacterium species and Streptococcus milleri, the cultures from the spinal biopsies remained negative. Histology of the spinal biopsies showed a purulent sclerosing osteomyelitis. The patient was successfully treated with intravenous piperacillin and tazobactam. Despite persisting back pain, no recurrence of infection was seen at 3 years of follow-up.

CONCLUSION

Lemierre syndrome and an extensive thoracolumbosacral vertebral osteomyelitis are rare but serious infections. Clinicians must maintain a high index of suspicion for infectious metastases leading to vertebral osteomyelitis when a patient presents with back pain after an episode of life-threatening septicaemia caused by Lemierre syndrome.

Distribution of HIV-1 in the genomes of AIDS patients

The localization of HIV-1 proviruses in compositional DNA fractions from 27 AIDS patients during the chronic phase of the disease with depletion of CD4+ and different levels of viremia showed the following. (1) At low viremia, proviruses are predominantly localized in the GC-richest isochores, which are characterized by an open chromatin structure; this result mimics findings on HIV-1 integration in early infected cells in culture. (2) At higher viremia, an increased distribution of proviruses in GC-poor isochores (which match the GC poorness of HIV-1) was found; this suggests a selection of cells in which the 'isopycnic' localization leads to a higher expression of proviruses and, in turn, to higher viremia. (3) At the highest viremia, integrations in GC-rich isochores are often predominant again, but generally not at the same level as in (1); this may be the consequence of new integrations from the extremely abundant RNA copies.