Primary spinal infection and the need for standardized treatment algorithms
BY DR JONATHAN DALTON AND DR GREGORY SCHROEDER

Primary spinal infection (PSI) is a broad term that describes an infection of any combination of the intervertebral disc, vertebral body, medullary canal, or adjacent paraspinal structures without prior spine surgery. Spine infections are frequently multicompartmental, and thus PSI represents a spectrum ranging from simple discitis, all the way to epidural or subdural abscess. PSI is typically caused by bacteria with a distant, hematogenous source.
The clinical presentation of PSI can range dramatically from very subtle, slowly increasing back pain to unrelenting, severe pain, neurological impairment, and spinal deformity. Because of this wide variety, PSI is often difficult to diagnose and can be associated with treatment delay, increased mortality rates, and substantially decreased quality of life.
Disclaimer: The article represents the opinion of individual authors exclusively and not necessarily the opinion of AO or its clinical divisions.
The global incidence of PSI continues to increase, despite substantial efforts at improving public sanitation and socioeconomic standing.1 Reasons for this trend have been proposed and include increased elderly and/or immunocompromised populations, and the widespread use of intravenous opioids and other drugs. The experience from our institution has certainly mirrored the global trend of increasing prevalence of PSI. We have noted a substantial rise over the past decade in spine consults and call cases for PSI, and a concordant relative decrease in high energy spine trauma.
Despite the ubiquity of PSI, management recommendations vary widely, even amongst seemingly similar patient presentations. Options range from nonoperative conservative treatment to often extensive surgery. Thus, developing universal treatment recommendations remains an important, but challenging, endeavor. In this blog post, we will provide a broad overview of the current data guiding treatment algorithms, with an emphasis on the lack of robust evidence and consensus.
Regional variability in diagnostic/treatment patterns between developed and developing countries is not wholly unexpected. The sources of this heterogeneity can include regional and international differences in causative pathogens, resource availability, and clinical attitudes and decision-making. Even within the same developed countries, however, the treatment algorithms can often vary significantly from one provider to the next .2,3
There is a notable lack of broadly accepted or universally applicable treatment algorithms for PSI. This is an important gap in the literature given that chronic infection and inadequate treatment is associated with neurological impairment, painful and potentially debilitating spinal deformity, increased mortality rates, and substantially decreased quality of life.4
Although nonoperative management, typically with at least four weeks of antibiotics, is the most commonly utilized treatment modality, duration of therapy and specific antibiotic agent strategies vary widely both between institutions and globally.5 One source of heterogeneity in the data regarding nonoperative antibiotic regimens is variability in blood or tissue culture positivity rates, which were noted to range from 24 to 93% in a recent systematic review and meta-analysis.4,6,7
The authors of this review emphasized that this influences the utilization of broad-spectrum antibiotics, and thus makes it more difficult to study specific, targeted antibiotic protocols.4 Duration of nonoperative therapy was also noted to be heterogeneous, and ranged from 4 to 12 weeks due to patient and infection-driven factors.8–10
Primary Spinal Infection—When to operate
Decision-making regarding operative versus nonoperative intervention for PSI, and timing of when to consider surgery have not been well defined algorithmically in the literature. The most common surgical indication noted in the literature is the somewhat broadly defined concept of a neurologic deficit, especially when it is considered to be progressive.10–13 This has been inconsistently defined with some works utilizing a binary definition of the presence or absence of a deficit, whereas others utilize a more quantitative measure such as the ASIA scale.7,14
Spinal instability is another commonly mentioned reason to consider surgery. However, there is not a consistent set of radiographic imaging criteria to provide easily reproducible guidelines to define instability. Thus, this assessment is left up to a multifactorial clinical decision-making process by operative surgeons.
Another commonly listed indication is the similarly nebulous concept of failure of conservative therapy. However, many prior works do not include well-defined criteria regarding when failure as an endpoint has been met, and thus operative timing is poorly delineated.7,11,13,15–17
Additionally, a range of definitions exist in the literature regarding definitions of clinical outcomes.
Differing treatment recommendations for PSI—sources of controversy
In light of these substantial sources of heterogeneity in the data regarding PSI management, it is not surprising that minimal algorithmic guidance exists. Thus, the clinical equipoise required for higher level, prospective study design is very difficult to define and achieve. Consequently, the vast majority of the current body of data is derived from small retrospective analysis.
It is also worth noting that the decision between operative and nonoperative management in the setting of suspected PSI is inherently complicated, apart from issues with the current literature. PSI surgeries are often associated with substantial risk. Infectious pathology can frequently be found in difficult to access regions either ventral to the spinal cord, or within the disc and intervertebral body, which can vastly increase the associated morbidity with these procedures.
The thoracic spine, in particular, can involve complicated approaches due to vulnerable neighboring thoracoabdominal anatomy, and minimal capacity for cord float-back with less invasive posterior-only decompressive strategies. These factors can result in substantial potential for blood loss, and postoperative pain and prolonged rehabilitation. Additionally, long or circumferential fusion constructs are frequently required due to bony destruction and concerns for instability after adequate decompression and debridement.
Finally, patients with PSI represent a mixed, somewhat bimodally distributed group in terms of infectious etiologies and age ranges. However, a large proportion of these patients have substantial medical co-morbidities, psychosocial risk factors for poor outcomes and difficult postoperative courses, and a high prevalence of immunosuppression.18,19
However, while surgery for PSI patients frequently involves substantial risk, delayed operative treatment when indicated can also cause devastating consequences. These outcomes can include permanent neurologic deficits, and increased rates of disability, and mortality.19,20
For these reasons, it is critically important to continue to strive to produce high quality data, with an emphasis on standardized diagnostic, prognostic, and outcome measurements. In light of these issues, and considering the growing prevalence of PSI globally, the AO Spine Knowledge Forum Trauma & Infection is developing a primary classification system and is planning an observational, multicenter study to address some of the most urgent questions on this topic. Further work of this caliber is needed in order to provide broadly useful diagnostic, management, and prognostic algorithms for PSI.
About the authors:
Dr Jonathan Dalton is currently pursuing a two-year fellowship in spine surgery and spine research at the Rothman Orthopaedic Institute in Philadelphia, PA. Dalton completed his residency in Orthopaedic Surgery at the University of Pittsburgh Medical Center in Pittsburgh, PA and attended medical school at Washington University School of Medicine in St. Louis, MO. He has authored over 40 peer-reviewed manuscripts, and continues to actively produce research during his fellowship at the Rothman Orthopaedics Institute.
Dalton is a member of AO Spine and has particular research interest in outcomes following spine trauma and infections.
Dr Gregory Schroeder is a fellowship trained spine surgeon, who currently serves as Associate Professor of Orthopaedic Surgery at Thomas Jefferson University. Schroeder completed his residency in Orthopaedic Surgery at Northwestern University Feinberg School of Medicine in Chicago, IL. He followed with a fellowship in spine surgery and spine research at the Rothman Orthopaedic Institute in Philadelphia, PA.
Schroeder is the chairperson on AO Spine Knowledge Forum Trauma and Infection. He has authored hundreds of peer-reviewed publications, has edited numerous textbook chapters, and has presented both nationally and internationally on spine surgery research and techniques. He has chaired multiple international spine surgery meetings including the Cervical Spine Research Society, and the North American Spine Society’s summer meeting. He holds several editorial positions, including Editor-in-Chief for Clinical Spine Surgery in Philadelphia, PA. He has conducted extensive research in the field of spine surgery and continues to actively do so.
You might also be interested in:
AO Spine Knowledge Forum Trauma and Infection
Systematically bringing the world on the same page by developing reliable classification systems and clinically useful, diagnostic, and therapeutic algorithms.
Making your patients and practice flourish
The Global Spine Journal and AO Spine Knowledge Forum collaboration aims to bridge the gaps between clinical research, knowledge dissemination, and evidence-based practice.
Treatment decisions in thoracolumbar burst fractures
The AO Spine Knowledge Forum Trauma focus issue in the Global Spine Journal explores the factors that influence surgeons’ decision-making and why there are such big differences globally.
Works cited:
1. Garg B, Mehta N. Spinal infections: What is new in 2023. N Am Spine Soc J. 2023;16:100300. doi:10.1016/j.xnsj.2023.100300
2. Berbari EF, Kanj SS, Kowalski TJ, et al. 2015 Infectious Diseases Society of America (IDSA) Clinical Practice Guidelines for the Diagnosis and Treatment of Native Vertebral Osteomyelitis in Adultsa. Clinical Infectious Diseases. 2015;61(6):e26-e46. doi:10.1093/cid/civ482
3. Epidemiological Insights from 1,652 Patients with Spinal Tuberculosis Managed at a Single Center: A Retrospective Review of 5-Year Data - PubMed. Accessed September 23, 2024. https://pubmed.ncbi.nlm.nih.gov/34461687/
4. Thavarajasingam SG, Vemulapalli KV, Vishnu K. S, et al. Conservative versus early surgical treatment in the management of pyogenic spondylodiscitis: a systematic review and meta-analysis. Sci Rep. 2023;13(1):15647. doi:10.1038/s41598-023-41381-1
5. Park KH, Cho OH, Lee JH, et al. Optimal Duration of Antibiotic Therapy in Patients With Hematogenous Vertebral Osteomyelitis at Low Risk and High Risk of Recurrence. Clin Infect Dis. 2016;62(10):1262-1269. doi:10.1093/cid/ciw098
6. Lener S, Wipplinger C, Stocsits A, Hartmann S, Hofer A, Thomé C. Early surgery may lower mortality in patients suffering from severe spinal infection. Acta Neurochir (Wien). 2020;162(11):2887-2894. doi:10.1007/s00701-020-04507-2
7. Khanna RK, Malik GM, Rock JP, Rosenblum ML. Spinal epidural abscess: evaluation of factors influencing outcome. Neurosurgery. 1996;39(5):958-964. doi:10.1097/00006123-199611000-00016
8. Zadran S, Pedersen PH, Eiskjær S. Vertebral Osteomyelitis: A Mortality Analysis Comparing Surgical and Conservative Management. Global Spine J. 2020;10(4):456-463. doi:10.1177/2192568219862213
9. McHenry MC, Easley KA, Locker GA. Vertebral osteomyelitis: long-term outcome for 253 patients from 7 Cleveland-area hospitals. Clin Infect Dis. 2002;34(10):1342-1350. doi:10.1086/340102
10. Nonspecific pyogenic spondylodiscitis: clinical manifestations, surgical treatment, and outcome in 24 patients in: Neurosurgical Focus Volume 17 Issue 6 (2004) Journals. Accessed September 23, 2024. https://thejns.org/focus/view/journals/neurosurg-focus/17/6/foc.2004.17.6.3.xml
11. Valancius K, Hansen ES, Høy K, Helmig P, Niedermann B, Bünger C. Failure modes in conservative and surgical management of infectious spondylodiscitis. Eur Spine J. 2013;22(8):1837-1844. doi:10.1007/s00586-012-2614-3
12. Adogwa O, Karikari IO, Carr KR, et al. Spontaneous spinal epidural abscess in patients 50 years of age and older: a 15-year institutional perspective and review of the literature: clinical article. J Neurosurg Spine. 2014;20(3):344-349. doi:10.3171/2013.11.SPINE13527
13. Giampaolini N, Berdini M, Rotini M, Palmisani R, Specchia N, Martiniani M. Non-specific spondylodiscitis: a new perspective for surgical treatment. Eur Spine J. 2022;31(2):461-472. doi:10.1007/s00586-021-07072-z
14. Lee JH, Kim J, Kim TH. Clinical Outcomes in Older Patients Aged over 75 Years Who Underwent Early Surgical Treatment for Pyogenic Vertebral Osteomyelitis. J Clin Med. 2021;10(22):5451. doi:10.3390/jcm10225451
15. Sobottke R, Zarghooni K, Krengel M, et al. Treatment of spondylodiscitis in human immunodeficiency virus-infected patients: a comparison of conservative and operative therapy. Spine (Phila Pa 1976). 2009;34(13):E452-458. doi:10.1097/BRS.0b013e3181a0aa5b
16. Canouï E, Zarrouk V, Canouï-Poitrine F, et al. Surgery is safe and effective when indicated in the acute phase of hematogenous pyogenic vertebral osteomyelitis. Infectious Diseases. 2019;51(4):268-276. doi:10.1080/23744235.2018.1562206
17. Kim SD, Melikian R, Ju KL, et al. Independent predictors of failure of nonoperative management of spinal epidural abscesses. The Spine Journal. 2014;14(8):1673-1679. doi:10.1016/j.spinee.2013.10.011
18. Pigrau C, Rodríguez-Pardo D, Fernández-Hidalgo N, et al. Health Care Associated Hematogenous Pyogenic Vertebral Osteomyelitis: A Severe and Potentially Preventable Infectious Disease. Medicine. 2015;94(3):e365. doi:10.1097/MD.0000000000000365
19. Tsantes AG, Papadopoulos DV, Vrioni G, et al. Spinal Infections: An Update. Microorganisms. 2020;8(4):476. doi:10.3390/microorganisms8040476
20. Davis DP, Wold RM, Patel RJ, et al. The clinical presentation and impact of diagnostic delays on emergency department patients with spinal epidural abscess. J Emerg Med. 2004;26(3):285-291. doi:10.1016/j.jemermed.2003.11.013