Detection of extended-spectrum ß-lactamases producing Enterobacteriaceae using a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry based MBT STAR-BL software module with ß-lactamase inhibition assay depends on the bacterial strains.

Rapid and sensitive detection of extended-spectrum ß-lactamases (ESBLs) is essential for infection control and antimicrobial treatment. Recently, a matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS)-based MBT STAR-BL software module has been used for detecting ß-lactamase activity; however, this system cannot differentiate ESBL producing bacteria from other third-generation cephalosporin-resistant strains. In this study, we utilized a MALDI-TOF MS-based MBT STAR-BL method to identify ESBL activity with ß-lactamase inhibitors. A cefotaxime (CTX) hydrolysis assay, ß-lactamase inhibition, clavulanic acid (CVA), and sulbactam (SBT) were used for detecting ESBL producers with the MBT STAR-BL software module. This software module automatically calculated the logRQ values in each assay. logRQ is the logarithm of the ratio of the summed hydrolyzed peak intensities to the summed non-hydrolyzed peak intensities and measured the efficiency of antibiotic hydrolysis. We divided the logRQ level of the ß-lactamase inhibition assay by the logRQ value in the CTX hydrolysis assay, and we used this logRQ ratio as a measure of ß-lactamase inhibition efficiency. We assessed the logRQ ratio calculated by this novel method for detecting ESBL producers in 132 Enterobacteriaceae. We performed the MALDI-TOF MS-based MBT STAR-BL approach with ß-lactamase inhibitors for detecting ESBL producers and showed that the results of the inhibition assay with ß-lactamase inhibitors depended on types of bacterial species. Furthermore, we improved elapsed times and accuracy in MBT STAR-BL methods by using proper ß-lactamase inhibitors against specific bacterial strains to compare with the conventional standard lab method. The results suggest that the target bacterial species and ß-lactamase inhibitors used were important for the utility of the MALDI-TOF MS-based MBT STAR-BL software module.

A rapid and simple detection method for phenotypic antimicrobial resistance in Escherichia coli by loop-mediated isothermal amplification.

PURPOSE: In infectious disease therapy, administration of adequate antimicrobial agents is essential for preventing the emergence and spread of resistant bacteria. However, conventional antimicrobial susceptibility testing (AST), based on bacterial growth, is time consuming; therefore, a rapid, simple assay is needed for the timely selection of appropriate antibiotics in clinical laboratories. Here, we established a simple, cost-effective, time-saving and highly sensitive AST assay based on loop-mediated isothermal amplification (LAMP). METHODOLOGY: The targeted bacteria were cultivated for a short period with or without antibiotic before the LAMP reaction. The time to detect a positive reaction with LAMP was used to generate a threshold time (Tt) value, and subtraction of the Tt value for an antibiotic-free sample from the Tt value in an antibiotic-exposed sample generated the ΔTt value, which was used as a marker of antimicrobial susceptibility. The ΔTt value generated using the LAMP-based assay simply and quickly detected antimicrobial resistance in clinical Escherichia coli isolates. RESULTS: Detection of susceptibility to levofloxacin using the ΔTt value perfectly matched with the results of the conventional assay. In addition, the sensitivity and specificity for the detection of ampicillin, trimethoprim-sulfamethoxazole and fosfomycin resistance were 100 %, 93.8 %, 100 % and 80.0 %, 93.3 %, 97.6 %, respectively. CONCLUSION: These results showed that this LAMP-based AST has high sensitivity and specificity for detecting resistant strains and a significant time advantage compared with the conventional method.

Preoperative brain temperature imaging on proton magnetic resonance spectroscopy predicts hemispheric ischemia during carotid endarterectomy for unilateral carotid stenosis with inadequate collateral blood flow.

Objective Preoperative magnetic resonance (MR) angiography sometimes shows the absence of collateral flow via the circle of Willis. This study examined whether brain temperature (BT) imaging on multi-voxel proton MR spectroscopy after this finding increases the accuracy of predicting hemispheric ischemia during internal carotid artery (ICA) clamping during endarterectomy for patients with symptomatic unilateral carotid stenosis. Methods In 52 patients with ICA stenosis (≥70%) and absence of collateral blood flow via the circle of Willis on preoperative MR angiography, BT imaging was displayed using proton multi-voxel MR spectroscopy. The difference between BTs in the affected and contralateral hemispheres (BTaffected hemisphere - BTcontralateral hemisphere) in the deep white matter of the centrum semiovale was calculated and defined as hemispheric ΔBT. Development of cerebral hemispheric ischemia during ICA clamping was determined from intraoperative electroencephalography (EEG). Results Multivariate analysis revealed that high preoperative hemispheric ΔBT was significantly associated with development of EEG-defined hemispheric ischemia (95% confidence intervals [CIs], 5.376-15.452; p = 0.006). The positive-predictive value for development of EEG-defined hemispheric ischemia was significantly greater for preoperative hemispheric ΔBT following preoperative MR angiography (95%CI, 42-87%) than for preoperative MR angiography alone (95%CI, 13-37%). Conclusions For patients without collateral flow via the circle of Willis, BT imaging increases the predictive accuracy for development of hemispheric ischemia during ICA clamping during CEA.

Apparent brain temperature imaging with multi-voxel proton magnetic resonance spectroscopy compared with cerebral blood flow and metabolism imaging on positron emission tomography in patients with unilateral chronic major cerebral artery steno-occlusive disease.

PURPOSE: The purpose of the present study was to determine whether apparent brain temperature imaging using multi-voxel proton magnetic resonance (MR) spectroscopy correlates with cerebral blood flow (CBF) and metabolism imaging in the deep white matter of patients with unilateral chronic major cerebral artery steno-occlusive disease. METHODS: Apparent brain temperature and CBF and metabolism imaging were measured using proton MR spectroscopy and 15O-positron emission tomography (PET), respectively, in 35 patients. A set of regions of interest (ROIs) of 5 × 5 voxels was placed on an MR image so that the voxel row at each edge was located in the deep white matter of the centrum semiovale in each cerebral hemisphere. PET images were co-registered with MR images with these ROIs and were re-sliced automatically using image analysis software. RESULTS: In 175 voxel pairs located in the deep white matter, the brain temperature difference (affected hemisphere - contralateral hemisphere: ΔBT) was correlated with cerebral blood volume (CBV) (r = 0.570) and oxygen extraction fraction (OEF) ratios (affected hemisphere/contralateral hemisphere) (r = 0.641). We excluded voxels that contained ischemic lesions or cerebrospinal fluid and calculated the mean values of voxel pairs in each patient. The mean ΔBT was correlated with the mean CBF (r = - 0.376), mean CBV (r = 0.702), and mean OEF ratio (r = 0.774). CONCLUSIONS: Apparent brain temperature imaging using multi-voxel proton MR spectroscopy was correlated with CBF and metabolism imaging in the deep white matter of patients with unilateral major cerebral artery steno-occlusive disease.

Subarachnoid hemorrhage due to ruptured intracranial aneurysm following posterior reversible encephalopathy syndrome.

Although posterior reversible encephalopathy syndrome (PRES) is rarely associated with subarachnoid hemorrhage, to our knowledge, rupture of a concomitant cerebral aneurysm following PRES has not been reported. We describe a patient with atypical PRES involving the brainstem, thalamus, and periventricular white matter without cortical or subcortical edema of the parietooccipital lobe on magnetic resonance imaging, with rupture of a concomitant cerebral aneurysm. Preexisting extremely high blood pressure may trigger atypical PRES, and failure to lower blood pressure may lead to a concomitant aneurysm rupture. In the future treatment of hypertensive urgency with a recurrence of symptoms and mean arterial blood pressure >150 mmHg, it is advisable to immediately hospitalize the patient for aggressive blood pressure management, especially if PRES is suspected based on clinical and radiological features.

Changes in cognitive function after carotid endarterectomy in older patients: comparison with younger patients.

Objective and subjective assessments of changes in cognition after carotid endarterectomy (CEA) were compared between older patients (≥76 years old) and younger patients (<76 years old). Patients underwent subjective cognitive assessment by a neurosurgeon and the patient's next of kin, and neuropsychological testing (five parameters) before and after surgery. Of 37 older patients studied, 4 (11%), 28 (75%), and 5 (14%) patients were defined as having subjectively improved, unchanged, and impaired cognition, respectively, following surgery. Differences in test scores (postoperative test score - preoperative test score: Δ score) in all neuropsychological tests were significantly lower in the older patients than in the 213 younger patients. The Δ score was able to statistically differentiate older patients with subjectively improved, unchanged, and impaired cognition after surgery. Receiver operating characteristic analysis showed that the Δ score cut-off point for detecting subjective improvement (upper cut-off point) and impairment (lower cut-off point) in cognition after surgery in older patients was identical to the mean or the mean +0.5 standard deviation (SD) and the mean -1.5 SD or the mean -1 SD, respectively, of the control value obtained from normal subjects. The upper and lower cut-off points were lower and higher, respectively, than those in younger patients. In conclusion, although neuropsychological test scores reflect the subjective assessment of postoperative change in cognition in older patients, the optimal cut-off points for the test scores to detect subjective improvement and impairment in cognition after CEA are different in older patients compared with younger patients.

Postoperative increase in cerebral white matter fractional anisotropy on diffusion tensor magnetic resonance imaging is associated with cognitive improvement after uncomplicated carotid endarterectomy: tract-based spatial statistics analysis.

BACKGROUND: Carotid endarterectomy (CEA) might improve cognitive function. Fractional anisotropy (FA) values in the cerebral white matter derived from diffusion tensor magnetic resonance imaging (DTI) correlate with cognitive function in patients with various central nervous system diseases. OBJECTIVE: To use tract-based spatial statistics to determine whether postoperative changes of FA values in the cerebral white matter derived from DTI are associated with cognitive improvement after uncomplicated CEA. METHODS: In 80 patients undergoing CEA for ipsilateral internal carotid artery stenosis (≥70%), FA values in the cerebral white matter were derived from DTI before and 1 month after surgery and were analyzed by using tract-based spatial statistics. Neuropsychological testing, consisting of the Wechsler Adult Intelligence Scale Revised, the Wechsler Memory Scale and the Rey-Osterreith Complex Figure test, was also performed preoperatively and after the first postoperative month. RESULTS: Based on the neuropsychological assessments, 11 (14%) patients were defined as having postoperatively improved cognition. The difference between the 2 mean FA values (postoperative values minus preoperative values) in the cerebral hemisphere ipsilateral to surgery was significantly associated with postoperative cognitive improvement (95% confidence intervals, 2.632-9.877; P = .008). White matter FA values in patients with postoperative cognitive improvement were significantly increased after surgery in the whole ipsilateral cerebral hemisphere, in the contralateral anterior cerebral artery territory, and in the watershed zone between the contralateral anterior and middle cerebral arteries. CONCLUSION: Postoperative increase in cerebral white matter FA on DTI is associated with cognitive improvement after uncomplicated CEA.

Postoperative cerebral white matter damage associated with cerebral hyperperfusion and cognitive impairment after carotid endarterectomy: a diffusion tensor magnetic resonance imaging study.

BACKGROUND: Cerebral hyperperfusion after carotid endarterectomy (CEA), even when asymptomatic, often impairs cognitive function. However, conventional magnetic resonance (MR) imaging rarely demonstrates structural brain damage associated with postoperative cognitive impairment. MR diffusion tensor imaging (DTI) is potentially more sensitive for detection of white matter damage. Among the common parameters derived by DTI, fractional anisotropy (FA) is a marker of tract integrity, and mechanical disruption of axonal cylinders and loss of continuity of myelin sheaths may be responsible for reduced FA in white matter. The purpose of the present study was to determine whether postoperative cerebral white matter damage that can be detected by FA derived by DTI is associated with cerebral hyperperfusion after CEA and correlates with postoperative cognitive impairment. METHODS: In 70 patients undergoing CEA for ipsilateral internal carotid artery stenosis (≥70%), cerebral blood flow (CBF) was measured using single-photon emission computed tomography (SPECT) before and immediately after CEA and on postoperative day 3. FA values in cerebral white matter were assessed using DTI before and 1 month after surgery. These values were normalized and analyzed using statistical parametric mapping 5. In each corresponding voxel in the pre- and postoperative normalized FA maps of each patient, a postoperative FA value minus a preoperative FA value was calculated, and a voxel with postoperatively reduced FA was defined based on data obtained from healthy volunteers. The number of voxels with postoperatively reduced FA was calculated and defined as the volume with postoperatively reduced FA. Neuropsychological testing, consisting of the Wechsler Adult Intelligence Scale Revised, the Wechsler Memory Scale and the Rey-Osterreith Complex Figure test, was also performed preoperatively and after the first postoperative month. Postoperative cognitive impairment on neuropsychological testing in each patient was defined based on data obtained from patients with asymptomatic unruptured cerebral aneurysms. RESULTS: Post-CEA hyperperfusion on brain perfusion SPECT (CBF increase ≥100% compared with preoperative values) and postoperative cognitive impairment on neuropsychological testing were observed in 11 (16%) and 9 patients (13%), respectively. The volume with postoperatively reduced FA in cerebral white matter ipsilateral to surgery was significantly greater in patients with post-CEA hyperperfusion than in those without (p < 0.0001). This volume in cerebral white matter ipsilateral to surgery was also significantly associated with postoperative cognitive impairment (95% confidence interval, 1.559-8.853; p = 0.0085). CONCLUSIONS: Cerebral hyperperfusion after CEA results in postoperative cerebral white matter damage that correlates with postoperative cognitive impairment.