2022 SPILF - Clinical Practice guidelines for the diagnosis and treatment of disco-vertebral infection in adults

Culture yield of 1st and 2nd biopsy in bacterial non-mycobacterial spondylodiscitis in a university hospital

INTRODUCTION

In cases of infectious spondylodiscitis (ISD) where blood cultures are negative, disco-vertebral puncture-biopsy (DVPB) is recommended. In the event of a sterile result, existing literature does not definitively answer the question of whether to initiate empirical antibiotic therapy or to conduct a second DVPB. The aim of this study was to assess the culture yield of DVPB in ISD and to identify the factors associated with a positive DVPB.

MATERIALS AND METHODS

A retrospective single-center study was conducted, encompassing all adult patients with ISD having undergone DVPB between 01/01/2009 and 31/10/2021.

RESULTS

A total of 177 patients were included. The yield of the first DVPB was 48.6 %. The second DVPB yielded 8.7 % (p < 0.001). Factors significantly associated with the yield of the first DVPB included younger age (p = 0.003), higher CRP levels (p = 0.0496), larger needle size (p = 0.023), and histopathology supporting ISD (p = 0.001), while prior antibiotic therapy (p = 0.001) is a factor associated with negative culture. The second DVPB increased the culture yield by 19.3 %.

CONCLUSION

The yield of the second biopsy is lower than that of the first biopsy but provides an additional diagnostic gain of 19.3%. Antibiotic therapy prior to DVB significantly decreases their yield. The utility of routine post-DVPB blood cultures appears to be limited.

Escherichia coli in the T11-12 Thoracic Vertebrae: A Case Report

Background

Pyogenic thoracic spondylitis is a rare but severe infection, particularly when complicated by sepsis and acute kidney injury (AKI). Early diagnosis and precise management are essential for improving outcomes, given the limitations of traditional microbiology detection methods in identifying the causative pathogens.

Case Presentation

A 68-year-old immunocompetent male presented with recurrent fever, fatigue, loss of appetite and initial evidence of sepsis and AKI upon admission. With the prompt computed tomography (CT)-guided percutaneous biopsy of the thoracic vertebrae, Escherichia coli was identified as the causative pathogen using metagenomic next-generation sequencing (mNGS). A diagnosis of pyogenic thoracic spondylitis was then made followed by the treatment of antibiotics optimized by therapeutic drug monitoring (TDM) techniques. With a total effective antibiotic treatment period of 7 weeks, the patient recovered without resorting to surgical interventions.

Conclusion

This is a rare case of acute thoracic spondylitis caused by E. coli, successfully treated without surgery. This case highlights the significant challenges in diagnosis and treatment. It underscores the value of mNGS in identifying rare infections and emphasizes the role of TDM in optimizing antibiotic therapy, providing a reference for future cases of rare and critical infections with fever of unknown origin.

Wide variability of the definitions used for native vertebral osteomyelitis: walking the path for a unified diagnostic framework with a meta-epidemiological approach

BACKGROUND CONTEXT

Native Vertebral Osteomyelitis (NVO) has seen a rise in incidence, yet clinical outcomes remain poor with high relapse rates and significant long-term sequelae. The 2015 IDSA Clinical Practice Guidelines initiated a surge in scholarly activity on NVO, revealing a patchwork of definitions and numerous synonyms used interchangeably for this syndrome.

PURPOSE

To systematically summarize these definitions, evaluate their content, distribution over time, and thematic clustering.

STUDY DESIGN/SETTING

Meta-epidemiological study with a systematic review of definitions.

PATIENTS SAMPLE

An extensive search of multiple databases was conducted, targeting trials and cohort studies dating from 2005 to present, providing a definition for NVO and its synonyms.

OUTCOME MEASURES

Analysis of the diagnostic criteria that composed the definitions and the breaking up of the definitions in the possible combinations of diagnostic criteria.

METHODS

We pursued a thematic synthesis of the published definitions with Boolean logic, yielding single or multiple definitions per included study. Using 8 predefined diagnostic criteria, we standardized definitions, focusing on the minimum necessary combinations used. Definition components were visualized using Sankey diagrams.

RESULTS

The literature search identified 8,460 references, leading to 171 studies reporting on 21,963 patients. Of these, 91.2% were retrospective, 7.6% prospective, and 1.2% RCTs. Most definitions originated from authors, with 29.2% referencing sources. We identified 92 unique combinations of diagnostic criteria across the literature. Thirteen main patterns emerged, with the most common being clinical features with imaging, followed by clinical features combined with imaging and microbiology, and lastly, imaging paired with microbiology.

CONCLUSIONS

Our findings underscore the need for a collaborative effort to develop standardized diagnostic criteria. We advocate for a future Delphi consensus among experts to establish a unified diagnostic framework for NVO, emphasizing the core components of clinical features and MRI while incorporating microbiological and histopathological insights to improve both patient outcomes and research advancements.

Streamlining the Journey of Research Into Clinical Practice: Making Your Patients and Practice Flourish Evaluation and Treatment of Pyogenic Spondylodiscitis of the Spine: AO Spine Knowledge Forum Trauma and Infection

STUDY DESIGN

Literature Review with clinical recommendations.

OBJECTIVE

To highlight impactful studies on pyogenic spondylodiscitis (PS), identified by the AO Spine Knowledge Forum Trauma and Infection, with recommendations for their integration into clinical practice.

METHODS

Five influential studies on PS that have the potential to shape current practice in spinal infections were selected and reviewed. Each study was chosen for its contribution to a critical phase in PS management: diagnosis, imaging, surgical vs conservative treatment, and antibiotic duration. Recommendations were graded as strong or conditional following the GRADE methodology.

RESULTS

Five studies were highlighted. Article 1: Pluemer et al introduced the Spinal Infection Treatment Evaluation (SITE) Score, a novel scoring tool for standardizing treatment decision-making. Conditional recommendation to incorporate the SITE Score or SISS Score for improved treatment outcomes. Article 2: Maamari et al conducted a meta-analysis comparing imaging modalities, with conditional recommendation to consider 18F-FDG PET/CT to diagnosis PS as an adjunct to MRI which remains the gold standard. Article 3: Thavarajasingam et al demonstrated the potential survival benefit of early surgery in specific PS cases, leading to a strong recommendation for early intervention in appropriate patients. Article 4: Neuhoff et al compared conservative and surgical treatments in well-resourced settings, concluding a strong recommendation for early surgery in appropriate patients. Article 5: Bernard et al evaluated antibiotic treatment duration, with a conditional recommendation for a 6-week course in confirmed cases, based on comparable efficacy to a 12-week regimen.

CONCLUSIONS

Management of PS remains complex and varied. This perspective provides spine surgeons with evidence-based recommendations to enhance standardization and effectiveness in clinical practice.

[Chronic Q fever. Literature review and a case report of culture negative spondylodiscitis]

INTRODUCTION

Fever is a cosmopolit zoonosis due to Coxiella burnetii. The diagnosis of chronic Q fever can be really misleading. The growth of this bacterium is difficult and blood cultures are often negatives.

CASE PRESENTATION

We rapport here the case of a 69-year-old man presenting with an alteration of his general condition and low back pain. He suffered from a well-controlled HIV infection and lower limb arteriopathy treated with a cross-femoral bypass. A computed tomography scan revealed a L3-L4 abscessed spondylodiscitis but multiple blood cultures remained sterile, and the transthoracic echocardiography was normal. PET scan showed a hypermetabolism on L3-L4 vertebrae but also indicated an intense uptake of the cross-femoral bypass. C. burnetii serology was in favour of a chronic Q fever. The management of this chronic Q fever needed a multidisciplinary discussion. Three months after the treatment initiation, C. burnetii serology was reduced by a titer and has stabilized 6months to a year.

CONCLUSION

Chronic Q fever and mostly osteoarticular diseases are difficult to diagnose. We have to evoke the diagnosis of osteoarticular chronic Q fever in case of insidious inflammatory syndrome, negatives blood cultures spondylodiscitis especially when associated to endocarditis or vascular infection, and in case of spondylodiscitis with a granulomatous histology without Mycobacterium tuberculosis. Although there are many complementary tests (PET scanner, PCR), serology remains the cornerstone of diagnosis.

Implementing Oral Antibiotics for Bone and Joint Infections: Lessons Learned and Opportunities for Improvement

Background

Although intravenous antibiotics have historically been the standard of care for bone and joint infections, clinical trial data have highlighted the safety and efficacy of oral antibiotics. Despite this, intravenous antibiotics are still commonly used, and evaluations of institutional guidelines advancing oral antibiotic use are limited.

Methods

In April 2023, we implemented a new institutional guideline to preferentially treat patients with bone and joint infections with oral antibiotics. The postguideline cohort was compared with a historical preguideline cohort via retrospective chart review. The primary outcome was the proportion of patients discharged exclusively on oral antibiotics. Secondary outcomes included 90-day treatment failure, length of stay, and adverse effects.

Results

One hundred eighty-six patients (53 preguideline and 133 postguideline) were included in the analysis. Patients in the postguideline cohort were more likely to be discharged exclusively on oral antibiotics (25% vs 70%; P < .01), with no difference in 90-day treatment failure (8% vs 9%; P = .75). Patients in the postguideline cohort had a shorter length of stay than preguideline (median, 8 vs 7 days; P = .04) and trended toward fewer peripherally inserted central catheter-related adverse events (6% vs 1%; P = .07).

Conclusions

An institutional guideline was effective in increasing the proportion of patients with bone and joint infections discharged on oral antibiotics. We observed similar clinical outcomes after implementing the guidelines while reducing length of hospital stay.

Culture-Negative Native Vertebral Osteomyelitis: A Narrative Review of an Underdescribed Condition

The incidence of culture-negative NVO (CN-NVO) cases is increasing, presenting significant diagnostic and therapeutic challenges due to the inability to isolate causative organisms with conventional microbiological methods. Factors influencing the diagnosis of CN-NVO include prior antimicrobial therapy, low pathogen burden, fastidious or intracellular organisms, technical issues, and non-infectious mimickers. Diagnosis often relies on imaging modalities like magnetic resonance imaging (MRI) and computed tomography (CT)-guided biopsy, though these methods can sometimes fail to yield positive microbiological results. Advanced diagnostic tools, such as polymerase chain reaction (PCR), metagenomic next-generation sequencing (mNGS), and cell-free DNA analysis, may be necessary to identify the pathogen. The causative pathogen cannot be isolated in some patients, among which an empirical antimicrobial therapy should be initiated. This narrative review discusses the management, monitoring, surgical indications, and outcomes for patients with CN-NVO.

Microbiological Profile of Instrumented Spinal Infections: 10-Year Study at a French Spine Center

OBJECTIVE

The objective was to compare the microbiological characteristics and treatment of early and late surgical site infections (SSIs) in instrumented spinal surgery.

METHODS

Those patients admitted for SSIs in a single center between January 2010 and December 2022 were included. The subjects were divided into early (eSSIs) and late (lSSIs) SSIs, and demographic, microbiological, treatment, and follow-up data were collected.

RESULTS

Instrumented spinal surgery was performed in 2136 patients. Ninety-six cases of infections were identified (prevalence = 4.5%), with 47.9% eSSIs and 52.1% lSSIs. In 58.7% of the cases, the eSSIs were monomicrobial: Staphylococcus aureus (37%) and Enterobacterales (33.3%) were the main bacteria involved. In 66% of the cases, the lSSIs, were monomicrobial: Cutibacterium acnes (30.3%) and staphylococci were predominant. Enterobacterales were isolated in more than 70% of the polymicrobial samples in both the eSSIs and lSSIs. The treatment of the eSSIs mostly consisted of lavage-debridement surgery associated with antibiotic treatment, while the treatment of the lSSIs combined hardware removal or replacement and long-duration antibiotic treatment. A negative outcome was observed in 17.1% of the eSSIs and 5.7% of the lSSIs. Enterobacterales were associated with negative outcomes of eSSIs.

CONCLUSIONS

Enterobacterales were found in most of the polymicrobial infections regardless of the time of infection onset. Further large studies should be conducted to precisely determine the management and prevention regarding the increasing Gram-negative bacteria SSIs.

Disability-adjusted life years from bone and joint infections associated with antimicrobial resistance: an insight from the 2019 Global Burden of Disease Study

PURPOSE

Bone and joint infections, complicated by the burgeoning challenge of antimicrobial resistance (AMR), pose significant public health threats by amplifying the disease burden globally. We leveraged results from the 2019 Global Burden of Disease Study (GBD) to explore the impact of AMR attributed to bone and joint infections in terms of disability-adjusted life years (DALYs), elucidating the contemporary status and temporal trends.

METHODS

Utilizing GBD 2019 data, we summarized the burden of bone and joint infections attributed to AMR across 195 countries and territories in the 30 years from 1990 to 2019. We review the epidemiology of AMR in terms of age-standardized rates, the estimated DALYs, comprising years of life lost (YLLs) and years lived with disability (YLDs), as well as associations between DALYs and socio-demographic indices.

RESULTS

The GBD revealed that DALYs attributed to bone and joint infections associated with AMR have risen discernibly between 1990 and 2019 globally. Significant geographical disparities and a positive correlation with socio-demographic indicators were observed. Staphylococcus aureus infections, Group A Streptococcus, Group B Streptococcus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Enterobacter-related bone and joint infections were associated with the highest DALYs because of a high proportion of antimicrobial resistance. Countries with limited access to healthcare, suboptimal sanitary conditions, and inconsistent antibiotic stewardship were markedly impacted.

CONCLUSIONS

The GBD underscores the escalating burden of bone and joint infections exacerbated by AMR, necessitating urgent, multi-faceted interventions. Strategies to mitigate the progression and impact of AMR should emphasize prudent antimicrobial usage and robust infection prevention and control measures, coupled with advancements in diagnostic and therapeutic modalities.

It is time for a unified definition of native vertebral osteomyelitis: a framework proposal

In recent years, there has been a notable increase in research output on native vertebral osteomyelitis (NVO), coinciding with a rise in its incidence. However, clinical outcomes remain poor, due to frequent relapse and long-term sequelae. Additionally, the lack of a standardized definition and the use of various synonyms to describe this condition further complicate the clinical understanding and management of NVO. We propose a new framework to integrate the primary diagnostic tools at our disposal. These collectively fall into three main domains: clinical, radiological, and direct evidence. Moreover, they and can be divided into seven main categories: (a) clinical features, (b) inflammatory biomarkers, (c) imaging techniques, microbiologic evidence from (d) blood cultures and (e) invasive techniques, (f) histopathology, and (g) empirical evidence of improvement following the initiation of antimicrobial therapy. We provide a review on the evolution of these techniques, explaining why no single method is intrinsically sufficient to formulate an NVO diagnosis. Therefore, we argue for a consensus-driven, multi-domain approach to establish a comprehensive and universally accepted definition of NVO to enhance research comparability, reproducibility, and epidemiological tracking. Ongoing research effort is needed to refine these criteria further, emphasizing collaboration among experts through a Delphi method to achieve a standardized definition. This effort aims to streamline research, expedite accurate diagnoses, optimize diagnostic tools, and guide patient care effectively.

Imaging in osteoarticular infection in adults

BACKGROUND

Osteoarticular infections are uncommon and required a multimodal approach for diagnosis. Imaging forms an important component of this multimodal approach.

OBJECTIVES

In this narrative review, we describe the different imaging modalities, features of osteoarticular infections present on these imaging approaches and recommendations for which imaging modality should be considered in different types of osteoarticular infections.

SOURCES

This narrative review was based on literature review from PubMed and was limited to bacterial infections in adult patients.

CONTENT

Imaging modalities include modalities that provide information on the anatomy or radionuclide imaging that provides information about the metabolic activity of the area of interest. Anatomical imaging includes plain radiographs (X-ray), computed tomography, and magnetic resonance imaging. Radionuclide approaches include three-phase bone scintigraphy, gallium scans, white blood cell scintigraphy, and 18F-fluorodeoxy-glucose positron emission tomography. The optimal radiological modality for diagnosis is influenced by multiple factors, including infection location, presence of metalware, timing of infection from any preceding surgery or fracture, antibiotic use, and patient comorbidities. Local availability of scanning modality, tracer supply, technical expertise, and patient access also influences choice.

IMPLICATIONS

A collaborative approach with imaging, pathology and clinical input in a multidisciplinary setting is paramount for the diagnosis of osteoarticular infections. Increasing research and improvements in technology will further improve the utility and accuracy of imaging approaches for imaging in osteoarticular infections.

Evaluation of diagnostic criteria and choice of treatment tactics for patients with infectious spondylodiscitis based on a case series

Objective. To present a brief description of a series of clinical cases of infectious spondylodiscitis with an assessment of the used diagnostic criteria in terms of their influence on the choice of sanifying treatment tactics.

Material and Methods. A continuous retrospective study of 39 cases of spondylodiscitis was carried out. Level of evidence is IIIC. The level of ESR, serum C-reactive protein, the results of the study of biopsy materials, and CT and MRI data were evaluated. Criteria of neurological deficit, instability of the spinal motion segment, and recommendations for assessing the clinical and radiological severity of the disease were used to select the treatment tactics. Treatment success was defined as primary wound healing, absence of recurrent infection and/or death, and satisfaction with treatment according to the EQ-5D and EQ-VAS scales at a follow-up period of 22.5 months.

Results. The average age of patients was 57.4 years. Primary spondylodiscitis accounted for 82 %, the predominant localization of the pathological focus was the lumbar spine (56.4 %), and staphylococci were predominant etiologic agents (59.1 %). On average, the increase in ESR was 45 mm/h, C-reactive protein – 57 ng/l, and D-dimer – 1235 pg/ml. The level of pain before sanation according to the VAS scale was 6.79 points, after the operation it was 2.3 points (p < 0.05). Instability of the spinal motion segment according to the SINS scale was revealed in 36 cases, paravertebral abscess according to MRI – in 51.3 % of cases, and neurological deficit – in 38.5 % of cases. Severe spondylodiscitis according to the SponDT scale was noted in 53.8 %, moderate – in 43.6 %, and mild – in 2.6 % of patients. According to the clinical and radiological classification of infectious spondylodiscitis severity (SSC), grade I was present in 2 patients, grade II – in 21, and grade III – in 6. Compliance of the chosen treatment tactics with current recommendations was noted in 94,9 % of cases. Recurrence of infection was observed in 7.7 %; lethal outcome – in 5.1 %. Satisfaction with the quality of life according to EQ-5D was 0.74 points, and according to EQ-VAS – 73.88 points.

Conclusions. The integrated use of criteria for neurological deficit, instability of spinal motion segments, and severity of the disease according to the SponDT classification with the account of Pola’s recommendations on treatment tactics made it possible to choose the optimal treatment tactics and achieve satisfactory results in the sanation of patients with infectious spondylodiscitis.

Advances in diagnosis and management of atypical spinal infections: A comprehensive review

Atypical spinal infections (ASIs) of the spine are a challenging pathology to management with potentially devastating morbidity and mortality. To identify patients with atypical spinal infections, it is important to recognize the often insidious clinical and radiographic presentations, in the setting of indolent and smoldering organism growth. Trending of inflammatory markers, and culturing of organisms, is essential. Once identified, the spinal infection should be treated with antibiotics and possibly various surgical interventions including decompression and possible fusion depending on spine structural integrity and stability. Early diagnosis of ASIs and immediate treatment of debilitating conditions, such as epidural abscess, correlate with fewer neurological deficits and a shorter duration of medical treatment. There have been great advances in surgical interventions and spinal fusion techniques for patients with spinal infection. Overall, ASIs remain a perplexing pathology that could be successfully treated with early diagnosis and immediate, appropriate medical, and surgical management.

What clindamycin dose should be administered by continuous infusion during combination therapy with rifampicin? A prospective population pharmacokinetics study

BACKGROUND

Despite its important drug-drug interaction, combined clindamycin/rifampicin therapy may achieve effective plasma clindamycin concentrations, provided clindamycin is administered by continuous infusion. However, the precise clindamycin dose remains unknown.

OBJECTIVES

This study was undertaken to determine the daily clindamycin dose to be administered by continuous infusion in combination with rifampicin to achieve effective plasma clindamycin concentrations.

PATIENTS AND METHODS

Two plasma clindamycin concentrations were determined prospectively for 124 patients with bone-and-joint infections treated with continuously infused clindamycin. Twenty patients received clindamycin monotherapy, 19 clindamycin combined with rifampicin and 85 received clindamycin successively without and with rifampicin. A population pharmacokinetic model was developed using NONMEM 7.5. Monte Carlo simulations were run to determine which regimens obtained clindamycin concentrations of at least 3 mg/L.

RESULTS

A linear one-compartment model with first-order elimination accurately described the data. Clindamycin distribution volume was not estimated. Mean clindamycin clearances with rifampicin and without, respectively, were 33.6 and 10.9 L/h, with 12.8% interindividual variability. The lowest daily clindamycin dose achieving plasma concentrations of at least 3 mg/L in >90% of the patients, when combined with rifampicin, was 4200 mg/24 h.

CONCLUSIONS

Our results support continuous infusion of 4200 mg of clindamycin/24 h, in combination with rifampicin. This high-dose regimen requires therapeutic drug monitoring-guided dose adaptation.

Association between radiographic and functional outcome in vertebral osteomyelitis SPONDIMMO, a 6-month prospective multicenter cohort

OBJECTIVES

This study aimed to describe radiographic and functional evolution over 6 months in a large cohort of VO patients.

METHODS

We prospectively recruited patients with VO from 2016 to 2019 in 11 French centers. X-rays were performed at baseline, 3 months, and 6 months to assess progression using structural and static criteria. Functional impairment was evaluated using the Oswestry Disability Index (ODI) at 3 months and 6 months.

RESULTS

Two hundred and twenty-two patients were included. Mean age was 67.8±14 years, mostly men (67.6%). After 3 months, there was a significant increase in vertebral fusion (16.4% vs 52.7%), destruction of vertebral bodies (10.1% vs 22.8%), and of all the static features (frontal angulation (15.2% vs 24.4%), segmental (34.6% vs 56%) and regional (24.5% vs 41%) kyphosis). From 3 to 6 months, among the different X-ray abnormalities, only the complete fusion progressed significantly (16.6% vs 27.2%). Median ODI showed significant improvement from 3 to 6 months (24, IQR [11.5-38] vs 16, IQR [6-34]). At 6 months, 14.1% of the patients had a severe disability, 2% a major disability. The persistence of vertebral destruction at 6 months was associated with a higher ODI (16, IQR [7.5-30.5] vs 27, IQR [11.5-44.5]). No differences in radiological progression were observed with immobilization using a rigid brace.

CONCLUSION

Our study demonstrates structural and static radiographic progression after 3 months. Only the complete fusion progressed over the long-term. Functional impairment was associated with persistence of vertebral destruction.

Pharmacokinetic and pharmacodynamic considerations for optimizing antimicrobial therapy used to treat bone and joint infections: an evidence-based algorithmic approach

INTRODUCTION

Bone and joint infections (BJIs) are a major health concern causing remarkable morbidity and mortality. However, which antimicrobial treatment could be the best according to specific clinical scenarios and/or to the pharmacokinetic/pharmacodynamic (PK/PD) features remains an unmet clinical need. This multidisciplinary opinion article aims to develop evidence-based algorithms for empirical and targeted antibiotic therapy of patients affected by BJIs.

AREAS COVERED

A multidisciplinary team of four experts had several rounds of assessment for developing algorithms devoted to empirical and targeted antimicrobial therapy of BJIs. A literature search was performed on PubMed-MEDLINE (until April 2023) to provide evidence for supporting therapeutic choices. Four different clinical scenarios were structured according to specific infection types (i.e. vertebral osteomyelitis, prosthetic joint infections, infected non-unions and other chronic osteomyelitis, and infectious arthritis), need or not of surgical intervention or revision, isolation or not of clinically relevant bacterial pathogens from blood and/or tissue cultures, and PK/PD features of antibiotics.

EXPERT OPINION

The proposed therapeutic algorithms were based on a multifaceted approach considering the peculiar features of each antibiotic (spectrum of activity, PK/PD properties, bone penetration rate, and anti-biofilm activity), and could be hopefully helpful in improving clinical outcome of BJIs.

Concentrations of Co-Administered Meropenem and Vancomycin in Spinal Tissues Relevant for the Treatment of Pyogenic Spondylodiscitis-An Experimental Microdialysis Study

Co-administration of meropenem and vancomycin has been suggested as a systemic empirical antibiotic treatment of pyogenic spondylodiscitis. The aim of this study was, in an experimental porcine model, to evaluate the percentage of an 8-h dosing interval of co-administered meropenem and vancomycin concentrations above the relevant minimal inhibitory concentrations (MICs) (%T>MIC) in spinal tissues using microdialysis. Eight female pigs (Danish Landrace breed, weight 78-82 kg) received a single-dose bolus infusion of 1000 mg of meropenem and 1000 mg vancomycin simultaneously before microdialysis sampling. Microdialysis catheters were applied in the third cervical (C3) vertebral cancellous bone, the C3-C4 intervertebral disc, paravertebral muscle, and adjacent subcutaneous tissue. Plasma samples were obtained for reference. The main finding was that for both drugs, the %T>MICs were highly reliant on the applied MIC target, but were heterogeneous across all targeted tissues, ranging from 25-90% for meropenem, and 10-100% for vancomycin. For both MIC targets, the highest %T>MIC was demonstrated in plasma, and the lowest %T>MIC was demonstrated in the vertebral cancellous bone for meropenem, and in the intervertebral disc for vancomycin. When indicated, our findings may suggest a more aggressive dosing approach of both meropenem and vancomycin to increase the spinal tissue concentrations to treat the full spectrum of potentially encountered bacteria in a spondylodiscitis treatment setting.