Vancomycin-resistant Enterococcus faecium and the emergence of new sequence types associated with hospital infection.

Enterococcus faecium is a major species in infections by vancomycin-resistant enterococci (VRE). New variants of the pathogen have emerged and become dominant in healthcare settings. Two such examples, vanB ST796 and vanA ST1421 sequence types, originally arose in Australia and proceeded to cause VRE outbreaks in other countries. Of concern is the detection in Europe of vancomycin variable enterococci (VVE) belonging to ST1421 that exhibit a vancomycin-susceptible phenotype but can revert to resistant in the presence of vancomycin. The recent application of genome sequencing for increasing our understanding of the evolution and spread of VRE is also explored here.

Assessment of Liver Fibrosis by Transient Elastography in Children and Young Adults With Sickle Cell Disease With and Without Iron Overload.

Transfusion-associated iron overload may cause liver fibrosis. We compared transient elastography (TE) and aspartate aminotransferase-platelet ratio index (APRI), noninvasive markers for hepatic fibrosis, to liver histology in children and young adults with sickle cell disease (SCD) who were iron overloaded (cohort 1). Age-matched subjects with SCD but without iron overload (cohort 2) were enrolled for APRI and TE assessments. Nineteen subjects ages 10 to 21 years were transfused for a mean of 9.67 years, had a mean serum ferritin of 4899±2849 ng/mL, and a liver iron concentration of 15.56±10.12 mg/g dry liver weight by R2-magnetic resonance imaging. Mean APRI was 0.33±0.13 in cohort 1 and 0.27±0.10 in cohort 2. The mean liver stiffness measures (LSM) in cohort 1, assessed by TE, was 8.46±3.95 kPa, ranging from 3.5 to 14.6 kPa (expected normal <7 kPa). Cohort 2 had a mean LSM of 5.72±1.74 kPa (4.6 to 8.7 kPa). There was a good correlation between LSM and histologic fibrosis (t value 6.94, P<0.0001). There was no significant correlation between APRI and histologic fibrosis and between APRI and LSM. A high LSM suggests liver fibrosis in children and adults with SCD with iron overload and may merit histologic confirmation especially if persistent.

Avoidance of Wrong-level Thoracic Spine Surgery Using Sterile Spinal Needles: A Technical Report.

STUDY DESIGN: A technical report. OBJECTIVE: The aim of the present study was to present an improvement on localization techniques employed for use in the thoracic spine using sterile spinal needles docked on the transverse process of each vertebra, which can be performed in both percutaneous and open spinal procedures. SUMMARY OF BACKGROUND DATA: Wrong-level surgery may have momentous clinical and emotional implications for a patient and surgeon. It is reported that one in every 2 spine surgeons will operate on the wrong level during his or her career. Correctly localizing the specific thoracic level remains a significant challenge during spine surgery. METHODS: Fluoroscopic anteroposterior and lateral views were obtained starting in the lower lumbar spine, and an 18-G spinal needle was placed in the transverse process of L3 counting up from the sacrum and also at T12. The fluoroscopy was then moved cephalad and counting from the spinal needle at T12, the other spinal needles were placed at the targeted operating thoracic vertebrae. Once this was done, we were able to accurately determine the thoracic levels for surgical intervention. RESULTS: Using this technique, the markers were kept in place even after the incisions were made. This prevented us from losing our location in the thoracic spine. Correctly placed instrumentation was made evident with postoperative imaging. CONCLUSIONS: We have described the successful use of a new technique using spinal needles docked against transverse processes to correctly and reliably identify thoracic levels before instrumentation. The technique was reproducible in both open surgeries and for a percutaneous procedure. This technique maintains the correct spinal level during an open procedure. We posit that wrong-level thoracic spine surgery may be preventable.

Mini-open or percutaneous bilateral lumbar transfacet pedicle screw fixation: a technical note.

STUDY DESIGN: Case report. OBJECTIVE: To describe the technique used to place bilateral lumbar transfacet pedicle screws. SUMMARY OF BACKGROUND DATA: Transfacet pedicle screw fixation is a growing alternative and biomechanically comparable with traditional pedicle screw fixation. There is no clear description of technique steps for placing transfacet pedicle screws available in the literature, despite recognizing that screw placement is not intuitive even with fluoroscopy, and is dissimilar to placing traditional pedicle screws or translaminar facet screws. METHODS: We present 2 illustrative cases where bilateral transfacet pedicle screws were placed for posterior instrumentation after a step-by-step technique that can be used in a mini-open or percutaenous procedure. RESULTS: Postoperatively, both patients had adequately placed transfacet pedicle screws bilaterally on x-ray imaging with 1 patient demonstrating fusion and intact fixation at 11 months follow-up. CONCLUSIONS: Transfacet pedicle screws were successfully placed in 2 patients in a stepwise technique described to achieve lumbar fusion.

Plasma concentration of platelet-derived microparticles is related to painful vaso-occlusive phenotype severity in sickle cell anemia.

High plasma level of microparticles (MPs) deriving mainly from erythrocytes and platelets has been detected in sickle cell anemia (SCA) patients. Flow cytometry was used to determine the concentration of MPs in two groups of SCA patients exhibiting marked differences in painful vaso-occlusive crisis rates [a non-severe group (n = 17) and a severe group (n = 12)], and in a control group composed of healthy subjects (n = 20). A 3- to 4-fold increase of total MP plasma concentration was detected in SCA patients. Higher platelet-derived MPs concentration was detected in the severe SCA group while erythrocyte-derived MPs concentration was increased in the non-severe SCA patient group only. Our results suggest that plasma concentration of MPs shed by platelets is a biomarker of the vaso-occlusive phenotype-related severity.

Ideal starting point and trajectory for C2 pedicle screw placement: a 3D computed tomography analysis using perioperative measurements.

BACKGROUND CONTEXT: C2 pedicle screws provide stable fixation for posterior cervical fusion. Placing C2 pedicle screws is fraught with risks, and a misplaced screw can result in cortical breach of the pedicle, resulting in injury to the vertebral artery or spinal cord. PURPOSE: We sought to identify a reproducible starting point and trajectory for C2 pedicle screw placement using three-dimensional (3D) computed tomography (CT) imaging. Our aims included identifying correct cephalad and mediolateral angles used for determining the most accurate trajectory through the C2 pedicle. STUDY DESIGN: A radiographic analysis of the anatomy of the C2 pedicle using CT. PATIENT SAMPLE: A random sample of 34 cervical spine CT scans in patients without medical or surgical pathology of the cervical spine. OUTCOME MEASURES: Normal anatomic measurements made in the axial and sagittal planes of the CT scans. Angles and measures in millimeters were recorded. METHODS: The C2 pedicles were evaluated using CT scanning with a 3D imaging application. The ideal trajectory through each pedicle was plotted. The mediolateral and cephalad angles were measured using the midline sagittal plane and the inferior vertebral body border as references. Other measurements made were the distances through the pedicle and vertebral bodies, and the surface distances along the laminae between the isthmus and the starting point of the chosen trajectories. Other measurements involving the height of the laminae were also made. The mean values, standard deviations, and intraobserver variations are presented. RESULTS: CT scans from 34 patients were reviewed. The sex of the patient did not predict angle measurements (p=.2038), so combined male and female patient measures are presented. The mean mediolateral angle measured was 29.2°, and the mean cephalad angle was 23.0°. The mean distance along the lamina surface between the isthmus and the starting point was 8.1 mm. The mean distance from the superior border of the lamina to the starting point was 5.7 mm. There were no statistically significant differences between the dataset collected in duplicate by the same observer (p=.74); as such, we present one data analysis on combined data from the two datasets collected. CONCLUSION: It is possible to determine an ideal trajectory through the C2 pedicle. These measurements may facilitate C2 pedicle screw fixation decreasing the risk of injury to the vertebral artery, spinal cord, or nerve roots. Delineating the individual anatomy in each case with imaging before surgery is recommended.

Effects of misalignment on static torsional strength of anterior cervical plate systems.

BACKGROUND CONTEXT: There is little understanding of cervical plate misalignment as a risk factor for plate failure at the plate-screw-bone interface. PURPOSE: To assess the torsional strength and mode of failure of cervical plates misaligned relative to the midsagittal vertical axis. STUDY DESIGN: Plastic and foam model spine segments were tested using static compression and torsion to assess effects of misaligned and various lengths anterior cervical plate (ACPs). METHODS: Different length ACPs and cancellous fixed angle screws underwent axial torsional testing on a servo-hydraulic test frame at a rate of 0.5°/s. A construct consisted of one ACP, four screws, one ultrahigh-molecular weight polyethylene inferior block, and one polyurethane foam superior block. Group 1 had ACPs aligned in the midsagittal vertical axis, group 2 plates were positioned 20° offset from the midline, and group 3 had the ACP shifted 5 mm away and 20° offset from midline. Torques versus angle data were recorded. The failure criterion was the first sign of pullout determined visually and graphically. RESULTS: Group 1 had a more direct screw pullout during failure. For the misaligned plates, failure was a combination of the screws elongating the holes and shear forces acting between the plate and block. The misaligned plates needed more torque to failure. The failure torque was 50% reduced for the longer versus the shorter plates in the neutral position. Graphically shown initial screw slippage inside the block preceded visual identification of slippage in some cases. CONCLUSIONS: We observed different failure mechanisms for neutral versus misaligned plates. Clinically, misalignment may have the benefit of needing more torque to fail. Misalignment was a risk factor for failure of the screw-bone interface, especially in longer plate constructs. These comparisons of angulations may be a solid platform for expansion toward a more applicable in vivo model.

Postoperative cervical haematoma complicated by ipsilateral carotid thrombosis and aphasia after anterior cervical fusion: a case report.

Hematoma alone is the most common vascular complication reported after anterior cervical decompression and fusion (ACDF). We present this case to report the occurrence of postoperative cervical hematoma complicated by ipsilateral carotid thrombosis and aphasia after an uncomplicated C4-6 ACDF. This is a case of a 65-year-old woman who underwent revision fusions of the C4-5 and C6-7 levels complicated by postoperative cervical hematoma and carotid thrombosis. The patient's history, clinical examination, imaging findings, and treatment are reported. The revision fusions were performed and deemed routine. Approximately eight hours later 200 mL of blood was evacuated from a postoperative cervical hematoma. The patient became unresponsive and disoriented a few hours after evacuating the hematoma. Computed tomography and magnetic resonance imaging of the brain were normal, but magnetic resonance angiography demonstrated total occlusion of the left carotid artery. Thrombectomy was performed and the patient was discharged without residual deficits. At the latest followup she is fully functional and asymptomatic in her neck. We suggest, after evacuating a cervical hematoma, an evaluation of the carotids be made with MRA or cerebral angiography, as this may demonstrate a clot before the patient develops symptoms.

"White cord syndrome" of acute tetraplegia after anterior cervical decompression and fusion for chronic spinal cord compression: a case report.

Paralysis is the most feared postoperative complication of ACDF and occurs most often due to an epidural hematoma. In the absence of a clear etiology, inadequate decompression or vascular insult such as ischemia/reperfusion injury are the usual suspects. Herewith we report a case of complete loss of somatosensory evoked potentials (SSEPs) during elective ACDF at C4-5 and C5-6 followed by postoperative C6 incomplete tetraplegia without any discernible technical cause. A postoperative MRI demonstrated a large area of high signal changes on T2-weighted MRI intrinsic to the cord "white cord syndrome" but no residual compression. This was considered consistent with spinal cord gliosis with possible acute edema. The acute decompression of the herniated disc resulted in cord expansion and rush-in reperfusion. We postulate that this may have led to disruption in the blood brain barrier (BBB) and triggered a cascade of reperfusion injuries resulting in acute neurologic dysfunction. At 16 months postoperatively our patient is recovering slowly and is now a Nurick Grade 4.

Relationship between acute chest syndrome and the sympatho-vagal balance in adults with hemoglobin SS disease; a case control study.

The present study evaluated the relationship between acute chest syndrome (ACS) and autonomic nervous system (ANS) activity in patients with hemoglobin SS disease (Hb SS). Nine patients had suffered ACS were matched by age and gender to patients who had not suffered ACS and ANS activity, pulmonary function and history of painful crisis were compared. Correlations between number of episodes of ACS suffered and these variables were determined. The results demonstrated that 1) patients with a history of ACS ever had lower parasympathetic nervous system (PNS) activity and lower global ANS activity than patients with no ACS ever (p < 0.05), 2) the number of ACS episodes ever negatively correlated (p < 0.05) with PNS activity and global ANS activity and 3) There were no significant associations between lung function or a history of painful crisis in these patients. In conclusion, a history of ACS was associated with ANS dysfunction in adults with Hb SS disease.

Postoperative magnetic resonance imaging assessment for potential compressive effects of retained posterior longitudinal ligament after anterior cervical fusions: a cross-sectional study.

STUDY DESIGN: A cross-sectional study. OBJECTIVE: To assess using postoperative magnetic resonance imaging whether the posterior longitudinal ligament (PLL) caused residual cord compression after anterior cervical decompression and fusion (ACDF) in a series of patients in whom the PLL was retained. SUMMARY OF BACKGROUND DATA: There is a lack of data evaluating the postoperative compressive effects of the PLL in patients undergoing ACDF providing guidance as to whether to remove or retain the PLL during discectomy to facilitate adequate decompression. METHODS: Postoperative gadolinium enhanced magnetic resonance images were reviewed in a series of 33 patients who underwent ACDF for cervical radiculomyelopathy and who had persistent or recurrent postoperative symptoms. Patients with ossification of the posterior longitudinal ligament or with a herniated disc behind the PLL were excluded from this study. RESULTS: There were no cases of discernible compression by the retained PLL identified on the magnetic resonance image (P < 0.001) as assessed by 2 independent reviewers. Four patients underwent subsequent revision surgery unrelated to the PLL. CONCLUSION: We were unable to demonstrate magnetic resonance imaging evidence to suggest that the retained PLL caused compression after ACDF in this patient cohort. Therefore we suggest that removing the PLL should be considered for reasons other than concern about residual compression.

Frequency of pain crises in sickle cell anemia and its relationship with the sympatho-vagal balance, blood viscosity and inflammation.

BACKGROUND: Recent evidence suggests that autonomic nervous system activity could be involved in the pathophysiology of sickle cell disease, but it is unclear whether differences in autonomic nervous system activity are detectable during steady state in patients with mild and severe disease. The aim of the present study was to compare the autonomic nervous system activity, blood rheology, and inflammation in patients with sickle cell anemia according to the frequency of acute pain crisis. DESIGN AND METHODS: Twenty-four healthy volunteers, 20 patients with sickle cell anemia with milder disease, and 15 patients with sickle cell anemia with more severe disease were recruited. Milder disease was defined as having no pain crisis within the previous year. More severe disease was defined as having had within the previous year three or more pain crises which were documented by a physician and required treatment with narcotics. The autonomic nervous system activity was determined by spectral analysis of nocturnal heart rate variability. Blood viscosity determination and measurements of several inflammatory markers (interleukin-6, soluble vascular cell adhesion molecule-1, soluble CD40 ligand and sL-selectin) were made on blood samples collected in steady-state conditions. RESULTS: Results showed that: 1) patients who had suffered more frequent pain crises had lower parasympathetic activity and greater sympatho-vagal imbalance than both controls and patients with milder disease. However, when adjusted for age, no significant difference was detected between the two sickle cell anemia patient groups; 2) patients who had suffered more frequent pain crises had higher blood viscosity than patients with milder disease, and this was not dependent on age. CONCLUSIONS: Results from the present study indicate that both the autonomic nervous system activity and blood viscosity are impaired in patients with sickle cell anemia exhibiting high frequency of pain crisis in comparison with those who did not experience a crisis within the previous year.

Asymptomatic bacteriuria in sickle cell disease: a cross-sectional study.

BACKGROUND: It is known that there is significant morbidity associated with urinary tract infection and with renal dysfunction in sickle cell disease (SCD). However, it is not known if there are potential adverse outcomes associated with asymptomatic bacteriuria (ASB) infections in sickle cell disease if left untreated. This study was undertaken to determine the prevalence of ASB, in a cohort of patients with SCD. METHODS: This is a cross-sectional study of patients in the Jamaican Sickle Cell Cohort. Aseptically collected mid-stream urine (MSU) samples were obtained from 266 patients for urinalysis, culture and sensitivity analysis. Proteinuria was measured by urine dipsticks. Individuals with abnormal urine culture results had repeat urine culture. Serum creatinine was measured and steady state haematology and uric acid concentrations were obtained from clinical records. This was completed at a primary care health clinic dedicated to sickle cell diseases in Kingston, Jamaica. There were 133 males and 133 females in the sample studied. The mean age (mean +/- sd) of participants was 26.6 +/- 2.5 years. The main outcome measures were the culture of > or = 10(5) colony forming units of a urinary tract pathogen per milliliter of urine from a MSU specimen on a single occasion (probable ASB) or on consecutive occasions (confirmed ASB). RESULTS: Of the 266 urines collected, 234 were sterile and 29 had significant bacteriuria yielding a prevalence of probable ASB of 10.9% (29/266). Fourteen patients had confirmed ASB (prevalence 5.3%) of which 13 had pyuria. Controlling for genotype, females were 14.7 times more likely to have confirmed ASB compared to males (95% CI 1.8 to 121.0). The number of recorded visits for symptomatic UTI was increased by a factor of 2.5 (95% CI 1.4 to 4.5, p < 0.005) but serum creatinine, uric acid and haematology values were not different in patients with confirmed ASB compared with those with sterile urine. There was no association with history of gram negative sepsis. CONCLUSION: ASB is a significant problem in individuals with SCD and may be the source of pathogens in UTI. However, further research is needed to determine the clinical significance of ASB in SCD.