Clinical assessment and medical treatment of spine infections

A comparative study of pyogenic and tuberculous spondylodiscitis

STUDY DESIGN

We performed a retrospective review of 126 cases of infectious spondylodiscitis over a 4-year period.

OBJECTIVE

Differentiation between pyogenic spondylodiscitis (PS) and tuberculous spondylodiscitis (TS) is essential for deciding on the appropriate therapeutic regimen. The aim of this study was to compare the characteristics of the 2 forms of spondylodiscitis.

SUMMARY OF BACKGROUND DATA

There has been much effort to distinguish the radiologic findings in PS versus TS, but classification based on radiologic findings alone had limitations yet.

METHODS

We compared the predisposing factors or associated illnesses, clinical, radiologic, and laboratory features of microbiologically confirmed cases of PS and TS in 2 university hospitals.

RESULTS

Of 126 patients, 79 had PS and 47 TS. PS was more frequently associated with the followings: previous invasive spinal procedures (PS vs. TS: 32.9% vs. 8.5%), preceding bacteremia (13.9% vs. 0%), chronic renal failure (12.7% vs. 0%), liver cirrhosis (13.9% vs. 0%), fever (temperature >38°C) (48.1% vs. 17.0%), white blood cell counts over 10,000/mm (41.8% vs. 19.1%), fraction of neutrophils >75% (49.4% vs. 27.7%), C-reactive protein levels over 5 mg/dL (58.2% vs. 27.7%), erythrocyte sedimentation rate levels over 40 mm/h (84.4% vs. 66.0%), and ALP levels over 120 IU/L (45.6% vs. 17.0%). TS was frequently associated with active tuberculosis of other organs (0% vs. 31.9%), longer diagnostic delay (47.6 vs. 106.3 days), involvement of thoracic spines (21.5% vs. 38.3%), and involvement of ≥3 spinal levels (11.4% vs. 36.2%).

CONCLUSION

Previous invasive spinal procedures, preceding bacteremia, fever, higher white blood cell counts, C-reactive protein, ALP, and higher fraction of neutrophils are suggestive of PS. Concurrent active tuberculosis, more indolent course and involvement of thoracic spines are suggestive of TS. When the causative organism is not identified despite all efforts at diagnosis, combination of the clinical, radiologic, and laboratory characteristics of the patient is helpful.

The presentation, incidence, etiology, and treatment of surgical site infections after spinal surgery

STUDY DESIGN

Descriptive, retrospective cohort analysis.

OBJECTIVE

To evaluate the presentation, etiology, and treatment of surgical site infections (SSI) after spinal surgery.

SUMMARY OF BACKGROUND DATA

SSI after spine surgery is frequently seen. Small case control studies have been published reporting the results of treatment options of SSI. We performed this study to identify the most common clinical and laboratory presentation of a SSI, the most frequently seen infective organism, and evaluate the effectiveness of current treatment.

METHODS

All patients who underwent spinal surgery at our institution for diagnosis other than infection between June 1996 and December 2005 (N=3174) were reviewed. All cases of SSI were identified. Patient and operative characteristics were reviewed. Infection type (deep or superficial), treatment course, laboratory and culture results were abstracted.

RESULTS

A total of 132 cases of SSI (84 deep and 48 superficial) were identified. About 72.7% of the SSI were detected as outpatients an average 28.7 days (deep, 29.9; superficial, 25.2) after the index procedure. Wound drainage was the most common complaint (68.2%). C-reactive protein level was elevated in 98.0%, erythrocyte sedimentation rate was elevated in 94.4%, but only 48.6% had elevated white blood cell count. Staphylococcus aureus was isolated in 72.6% of deep and 85.7% of superficial positive cultures. Seventy-six percent of deep SSI could be treated with a single debridement to clear the SSI. Instrumentation was retained or primarily exchanged if loose in all cases. Around 72.9% of superficial SSI were treated without formal debridement in the operating room. Antibiotic treatment was longer in deep SSI (40.8 vs. 19.6 days).

CONCLUSION

Deep SSI following spinal surgery was effectively treated with single stage debridement and intravenous antibiotics. Superficial SSI could be treated effectively with local wound care and oral antibiotic therapy.

Surgical site infection after osteotomy of the adult spine: does type of osteotomy matter?

BACKGROUND CONTEXT

Surgical site infection after spinal surgery is frequently seen. It occurs between 0.7% and 12% of patients, leading to higher morbidity, mortality, and health-care costs. Osteotomy procedures are known to have increased blood losses and surgical times when compared with other spinal surgeries. Both of these factors have previously been identified as significant risk factors for SSI. We performed a cohort study of this high-risk population to identify risk factors and rates of SSI after spinal osteotomy surgery and identify difference in risk between different types of osteotomies.

PURPOSE

The objective of the study was to assess the incidence and identify significant risk factors for surgical site infection (SSI) after spinal osteotomy.

STUDY DESIGN

Retrospective review of all adult patients who underwent spinal osteotomy surgery for deformity by an orthopedic surgeon in our university.

METHODS

All electronic records of adult orthopedic patients whom underwent a spinal osteotomy procedure at our department between January 1998 and December 2005 (n=363) were abstracted. During surgery, a pedicle subtraction osteotomy (transpedicular wedge resection), anterior spine osteotomy (resection of anterior and middle columns), posterior Smith-Petersen osteotomy (resection of a portion of the superior and inferior lamina, ligamentum flavum, and the inferior and superior articular processed), or a combined anterior and posterior osteotomy (vertebral column resection [VCR]) (circumferential resection of the vertebrae via either a combined anterior/posterior or posterior-only approach) was performed. Primary outcome measurement was SSI. Subanalysis to deep and superficial SSI was performed.

RESULTS

Twenty patients (5.5%) were found to have an SSI, with nine (2.5%) having deep SSI. Analysis showed that patients undergoing VCR (p=.042) had a significant increased risk for deep SSI (11.1%). Obese patients had a significant increased risk (p=.045) for superficial SSI.

CONCLUSIONS

Vertebral column resection has a significant increased risk for SSI (11.1%) compared with other types of osteotomies (4.1%). When possible, osteotomy techniques that involve less extensive exposures and soft-tissue dissection should be chosen to minimize deep SSI risk. Obese patients should be counseled on weight loss to try minimizing superficial SSI risk.

Incidence of surgical site infection following adult spinal deformity surgery: an analysis of patient risk

Surgical site infection (SSI) following spinal surgery is a frequent complication and results in higher morbidity, mortality and healthcare costs. Patients undergoing surgery for spinal deformity (scoliosis/kyphosis) have longer surgeries, involving more spinal levels and larger blood losses than typical spinal procedures. Previous research has identified risk factors for SSI in spinal surgery, but few studies have looked at adult deformity surgeries. We retrospectively performed a large case cohort analysis of all adult patients who underwent surgery for kyphosis or scoliosis, between June 1996 and December 2005, by our adult spine division in an academic institution to asses the incidence and identify risk factors for SSI. We reviewed the electronic patient records of 830 adult patients. SSI was classified as deep or superficial to the fascia. 46 (5.5%) patients were found to have a SSI with 29 patients (3.5%) having deep infections. Obesity was found to be an independent risk factor for all SSI and superficial SSI (P = 0.014 and P = 0.013). As well, a history of prior SSI was also found to be a risk factor for SSI (P = 0.041). Patient obesity and history of prior SSI lead to increased risk of infection. Since obesity was related to an increased risk of both superficial and deep SSI, counseling and treatment for obesity should be considered before elective deformity surgery.

Expanding role of 18F-fluoro-D-deoxyglucose PET and PET/CT in spinal infections

(18)F-fluoro-D -deoxyglucose positron emission tomography ([(18)F]-FDG PET) is successfully employed as a molecular imaging technique in oncology, and has become a promising imaging modality in the field of infection. The non-invasive diagnosis of spinal infections (SI) has been a challenge for physicians for many years. Morphological imaging modalities such as conventional radiography, computed tomography (CT), and magnetic resonance imaging (MRI) are techniques frequently used in patients with SI. However, these methods are sometimes non-specific, and difficulties in differentiating infectious from degenerative end-plate abnormalities or postoperative changes can occur. Moreover, in contrast to CT and MRI, FDG uptake in PET is not hampered by metallic implant-associated artifacts. Conventional radionuclide imaging tests, such as bone scintigraphy, labeled leukocyte, and gallium scanning, suffer from relatively poor spatial resolution and lack sensitivity, specificity, or both. Initial data show that [(18)F]-FDG PET is an emerging imaging technique for diagnosing SI. [(18)F]-FDG PET appears to be especially helpful in those cases in which MRI cannot be performed or is non-diagnostic, and as an adjunct in patients in whom the diagnosis is inconclusive. The article reviews the currently available literature on [(18)F]-FDG PET and PET/CT in the diagnosis of SI.

Hematogenous spinal infection in central Greece

STUDY DESIGN

We retrospectively analyzed spinal infection (SpI), in a teaching Hospital, in Central Greece.

OBJECTIVE

To study presentation, etiology, and outcome of SpI in Central Greece.

SUMMARY OF BACKGROUND DATA

SpI most frequently involves the intervertebral disc and adjacent vertebral bodies and can cause neurologic impairment.

METHODS

Thirty three patients (23 men; age [mean +/- standard deviation], 60.6 +/- 11.3 years; disease duration, 44.5 [+/-54.7] days) hospitalized with SpI between January 2000 and December 2007 were included in the study. All patients had magnetic resonance imaging of the spine.

RESULTS

Nineteen patients had pyogenic SpI (57.6%) and 14 patients had granulomatous SpI, 11 due to Brucella spp (34.4%), 3 due to Mycobacterium tuberculosis (9.4%). Staphylococcus aureus was the most frequent cause of pyogenic SpI, and spondylodiscitis (SpD) was the most frequent localization. Epidural entension was found in 8 of 17 pyogenic SpD and in 2 of 11 brucellar SpD patients. Subdural extension was detected in 3 patients with pyogenic SpD. Blood cultures were positive in 17 of 19 patients with pyogenic SpI. Two patients had concomitant endocarditis (staphylococcal 1, enterococcal 1). The most common associated disease was diabetes mellitus. All but 2 patients received medical treatment alone. Two patients died of uncontrollable sepsis.

CONCLUSION

Back pain in presence of fever, constitutional symptoms, and/or high inflammation markers should alert physicians for spinal infection. In endemic areas, Brucella is a frequent cause of SpI.

Evaluation of conservative treatment of non specific spondylodiscitis

The objective of this study was to analyse the presentation, aetiology, conservative management, and outcome of non-tuberculous pyogenic spinal infection in adults. We performed a retrospective review of 56 patients (35 women and 21 men) of pyogenic spinal infection presenting over a 7-year period (1999-2006) to the Department of Spinal Surgery of Hesperia Hospital. The medical records, radiologic imaging, bacteriology results, treatment, and complications of all patients were reviewed. The mean age at presentation was 47.8 years (age range 35-72 years), the mean follow-up duration was 12.5 months. The most common site of infection was lumbar spine (n: 48), followed by the thoracic spine (n: 8). Most patients were symptomatic for between 4 and 10 weeks before presenting to hospital. The frequently isolated pathogen was Staphylococcus aureus in 31 of 56 cases (57.6%). Percutaneous biopsies were diagnostic in 57% of patients; the open biopsy was indicated if closed biopsy failed and when the infection was not accessible by percutaneous technique. The patients were managed by conservative measures alone, including antibiotic therapy and spinal bracing. The mean period of antibiotic therapy was 8.5 weeks (range 6-9 weeks), followed by oral antibiotics for 6 weeks. All patients had a supportive spinal brace for mean 8 weeks (range 6-10 weeks). The duration of the administration of oral antibiotics was dependent on clinical and laboratory evidence (white cell count, erythrocyte sedimentation rate, C-reactive protein) that the infection was resolved. The follow-up MR gadolinium scans were essential to monitor the response to medical treatment. The diagnosis of pyogenic spinal infection should be considered in any patient presenting with severe localised unremitting back and neck pain, especially when accompanied with systemic features, such as fever and weight loss and in the presence of elevated inflammatory markers. The conservative management of infection with antibiotic therapy and spinal bracing was very successful.

Histopathology and genotyping in infectious spondylitis of HIV- and HIV+ patients

Approximately 2 million South Africans are HIV/TB coinfected, and many develop skeletal disease. The resurgence of spinal tuberculosis, including atypical forms, is due largely to HIV-associated immune suppression. We investigated the impact of HIV coinfection on the histological features of the disease and the occurrence of atypical opportunistic organisms in infectious spondylitis in an HIV/TB endemic region. We analyzed blood and tissue biopsies from 60 patients with tuberculous spondylitis. Investigations included full blood counts, CD4/CD8 counts, HIV-1 serology and RNA quantification (tissue and plasma), acid-fast bacilli localization and routine TB culture, histopathologic evaluation of biopsies, and bacterial genotyping using the 16S rDNA gene. Twenty-two patients (37%) were HIV positive with a mean age of 29 years (range, 2-65 years). Forty-one (68%) tissue specimens were culture negative for Mycobacterium tuberculosis (Mtb), although nontuberculous mycobacteria (NTM) were identified in three HIV-negative patients. Histopathologic features were characteristic of TB infection in 91.4% of all specimens tested and 100% of the HIV-infected group. Genotyping of 10 culture-positive isolates identified Mtb (3/10), NTMs (2/10), and environmental bacilli (3/10). Our observations suggest HIV-induced immune suppression impacts the histological and clinical features of infectious spondylitis but has no impact on the incidence of NTMs in this setting.

Recent advances: Infections of the spine

The global increase of spinal infections is concomitant with the rise of its risk factors, including HIV/AIDS, diabetes mellitus, intravenous drug use, advanced age, and gunshot wounds to the spine. Because spinal infections have a wide span of presentation, early detection and differentiation are notoriously challenging. Current advances in laboratory and imaging techniques, such as polymerase chain reaction, fluorodeoxyglucose positron emission tomography, and 99mTc-ciprofloxacin scintigraphy, allow for better diagnostic rendering of the infection and its degree of spinal involvement. Less invasive surgical procedures and preventive surgical management have helped reduce spinal infection morbidities such as deformity and neurologic deficit. Although proper antibiotic regimen and correct surgical management are of vital importance to successful patient outcome, early detection remains the most critical factor.