Evaluation of a real-time PCR assay for rectal screening of OXA-48-producing Enterobacteriaceae in a general intensive care unit of an endemic hospital.

Carbapenemase-producing Enterobacteriaceae are increasing worldwide. Rectal screening for these bacteria can inform the management of infected and colonized patients, especially those admitted to intensive care units (ICUs). A laboratory developed, qualitative duplex real-time polymerase chain reaction assay for rapid detection of OXA-48-like and VIM producing Enterobacteriaceae, performed on rectal swabs, was designed and evaluated in an intensive care unit with endemic presence of OXA-48. During analytical assay validation, no cross-reactivity was observed and 100% sensitivity and specificity were obtained for both blaOXA-48-like and blaVIM in all spiked clinical samples. During the clinical part of the study, the global sensitivity and specificity of the real-time PCR assay for OXA-48 detection were 95.7% and 100% (P=0.1250), respectively, in comparison with culture; no VIM-producing Enterobacteriaceae were detected. Clinical features of patients in the ICU who were colonized or infected with OXA-48 producing Enterobacteriaceae, including outcome, were analyzed. Most had severe underlying conditions, and had risk factors for colonization with carbapenemase-producing Enterobacteriaceae before or during ICU admission, such as receiving previous antimicrobial therapy, prior healthcare exposure (including long-term care), chronic disease, immunosuppression and/or the presence of an intravascular catheter and/or mechanical ventilation device. The described real-time PCR assay is fast (~2-3hours, if DNA extraction is included), simple to perform and results are easy to interpret, features which make it applicable in the routine of clinical microbiology laboratories. Implementation in endemic hospitals could contribute to early detection of patients colonized by OXA-48 producing Enterobacteriaceae and prevention of their spread.

Ureaplasma parvum causes hyperammonemia in a pharmacologically immunocompromised murine model.

A relationship between hyperammonemia and Ureaplasma infection has been shown in lung transplant recipients. We have demonstrated that Ureaplasma urealyticum causes hyperammonemia in a novel immunocompromised murine model. Herein, we determined whether Ureaplasma parvum can do the same. Male C3H mice were given mycophenolate mofetil, tacrolimus, and prednisone for 7 days, and then challenged with U. parvum intratracheally (IT) and/or intraperitoneally (IP), while continuing immunosuppression over 6 days. Plasma ammonia concentrations were determined and compared using Wilcoxon rank-sum tests. Plasma ammonia concentrations of immunosuppressed mice challenged IT/IP with spent broth (median, 188 µmol/L; range, 102-340 µmol/L) were similar to those of normal (median, 226 µmol/L; range, 154-284 µmol/L, p > 0.05), uninfected immunosuppressed (median, 231 µmol/L; range, 122-340 µmol/L, p > 0.05), and U. parvum IT/IP challenged immunocompetent (median, 226 µmol/L; range, 130-330 µmol/L, p > 0.05) mice. Immunosuppressed mice challenged with U. parvum IT/IP (median 343 µmol/L; range 136-1,000 µmol/L) or IP (median 307 µmol/L; range 132-692 µmol/L) had higher plasma ammonia concentrations than those challenged IT/IP with spent broth (p < 0.001). U. parvum can cause hyperammonemia in pharmacologically immunocompromised mice.

Inhibition controls for qualitative real-time PCR assays: are they necessary for all specimen matrices?

A retrospective analysis of 386,706 specimens representing a variety of matrix types used in qualitative real-time PCR assays determined the overall inhibition rate to be 0.87% when the inhibition control was added preextraction to 5,613 specimens and 0.01% when the inhibition control was added postextraction but preamplification in 381,093 specimens. Inhibition rates of ≤ 1% were found for all specimen matrix types except urine and formalin-fixed, paraffin-embedded tissue.

Serologic diagnosis of NMO: a multicenter comparison of aquaporin-4-IgG assays.

OBJECTIVES: Neuromyelitis optica (NMO) immunoglobulin G (IgG) (aquaporin-4 [AQP4] IgG) is highly specific for NMO and related disorders, and autoantibody detection has become an essential investigation in patients with demyelinating disease. However, although different techniques are now used, no multicenter comparisons have been performed. This study compares the sensitivity and specificity of different assays, including an in-house flow cytometric assay and 2 commercial assays (ELISA and transfected cell-based assay [CBA]). METHODS: Six assay methods (in-house or commercial) were performed in 2 international centers using coded serum from patients with NMO (35 patients), NMO spectrum disorders (25 patients), relapsing-remitting multiple sclerosis (39 patients), miscellaneous autoimmune diseases (25 patients), and healthy subjects (22 subjects). RESULTS: The highest sensitivities were yielded by assays detecting IgG binding to cells expressing recombinant AQP4 with quantitative flow cytometry (77; 46 of 60) or visual observation (CBA, 73%; 44 of 60). The fluorescence immunoprecipitation assay and tissue-based immunofluorescence assay were least sensitive (48%-53%). The CBA and ELISA commercial assays (100% specific) yielded sensitivities of 68% (41 of 60) and 60% (36 of 60), respectively, and sensitivity of 72% (43 of 60) when used in combination. CONCLUSIONS: The greater sensitivity and excellent specificity of second-generation recombinant antigen-based assays for detection of NMO-IgG in a clinical setting should enable earlier diagnosis of NMO spectrum disorders and prompt initiation of disease-appropriate therapies.

Azathioprine: tolerability, efficacy, and predictors of benefit in neuromyelitis optica.

OBJECTIVE: To evaluate the efficacy, tolerability, optimal dosing, and monitoring of azathioprine in patients with neuromyelitis optica (NMO). METHODS: This was a chart review and telephone follow-up study of 99 patients with NMO spectrum of disorders (NMOSD) treated with azathioprine (1994-2009). NMOSD were NMO (2006 diagnostic criteria) or partial NMO forms (NMO-immunoglobulin G seropositive). Wilcoxon signed rank test was used to compare pretreatment and postinitiation of azathioprine (posttreatment) annualized relapse rates (ARR), Expanded Disability Status Scale (EDSS) score, and visual acuity outcome. Linear regression was used to assess the effects of various factors on ARR change and disability. RESULTS: The median duration of NMOSD symptoms prior to initiation of azathioprine was 2 years (range 1-27); 79 patients were women. Eighty-six patients had NMO and 13 limited NMO versions, including transverse myelitis in 8 and optic neuritis in 5. Median posttreatment follow-up was 22 months. Thirty-eight patients discontinued drug (side effects, 22; no efficacy, 13; lymphoma, 3). Among 70 patients with >12 months follow-up, 48 received ≥2.0 mg/kg/day (ARR: pretreatment, 2.20; posttreatment, 0.52); 22 received <2.0 mg/kg/day (ARR: pretreatment, 2.09; posttreatment, 0.82); 52 received concomitant prednisone (ARR: pretreatment, 2.20; posttreatment, 0.89) and 18 did not (ARR: pretreatment, 1.54; posttreatment, 0.23); p < 0.0001 for each comparison. EDSS was stable or improved despite ongoing attacks in 22 patients (31%). Twenty-six patients tolerated azathioprine and were relapse-free (37%, median follow-up 24 months; range 12-151). Mean corpuscular volume increase influenced ARR change (p = 0.049). CONCLUSIONS: Azathioprine is generally effective and well-tolerated. Early initiation, adequate dosing, and hematologic parameter monitoring may optimize efficacy. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that azathioprine is effective for reducing relapse rates and improving EDSS and visual acuity scores in patients with NMO spectrum of disorders.

Optimal presentation modes for detecting brain tumor progression.

BACKGROUND AND PURPOSE: A common task in radiology interpretation is visual comparison of images. The purpose of this study was to compare traditional side-by-side and in-place (flicker) image presentation modes with advanced methods for detecting primary brain tumors on MR imaging. MATERIALS AND METHODS: We identified 66 patients with gliomas and 3 consecutive brain MR imaging examinations (a "triplet"). A display application that presented images in side-by-side mode with or without flicker display as well as display of image subtraction or automated change detection information (also with and without flicker display) was used by 3 board-certified neuroradiologists. They identified regions of brain tumor progression by using this display application. Each case was reviewed using all modes (side-by-side presentation with and without flicker, subtraction with and without flicker, and change detection with and without flicker), with results compared via a panel rating. RESULTS: Automated change detection with or without flicker (P < .0027) as well as subtraction with or without flicker (P < .0027) were more sensitive to tumor progression than side-by-side presentation in cases where all 3 raters agreed. Change detection afforded the highest interrater agreement, followed by subtraction. Clinically determined time to progression was longer for cases rated as nonprogressing by using subtraction images and change-detection images both with and without flicker display mode compared with side-by-side presentation. CONCLUSIONS: Automated change detection and image subtraction, with and without flicker display mode, are superior to side-by-side image comparison.

Factors influencing time to death after withdrawal of life support in neurocritical patients.

OBJECTIVE: Improving our ability to predict the time of death after withdrawal of life-sustaining measures (WLSM) could have a significant impact on rates of organ donation after cardiac death and allocation of appropriate medical resources. We sought to determine which pre-WLSM clinical factors were associated with earlier time to death in patients with catastrophic neurologic disease. METHODS: We retrospectively analyzed all patients who underwent WLSM from 2002 to 2008 in a neurologic intensive care unit. Individuals who died within 60 minutes were compared to those who died beyond this time from the point of WLSM. Patients declared brain dead or not intubated and cases with insufficient data were excluded. Demographic, clinical, laboratory, and radiographic data were reviewed. Statistical analysis was based on multivariate logistic regression. RESULTS: A total of 149 comatose patients satisfied our inclusion criteria. A total of 75 patients had cardiac arrest in <60 minutes; 57% were male and 52% were older than 66 years. Ischemic stroke (30%) and intraparenchymal hemorrhage (52%) were the most frequent diagnoses. Absent corneal (odds ratio [OR] = 4.24, 95% confidence interval [CI] 1.57-11.5, p = 0.005) and cough reflexes (OR = 4.46, 95% CI 1.93-10.3, p = 0.0005), extensor or absent motor response (OR = 2.83, 95% CI 1.01-7.91, p = 0.048), and an oxygenation index greater than 4.2 (OR = 3.36, 95% CI 1.33-8.5, p = 0.011) were associated with earlier death. CONCLUSIONS: Specific neurologic signs and respiratory measurements are associated with earlier death after withdrawal of life-sustaining measures in the neurologic intensive care unit. This subset of comatose patients with irreversible neurologic injury may be suitable for organ donation after cardiac death protocols. These attributes need validation in a prospective data set.

A prospective trial of 3T and 1.5T time-of-flight and contrast-enhanced MR angiography in the follow-up of coiled intracranial aneurysms.

BACKGROUND AND PURPOSE: Endovascularly coiled intracranial aneurysms are increasingly being followed up with noninvasive MRA imaging to evaluate for aneurysm recurrences. It has not been well-established which MRA techniques are best for this application, however. Our aim was to prospectively compare 4 MRA techniques, TOF and CE-MRA at 1.5T and 3T, to a reference standard of DSA in the evaluation of previously endovascularly coiled intracranial aneurysms. MATERIALS AND METHODS: Fifty-eight subjects with 63 previously coiled intracranial aneurysms underwent all 4 MRA techniques within 8 days of DSA. There were 2 outcome variables: coil occlusion class (class 1, complete; class 2, dog ear; class 3, residual neck; class 4, aneurysm filling) and change in degree of occlusion since the previous comparison. Sensitivity and specificity were computed for each MRA technique relative to the reference standard of DSA. Differences among the MRA techniques were evaluated in pair-wise fashion by using the McNemar test. RESULTS: For the detection of any aneurysm remnant, the sensitivity was 85%-90% for all MRA techniques. Sensitivity dropped to 50%-67% when calculated for the detection of only the class 3 and 4 aneurysm remnants, because several class 3 and 4 remnants were misclassified as class 2 by MRA. CE-MRA at 1.5T and 3T misclassified fewer of the class 3 and 4 remnants than did TOF-MRA at 1.5T, as reflected by the significantly greater sensitivity for larger aneurysm remnants with CE-MRA relative to TOF-MRA at 1.5T (P = .0455 for both comparisons). CONCLUSIONS: CE-MRA is more likely than TOF-MRA to classify larger aneurysm remnants appropriately. We recommend performing both CE-MRA and TOF-MRA in the follow-up of coiled intracranial aneurysms and at 3T if available.

The Geneva prognostic score and mortality in patients diagnosed with pulmonary embolism by CT pulmonary angiogram.

This study prospectively evaluates whether a previously established adverse outcome score (the Geneva prognostic score) predicts 3 and 12-month overall mortality among the patients diagnosed with pulmonary embolism (PE) by a CT pulmonary angiogram (CTPA). Five hundred twenty-three consecutive patients who had CTPA for suspected PE were recruited prospectively from March 2003 to October 2004. The Geneva prognostic score was calculated for all patients. Twelve-month follow up was completed in all patients in December 2005. There were 105 patients diagnosed with PE. The mean score was 2.71 (standard deviation (SD) 1.25) for those patients who had died (n = 7) and 1.14 (SD 1.19) for those patients who were alive (n = 98) at 3-month follow up (P < 0.001). The mean scores were 2.69 (SD 0.95) for those who had died (n = 13) and 1.04 (SD 1.15) for those patients who were alive (n = 92) at 12-month follow up (P < 0.001). At 3-month follow up, among the 88 patients with a score of 2 or less, three patients (3.4%) died and among 17 patients with a score of greater than 2, four patients (23.5%) died (P = 0.01). At 12-month follow up, five patients (5.7%) with a score of 2 or less died and eight patients (47.1%) with a score of three or more died (P < 0.0001). The Geneva prognostic score stratifies patients with low and high risk for overall mortality at 3 and 12 months among patients diagnosed with PE by CTPA.

Subcutaneous IGF-1 is not beneficial in 2-year ALS trial.

BACKGROUND: Previous human clinical trials of insulin-like growth factor type I (IGF-1) in amyotrophic lateral sclerosis (ALS) have been inconsistent. This phase III, randomized, double-blind, placebo-controlled study was undertaken to address whether IGF-1 benefited patients with ALS. METHODS: A total of 330 patients from 20 medical centers were randomized to receive 0.05 mg/kg body weight of human recombinant IGF-1 given subcutaneously twice daily or placebo for 2 years. The primary outcome measure was change in their manual muscle testing score. Secondary outcome measures included tracheostomy-free survival and rate of change in the revised ALS functional rating scale. Intention to treat analysis was used. RESULTS: There was no difference between treatment groups in the primary or secondary outcome measures after the 2-year treatment period. CONCLUSIONS: Insulin-like growth factor type I does not provide benefit for patients with amyotrophic lateral sclerosis.

Clinical and radiographic spectrum of pathologically confirmed tumefactive multiple sclerosis.

Atypical imaging features of multiple sclerosis lesions include size >2 cm, mass effect, oedema and/or ring enhancement. This constellation is often referred to as 'tumefactive multiple sclerosis'. Previous series emphasize their unifocal and clinically isolated nature, however, evolution of these lesions is not well defined. Biopsy may be required for diagnosis. We describe clinical and radiographic features in 168 patients with biopsy confirmed CNS inflammatory demyelinating disease (IDD). Lesions were analysed on pre- and post-biopsy magnetic resonance imaging (MRI) for location, size, mass effect/oedema, enhancement, multifocality and fulfilment of Barkhof criteria. Clinical data were correlated to MRI. Female to male ratio was 1.2 : 1, median age at onset, 37 years, duration between symptom onset and biopsy, 7.1 weeks and total disease duration, 3.9 years. Clinical course prior to biopsy was a first neurological event in 61%, relapsing-remitting in 29% and progressive in 4%. Presentations were typically polysymptomatic, with motor, cognitive and sensory symptoms predominating. Aphasia, agnosia, seizures and visual field defects were observed. At follow-up, 70% developed definite multiple sclerosis, and 14% had an isolated demyelinating syndrome. Median time to second attack was 4.8 years, and median EDSS at follow-up was 3.0. Multiple lesions were present in 70% on pre-biopsy MRI, and in 83% by last MRI, with Barkhof criteria fulfilled in 46% prior to biopsy and 55% by follow-up. Only 17% of cases remained unifocal. Median largest lesion size on T2-weighted images was 4 cm (range 0.5-12), with a discernible size of 2.1 cm (range 0.5-7.5). Biopsied lesions demonstrated mass effect in 45% and oedema in 77%. A strong association was found between lesion size, and presence of mass effect and/or oedema (P < 0.001). Ring enhancement was frequent. Most tumefactive features did not correlate with gender, course or diagnosis. Although lesion size >5 cm was associated with a slightly higher EDSS at last follow-up, long-term prognosis in patients with disease duration >10 years was better (EDSS 1.5) compared with a population-based multiple sclerosis cohort matched for disease duration (EDSS 3.5; P < 0.001). Given the retrospective nature of the study, the precise reason for biopsy could not always be determined. This study underscores the diagnostically challenging nature of CNS IDDs that present with atypical clinical or radiographic features. Most have multifocal disease at onset, and develop RRMS by follow-up. Although increased awareness of this broad spectrum may obviate need for biopsy in many circumstances, an important role for diagnostic brain biopsy may be required in some cases.

Vancomycin-resistant enterococcal colonization appears associated with increased mortality among allogeneic hematopoietic stem cell transplant recipients.

There are no cohort studies describing outcomes of patients colonized with vancomycin-resistant enterococci (VRE) undergoing allogeneic hematopoietic stem cell transplantation (AHSCT). We therefore conducted a retrospective cohort study of 217 consecutive adults undergoing AHSCT at the Mayo Clinic (Rochester, MN, USA) from 1998 to 2004. We analyzed the association between VRE colonization prior to transplant and 100-day post transplant mortality and morbidity. We identified 22 pretransplant VRE colonized patients and 195 non-colonized patients. Both groups had similar baseline characteristics with the following six exceptions. Colonized patients were more likely to have had pretransplant Clostridium difficile-associated diarrhea, pretransplant acute renal failure, AML, Cy/TBI conditioning, decreased platelet count at time of transplantation and myeloablative conditioning regimens. Overall, patients colonized with VRE were twice as likely to die by day 100 post transplant compared to non-colonized patients (hazard ratio: 2.1, P=0.028). This association persisted even after adjusting for differences in baseline characteristics. Increased mortality in the colonized group correlated with the presence of VRE bacteremia. Overall, pretransplant VRE colonization appears to be an independent risk factor for increased mortality post-AHSCT.

Can neck size in elastase-induced aneurysms be controlled? A retrospective study.

BACKGROUND AND PURPOSE: Reproducible animal models with appropriate neck size are crucial for preclinical assessment of aneurysm therapies. Our purpose was to determine whether the neck size of elastase-induced aneurysms could be controlled by adjusting the position of the temporary occlusion balloon. METHODS: Seventy-two elastase-induced aneurysms in rabbits were retrospectively analyzed. Three groups (group 1, n = 35; group 2, n = 32; group 3, n = 5) were defined according to different balloon position (lowest, intermediate, and highest, respectively) related to the origin of right common carotid artery (CCA). Aneurysm sizes in different groups were measured and compared; parent artery dilation was assessed as present or absent. The Wilcoxon rank sum test, the Fisher exact test, and the chi(2) test were used for statistics process. RESULTS: The mean aneurysm neck diameter in group 1 was significantly wider than that in group 2 (P = .0001). The proportion of wide-necked (diameter of neck >4 mm) aneurysms in group 1 was significantly higher than that in group 2 (P = .0011). The mean dome/neck ratio in group 1 was smaller than that of group 2 (P = .0031). Aneurysm width and height and the frequency of parent artery dilation were not different in groups 1 and 2 (P = .43, P = .10, and P = .25). No aneurysms formed in group 3. CONCLUSION: The neck size of elastase-induced aneurysms can be controlled by adjusting the position of the inflated balloon, with balloon positioning that bridges from the CCA to the subclavian/brachiocephalic arteries yielding narrow-necked aneurysms.

Outcome of prosthetic joint infections treated with debridement and retention of components.

BACKGROUND: Debridement and retention of the prosthesis represents an attractive surgical modality for treatment of prosthetic joint infection, but risk factors for treatment failure require clarification. METHODS: We conducted a retrospective cohort analysis of all patients with a prosthetic joint infection who were treated with debridement and retention of the prosthesis at the Mayo Clinic (Rochester, Minnesota) between 1995 and 1999. RESULTS: Debridement and retention of the prosthesis was the initial treatment modality for 99 episodes of prosthetic joint infection that occurred in 91 patients who presented to the Mayo Clinic during 1995-1999. A total of 32% and 23% of all episodes were due to Staphylococcus aureus and coagulase-negative staphylococci, respectively. The median duration of intravenous antimicrobial therapy was 28 days (range, 1-90 days). Oral antimicrobial suppression was used in 89% of the episodes, for a median duration of 541 days (range, 5-2673 days). Treatment failure occurred in 53 episodes during a median follow-up period of 700 days (range, 1-2779 days). The 2-year survival rate free of treatment failure was 60% (95% confidence interval [CI], 50%-71%). Variables associated with an increased risk of treatment failure in multivariable analysis included the presence of a sinus tract (hazard ratio, 2.84; 95% CI, 1.48-5.44; P = .002) and a duration of symptoms prior to debridement of > or = 8 days (hazard ratio, 1.77; 95% CI, 1.02-3.07; P = .04). CONCLUSIONS: Debridement and retention of the prosthesis is a common surgical modality at our institution to treat prosthetic joint infection. Risk factors independently associated with treatment failure include the presence of a sinus tract and duration of symptoms prior to debridement of > or = 8 days.

Comparison of specimen processing and nucleic acid extraction by the swab extraction tube system versus the MagNA Pure LC system for laboratory diagnosis of herpes simplex virus infections by LightCycler PCR.

A total of 563 specimens (234 dermal and 329 genital swabs) from patients suspected of having herpes simplex virus (HSV) infections were processed using two different extraction methods (the MagNA Pure LC system and the swab extraction tube system [SETS]); HSV DNA was amplified by LightCycler PCR. HSV DNA was detected in 157 of 563 specimens (27.9%) processed by the MagNA Pure LC system and in 179 of 563 specimens (31.8%) processed by SETS (P < 0.0001). There was no specimen processed by the MagNA Pure LC extraction method that was positive only for HSV DNA. Of 157 specimens positive by both methods, HSV DNA copy levels were higher (using cycle crossover points [cycle threshold {C(T)}]) with SETS (mean C(T), 25.9 cycles) than with the MagNA Pure LC system (mean C(T), 32.0 cycles) (P < 0.0001). The time to process 32 samples was longer with the MagNA Pure LC extraction system (90 min) than with SETS (35 min). HSV DNA extraction using SETS is faster, less expensive, and more sensitive than the MagNA Pure LC system and could replace the latter for the laboratory diagnosis of HSV infections using LightCycler PCR.