Diagnostic yield of computed tomography‐guided biopsy and aspiration for vertebral osteomyelitis

Diagnostic performance of metagenomic next-generation sequencing and conventional microbial culture for spinal infection: a retrospective comparative study

PURPOSE

The study evaluated the diagnostic performance of metagenomic next-generation sequencing (mNGS) as a diagnostic test for biopsy samples from patients with suspected spinal infection (SI) and compared the diagnostic performance of mNGS with that of microbial culture.

METHODS

All patients diagnosed with clinical suspicion of SI were enrolled, and data were collected through a retrospective chart review of patient records. Biopsy specimens obtained from each patient were tested via mNGS and microbial culture. Samples were enriched for microbial DNA using the universal DNA extraction kit, whole-genome amplified, and sequenced using MGISEQ-200 instrument. After Low-quality reads removed, the remaining sequences for microbial content were analyzed and aligned using SNAP and kraken2 tools.

RESULTS

A total of 39 patients (19 men and 20 women) were deemed suitable for enrollment. The detection rate for pathogens of mNGS was 71.8% (28/39), which was significantly higher than that of microbial culture (23.1%, p = 0.016). Mycobacterium tuberculosis complex was the most frequently isolated. Using pathologic test as the standard reference for SI, thirty-one cases were classified as infected, and eight cases were considered aseptic. The sensitivity and specificity values for detecting pathogens with mNGS were 87.1% and 87.5%, while these rates were 25.8% and 87.5% with conventional culture. mNGS was able to detect 88.9% (8/9) of pathogens identified by conventional culture, with a genus-level sensitivity of 100% (8/8) and a species-level sensitivity of 87.5% (7/8).

CONCLUSION

The present work suggests that mNGS might be superior to microbial culture for detecting SI pathogens.

Site matters: Image-guided percutaneous sampling of intervertebral disc results in increased positive diagnostic yield in spondylodiscitis

Spondylodiscitis is a common referral to spinal on call services. Identification of the causative organism is vital in order to dictate the appropriate antibiotic treatment. In this context, the surgical and interventional radiology team is often asked to perform a diagnostic biopsy. The aim of the present study was to assess whether the sampling location affects the diagnostic yield. Our results suggest that the overall positive diagnostic yield was 35%. When disc material was included in the sample the diagnostic yield significantly improved to 47%. Bone sampling alone had a positive yield of 15%. Age, pre-biopsy CRP, pre-biopsy use of antibiotics did not seem to affect the likelihood of obtaining a positive yield. These results suggests that when performing image guided biopsies for suspected cases of spondylodiscitis the inclusion of disc material is important.

Factors Impacting the Yield of Image-Guided Biopsy in Native Vertebral Osteomyelitis: A 10-Year Retrospective Study

Background

Image-guided biopsies in patients with suspected native vertebral osteomyelitis (NVO) are recommended to establish the microbiological diagnosis and guide antibiotic therapy. Despite recent advances, the microbiological yield of this procedure remains between 48% and 52%. A better understanding of factors associated with this low yield may lead to improved microbiological diagnosis.

Methods

We retrospectively identified patients with suspected NVO undergoing image-guided biopsies from January 2011 to June 2021 at our institution. Two hundred nine patients undergoing 248 percutaneous biopsies were included. Demographic data, biopsy and microbiologic techniques, clinical characteristics, and antibiotic use were collected. Multivariable logistic regression analysis was conducted to determine factors associated with microbiological yield.

Results

A total of 110 of 209 (52.6%) initial image-guided biopsies revealed positive microbiological results. This number increased to 121 of 209 (57.9%) when repeat image-guided biopsies were included. In multivariable analysis, aspiration of fluid was associated with a 3-fold increased odds of yielding a positive result (odds ratio [OR], 3.13; 95% confidence interval [CI], 1.39-7.04; P = .006), whereas prior antibiotic use was associated with a 3-fold decreased yield (OR, 0.32; 95% CI, .16-.65; P = .002). A univariate subgroup analysis revealed a significant association between the length of the antibiotic-free period and microbiological yield, with the lowest rates of pathogen detection at 0-3 days and higher rates as duration increased (P = .017).

Conclusions

Prior antibiotic use in patients with suspected NVO was associated with a decrease in the microbiological yield of image-guided biopsies. An antibiotic-free period of at least 4 days is suggested to maximize yield. Successful fluid aspiration during the procedure also increases microbiological yield.

Diagnostic Yield of Computed Tomography-Guided Procedures for Spondylodiscitis

PURPOSE

To identify the diagnostic yield and predictive factors for microbiological diagnosis in patients with spondylodiscitis through computed tomography (CT)-guided biopsy or aspiration.

MATERIALS AND METHODS

A retrospective review of 102 patients with suspected spondylodiscitis who underwent CT-guided procedures in an 8-year period was conducted. Analyzed variables were demographic data, C-reactive protein, pre-biopsy MRI findings, prior antibiotic use, site of biopsy/aspiration, histopathological findings, culture results and radiation dose.

RESULTS

The culture yield among all sites was 56%, 85.6% for paravertebral/discal fluid aspiration, 66.7% for disk-only biopsy, 52.9% for paravertebral soft tissue biopsy, and 39.6% for endplate bone-disk unit. Patients with paravertebral/disk collection on MRI had better yields when submitted to fluid aspiration instead of biopsy of other sites (78.9% vs. 36.6%; p = 0,006). Pyogenic etiology corresponded to 68.3% of cases and Staphylococcus aureus was the most common agent. Prior antibiotics exposure was associated with a lower yield (66.2% vs. 40.9%, p = 0,016).

CONCLUSIONS

CT-guided procedures are safe and well-tolerated in patients with suspected spondylodiscitis, with good microbiologic yield particularly in the presence of paravertebral/discal abscess.

Culture Yield in the Diagnosis of Native Vertebral Osteomyelitis: A Single Tertiary Center Retrospective Case Series with Literature Review

Background

Vertebral osteomyelitis is a serious condition that requires prompt diagnosis to avoid delays in proper management. There is no well-defined gold standard for diagnosis. We describe the current diagnostic approach at our institution, with a focus on the yield of image-guided vertebral biopsy.

Methods

We performed a single-centre 10-year retrospective case series, including adults with imaging suggestive of vertebral osteomyelitis/discitis, with either positive blood cultures, and/or a vertebral biopsy. We defined positive histopathology as our gold standard for test characteristic evaluation of biopsy cultures.

Results

Out of 694 patients identified, 221 met our inclusion criteria, and 173/221 (78.2%) patients underwent a spinal biopsy. Of those patients with biopsies, 113 (65%) had received antibiotics within 2 weeks preceding their evaluation. Six of 43 (13.9%) bone specimens were positive by culture, while 66/152 (43.4%) of disc specimens were culture positive. Forty-seven of 84 (55.9%) histopathology (bone or disc) specimens were diagnostic for osteomyelitis/discitis. The sensitivity of bone and disk culture were 30.0% and 56.0%, respectively, with specificities of 92.8% and 75.0%, respectively. Twenty-three (13.4%) patients had repeat biopsies, including 10 bone specimens and 14 disc specimens, and 11 (47.8%) specimens had histopathology performed which diagnosed an additional 3/23 patients (13% additional diagnostic yield).

Conclusions

Culture of percutaneous biopsy of disc resulted in the highest diagnostic yield. Histopathology added to the diagnostic yield in culture-negative specimens. Histopathologic evaluation of bone had better yield than bone culture. A repeat biopsy can add to the diagnostic yield.

CT-Guided Needle Biopsy in Vertebral Osteomyelitis: Study of Factors That Could Influence in Culture Yield

OBJECTIVE

The aim of this study was to analyze which are the main factors that could influence the result of a CT guided biopsy in vertebral osteomyelitis (VO) patients.

METHODS

A single center retrospective observational study was performed including adult patients who had been diagnosed with VO and undergone CT guided needle biopsy from January 2010 to January 2020. Demographical features, concurrent diseases, laboratory findings, microbiological diagnosis, radiological data, medical complications, antibiotic exposure were compiled. Multivariate analysis was performed with a logistic regression comparing the patients depending on the culture result.

RESULTS

Seventy-seven patients were included in the study. Baseline characteristics were comparable between groups. Sample culture was positive in 43 cases (56%). Microorganism isolated were gram+(72%), gram-(14%), mycobacteria (7%) and fungi (7%). Delay in the procedure, antibiotic exposure and blood culture positivity were also similar among both groups. The biopsy results were not influenced by the CRP value, the presence of fever nor antibiotic exposure. The longer duration of back pain was associated to a lower probability of a positive culture.

CONCLUSIONS

In conclusion, our study displays an acceptable reliability of CT guided needle biopsy in VO patients, even in cases under antibiotic treatment. The presence of fever or CRP values did not predict a positive culture. Delay in diagnosis could impact negatively on culture yield.

Does image-guided biopsy of discitis-osteomyelitis provide meaningful information to impact clinical management?

OBJECTIVE

The aims of this study are to assess the diagnostic yield of image-guided biopsy for discitis-osteomyelitis (DO), identify factors associated with biopsy yield (laboratory, pre-defined MRI findings, and biopsy technique), and impact of biopsy on management of patients appropriately selected according to the Infectious Disease Society of America guidelines (IDSA).

MATERIALS AND METHODS

This is a retrospective review of patients who underwent biopsy for suspected DO from 2011 to 2019. Reference standards to establish diagnosis of DO in order were histopathology/microbiology from biopsy or subsequent surgical sampling, positive blood culture or serology, and imaging/clinical follow-up. Laboratory markers, pre-biopsy antibiotics and MRI features, procedural-related variables, and impact of biopsy on management were assessed. Multivariable logistic regression was also performed.

RESULTS

Out of 97 included patients, 78 were diagnosed with DO. Overall sensitivity of biopsy for detecting DO was 41.0% (32/78), including 10 patients with positive histopathology only, 14 with positive biopsy culture only, and 8 with both. Elevated ESR (p < 0.001) and epidural collection on MRI (p = 0.008) were associated with higher biopsy yield (63.6% and 68.6%, respectively) in a multivariable model. Procedural variables were not associated with yield. Biopsy results impacted the management in 19/77 (24.7%) patients, of whom 15/19 (78.9%) had treatment de-escalation and 4/19 (21.0%) had treatment escalation including starting new anti-tuberculous and anti-fungal regimens.

CONCLUSION

Sensitivity of biopsy for detecting DO was 41.0%. When IDSA guidelines are followed, biopsy provided impactful information that changed the management in 24.7% of patients. Evaluation for elevated ESR and epidural collection can help improve yield and patient selection for biopsy.

A minimally invasive lateral approach with CT navigation for open biopsy and diagnosis of Nocardia nova L4–5 discitis osteomyelitis: illustrative case

BACKGROUND

Lumbar spine osteomyelitis can be refractory to conventional techniques for identifying a causal organism. In cases in which a protracted antibiotic regimen is indicated, obtaining a conclusive yield on biopsy is particularly important. Although lateral transpsoas approaches and intraoperative computed tomography (CT) navigation are well documented as techniques used for spinal arthrodesis, their utility in vertebral biopsy has yet to be reported in any capacity.

OBSERVATIONS

In a 44-year-old male patient with a history of Nocardia bacteremia, CT-guided biopsy failed to confirm the microbiology of an L4–5 discitis osteomyelitis. The patient underwent a minimally invasive open biopsy in which a lateral approach with intraoperative guidance was used to access the infected disc space retroperitoneally. A thin film was obtained and cultured Nocardia nova, and the patient was treated accordingly with a long course of trimethoprim-sulfamethoxazole.

LESSONS

The combination of a lateral transpsoas approach with intraoperative navigation is a valuable technique for obtaining positive yield in cases of discitis osteomyelitis of the lumbar spine refractory to CT-guided biopsy.

The impact of antibiotic pre-treatment on diagnostic yield of CT-guided biopsy for spondylodiscitis: A multi-centre retrospective study and meta-analysis

INTRODUCTION

Patients with suspected spondylodiscitis often undergo CT-guided biopsy to identify a causative microbiological organism. Antibiotic pre-treatment has been postulated as a cause for a negative biopsy, although previous clinical studies have been heterogenous with a meta-analysis suggesting no effect. The aim of this study was to assess the impact of antibiotic pre-treatment on microbiological yield.

METHODS

Retrospective review of consecutive adult patients undergoing CT-guided biopsy for suspected spondylodiscitis in two tertiary centres between 2010 and 2016. Demographic, procedural and clinical data were collected. Antibiotic pre-treatment was ascertained from patient drug charts.

RESULTS

Over the 6-year period, 104 biopsies in 104 patients were included. 51% had a positive microbiological yield at CT-guided biopsy, with the most common isolated organism being Staphylococcus aureus (10.6%). Over two thirds of patients (69.3%) were off antibiotics at time of biopsy. There was no significant difference in microbiological yield in those patients on versus off antibiotics (48.2% vs 54.2%, P = 0.55). 10.6% patients had a final diagnosis of Mycobacterium tuberculosis spondylodiscitis, and this organism was significantly associated with a positive microbiological yield (90.9% vs 46.2%, P = 0.01). There was an inverse association between the presence of fever and sepsis with positive microbiological yield.

CONCLUSIONS

CT-guided biopsy in suspected spondylodiscitis obtains a positive microbiological yield in about half of patients. This was significantly higher in patients diagnosed with tuberculosis spondylodiscitis, but there was no significant difference with antibiotic pre-treatment. Therefore, antibiotic pre-treatment should not preclude clinicians from pursuing a microbiological sample through CT-guided biopsy.

Microbiological diagnosis of suspected vertebral osteomyelitis with a focus on the yield of percutaneous needle biopsy: a 10-year cohort study

This study aims to evaluate in patients hospitalized for vertebral osteomyelitis (VO) the effectiveness of bacteriological diagnosis and the yield of percutaneous needle biopsy (PNB) and to identify factors associated with the result of PNB. This retrospective, two-centre study was conducted between 2000 and 2009. Data on patients with VO were retrieved from the diagnosis database and confirmed by checking medical records. A total of 300 patients with VO were identified; 31 received antibiotics without bacteriological diagnosis, and 269 patients with spondylodiscitis imaging were included. Eighty-three (30.9%) and 18 (6.7%) infections were documented by blood cultures and by bacteriological samples other than PNB, respectively; 168 patients with no bacteriological diagnosis had PNB. Of these, 92 (54.8%) were positive and identified the pathogen and 76 (45.2%) were negative. The most common bacteria were Staphylococcus aureus (34.3%), Streptococcus spp. (20.6%) and coagulase-negative staphylococcus (14.8%). After multivariate analysis, the only factor associated with negative PNB was previous antibiotic intake (OR: 2.31 [1.07-5.00]). When VO was suspected on imaging, bacteriological investigation identified the microorganism in 209/300 (70%) of the cases. The yield of PNB was 54.8%. The only predictor of PNB negativity was previous antibiotic intake. Therefore, we believe that a second PNB should be done after a sufficient delay withdrawal of antibiotics if the first sample was negative. The study was retrospectively registered by the local ethics committee (N°E2019-61).

Extensive multifocal emphysematous osteomyelitis: fatal outcome in a patient with psychiatric history

Emphysematous osteomyelitis is a rare entity with potentially devastating consequences, even after prompt and aggressive intervention. It is characterized by intraosseous gas and may be complicated by adjacent abscess formation. There are a handful of previously reported cases of emphysematous osteomyelitis, but none to the degree as reported here. Specifically, we report an extremely rare case of extensive multifocal emphysematous osteomyelitis involving both the axial and appendicular skeleton in a 20-year-old woman.

Predicting osteomyelitis in patients whose initial MRI demonstrated bone marrow edema without corresponding T1 signal marrow replacement

PURPOSE

We endeavored to determine which characteristics of diabetic ulcers portend the strongest risk for osteomyelitis in patients whose initial T1-weighted imaging was normal. By determining which features have a greater risk for osteomyelitis, clinicians can treat patients more aggressively to reduce the sequela of inadequately treated osteomyelitis.

MATERIALS AND METHODS

We performed a retrospective analysis of MR imaging from 60 pedal ulcers with suspected osteomyelitis. Ulcer dimensions and depth were measured. Ratios of marrow ROI/joint fluid ROI on T2/STIR sequences were obtained. Progression to osteomyelitis on subsequent MRI was characterized by loss of normal marrow signal on T1-weighted images. Statistical analysis was performed with a two-sample t test and Cox proportional hazard model. A p value < 0.05 was used as the threshold for statistical significance.

RESULTS

Sixty MR exams were identified. Thirty-four progressed to osteomyelitis. Marrow ROI/joint fluid ratios averaged 65% in the osteomyelitis group, and 45% in the non-osteomyelitis group, p < 0.001. ROI ratios > 53% had a 6.5-fold increased risk of osteomyelitis, p < 0.001. Proximity to bone averaged 6 mm in the osteomyelitis group and 9 mm in the non-osteomyelitis group, p = 0.02. Ulcer size averaged 4 cm² in the osteomyelitis group versus 2.4 cm² in the non-osteomyelitis group, p = 0.07. Ulcers greater than 3 cm² has a 2-fold increase in the risk of osteomyelitis, p = 0.04.

CONCLUSION

Increasing bone marrow ROI signal/joint fluid ratios on T2/STIR images were the strongest risk factors for developing osteomyelitis, while ulcer size and depth are weaker predictors.

Predictors of positive bone cultures from CT-guided bone biopsies performed for suspected osteomyelitis

INTRODUCTION

Bone biopsies are often used to direct antibiotic choice in patients with suspected osteomyelitis. The aim of this study was to identify the best predictors of positive bone biopsy cultures.

METHODS

A retrospective review of 845 patients who underwent computed tomography (CT)-guided non-spine bone biopsies at a tertiary academic healthcare institution. Thirty-seven patients (4.4%) had biopsies performed for suspected osteomyelitis. Laboratory markers, as well as imaging features, were measured. t-Tests and Fisher's exact tests were used to compare clinical and demographic variables between patients with positive bone cultures and patients with negative bone cultures. Multivariable logistic regression was used to identify the best predictors of bone culture positivity.

RESULTS

All patients had negative blood cultures; however, only eight patients (21.6%) had positive bone cultures, with Staphyloccocus the most common organism. Multivariable logistic regression analysis showed that an open wound (OR = 14.00, 95% CI (1.74, 112.4), p = 0.013) and any fluid aspirated at the time of biopsy (OR = 10.50, 95% CI (1.21, 91.01), p = 0.033) were the best predictors of bone culture positivity. The area under the curve (AUC) for this multivariable model was 0.784 with sensitivity and specificity of 0.778 and 0.778, respectively. Interestingly, and contrary to popular belief, open wounds with exposed bone did not always yield positive bone cultures, and when cultures were positive, were not polymicrobial.

CONCLUSIONS

Aspiration of fluid at the time of biopsy and the presence of an open wound are the best predictors of positive bone cultures.

Diagnosis and Management of Osteomyelitis Associated With Stage 4 Pressure Ulcers: Report of a Query to the Emerging Infections Network of the Infectious Diseases Society of America

Background

Few studies exist to guide the management of patients with stage 4 pressure ulcers with possible underlying osteomyelitis. We hypothesized that infectious disease (ID) physicians would vary widely in their approach to such patients.

Methods

The Emerging Infections Network distributed a 10-question electronic survey in 2018 to 1332 adult ID physicians in different practice settings to determine their approach to such patients.

Results

Of the 558 respondents (response rate: 42%), 17% had managed no such patient in the past year. Of the remaining 464 respondents, 60% usually felt confident in diagnosing osteomyelitis; the strongest clinical indicator of osteomyelitis reported was palpable or visible bone at the ulcer base. Approaches to diagnosing osteomyelitis in patients with visible and palpable bone varied: 41% of respondents would assume osteomyelitis, 27% would attempt pressure off-loading first, and 22% would perform diagnostic testing immediately. Preferred tests for osteomyelitis were bone biopsy (for culture and histopathology) and magnetic resonance imaging. Respondents differed widely on favored route(s) (intravenous, oral, or both) and duration of antimicrobial therapy but would treat longer in the absence, vs presence, of full surgical debridement (P < .001). Overall, 62% of respondents opined that osteomyelitis under stage 4 pressure ulcers is usually or almost always treated excessively, and most (59%) suggested multiple topics for future research.

Conclusions

Regarding osteomyelitis underlying stage 4 pressure ulcers, ID physicians reported widely divergent diagnostic and treatment approaches. Most of the reported practice is not supported by the available evidence, which is quite limited and of low quality.

Intra-discal drain insertion for culture and drainage of pyogenic spondylodiscitis: A one-step diagnostic and therapeutic procedure

BACKGROUND

Pyogenic spondylodiscitis is diagnosed in recent years at higher rates due to the aging population, increased survival of chronic and immune suppressed patients, and the higher rate of invasive procedures leading to bacterial seeding or direct contamination of the disc space. Treatment guidelines encourage bacterial sampling before initiation of antibiotic therapy, and drainage of pus collections. We present our experience with percutaneous CT-guided drain insertion into the disc space itself as a one-step procedure for both culturing and subsequent continuous drainage of the infected disc space.

MATERIALS AND METHODS

We retrospectively reviewed all cases of pyogenic spondylodiscitis admitted to our spine surgery unit during the past five years and treated with CT-guided percutaneous drain insertion into the infected disc space. All patients were followed until complete resolution of the infection.

RESULTS

We retrieved electronic records of 12 patients, none presenting with neurological compression symptoms. Cultures taken at the time of drain insertion were positive in 10 patients (83.3%), much higher than the reported yield for needle aspiration (14-48%) and comparable to the yield of open biopsy. In all patients complete resolution of the infection was reached, determined by clinical, laboratory, and imaging parameters.

CONCLUSIONS

Our retrospective case series demonstrates the feasibility and effectiveness of intra-discal CT-guided drainage of an infected disc space. The procedure does not add much burden to current practice as disc-space sampling for culture is commonly performed anyway, and adds the benefit of direct drainage of the pus at its source.