The bacteria-positive proportion in the disc tissue samples from surgery: a systematic review and meta-analysis

Abstract

Purpose

The role of bacteria, especially Propionibacterium acnes (P. acnes), in human intervertebral disc diseases has raised attention in recent years. However, limited sample size of these studies and diverse bacteria-positive proportion made this topic still controversial. We aimed to review related articles and summarize the bacteria-positive proportion in these studies.

Methods

We searched the PubMed, Cochrane Library, Embase for related literature from January 2001 to May 2018, and the reference articles were also searched. The random effects or fixed effects meta-analysis was used to pool the overall positive proportion or odds ratio of these studies.

Results

We found 16 relevant articles and 2084 cases of the bacteria culture from surgery. Within the 16 included studies, 12 studies’ results supported the infection in the discs. The pooled bacterial infection rate was 25.3%. The pooled P. acnes infection rate was 15.5%. The overall pooled P. acnes proportion in bacteria-positive discs was 56.4%. We also found that the presence of bacteria may contribute to the development of Modic change with the odds ratio as 1.27 (95% CI: 0.44–3.64), but this result is not significant due to heterogeneity, so further study is needed.

Conclusion

The existence of bacteria in the intervertebral discs was proved by many studies. However, the variety in sample collecting and culture methods is still obvious and the positive rate also fluctuated within the studies. Standardized and reliable methods should be taken to promote the study in the future.

Graphic abstract

These slides can be retrieved under Electronic Supplementary Material.

Announcements

Answer to the Letter to the Editor of Wang H, et al. concerning “Indirect foraminal decompression and improvement in the lumbar alignment after percutaneous cement discoplasty” by Laszlo Kiss et al. (Eur Spine J; 28(6):1441–1447)

Letter to the Editor concerning “Can standard anterior Smith–Robinson supramanubrial approach be utilized for approach down to T2 or T3?” by Singhatanadgige W, Zebala LP, Luksanapruksa P, Riew KD [Eur Spine J (2017) 26:2357–2362]

Letter to the Editor concerning “Indirect foraminal decompression and improvement in the lumbar alignment after percutaneous cement discoplasty” by Laszlo Kiss et al. (Eur Spine J; 28(6):1441–1447)

Answer to the Letter to the Editor of V. Kumar et al. concerning "Can standard anterior Smith–Robinson supramanubrial approach be utilized for approach down to T2 or T3?" by Singhatanadgige W, Zebala LP, Luksanapruksa P, Riew KD [Eur Spine J (2017) 26:2357–2362]

C-reactive protein misdiagnoses delayed postoperative spinal implant infections in patients with low-virulent microorganisms Abstract Purpose C-reactive protein (CRP) has been shown to be a powerful parameter for detecting acute postoperative spinal implant infections (PSII) with a high sensitivity and specificity. However, little data are available on the performance of CRP in the diagnosis of delayed PSII. The aim of the current study was therefore to establish cutoff values for diagnosing delayed infection based on serum CRP. Methods All patients who underwent a revision surgery after instrumented spinal fusion from January 2013 through January 2016 were included. Demographic data, laboratory values, type of infection (including microbiological and pathological results), comorbidities and clinical manifestation were collected. The European Bone and Joint Infection Society criteria, proposed to diagnose periprosthetic joint infection, were used to diagnose PSII. Results A total of 257 patients were included. PSII was diagnosed in 61 patients, representing 24% of the study cohort. There was a significant difference in serum CRP levels between septic and aseptic cohorts (19.3 vs. 4.8 mg/l, p < 0.001). However, 26 patients (43%) from the PSII group had a normal (< 5 mg/l) serum CRP level prior to revision surgery. According to the ROC curve, a serum CRP threshold of 4.05 mg/l had a sensitivity of 64% and specificity of 68%. The most common isolated microorganism was Propionibacterium spp. followed by coagulase-negative staphylococci. Conclusion Serum CRP showed low sensitivity and specificity for diagnosis of delayed PSII, even after applying cutoffs optimized by using receiver operating curve analysis, because of the high incidence of low-virulent pathogens. Graphical abstract These slides can be retrieved under Electronic Supplementary Material.

Vertebral rotation estimation from frontal X-rays using a quasi-automated pedicle detection method Abstract Purpose Measurement of vertebral axial rotation (VAR) is relevant for the assessment of scoliosis. Stokes method allows estimating VAR in frontal X-rays from the relative position of the pedicles and the vertebral body. This method requires identifying these landmarks for each vertebral level, which is time-consuming. In this work, a quasi-automated method for pedicle detection and VAR estimation was proposed. Method A total of 149 healthy and adolescent idiopathic scoliotic (AIS) subjects were included in this retrospective study. Their frontal X-rays were collected from multiple sites and manually annotated to identify the spinal midline and pedicle positions. Then, an automated pedicle detector was developed based on image analysis, machine learning and fast manual identification of a few landmarks. VARs were calculated using the Stokes method in a validation dataset of 11 healthy (age 6–33 years) and 46 AIS subjects (age 6–16 years, Cobb 10°–46°), both from detected pedicles and those manually annotated to compare them. Sensitivity of pedicle location to the manual inputs was quantified on 20 scoliotic subjects, using 10 perturbed versions of the manual inputs. Results Pedicles centers were localized with a precision of 84% and mean difference of 1.2 ± 1.2 mm, when comparing with manual identification. Comparison of VAR values between automated and manual pedicle localization yielded a signed difference of − 0.2 ± 3.4°. The uncertainty on pedicle location was smaller than 2 mm along each image axis. Conclusion The proposed method allowed calculating VAR values in frontal radiographs with minimal user intervention and robust quasi-automated pedicle localization. Graphic abstract These slides can be retrieved under Electronic Supplementary Material.

Usefulness of dynamic contrast-enhanced magnetic resonance images for distinguishing between pyogenic spondylitis and tuberculous spondylitis Abstract Purpose Dynamic contrast-enhanced (DCE)-MRI is used for examining the features of malignant tumours in radiology, and we can obtain more information in terms of the diffusion of the media over the course of time. The purpose of this study was to clarify the usefulness of DCE-MRI for distinguishing pyogenic spondylitis (PS) and tuberculous spondylitis (TB). Methods Forty-five consecutive patients diagnosed with PS (68.6 ± 11.1 years old, males 30 and females 15) and 14 with TB (73.9 ± 9.1 years old, males 6 and females 8) were involved. DCE-MRI consisted of serial six sagittal images which were taken every 20 s after intravenous gadolinium administration. Degree of enhancement, presence of epidural abscess, presence of necrosis in vertebra, presence of enhancement in disc lesion, pattern of diffusion, and maximum contrast index were examined and compared between PS and TB. Results Degree of enhancement, percentage of epidural abscess, and percentage of necrosis in vertebra were 2.1 ± 0.5 and 1.8 ± 0.8, 60.7% and 100%, 50.0% and 66.7% for PS and TB, respectively, without statistical difference. Maximum contrast index, percentage of the diffusion pattern from the disc, and percentage of enhanced disc were 108.1 ± 22.3 and 78.2 ± 35.6 s, 89.3% and 0%, and 53.6% and 0% for PS and TB, respectively, with statistical significance. Conclusions This study indicated that longer maximum contrast index, higher likelihood of diffusion pattern from the disc, and higher likelihood of enhanced disc are more specific to PS than TB. This less invasive imaging technique is useful for more accurate diagnosis of PS and TB. Graphic abstract These slides can be retrieved under Electronic Supplementary Material.

Diagnostic accuracy of whole spine magnetic resonance imaging in spinal tuberculosis validated through tissue studies Abstract Introduction Conventional diagnosis of spinal tuberculosis (TB) is based on a combination of clinical features, laboratory tests and imaging studies, since none of these individual diagnostic features are confirmatory. Despite the high sensitivity of MRI findings in evaluating spinal infections, its efficacy in diagnosing spinal TB is less emphasized and remains unvalidated through tissue studies. Methodology We reviewed consecutive patients evaluated for spondylodiscitis with documented clinical findings, MRI spine, and tissue analysis for histopathology, TB culture and genetic TB PCR. MRI features documented include location, contiguous/non-contiguous skip lesions, para/intraosseous abscess, subligamentous spread, vertebral collapse, abscess size/wall, disc involvement, end plate erosion and epidural abscess. Based on the results, patients were divided into two groups—CONFIRMED TB with positive culture/histopathology and NON-TB. The efficacy of MRI findings in accurately diagnosing spinal TB was compared between the two groups. Results Among 150 patients, 79 patients were TB positive, and 71 were TB negative. Three MRI parameters showed significant differences (p < 0.001), namely subligamentous spread (67/79, 84.8%), vertebral collapse > 50% (55/79, 69.6%) and large abscess collection with thin abscess wall (72/79, 91.1%) being strongly predictive of TB. Combination of MRI findings had a higher predictive value. 97.5% of TB positive patients had at least one of these three MRI features, 89.8% patients had any two and 58.2% had all three. Conclusion Our study validated different MRI findings with tissue studies and showed spinal infections with large abscess with thin wall, subligamentous spread of abscess and vertebral collapse were highly suggestive of spinal tuberculosis. Graphical abstract These slides can be retrieved under Electronic Supplementary Material.