Chronic low back pain, Modic changes and low-grade virulent infection: efficacy of antibiotic treatment

A systematic review of distinction of colonization and infection in studies that address Cutibacterium acnes and shoulder surgery

BACKGROUND

After shoulder surgery, infection is often diagnosed in the absence of an inflammatory host response (purulence, sepsis). In the absence of inflammation, the more appropriate diagnoses may be colonization or contamination. We reviewed the available data regarding culture of Cutibacterium acnes during primary and revision shoulder surgery and asked; 1) what is the prevalence of air, skin, and deep tissue colonization? 2) How often is an inflammatory host response associated with diagnosis of postoperative shoulder infection diagnosed on the basis of culture of C. acnes? 3) Is there any relation between culture of C. acnes and outcomes of shoulder surgery?

METHODS

Three databases were searched for studies that address C. acnes and colonization or infection related to shoulder surgery. We analyzed data from 80 studies addressing the rates of C. acnes colonization/infection in patients undergoing shoulder surgery, evidence of an inflammatory host response, and relationship of C. acnes culture to surgery outcomes.

RESULTS

C. acnes is often cultured in the air in the operating room (mean 10%), the skin before preparation (mean 47%), and deep tissue in primary shoulder arthroplasty (mean 29%), arthroscopy (mean 27%), and other shoulder surgery (mean 21%). C. acnes was cultured from a mean of 39% of deep tissue samples during revision arthroplasty. C. acnes was believed to be the causative organism of a high percentage of the infections diagnosed after surgery, 39% in primary shoulder arthroplasties, 53% in revisions, 55% in arthroscopic surgeries, and 44% in a mixture of shoulder surgeries. Infection was nearly always diagnosed in the absence of an inflammatory host response. Documented purulence and sepsis were not specifically ascribed to C. acnes (rather than more virulent organisms such as S. aureus). Diagnosis of infection, or unexpected positive culture, with C. acnes during shoulder surgery is associated with outcomes comparable to shoulders with no bacterial growth.

CONCLUSIONS

The evidence to date supports conceptualization of C. acnes as a common commensal (colonization), and perhaps a frequent contaminant, and an uncommon cause of an inflammatory host response (infection). This is supported by the observations that 1) unexpected positive culture for C. acnes is not associated with adverse outcomes after shoulder surgery, and 2) diagnosed infection with C. acnes is associated with outcomes comparable to noninfected revision shoulder arthroplasty. We speculate that diagnosis of C. acnes infection might represent an attempt to account for unexplained discomfort, incapability or stiffness after technically sound shoulder surgery. If so, the hypothesis that stiffness and pain are host responses to C. acnes needs better experimental support.

The efficacy and safety of oral antibiotic treatment in patients with chronic low back pain and Modic changes: A systematic review and meta-analysis

Background

This systematic review and meta-analysis aimed to summarize evidence regarding the effectiveness and safety of oral antibiotic intervention for chronic low back pain (CLBP) patients with/without type-1 Modic changes (MC1).

Methods

AMED, CINAHL, Cochrane Library, Embase, and Medline were searched from inception to March 3, 2023. Randomized controlled trials (RCTs) or non-RCTs that investigated the effectiveness or safety of oral antibiotics in treating CLBP patients were eligible for inclusion. Two independent reviewers screened abstracts, full-text articles, and extracted data. The methodological quality of each included article were evaluated by RoB2 and NIH quality assessment tools. The quality of evidence was appraised by GRADE. Meta-analyses were performed, where applicable. A subgroup analysis was conducted to evaluate the RCTs and case series separately, and to evaluate the effect of removing a low-quality RCT.

Results

Three RCTs and four case series were included. All Amoxicillin-clavulanate/Amoxicillin treatments lasted for approximately 3 months. Moderate- and low-quality evidence suggested that antibiotic was significantly better than placebo in improving disability and quality of life in CLBP patients with MC1 at 12-month follow-up, respectively. Low-quality evidence from meta-analyses of RCTs showed that oral antibiotic was significantly better than placebo in improving pain and disability in CLBP patients with MC1 immediately post-treatment. Very low-quality evidence from the case series suggested that oral Amoxicillin-clavulanate significantly improved LBP/leg pain, and LBP-related disability. Conversely, low-quality evidence found that oral Amoxicillin alone was not significantly better than placebo in improving global perceived health in patients with CLBP at the 12-month follow-up. Additionally, oral antibiotic users had significantly more adverse effects than placebo users.

Conclusions

Although oral antibiotics were statistically superior to placebo in reducing LBP-related disability in patients with CLBP and concomitant MC1, its clinical significance remains uncertain. Future large-scale high-quality RCTs are warranted to validate the effectiveness of antibiotics in individuals with CLBP.

Low back pain patients with Modic type 1 changes exhibit distinct bacterial and non-bacterial subtypes

Objectives

Modic type 1 changes (MC1) are vertebral endplate bone marrow (BM) lesions observed on magnetic resonance images in sub-populations of chronic low back pain (CLBP) patients. The etiopathogenesis remains unknown and treatments that modify the underlying pathomechanisms do not exist. We hypothesized that two biological MC1 subtypes exist: a bacterial and a non-bacterial. This would have important implications for developing treatments targeting the underlying pathomechanisms.

Methods

Intervertebral disc (IVD) samples adjacent to MC1 (n ​= ​34) and control (n ​= ​11) vertebrae were collected from patients undergoing spinal fusion. Cutibacterium acnes (C.acnes) genome copy numbers (GCNs) were quantified in IVD tissues with 16S qPCR, transcriptomic signatures and cytokine profiles were determined in MC1 and control BM by RNA sequencing and immunoassay. Finally, we assessed if C.acnes GCNs are associated with blood plasma cytokines.

Results

IVD tissues from control levels had <870 ​C.acnes GCNs/gram IVD. MC1-adjacent IVDs had either "low" (<870) or "high" (>870) C.acnes GCNs. MC1 patients with "high" C.acnes GCNs had upregulated innate immune cell signatures (neutrophil, macrophage/monocyte) and pro-inflammatory cytokines related to neutrophil and macrophage/monocyte function in the BM, consistent with a host defense against bacterium. MC1 patients with "low" C.acnes GCNs had increased adaptive immune cell signatures (T-and B-cell) in the BM and elevated IL-13 blood plasma levels.

Conclusion

Our study provides the first evidence for the existence of bacterial (C.acnes "high") and non-bacterial (C.acnes "low") subtypes in MC1 patients with CLBP. This supports the need for different treatment strategies.

Efficacy of stepped care treatment for chronic discogenic low back pain patients with Modic I and II changes

Objective

This study investigated whether patients with Modic changes (MC) of types I, I/II, and II would respond to an anti-inflammatory-based, stepped care treatment with three treatment steps: first, oral administration of NSAIDs, 2 × 200 mg celecoxib daily for two weeks; second, an intradiscal steroid injection (ID) with dexamethasone and cefazolin; and third, oral treatment with antibiotics (AB), 3 × 1 g amoxicillin daily for 100 days.

Design

This was an observational clinical study based on analyses of categorical data of patient-reported outcome measurements.

Subjects

Subjects were consecutive patients with chronic low back pain (CLBP), diagnosed by assessment of anamnestic signs of inflammation; a pain score ≥6 on the Numeric Pain Rating Scale (NPRS); a mechanical assessment; MC I, I/II, or II based on MRI; and lack of response to conservative treatment.

Methods

From January 1, 2015, to December 31, 2021, 833 eligible patients were selected for the stepped care treatment. A total of 332 patients completed requested follow-up questionnaires at baseline and 12 months (optional at 3 and 6 months). Primary outcomes were pain (at least 50 % pain relief) and/or a minimum of 40 % improvement in functionality as measured by the Roland Morris Disability Questionnaire (RMDQ) or the Oswestry Disability Questionnaire (ODI). Secondary outcome measures were use of pain medication and return to work.

Results

At 1 year of follow-up, 179 (53.6 %) of 332 patients reported improvement according to the responder criteria. Of the 138 patients that had received only NSAIDs, 88 (63.8 %) had improved. In addition, 50 (56.8 %) of the 183 patients that had received ID had improved, and 41 (38.7 %) of the 106 patients treated with AB had improved. None of the patients reported complications. 12.0 % of patients using AB stopped preterm due to undesirable side effects.

Conclusion

Treatment with a stepped care model for inflammatory pain produced clinically relevant, positive reported outcomes on pain and/or function. Our stepped care model appears to be a useful, safe, and cost-saving treatment option that is easily reproducible. Further studies, including randomized controlled trials and analyses of subgroups, may help to develop a more patient-tailored approach and further avoidance of less-effective treatments and costs.

Modic changes as seen on MRI are associated with nonspecific chronic lower back pain and disability

BACKGROUND

Estimating the contribution of endplate oedema known as Modic changes to lower back pain (LBP) has been the subject of multiple observational studies and reviews, some of which conclude that the evidence for an association of Modic change with LBP is uncertain while others demonstrate a clear link. The clinical trials demonstrating the benefit of basivertebral nerve ablation, a therapeutic intervention, in a tightly defined homogenous patient group with chronic LBP and Modic changes type 1 or type 2, provides further evidence for the contribution of Modic changes to LBP and shows that in these subjects, nerve ablation substantially reduces pain and disability. These interventional studies provide direct evidence that Modic changes can be associated with lower back pain and disability. This review set out to explore why the literature to date has been conflicting.

METHODS

A narrative, forensic, non-systematic literature review of selected articles to investigate why the published literature investigating the association between Modic imaging changes and chronic low back pain is inconsistent.

RESULTS

This review found that previous systematic reviews and meta-analyses included both heterogeneous study designs and diverse patient syndromes resulting in an inconsistent association between Modic changes and nonspecific chronic lower back pain. Re-analysis of literature data focussing on more homogenous patient populations provides clearer evidence that Modic changes are associated with nonspecific chronic lower back pain and that type 1 Modic changes are more painful than type 2.

CONCLUSIONS

Studies using tightly defined homogenous patient groups may provide the best test for association between MRI-findings and pain and disability. Clinical benefit of basivertebral nerve ablation observed in randomised controlled trials further supports the association between type 1 and type 2 Modic changes with pain and disability.

Would Cutibacterium acnes Be the Villain for the Chronicity of Low Back Pain in Degenerative Disc Disease? Preliminary Results of an Analytical Cohort

In the last decade, several studies have demonstrated Cutibacterium acnes colonization in intervertebral discs (IVDs) in patients with lumbar disc degeneration (LDD) and low back pain (LBP), but the meaning of these findings remains unclear. Being aware of this knowledge gap, we are currently conducting a prospective analytical cohort study with LBP and LDD patients undergoing lumbar microdiscectomy and posterior fusion. The IVDs samples collected during the surgeries are subjected to a stringent analytical protocol using microbiological, phenotypic, genotypic, and multiomic techniques. Additionally, pain-related scores and quality-of-life indexes are monitored during patient follow-up. Our preliminary results for 265 samples (53 discs from 23 patients) revealed a C. acnes prevalence of 34.8%, among which the phylotypes IB and II were the most commonly isolated. The incidence of neuropathic pain was significantly higher in the colonized patients, especially between the third and sixth postoperative months, which strongly suggests that the pathogen plays an important role in the chronicity of LBP. The future results of our protocol will help us to understand how C. acnes contributes to transforming inflammatory/nociceptive pain into neuropathic pain and, hopefully, will help us to find a biomarker capable of predicting the risk of chronic LBP in this scenario.

Should Degenerated Intervertebral Discs of Patients with Modic Type 1 Changes Be Treated with Mesenchymal Stem Cells?

Low back pain (LBP) has been among the leading causes of disability for the past 30 years. This highlights the need for improvement in LBP management. Many clinical trials focus on developing treatments against degenerative disc disease (DDD). The multifactorial etiology of DDD and associated risk factors lead to a heterogeneous patient population. It comes as no surprise that the outcomes of clinical trials on intradiscal mesenchymal stem cell (MSC) injections for patients with DDD are inconsistent. Intradiscal MSC injections have demonstrated substantial pain relief and significant disability-related improvements, yet they have failed to regenerate the intervertebral disc (IVD). Increasing evidence suggests that the positive outcomes in clinical trials might be attributed to the immunomodulatory potential of MSCs rather than to their regenerative properties. Therefore, patient stratification for inflammatory DDD phenotypes may (i) better serve the mechanisms of action of MSCs and (ii) increase the treatment effect. Modic type 1 changes—pathologic inflammatory, fibrotic changes in the vertebral bone marrow—are frequently observed adjacent to degenerated IVDs in chronic LBP patients and represent a clinically distinct subpopulation of patients with DDD. This review discusses whether degenerated IVDs of patients with Modic type 1 changes should be treated with an intradiscal MSC injection.