Etablierung und Validierung von diagnostischen Standards bei implantatassoziierten Infektionen der Wirbelsäulenchirurgie

Einleitung. In den letzten Jahren wurde ein stetiger Anstieg bei der Durchführung instrumentierter Wirbelsäuleneingriffe beobachtet. Daraus resultiert allerdings auch eine Häufung der Notwendigkeit für eine Revisionsoperation. Eine Ursache dafür kann neben aseptischem Implantatversagen eine Infektion sein. Besonders sogenannte Low-grade-Infektionen, die häufig implantatassoziiert sind, lassen sich oftmals nur schwer diagnostizieren und stellen eine Herausforderung im klinischen Alltag dar. Ziel dieser Arbeit ist es deshalb, den Anteil von implantatassoziierten Infektionen bei Revisionsoperationen zu bestimmen, mögliche Risikofaktoren zu identifizieren, verschiedene diagnostische Hilfsmittel zu vergleichen und einen Überblick über die identifizierten Erreger zu geben. Methodik. Bei dieser Arbeit handelt es sich um eine prospektive Beobachtungsstudie. Implantatassoziierte Infektionen wurden anhand der Richtlinien der Centers for Disease Control and Prevention (CDC) diagnostiziert und eingeteilt. Es wurden unterschiedliche Anzeichen eines Infektes auf ihre Aussagekraft untersucht und bewertet und die Sensitivität und Spezifität von Sonikation und Gewebeprobe ermittelt und miteinander verglichen. Ergebnisse. Insgesamt wurden 118 Patienten in die Studie eingeschlossen. Bei 39 Patienten wurde eine Infektion diagnostiziert, davon 35 implantatassoziiert und vier mit reinen Wundinfektionen. Als Risikofaktor wurde die Anzahl vorherig operierter Segmente identifiziert. Zudem zeigte sich, dass Infektionen signifikant häufiger zu einer Revisionsoperation innerhalb des ersten Jahres nach dem letzten Eingriff führten als aseptische Ursachen. Klinische, labormedizinische, intraoperative und radiologische Infektionszeichen stellten sich als nicht ausreichend sensitiv für die Identifizierung einer implantatassoziierten Infektion heraus. Die mikrobiologische Untersuchung von intraoperativ gewonnenem Material zeigte hingegen eine gute Sensitivität und Spezifität. Für die Sonikation wurde eine Sensitivität von 94,3 % und für die Gewebeprobe eine Sensitivität von 68,6 % für implantatassoziierte Infektionen ermittelt. Die Spezifität betrug 98,7 % für die Sonikation und 96,2 % für die Gewebeprobe. Die am häufigsten nachgewiesenen Erreger waren Koagulase-negative Staphylokokken (KNS), insbesondere Staphylococcus epidermidis und Propionibacterium acnes. Schlussfolgerung. Implantatassoziierte Infektionen sind eine häufige Ursache für Revisionsoperationen an der Wirbelsäule. Sie zu erkennen, ist präoperativ schwierig und oftmals nicht eindeutig möglich. Daher ist die Untersuchung von intraoperativ gewonnenem Material notwendig, um eine zuverlässige Diagnose zu gewährleisten und „stumme“ Infektionen zu erkennen. Dabei zeigt die Sonikation bessere Ergebnisse als die periimplantäre Gewebeprobe. Allerdings sollten stets mehrere Parameter in die Beurteilung einfließen, um eine Infektion sicher diagnostizieren zu können. Da die häufigsten Erreger einer implantatassoziierten Infektion Bakterien der physiologischen Hautflora sind, kommt der Prävention durch eine sterile intra- und postoperative Behandlung große Bedeutung zu.Introduction. The number of instrumented spine surgery has been increasing over the last decades. Consequently, revision spine surgery is also more often than it used to be. In addition to aseptic failure, another reason for such revision spine surgeries may be infection. Especially low-grade spinal implant infections are frequently difficult to diagnose and may challenge the practitioner. Therefore, the aim of this study was to detect the number of spinal infections in revision spine surgery, identify risk factors for it, compare different diagnostic tools for infections and show the most frequent microorganisms in spinal implant infections. Methods. This study is a prospective follow-up study. Spinal implant infections were diagnosed and categorized by the criteria of the Centers for Disease Control and prevention (CDC). Different signs of an infection were analyzed and sensitivity and specificity for sonicate fluid culture and peri-implant tissue culture were calculated and compared. Results. In total 118 patients were included in this study. In 39 patients infection was diagnosed, 35 of them showed spinal implant infection and 4 of them showed superficial or deep wound infection without involvement of implants. As risk factor for spinal implant infections, the number of previous surgeries included segments was identified. Furthermore, infection was more often within one year after previous spine surgery than aseptic failure. Clinical, laboratory, intraoperative and radiological signs of infection didn´t show acceptable sensitivity for the diagnosis of infection. Microbiological and histopathological analyzing of intraoperatively explanted materials showed good results for sensitivity in diagnosis of a spinal implant infection. Sonicate fluid had sensitivity of 94,3 % and peri-implant tissue culture had sensitivity of 68,6 %. Specificity for spinal implant infection were 98,7 % for sonicate fluid and 96,2 % for peri-implant tissue culture. Most frequent microorganisms identified at revision spine surgery were Coagulase-negative staphylococci and Propionibacterium acnes. Conclusion. Spinal implant infection is frequently found in revision spine surgery. Preoperative tools often miss diagnosis of such an infection. Therefore, analyzing of explanted material while revision spine surgery is often needed to detect postoperative spinal infections. In comparison, sonicate fluid shows better results than peri-implant tissue culture. However, it seems useful to use all available parameters for a solid diagnosis of postoperative spinal infection. The most frequent microorganisms of spinal implant infection are part of physiological skin microbiome. Therefore, there should be a special focus on preventing spinal implant infection by a sterile treatment before and after surgery

Kyphoplasty Restores the Global Sagittal Balance of the Spine Independently from Pain Reduction

Kyphoplasty is the standard surgical treatment of vertebral compression fractures. We aimed to clarify the influence of kyphoplasty on the sagittal profile as well as the relation between posture improvement and pain relief. For this purpose, we evaluated various radiological parameters of the sagittal profile on whole spine standing radiographs of 73 Patients with a single vertebral fracture treated by kyphoplasty. The key outcome was the postoperative change of the sagittal vertical axis (SVA). Additionally, clinical parameters including pain scores on visual analogue scale (VAS) and use of analgesics were obtained from medical records. Pre- and postoperative radiological as well as clinical parameters were compared. Additionally, the correlation between changes of SVA and changes of local kyphotic angle (LKA) or VAS was examined. The clinical parameters as well as various radiographic parameters (SVA, LKA, Gardner, Cobb) improved significantly postoperatively. The improvement of SVA correlated significantly with the correction of the LKA but not with postoperative pain relief. We conclude that kyphoplasty helps to restore the global sagittal balance of the spine after vertebral fractures. The correction of the sagittal profile seems to depend on the correction of the local kyphotic angle but does not correlate with postoperative pain relief

Influence of operative timing on the early post-operative radiological and clinical outcome after kyphoplasty

Purpose: To clarify the relationship between operative timing and the early post-operative radiological and clinical outcome after kyphoplasty. Methods: We conducted a retrospective cohort study including patients who underwent kyphoplasty of a single vertebra. Patients were divided into three groups (acute [< 2 weeks], subacute [2–6 weeks] or chronic [6–51 weeks]) based on the interval between fracture and surgery. The relative vertebral body height (VBH) and local kyphotic angle (LKA) of the fractured vertebra (measured on plain radiographs) as well as pain and use of analgesics were compared pre- and post-operatively (day 2) and between the groups. Results: A total of 230 patients (100 with acute, 91 with subacute and 39 with chronic fractures) with fractures from T4 to L5 were included. In all groups, there was a significant post-operative improvement in the anterior (8.9–12.9%) and middle (10.7–13.4%) VBH (all groups: p < 0.001), LKA (acute: 3.8°, p < 0.001; subacute: 4.3°, p < 0.001; chronic: 1.7°, p = 0.046) and pain. The use of analgesics significantly decreased post-operatively in the acute and subacute groups, but did not significantly change in the chronic group. Patients from acute (p = 0.042) and subacute (p = 0.027) groups showed significantly better post-operative correction of the LKA than the chronic group. Conclusion: Kyphoplasty is effective for vertebral height restoration as well as pain relief for both acute, subacute and chronic fractures. However, the achievable correction of the fracture-related local kyphosis decreases significantly after 6 weeks. Therefore, we recommend making a final decision about conservative vs. operative treatment within 6 weeks to ensure better height restoration in surgically treated patients

Intraoperative blood loss as indicated by haemoglobin trend is a predictor for the development of postoperative spinal implant infection—a matched-pair analysis

Abstract Background With a reported rate of 0.7–20%, postoperative spinal implant infection (PSII) is one of the most common complications after spine surgery. While in arthroplasty both haematoma formation and perioperative blood loss have been identified as risk factors for developing periprosthetic joint infections and preoperative anaemia has been associated with increased complication rates, literature on the aetiology of PSII remains limited. Methods We performed a matched-pair analysis of perioperative haemoglobin (Hb) and haematocrit (Hct) levels in aseptic and septic spine revision surgeries. 317 patients were included, 94 of which were classified as septic according to previously defined criteria. Patients were matched according to age, body mass index, diabetes, American Society of Anesthesiologists score and smoking habits. Descriptive summaries for septic and aseptic groups were analysed using Pearson chi-squared for categorical or Student t test for continuous variables. Results Fifty patients were matched and did not differ significantly in their reason for revision, mean length of hospital stay, blood transfusion, operating time, or number of levels operated on. While there was no significant difference in preoperative Hb or Hct levels, the mean difference between pre- and postoperative Hb was higher in the septic group (3.45 ± 1.25 vs. 2.82 ± 1.48 g/dL, p = 0.034). Conclusions We therefore show that the intraoperative Hb-trend is a predictor for the development of PSII independent of the amount of blood transfusions, operation time, number of spinal levels operated on and hospital length of stay, which is why strategies to reduce intraoperative blood loss in spine surgery need to be further studied

Structure of the actively translating plant 80S ribosome at 2.2 Å resolution

In plant cells, translation occurs in three compartments: the cytosol, the plastids and the mitochondria. While the structures of the (prokaryotic-type) ribosomes in plastids and mitochondria are well characterized, high-resolution structures of the eukaryotic 80S ribosomes in the cytosol have been lacking. Here the structure of translating tobacco (Nicotiana tabacum) 80S ribosomes was solved by cryo-electron microscopy with a global resolution of 2.2 Å. The ribosome structure includes two tRNAs, decoded mRNA and the nascent peptide chain, thus providing insights into the molecular underpinnings of the cytosolic translation process in plants. The map displays conserved and plant-specific rRNA modifications and the positions of numerous ionic cofactors, and it uncovers the role of monovalent ions in the decoding centre. The model of the plant 80S ribosome enables broad phylogenetic comparisons that reveal commonalities and differences in the ribosomes of plants and those of other eukaryotes, thus putting our knowledge about eukaryotic translation on a firmer footing

tRNA Translocation by the Eukaryotic 80S Ribosome and the Impact of GTP Hydrolysis

Summary: Translocation moves the tRNA2⋅mRNA module directionally through the ribosome during the elongation phase of protein synthesis. Although translocation is known to entail large conformational changes within both the ribosome and tRNA substrates, the orchestrated events that ensure the speed and fidelity of this critical aspect of the protein synthesis mechanism have not been fully elucidated. Here, we present three high-resolution structures of intermediates of translocation on the mammalian ribosome where, in contrast to bacteria, ribosomal complexes containing the translocase eEF2 and the complete tRNA2⋅mRNA module are trapped by the non-hydrolyzable GTP analog GMPPNP. Consistent with the observed structures, single-molecule imaging revealed that GTP hydrolysis principally facilitates rate-limiting, final steps of translocation, which are required for factor dissociation and which are differentially regulated in bacterial and mammalian systems by the rates of deacyl-tRNA dissociation from the E site. : Translocation, the process by which tRNA and mRNA are moved relative to the ribosome during protein synthesis, is facilitated in eukaryotic cells by the conserved GTPase elongation factor 2. Here Flis et al. combine cryo-EM and single-molecule FRET to elucidate features and intermediate states of translocation on mammalian ribosomes. Keywords: mammalian ribosome, translation elongation, translocation, elongation factor eEF2, macromolecular machine, large-scale conformational changes, smFRET, cryo-EM, EF-

It takes two transducins to activate the cGMP-phosphodiesterase 6 in retinal rods

Among cyclic nucleotide phosphodiesterases (PDEs), PDE6 is unique in serving as an effector enzyme in G protein-coupled signal transduction. In retinal rods and cones, PDE6 is membrane-bound and activated to hydrolyse its substrate, cGMP, by binding of two active G protein α-subunits (Gα*). To investigate the activation mechanism of mammalian rod PDE6, we have collected functional and structural data, and analysed them by reaction–diffusion simulations. Gα* titration of membrane-bound PDE6 reveals a strong functional asymmetry of the enzyme with respect to the affinity of Gα* for its two binding sites on membrane-bound PDE6 and the enzymatic activity of the intermediary 1 : 1 Gα* · PDE6 complex. Employing cGMP and its 8-bromo analogue as substrates, we find that Gα* · PDE6 forms with high affinity but has virtually no cGMP hydrolytic activity. To fully activate PDE6, it takes a second copy of Gα* which binds with lower affinity, forming Gα* · PDE6 · Gα*. Reaction–diffusion simulations show that the functional asymmetry of membrane-bound PDE6 constitutes a coincidence switch and explains the lack of G protein-related noise in visual signal transduction. The high local concentration of Gα* generated by a light-activated rhodopsin molecule efficiently activates PDE6, whereas the low density of spontaneously activated Gα* fails to activate the effector enzyme.ISSN:2046-244

S1 Movie from It takes two transducins to activate the cGMP-phosphodiesterase 6 in retinal rods

Spatio-temporal development of PDE6 activation in the PBRD signal scenario

Supplementary Information from It takes two transducins to activate the cGMP-phosphodiesterase 6 in retinal rods

Numerical fitting procedure of PDE6 activation, Electron microscopy, image processing and rigid body docking, and Particle-based reaction-diffusion simulation