Xpert(®) MTB/RIF detection of Mycobacterium tuberculosis from sputum collected in molecular transport medium.

BACKGROUND: The Xpert(®) MTB/RIF assay is widely used for Mycobacterium tuberculosis detection. However, specimen transport remains a challenge. PrimeStore Molecular Transport Medium(®) (PS-MTM) inactivates specimens and stabilizes DNA/RNA at ambient temperature for subsequent molecular detection. OBJECTIVE: To compare the detection of M. tuberculosis concentrations in PS-MTM using Xpert and real-time polymerase chain reaction (RT-PCR), and smear-positive sputum specimens collected using a flocked swab. METHODS: Dilutions of M. tuberculosis in PS-MTM and phosphate buffered saline (PBS) were analyzed using the Xpert assay and commercial RT-PCR. Smear-positive (1+ to 3+) sputum specimens (n = 17) were transferred by flocked swab into PS-MTM and PBS, and were compared to standard 1.0 ml sputum Xpert analysis. RESULTS: Using the Xpert assay, cycle threshold values from high M. tuberculosis concentrations in PS-MTM (>10(3) colony forming units [cfu]/ml) were increased compared to control. In contrast, M. tuberculosis samples containing <10(3) cfu/ml, i.e., low concentrations, suspended in PS-MTM resulted in detection down to 10 cfu/ml. Xpert detection efficiency in PS-MTM treated samples (63.2%) was improved compared to PBS controls (34.9%). Xpert detected M. tuberculosis in all sputum specimens collected by flocked swabs in PS-MTM, and correlated with routine Xpert detection. CONCLUSIONS: PS-MTM enhances M. tuberculosis detection at low concentrations of M. tuberculosis, and provides a simplified and efficient collection method for Xpert detection.

Molecular detection of Mycobacterium tuberculosis from sputum transported in PrimeStore(®) from rural settings.

SETTING: Mopani District, South Africa. OBJECTIVE: To explore remote, molecular detection of Mycobacterium tuberculosis from sputum transported using PrimeStore(®) Molecular Transport Medium (PS-MTM) compared to settings where microscopy or Xpert(®) MTB/RIF is used as the baseline test. DESIGN: Two sputum specimens were collected from patients with cough of ⩾ 2 weeks at clinics in rural South Africa. Shortly after expectoration and before processing using Xpert, microscopy and liquid culture, a flocked swab was swirled in each of these specimens and placed in PS-MTM. Swabs were stored and transported to the United States at ambient temperature for real-time PrimeMix(®) polymerase chain reaction (PM-PCR). RESULTS: Of 132 patients, 23 (17%) were positive on microscopy, 39 (30%) on Xpert and 44 (33%) by PS-MTM/PM-PCR. Concordance of PS-MTM/PM-PCR with positive microscopy and Xpert was respectively 96% and 85%. Of 107 microscopy-negative samples, 22 (21%) were positive using PS-MTM/PM-PCR, while 11/91 (12%) Xpert-negative samples were PS-MTM/PM-PCR-positive. PS-MTM/PM-PCR positivity was significantly higher than smear microscopy positivity (P < 0.001), but similar to Xpert (P = 0.33). CONCLUSION: PCR testing of specimens transported in PS-MTM would enhance TB diagnosis in settings where smear microscopy is the baseline diagnostic test, and could provide an alternative in settings where Xpert testing is not available.

A molecular transport medium for collection, inactivation, transport, and detection of Mycobacterium tuberculosis.

In many parts of the world, the diagnosis of tuberculosis (TB) has rapidly shifted to molecular detection and sequencing formats. The collection and transport of Mycobacterium tuberculosis specimens thus remains a challenging problem where TB is common and the infrastructure required for ensuring sample integrity is lacking. PrimeStore(®) Molecular Transport Medium (MTM) addresses this problem, rapidly inactivating/killing M. tuberculosis while preserving genomic DNA even at elevated temperatures for subsequent downstream molecular analysis.

Phenotyping adults with non-cystic fibrosis bronchiectasis: a prospective observational cohort study.

BACKGROUND: Bronchiectasis is the outcome of a number of different airway insults. Very few studies have characterised the aetiology and utility of a dedicated screening proforma in adult patients attending a general bronchiectasis clinic. METHODS: A prospective observational study of 189 bronchiectasis patients attending two centres in the North East of England over a two-year period was performed. RESULTS: The aetiology of bronchiectasis was identified in 107/189(57%) patients. Idiopathic bronchiectasis (IB) represented the largest subgroup (43%). Post-infection bronchiectasis (PIB) constituted the largest proportion (24%) of known causes. Mean age (SD) at diagnosis was 54(20) years with a mean age at symptom onset of 37(24) years, accounting for a diagnostic delay of 17 years. Age of symptom onset was significantly younger in patients with PIB compared to IB (p < 0.0001) and in Pseudomonas sputum positive patients (p = 0.007). Screening for APBA and total immunoglobulin deficiency identified 9 (5%) patients who then had tailored treatment. Routine screening for other aetiologies was deemed unnecessary. CONCLUSION: IB and PIB accounted for two thirds of cases of bronchiectasis in a general population. We recommend routine screening for ABPA and total immunoglobulin deficiency but not for other rarer aetiologies.

A clinical specimen collection and transport medium for molecular diagnostic and genomic applications.

Pathogen detection and genetic characterization has dramatically changed in recent years. Clinical laboratories are transitioning from traditional culture and primer-specific sequencing to more robust and rapid nucleic acid testing such as real-time PCR and meta-genomic characterization, respectively. Specimen collection is the first step in any downstream molecular diagnostic procedure. PrimeStore Molecular Transport Medium (MTM) is an optimized blend of nucleic acid stabilizing reagents that includes a non-specific internal positive control that can be amplified using real-time RT-PCR for tracking the integrity of a specimen from the point of collection to detection. PrimeStore MTM is shown here to effectively kill pathogens, including highly pathogenic H5 influenza virus, inactivate nucleases and to protect and preserve released RNA at ambient temperature for up to 30 days for downstream real-time and traditional RT-PCR detection and genetic characterization. PrimeStore MTM is also compatible with a variety of commercial extraction kits. PrimeStore is suited for routine clinical specimens and has added utility for field collection in remote areas, triage centres, border crossings and during pandemics where cold-chain, transport, and dissemination of potentially infectious pathogens are a concern.

Are clinical parameters and biomarkers predictive of severity of acute pulmonary emboli on CTPA?

BACKGROUND: Previous studies have shown that findings of computed tomography pulmonary angiography (CTPA) relate to outcome in pulmonary embolus (PE). These include clot burden as quantified using an obstruction index and markers of pressure overload such as right ventricle to left ventricle size ratio (RV/LV ratio). Little data exists correlating these findings with clinical presentation and biomarkers. AIM: To explore the link between clinical presentation and biomarkers with CTPA findings. METHODS: Retrospective case note analysis of consecutive cases presenting to a large teaching hospital. An independent radiologist reviewed CTPAs and clot burden quantified using an obstruction index. RESULTS: One hundred and seventy cases were identified and notes retrieved in 137 cases. (i) CLINICAL PRESENTATION: correlation was seen between clot burden and systolic blood pressure (BP) (r = -0.299, P = 0.0006) and heart rate (r = 0.240, P = 0.0056). Median obstruction index was significantly higher in those with a presenting BP <90 mmHg [41.25% (95% CI 30-50) vs. 15% (95% CI 12.5-25), (P = 0.0004)]. Clot burden was significantly higher in patients with temperature of >37.5 degrees C [30% (95% CI 25.0-42.5) vs. 15% (95% CI 12.5-28.3), P = 0.02)] and (ii)Biomarkers: significant correlation between clot burden and D-dimer was seen (r = 0.36, P = 0.0001). Location of thrombus was associated with significant differences in D-dimer level. A subgroup of patients had cardiac biomarkers measured (n = 24). There was a statistically significant correlation between troponin I and clot burden (r = 0.412, P = 0.048) and RV/LV ratio (r = 0.699, P = 0.0013). DISCUSSION: These findings suggest that clinical parameters and biomarkers have a role in predicting the radiological severity of PE. These data support the need for further studies of risk stratification in patients presenting with acute PE.

The appearance on MRI of vertebrae in acute compression of the spinal cord due to metastases.

We studied MR images of the spine in a consecutive series of 100 patients with acute compression of the spinal cord due to metastases. All patients had documented neurological deficit and histologically proven carcinoma. MRI was used to localise bony metastatic involvement and soft-tissue impingement of the cord. A systematic method of documenting metastatic involvement is described. A total of 43 patients had compression at multiple levels; 160 vertebral levels were studied. In 120 vertebrae (75%), anterior, lateral and posterior bony elements were involved. Soft-tissue impingement of the spinal cord often involved more than one quadrant of its circumference. In 69 vertebrae (43%) there was concomitant anterior and posterior compression. Isolated involvement of a vertebral body was observed in only six vertebrae (3.8%). We have shown that in most cases of acute compression of the spinal cord due to metastases there is coexisting involvement of both anterior and posterior structures.

Technical report: Cystic air spaces in the lung: change in size on expiratory high-resolution CT in 23 patients.

PURPOSE: To determine the presence of change in size of air-filled cysts in the lung on expiration by comparison between inspiratory and expiratory high-resolution computed tomography (CT) scans. MATERIALS AND METHODS: Inspiratory and expiratory high-resolution (1-mm collimation) CT scans were obtained in 23 patients with lung cysts due to a variety of lung diseases. The 23 patients had a total of 27 types of cystic lesions including bullae (n=7), honeycomb cysts due to fibrosing alveolitis (n=11), lymphangioleiomyomatosis (LAM, n=2), cystic adenomatoid malformation (n=1), and bronchiectasis (n=6). An adequate expiratory effort, with at least 5% decrease in the anteroposterior or transverse thoracic diameter, was required for inclusion in the study. Inspiratory and expiratory scans at corresponding anatomic levels were compared to determine any change in size of the cysts on expiration. RESULTS: Cystic lesions due to bronchiectasis, LAM and fibrosing alveolitis decreased in size on expiratory CT. In six of seven cases bullae decreased in size, and in one patient with a single bulla it remained unchanged. In one case a single cyst due to cystic adenomatoid malformation increased in size on expiration. CONCLUSION: The majority of lung cysts decrease in size on expiration suggesting that they communicate with the airways.

Invasive aspergillosis in the immunocompromised host: utility of computed tomography and bronchoalveolar lavage.

OBJECTIVE: Bronchoalveolar lavage is performed almost routinely in immunocompromised patients with suspected pneumonia, but it has a low yield in the diagnosis of pulmonary aspergillosis. The aim of this study was to determine whether computed tomography (CT) is helpful in determining the likelihood of a positive bronchoalveolar lavage by allowing distinction of patients with angioinvasive aspergillosis from those with Aspergillus bronchopneumonia. METHODS AND RESULTS: A retrospective study was performed including consecutive immunocompromised patients with suspected pneumonia who underwent CT scanning of the chest and bronchoalveolar lavage and who had definite diagnosis of pulmonary aspergillosis. The CT scans were reviewed by two chest radiologists and classified as showing features consistent with angioinvasive or airway invasive aspergillosis. Twenty-one patients met the inclusion criteria. Bronchoalveolar lavage was positive for fungi in two of 11 patients with CT findings consistent with angioinvasive aspergillosis and eight of 10 patients with CT scans consistent with Aspergillus bronchopneumonia (P < 0.01, chi-squared test). CT findings of angioinvasive aspergillosis included nodules measuring 1-3.5 cm in diameter in six, segmental consolidation in three, and both nodules and segmental consolidation in two patients. CT findings of Aspergillus bronchopneumonia including peribronchial consolidation in five, small centrilobular micronodules in one, and both in four patients. CONCLUSIONS: Chest CT is helpful in determining the likelihood of successful diagnosis of pulmonary aspergillosis by bronchoalveolar lavage.

Small airway diseases.

High-resolution CT scan is currently the best imaging technique for assessment of diseases of the bronchioles. This article describes the anatomic basis for the findings. This is followed by a presentation of the findings in bronchiolitis, as it is currently classified, into five main groups: (1) cellular bronchiolitis, (2) panbronchiolitis, (3) respiratory bronchiolitis, (4) constrictive bronchiolitis, and (5) bronchiolitis obliterans with intraluminal polyps.

Churg-Strauss syndrome: the spectrum of pulmonary CT findings in 17 patients.

OBJECTIVE: The aim of this study was to evaluate the pulmonary CT findings in patients with Churg-Strauss syndrome to determine the frequency and nature of parenchymal abnormalities. MATERIALS AND METHODS: CT examinations performed at the time of diagnosis in 17 patients with Churg-Strauss syndrome were retrospectively evaluated by two observers who reached a decision by consensus about the presence and nature of parenchymal abnormalities. High-resolution CT (1- to 3-mm collimation) was performed in 14 patients and conventional CT (6- to 10-mm collimation) was performed in three cases. RESULTS: Predominant CT findings consisted of parenchymal opacification (consolidation or ground-glass attenuation) (n = 10), pulmonary nodules (n = 2), bronchial wall thickening or dilatation (n = 2), interlobular septal thickening (n = 1), and normal anatomy (n = 2). Parenchymal opacification was predominantly peripheral (n = 6) or random in distribution (n = 4). CONCLUSION: The most common CT finding in patients with Churg-Strauss syndrome consists of areas of parenchymal opacification that may be random or peripheral in distribution. These findings are nonspecific.

Pulmonary complications after bone marrow transplantation: high-resolution CT and pathologic findings.

A wide variety of pulmonary complications occur in bone marrow transplant (BMT) recipients and are a major cause of morbidity and death. High-resolution computed tomography (CT) is excellent in the detection of pulmonary abnormalities, but these findings are generally nonspecific. However, the different complications, which reflect the immunologic status of the patients, occur in three phases. This pattern can be used to interpret CT scans. The neutropenic phase (up to 3 weeks after BMT) is characterized by fungal infections, notably angioinvasive aspergillosis, alveolar hemorrhage, pulmonary edema, and drug reactions. At CT, angioinvasive aspergillosis appears as a nodule surrounded by a halo of ground-glass attenuation; alveolar hemorrhage and drug reactions, as bilateral areas of ground-glass attenuation or consolidation; and pulmonary edema, as prominent pulmonary vessels, interlobar septal thickening, ground-glass attenuation, and pleural effusions. The second phase (3 weeks to 100 days after BMT) is dominated by cytomegalovirus pneumonia, which appears as multiple small nodules with associated areas of consolidation or ground-glass attenuation, and Pneumocystis carinii pneumonia, which appears predominantly as ground-glass attenuation. The late phase (more than 100 days after BMT) is characterized by bronchiolitis obliterans, bronchiolitis obliterans with organizing pneumonia (BOOP), and chronic graft-versus-host disease. In bronchiolitis obliterans, CT reveals bronchial dilatation and a mosaic pattern of attenuation; in BOOP, CT findings usually consist of patchy consolidation or ground-glass attenuation. If CT findings are considered in relation to the time elapsed after BMT, diagnostic options can be narrowed sufficiently to enable accurate diagnosis.

Mosaic attenuation pattern on thin-section CT scans of the lung: differentiation among infiltrative lung, airway, and vascular diseases as a cause.

PURPOSE: To determine whether infiltrative lung, airway, or vascular disease can be differentiated as the cause of mosaic attenuation on thin-section computed tomographic (CT) scans of the lung. MATERIALS AND METHODS: Thin-section CT scans were reviewed in 70 patients examined at three institutions. A mosaic attenuation pattern and pathologic or clinical proof of a specific type of disease were demonstrated. Causes of the mosaic pattern included infiltrative lung disease (n = 37), airway disease (n = 22), and vascular disease (n = 11). Thin-section CT findings were assessed independently by two observers blinded to clinical findings. RESULTS: The type of disease was identified correctly at CT in 58 (83%) of 70 patients by observer 1 and 57 (81%) of 70 patients by observer 2. Infiltrative lung disease was diagnosed correctly by both observers in 34 (92%) of 37 cases. Observer 1 identified 21 (95%) of 22 cases of airway disease and three (27%) of 11 cases of vascular disease. Observer 2 identified 19 (86%) of 22 cases of airway disease and four (36%) of 11 cases of vascular disease. CONCLUSION: Infiltrative lung disease and airway disease may be differentiated reliably as the cause of mosaic attenuation on lung CT scans, whereas vascular disease is often misinterpreted as infiltrative lung disease or airway disease.

Bronchiolitis obliterans after lung transplantation: high-resolution CT findings in 15 patients.

OBJECTIVE: The purpose of this study was to compare the high-resolution CT findings in patients with pathologically proven bronchiolitis obliterans after lung transplantation with high-resolution CT findings in control subjects. MATERIALS AND METHODS: High-resolution CT examinations of 15 patients with pathologically proven bronchiolitis obliterans after lung transplantation and 18 control subjects were retrospectively evaluated by two independent observers who were unaware of the diagnosis in each case. All 33 subjects underwent inspiratory high-resolution CT. Five patients with bronchiolitis obliterans and 16 control subjects underwent expiratory CT. RESULTS: Findings in patients with bronchiolitis obliterans included bronchial dilatation in 80%, mosaic perfusion in 40%, bronchial wall thickening in 27%, and air trapping in 80%, compared with the control subjects with bronchial dilatation in 22%, mosaic perfusion in 22%, and air trapping in 6%. The combination of bronchial dilatation on the inspiratory CT scan and air trapping on the expiratory CT scan was seen only in patients with bronchiolitis obliterans. We calculated good agreement between the two observers (kappa > or = .63). CONCLUSION: Air trapping and bronchial dilatation were the two most sensitive and specific findings on high-resolution CT scans of patients with bronchiolitis obliterans. The combination of these two findings was seen exclusively in patients with bronchiolitis obliterans.

Airway obstruction in asthmatic and healthy individuals: inspiratory and expiratory thin-section CT findings.

PURPOSE: To determine differences in computed tomographic (CT) findings in asthmatic and healthy individuals and to correlate the findings with severity of airway obstruction. MATERIALS AND METHODS: Thirty-nine asthmatic patients and 14 healthy subjects were prospectively evaluated with thin-section CT. Inspiratory CT scans were subjectively evaluated for presence of bronchial wall thickening, bronchial dilatation, and mosaic lung attenuation; expiratory scans were subjectively evaluated for presence of air trapping. Objective measurement of bronchoarterial-diameter ratio was performed on inspiratory scans. CT findings were compared with pulmonary function test results. RESULTS: Bronchial wall thickening, severe air trapping, and reduced bronchoarterial-diameter ratio were observed more commonly in asthmatic patients than in healthy subjects. Bronchial wall thickening was more prevalent among patients with severe airflow obstruction (10 of 12 readings [83%]) than in patients with normal airflow (15 of 40 readings [38%]) or mild obstruction (nine of 26 readings [35%]). Other subjectively determined CT findings did not correlate with pulmonary function test results. The mean bronchoarterial-diameter ratios +/- 1 standard deviation were 0.65 +/- 0.16 in healthy subjects and 0.60 +/- 0.16, 0.60 +/- 0.18, and 0.48 +/- 0.11 in patients with normal airflow and mild and severe obstruction, respectively. CONCLUSION: Thin-section CT is of limited value in distinguishing asthmatic patients with normal airflow or mild airflow obstruction from healthy subjects.

The role of duplex sonography and angiography in the investigation of carotid artery disease.

Some patients with symptomatic carotid stenoses of greater than 70 % benefit from carotid endarterectomy. This study was designed to compare the accuracy of duplex ultrasound with angiography in assessing the degree of carotid stenosis in 73 patients with symptoms of recent carotid territory ischaemia. Ultrasound was found to be most accurate in the group of patients with normal vessels or mild stenoses (0-29 %) when there was 90 % concordance between ultrasound and angiography. Ultrasound was found to be least accurate in the group of patients with severe stenoses (70-99 %) in whom it was more likely to underestimate than to overestimate the degree of stenosis. Only one patient said to have < 30 % stenosis on ultrasonography had a > 70 % stenosis on IADSA. Our results indicate that patients with normal arteries or mild disease shown by ultrasound have a very small chance of having surgically amenable lesions in the neck. Ultrasound is reliable as an exclusory screening test. However, all other stenoses should also be investigated by catheter angiography if surgery is considered. Taking angiography as the reference, only 52 % of patients with severe stenoses, which might be taken as an indication for surgery, were correctly identified on ultrasonography. Ultrasound alone is a poor technique for identifying patients for surgery and a combination of ultrasound screening with angiography for > 30 % stenoses detected by ultrasound is recommended.

Case report: multiple thoracic haemangiomas--a rare cause of spinal cord compression.

Benign haemangiomas are a rare cause of mediastinal masses. We present a patient with multiple thoracic wall and mediastinal haemangiomas who developed spinal cord compression as a result of extradural extension of the haemangiomas. This is a rare cause of spinal cord compression.

Diaphragmatic rupture: CT findings in 11 patients.

PURPOSE: To determine the signs of diaphragmatic rupture at computed tomography (CT) and the frequency of preoperative diagnosis with CT. MATERIALS AND METHODS: CT scans in 11 consecutive patients with surgically proved tears of the diaphragm due to blunt trauma were reviewed by two chest radiologists. The observers assessed the presence of discontinuity of the diaphragm, herniation of abdominal viscera or omentum, and waistlike constriction of the herniated stomach or bowel (collar sign). Hospital records were reviewed to confirm surgical findings and ascertain whether the diagnosis has been suggested at CT. RESULTS: In eight of 11 patients, rupture of the diaphragm was on the left, and in three it was on the right. In nine patients, diagnostic findings were identified retrospectively on CT scans; these included discontinuity of the diaphragm (n = 9), herniation of the abdominal organs or bowel (n = 7), and constriction of the stomach (n = 3). CONCLUSION: CT enables detection of most diaphragmatic tears due to blunt trauma.